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Showing posts with label ZOOLOGY. Show all posts
Showing posts with label ZOOLOGY. Show all posts

Monday, January 20, 2020

January 20, 2020

Human Diseases - Part 7

HUMAN DISEASES - PART 7

CANCER
•    Cancer is one of the most dreaded diseases of human beings and is a major cause of death all over the globe.
•    More than a million Indians suffer from cancer and a large number of them die from it annually.
•    The mechanisms that underlie development of cancer or oncogenic transformation of cells, its treatment and control have been some of the most intense areas of research in biology and medicine.
•    In our body, cell growth and differentiation is highly controlled and regulated. In cancer cells, there is breakdown of these regulatory mechanisms.
•    Normal cells show a property called contact inhibition by virtue of which contact with other cells inhibits their uncontrolled growth.
•    Cancer cells appears to have lost this property of contact inhibition. As a result of this, cancerous cells just continue to divide giving rise to masses of cells called tumors.

 TYPES OF TUMORS
•    Tumors are of two types: benign and malignant.
•    Benign tumors normally remain confined to their original location and do not spread to other parts of the body and cause little damage.
•    The malignant tumors, on the other hand are a mass of proliferating cells called neoplastic or tumor cells. These cells grow very rapidly, invading and damaging the surrounding normal tissues.
•    As these cells actively divide and grow they also starve the normal cells by competing for vital nutrients.
•    Cells sloughed from such tumors reach distant sites through blood, and wherever they get lodged in the body, they start a new tumor there. This property called Metastasis is the most feared property of malignant tumors.

CAUSES OF CANCER
•    Transformation of normal cells into cancerous neoplastic cells may be induced by physical, chemical or biological agents. These agents are called carcinogens.
•    Ionizing radiations like X-rays and gamma rays and non-ionizing radiations like UV cause DNA damage leading to neoplastic transformation.
•    The chemical carcinogens present in tobacco smoke have been identified as a major cause of lung cancer.
•    Cancer causing viruses called oncogenic viruses have genes called viral oncogenes.
•    Furthermore, several genes called cellular oncogenes (c-onc) or proto oncogenes have been identified in normal cells which, when activated under certain conditions, could lead to oncogenic transformation of the cells.

CANCER DETECTION AND DIAGNOSIS
•    Early detection of cancers is essential as it allows the disease to be treated successfully in many cases.
•    Cancer detection is based on biopsy and histopathological studies of the tissue and blood and bone marrow tests for increased cell counts in the case of leukemias.
•    In biopsy, a piece of the suspected tissue cut into thin sections is stained and examined under microscope (histopathological studies) by a pathologist.
•    Techniques like radiography (use of X-rays), CT (computed tomography) and MRI (magnetic resonance imaging) are very useful to detect cancers of the internal organs.
•    Computed tomography uses X-rays to generate a three-dimensional image of the internals of an object.
•    MRI uses strong magnetic fields and non-ionising radiations to accurately detect pathological and physiological changes in the living tissue.
•    Antibodies against cancer-specific antigens are also used for detection of certain cancers.
•    Techniques of molecular biology can be applied to detect genes in individuals with inherited susceptibility to certain cancers. Identification of such genes, which predispose an Individual to certain cancers, may be very helpful in prevention of cancers.
•    Such individuals may be advised to avoid exposure to particular carcinogens to which they are susceptible (e.g., tobacco smoke in case of lung cancer).

CANCER IN HUMAN BODY

 

TREATMENT OF CANCER
•    The common approaches for treatment of cancer are surgery, radiation therapy and immunotherapy.
•    In radiotherapy, tumor cells are Irradiated lethally, taking proper care of the normal tissues surrounding the tumor mass.
•    Several chemotherapeutic drugs are used to kill cancerous cells. Some of these are specific for particular tumors. Majority of drugs have side effects like hair loss, anemia, etc.
•    Most cancers are treated by combination of surgery, radiotherapy and chemotherapy.
•    Tumor cells have been shown to avoid detection and destruction by immune system. Therefore, the patients are given substances called biological response modifiers such as a-interferon which activate their immune system and help in destroying the tumor.

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January 20, 2020

Human Diseases - Part 6

HUMAN DISEASES - PART 6

SEXUALLY TRANSMITTED DISEASES

AIDS – ACQUIRED IMMUNO DEFICIENCY SYNDROME
•    The word AIDS stands for Acquired Immuno Deficiency Syndrome. This means deficiency of immune system, acquired during the lifetime of an individual indicating that it is not a congenital disease [disease or abnormality present from birth]. ‘Syndrome’ means a group of symptoms.
•    AIDS was first reported in 1981 and in the last twenty-five years or so, it has spread all over the world.

CAUSES OF AIDS
•    AIDS is caused by the Human Immuno Deficiency Virus (HIV), a member of a group of viruses called Retrovirus, which have an envelope enclosing the RNA genome.

•    Transmission of HIV-infection generally occurs by
      1.    sexual contact with infected person,
      2.    by transfusion of contaminated blood and blood products,
      3.    by sharing infected needles as in the case of intravenous drug abusers.
      4.    from infected mother to her child through placenta.

•    So, people who are at high risk of getting this infection includes
     1.    individuals who have multiple sexual partners,
     2.    drug addicts who take drugs intravenously,
     3.    individuals who require repeated blood transfusions and
     4.    children born to an HIV infected mother.

•    It is important to note that HIV/AIDS is not spread by mere touch or physical contact; it spreads only through body fluids. It is, hence, imperative, for the physical and psychological well-being, that the HIV/AIDS infected persons are not isolated from family and society.

•    There is always a time-lag between the infection and appearance of AIDS symptoms. This period may vary from a few months to many years (usually 5-10 years).

MECHANISM OF HIV PROLIFERATION IN HUMAN BODY

•    After getting Into the body of the person, the virus enters into macrophages where RNA genome of the virus replicates to form viral DNA with the help of the enzyme Reverse Transcriptase.

•    This viral DNA gets incorporated into host cell’s DNA and directs the infected cells to produce virus particles. The macrophages continue to produce virus and in this way acts like a HIV factory.



•    Simultaneously, HIV enters into helper T-lymphocytes (Th), replicates and produce progeny viruses. The progeny viruses released in the blood attack other helper T-lymphocytes. This is repeated leading to a progressive decrease in the number of helper T-lymphocytes in the body of the infected person. During this period, the person suffers from bouts of fever, diarrhoea and weight loss.

•    Due to decrease in the number of helper T lymphocytes, the person starts suffering from infections that could have been otherwise overcome such as those due to bacteria especially Mycobacterium, viruses, fungi and even parasites like Toxoplasma. The patient becomes so immuno-deficient that he/she is unable to protect himself/herself against these infections.

PREVENTION OF AIDS
•    A widely used diagnostic test for AIDS is Enzyme Linked Immuno-Sorbent Assay (ELISA).
•    Treatment of AIDS with anti-retroviral drugs is only partially effective. They can only prolong the life of the patient but cannot prevent death, which is inevitable.
•    As AIDS has no cure, prevention is the best option. Moreover, HIV infection, more often, spreads due to conscious behavior patterns and is not something that happens inadvertently, like pneumonia or typhoid.
•    Of course, infection in blood transfusion patients, new-borns (from mother) etc., may take place due to poor monitoring. The only excuse may be ignorance and it has been rightly said – “don’t die of ignorance”.
•    In our country the National AIDS Control Organization (NACO) and other non-governmental organizations (NGOs) are doing a lot to educate people about AIDS.
•    WHO has started a number of programmes to prevent the spreading of HIV infection.
•    Making blood (from blood banks) safe from HIV, ensuring the use of only disposable needles and syringes in public and private hospitals and clinics, free distribution of condoms, controlling drug abuse, advocating safe sex and promoting regular check-ups for HIV in susceptible populations, are some such steps taken up.
•    Infection with HIV or having AIDS is something that should not be hidden – since then, the infection may spread to many more people.
•    HIV/AIDS-infected people need help and sympathy instead of being shunned by society.
•    Unless society recognizes it as a problem to be dealt with in a collective manner – the chances of wider spread of the disease increase manifold.
•    It is a malady that can only be tackled, by the society and medical fraternity acting together, to prevent the spread of the disease.

To be Continued in Part 7
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Human Diseases - Part 5
January 20, 2020

Human Diseases - Part 5

HUMAN DISEASES - PART 5

SOME OTHER DISEASES

Diseases Caused by Worms
•    Ascaris, the common round worm and Wuchereria, the filarial worm, are some of the helminths which are known to be pathogenic to man. Ascaris, an intestinal parasite causes ascariasis.

•    Symptoms of these disease include internal bleeding, muscular pain, fever, anemia and blockage of the intestinal passage. The eggs of the parasite are excreted along with the faeces of infected persons which contaminate soil, water, plants, etc. A healthy person acquires this infection through contaminated water, vegetables, fruits, etc.

•    Wuchereria (W. bancrofti and malayi), the filarial worms cause a slowly developing chronic inflammation of the organs in which they live for many years, usually the lymphatic vessels of the lower limbs and the disease is called elephantiasis or filariasis. The genital organs are also often affected, resulting in gross deformities. The pathogens are transmitted to person through the bite by the female mosquite.

Old Age Diseases: Dementia
•    Dementia is “one of the major causes of disability and dependency among older people worldwide”

Pollution related diseases: Silicosis
•    Silicosis is a lung disorder caused by inhalation, retention and pulmonary reaction to crystalline silica, as a result of exposure during mining, stone crushing and quarrying activities.

Zoonotic Diseases
•    zoonotic diseases — are spread between animals and humans, and are common in societies where poverty is widespread
•    Chikungunya, dengue, Avian influenza, plague, SARS and acute encephalitis syndrome (AES) are some of the zoonotic diseases.

MALARIA:
•    Malaria has been for thousands of years a very serious disease of the tropical and temperate regions.
•    It was almost eliminated a few years back with the efforts of World Health Organization (WHO) and our National Malaria Eradication Programme (NMEP), but unfortunately, it has appeared again.

Symptoms:
•    The attack of malaria is preceded by yawning, tiredness, headache and muscular pain.
•    During the fever, the patient feels chilly and shivers, and has acute headache, nausea and high temperature.
•    After a few hours, the body perspires freely and the temperature becomes normal.
•    The cycle is repeated if no medicine is taken. Blood smear made during fever shows the malarial parasites.
•    No parasites are seen at other times. In chronic cases, there is general weakness and anaemia (paleness) due to large-scale destruction of red blood corpuscles.
•    This is also accompanied by enlargement of spleen and liver.

Cause:
•    Malaria is caused by the toxins produced in the human body by the malarial parasites, Plasmodium.

Transmission:
•    The malarial parasites are carried from the infected to the healthy persons by the female Anopheles mosquito.
•    The mosquito picks up the parasites with the blood, when it bites an infected person. When this infected mosquito bites a healthy person, parasites migrate into his blood with the saliva, which the mosquito injects before sucking up blood to prevent its clotting.

Types:
There are four species of Plasmodium, which cause different kinds of human malaria –
a.    P. Vivax : It causes benign tertian malaria, which attacks every third day, i.e., after 48 hours. The fever is mild and seldom fatal. This species is wide-spread in the tropical and temperate regions.
b.    P. ovale : It also causes benign tertian malaria, which recurs every 48 hours. This species is found only in West Africa and South America.
c.    P. malariae : It causes quartan malaria, which recurs every fourth day, i.e., after 72 hours. This species is found in both tropical and temperate regions, but it is not very common.
d.    P. falciparum : It alone is capable of causing three types of malaria, viz., quotidian malaria, which attacks almost daily, malignant tertian malaria, which occurs every 48 hours, but is very severe and often fatal; and irregular malaria. This species is found only in the tropical region.
Incubation Period:
•    The incubation period for malaria caused by Plasmodium vivax is about 10 days.

Life-history:
•    Plasmodium completes its life cycle in two phases and two hosts: asexual phase in the human host and sexual phase in the female Anopheles mosquito host.

To be Continued in Part 6
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Thursday, January 9, 2020

Human Diseases - Part 4
January 09, 2020

Human Diseases - Part 4

HUMAN DISEASES - PART 4

DISEASES IN INDIAN CHILDREN

Gastroentitis
•    Gastroentitis is an infection in the digestive system and it is one of the most common childhood illnesses.
•    Symptoms of gastroentitis include diarrhoea, nausea and vomiting, tummy cramps, and fever.
•    One of the main risks with gastroentitis is that it causes dehydration in children.

Rickets
•    Rickets occurs due to Vitamin D deficiency.
•    Deficiency of Vitamin D occurs in a child because of lack of exposure to sunlight.
•    Lack of adequate calcium in the diet can also cause rickets.
•    Rickets is a disease which involves softening and weakening of bones in children.
•    Children between the ages of 6 to 24 months are at the highest risk of developing the disease because that is the age when their bones are rapidly growing.

Conjunctivitis
•    Conjunctivitis is caused due to inflammation of the conjunctiva.
•    Conjunctiva is the outermost layer of the eye and the inner surface of the eyelids.
•    Conjunctivitis often starts in one eye at first and then spreads to the other eye.
•    For children suffering from conjunctivitis it is important to see a doctor to know what kind of conjunctivitis it is.
•    Symptoms of conjunctivitis include redness of eyes, irritation in the eye, and eye watering.

Scabies
•    Scabies is an infection of the skin.
•    Scabies is caused by tiny insects called mites.
•    These scabies mites burrow into the skin and lay eggs which become adult mites very soon.
•    Symptoms of this infection include superficial burrows, rash and severe itching.
•    Blisters on the palm and soles of the feet are characteristic symptoms of scabies in infants.
•    Scabies is one of the highly contagious diseases and a child can develop it by coming into contact with someone else who has been infected.
•    Children with scabies must not be sent to school or day care until it gets completely cured.

Upper Respiratory Tract infection (URTI)
•    Upper Respiratory Tract Infections are extremely common due to air pollution and vehicular emission.
•    Upper respiratory tract infections include common cold, influenza and sore throat.
•    Tonsillitis is also one of upper respiratory tract infections.
•    Tonsillitis is caused due to infection of the tonsils.
•    Tonsils are the areas of lymphoid tissue on either side of the throat.
•    Symptoms of tonsillitis include a severe sore throat, coughing, headache and difficulty swallowing.

Tuberculosis
•    Tuberculosis also affects children and is known as Primary Complex or Childhood Tuberculosis infection.
•    Children under the age of two years are more at risk of developing tuberculosis because their immune system is under developed or still developing.
•    Tuberculosis is completely curable and early diagnosis can help in effective treatment.

Typhoid
•    It is a water borne disease rampant in children due to poor sanitation.
•    Cases of typhoid are more common in countries like India and some other South Asian countries and in other low developed nations and have been seen lesser in countries like the USA.
•    Symptoms of typhoid in children are poor appetite, body ache, discomfort in abdomen, lethargy and weakness, fever with rising and falling pattern.
•    Some children may also experience headache, chest congestion, diarrhoea and vomiting and rose spots on the abdomen.

Bronchitis and Asthma
•    Bronchitis and asthma are common in children.
•    Bronchitis and asthma are caused due to high exposure to air borne pollutants.
•    Bronchitis and asthma need to be treated with antibiotics and bronchodilators.
To be Continued in Part 5
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January 09, 2020

Human Diseases - Part 3

HUMAN DISEASES - PART 3

ORGAN-SPECIFIC AND TISSUE SPECIFIC DISEASES
•    Different species of microbes seem to have evolved to home in on different parts of the body. In part, this selection is connected to their point of entry.

•    If they enter from the air via the nose, they are likely to go to the lungs. This is seen in the bacteria causing tuberculosis.

•    If they enter through the mouth, they can stay in the gut lining like typhoid causing bacteria. Or they can go to the liver, like the viruses that cause jaundice.
•    An infection like HIV, that comes into the body via the sexual organs, will spread to lymph nodes all over the body.

•    Malaria-causing microbes, entering through a mosquito bite, will go to the liver, and then to the red blood cells.

•    The virus causing Japanese Encephalitis, or brain fever, will similarly enter through a mosquito bite. But it goes on to infect the brain.

•    The signs and symptoms of a disease will thus depend on the tissue or organ which the microbe targets. If the lungs are the targets, then symptoms will be cough and breathlessness. If the liver is targeted, there will be jaundice. If the brain is the target, we will observe headaches, vomiting, fits or unconsciousness.

•    In addition to these tissue-specific effects of infectious disease, there will be other common effects too.

•    Most of these common effects depend on the fact that the body’s immune system is activated in response to infection.

•    An active immune system recruits many cells to the affected tissue to kill off the disease-causing microbes. This recruitment process is called inflammation. As a part of this process, there are local effects such as swelling and pain, and general effects such as fever.

•    In some cases, the tissue-specificity of the infection leads to very general-seeming effects. For example, in HIV infection, the virus goes to the immune system and damages its function. Thus, many of the effects of HIV-aids are because the body can no longer fight off the many minor infections that we face every day. Instead, every small cold can become pneumonia. Similarly, a minor gut infection can produce major diarrhoea with blood loss. Ultimately, it is these other infections that kill people suffering from HIV-aids.

PRINCIPLES OF TREATMENT
•    There are two ways to treat an infectious disease. One would be to reduce the effects of the disease and the other to kill the cause of the disease.

•    For the first, we can provide treatment that will reduce the symptoms. The symptoms are usually because of inflammation. For example, we can take medicines that bring down fever, reduce pain or loose motions. We can take bed rest so that we can conserve our energy. This will enable us to have more of it available to focus on healing.

•    But this kind of symptom-directed treatment by itself will not make the infecting microbe go away and the disease will not be cured. For that, we need to be able to kill off the microbes.

•    How do we kill microbes? One way is to use medicines that kill microbes. We have seen earlier that microbes can be classified into different categories. They are viruses, bacteria, fungi or protozoa.

•    Each of these groups of organisms will have some essential biochemical life process which is peculiar to that group and not shared with the other groups. These processes may be pathways for the synthesis of new substances or respiration. These pathways will not be used by us either.

•    For example, our cells may make new substances by a mechanism different from that used by bacteria. We have to find a drug that blocks the bacterial synthesis pathway without affecting our own. This is what is achieved by the antibiotics that we are all familiar with. Similarly, there are drugs that kill protozoa such as the malarial parasite.

Note : Why are Antibiotics effective against Bacterial Infections but not Viral Infections?

•    One reason why making anti-viral medicines is harder than making antibacterial medicines is that viruses have few biochemical mechanisms of their own. This means that there are relatively few virus-specific targets to aim at.

•    Despite this limitation, there are now effective anti-viral drugs, for example, the drugs that keep HIV infection under control.

•    Taxonomically, all bacteria are closely related to each other than to viruses and vice versa. This means that many important life processes are similar in the bacteria group but are not shared with the virus group. As a result, drugs that block one of these life processes in one member of the group is likely to be effective against many other members of the group. But the same drug will not work against a microbe belonging to a different group.

•    As an example, let us take antibiotics. They commonly block biochemical pathways important for bacteria. Many bacteria, for example, make a cell-wall to protect themselves. The antibiotic penicillin blocks the bacterial processes that build the cell wall. As a result, the growing bacteria become unable to make cell-walls, and die easily.

•    Human cells don’t make a cell-wall anyway, so penicillin cannot have such an effect on us. Penicillin will have this effect on any bacteria that use such processes for making cell-walls. Similarly, many antibiotics work against many species of bacteria rather than simply working against one group.

•    But viruses do not use these pathways at all, and that is the reason why antibiotics do not work against viral infections. If we have a common cold, taking antibiotics does not reduce the severity or the duration of the disease. However, if we also get a bacterial infection along with the viral cold, taking antibiotics will help. Even then, the antibiotic will work only against the bacterial part of the infection, not the viral infection.


PRINCIPLES OF PREVENTION
 
•    What are the specific ways of prevention? They relate to a peculiar property of the immune system that usually fights off microbial infections.

•    Let us cite an example to try and understand this property. These days, there is no smallpox anywhere in the world. But as recently as a hundred years ago, smallpox epidemics were not at all uncommon.

•    In such an epidemic, people used to be very afraid of coming near someone suffering from the disease since they were afraid of catching the disease.

•    However, there was one group of people who did not have this fear. These people would provide nursing care for the victims of smallpox.

•    This was a group of people who had had smallpox earlier and survived it, although with a lot of scarring. In other words, if you had smallpox once, there was no chance of suffering from it again.

•    So, having the disease once was a means of preventing subsequent attacks of the same disease. This happens because when the immune system first sees an infectious microbe, it responds against it and then remembers it specifically.

•    So the next time that particular microbe, or its close relatives enter the body, the immune system responds with even greater vigour. This eliminates the infection even more quickly than the first time around. This is the basis of the principle of ‘vaccination’ has come into our usage.

•    We can now see that, as a general principle, we can ‘fool’ the immune system into developing a memory for a particular infection by putting something, that mimics the microbe we want to vaccinate against, into the body. This does not actually cause the disease but this would prevent any subsequent exposure to the infecting microbe from turning into actual disease.

•    Many such vaccines are now available for preventing a whole range of infectious diseases, and provide a disease-specific means of prevention.

•    There are vaccines against tetanus, diphtheria, whooping cough, measles, polio and many others.

•    Introducing fishes like Gambusia in ponds that feed on mosquito larvae, spraying of insecticides in ditches, drainage areas and swamps, etc. can prevent proliferation of mosquitoes. Such precautions have become all the more important especially in the light of recent widespread incidences of the vector-borne (Aedes mosquitoes) diseases like dengue and chikungunya in many parts of India.

•    Traditional Indian and Chinese medicinal systems sometimes deliberately rubbed the skin crusts from smallpox victims into the skin of healthy people. They thus hoped to induce a mild form of smallpox that would create resistance against the disease.

•    Famously, two centuries ago, an English physician named Edward Jenner, realized that milkmaids who had had cowpox did not catch smallpox even during epidemics.

•    Cowpox is a very mild disease. Jenner tried deliberately giving cowpox to people, and found that they were now resistant to smallpox. This was because the smallpox virus is closely related to the cowpox virus. ‘Cow’ is ‘Vacca’ in latin, and cowpox is ‘Vaccinia’.

To be Continued in Part 4
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January 09, 2020

Human Diseases - Part 2

HUMAN DISEASES - PART 2

THE IMMUNE SYSTEM

•    Immunity : The ability of the body to protect against all types of foreign bodies like bacteria, virus, toxic substances etc. which enter the body.

•    The science dealing with the various phenomena of immunity, induced sensitivity and allergy is called immunology.

•    Immune Response :  Third line of defence.  Involve production of antibodies and generation of specialized lymphocytes against specific antigens.

•    Antigens: Substances which stimulate the production of antibodies, when introduced into the body.

•    Antibodies: Immunoglobulins (Igs) which are produced in the body in response to the antigen or foreign bodies.

•    All antibodies are immunoglobulins but all immunoglobulins are not antibodies.

•    There are two major types of immunity: Innate or Natural or Non-specific immunity and Acquired or Adaptive or Specific Immunity.


TYPES OF DISEASES

ACUTE AND CHRONIC DISEASES
•    Some diseases last for only very short periods of time, and these are called acute diseases. We all know from experience that the common cold lasts only a few days.
•    Other ailments can last for a long time, even as much as a lifetime, and are called chronic diseases. An example is the infection causing elephantiasis, which is very common in some parts of India.

COMMUNICABLE DISEASES
•    Microbial diseases that can spread from an infected person to a healthy person through air, water, food or physical contact are called communicable diseases.
•    Examples of such diseases include cholera, common cold, chicken pox and tuberculosis.
•    Example of a carrier is the female Anopheles mosquito, which carries the parasite of malaria. Female Aedes mosquito acts as carrier of dengue virus.
•    Robert Köch (1876) discovered the bacterium (Bacillus anthracis) which causes anthrax
•    How do infectious diseases spread? Many microbial agents can commonly move from an affected person to someone else in a variety of ways. In other words, they can be ‘communicated’, and so are also called communicable diseases.
•    Such disease-causing microbes can spread through the air. Examples of such diseases spread through the air are the common cold, pneumonia and tuberculosis.
•    Diseases can also be spread through water. This occurs if the excreta from someone suffering from an infectious gut disease, such as cholera, get mixed with the drinking water used by people living nearby.
•    The sexual act is one of the closest physical contact two people can have with each other. Not surprisingly, there are microbial diseases such as Syphilis or AIDS that are transmitted by sexual contact from one partner to the other.
•    Other than the sexual contact, the aids virus can also spread through blood-to-blood contact with infected people or from an infected mother to her baby during pregnancy or through breast feeding.
•    We live in an environment that is full of many other creatures apart from us. It is inevitable that many diseases will be transmitted by other animals. These animals carry the infecting agents from a sick person to another potential host. These animals are thus the intermediaries and are called vectors. The commonest vectors we all know are mosquitoes.
•    In many species of mosquitoes, the females need highly nutritious food in the form of blood in order to be able to lay mature eggs. Mosquitoes feed on many warm-blooded animals, including us. In this way, they can transfer diseases from person to person.

To be Continued in Part 3
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Human Diseases - Part 1
January 09, 2020

Human Diseases - Part 1

HUMAN DISEASES - PART 1


TYPES OF DISEASES : The diseases may be broadly classified into two types: Congenital and acquired.

1.    CONGENITAL DISEASES:
These are anatomical or physiological abnormalities present from birth. They may be caused by
       •    A single gene mutation (alkaptonuria, phenylketonuria, albinism, sickle-cell anaemia, haemophilia, colour blindness)
      •    Chromosomal aberrations (Down’s syndrome, Klinefelter’s syndrome, Turner’s syndrome)
     •    Environmental factors (cleft palate, harelip). Unlike the gene-and chromosome-induced congenital defects, environmentally caused abnormalities are not transmitted to the children.

2.    ACQUIRED DISEASES:
These diseases develop after birth. They are further of two types: Communicable and Non-communicable.
      •    Communicable (Infectious) Diseases: These diseases are caused by viruses, rickettsias, bacteria, fungi, protozoans and worms.
     •    Noncommunicable (Noninfectious) Diseases: These diseases remain confined to the person who develops them and do not spread to others. The non-communicable diseases are of four kinds

I.    Organic or Degenerative Diseases: These diseases are due to malfunctioning of some of the important organs, e.g, heart diseases, epilepsy. Heart diseases result from the abnormal working of some part of this vital organ. Epilepsy may result from abnormal pressure on regions of the brain.

II.     Deficiency Diseases : These diseases are produced by deficiency of nutrients, minerals, vitamins, and hormones, e.g., kwashiorkor, beriberi, goitre, diabetes are just a few from a long list.

III.     Allergies: These diseases are caused when the body, which has become hypersensitive to certain foreign substance, comes in contact with that substance. Hay fever is an allergic disease.

IV.    Cancer: This is caused by a uncontrolled growth of certain tissues in the body.

To be Continued in Part 2
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January 09, 2020

Bio-Diversity & Its Convervation - Part 5

BIO – DIVERSITY & ITS CONSERVATION

PART 5


HOT SPOTS OF BIODIVERSITY :
     •    They are the areas with high density of biodiversity or megadiversity which are also the most threatened one.
   •    To designate priority areas for in situ conservation, Norman Myers developed the 'hot spots' concept in 1988.
     •    'The hot spots are the richest and the most threatened reservoirs of plant and animal life on earth'.

Ecologically hot spots are determined by four factors.          
(i)    Number of species/species diversity.
(ii)    Degree of endemism.
(iii)    Degree of threat to habitat due to its degradation and fragmentation.
(iv)    Degree of exploitation.

      •    Over the world 25 terrestrial hot spots have been identified for the conservation of biodiversity.
       •    Out of these 15 hot spots have tropical forests, 5 occur in Mediterranian-type zones and 9 hot spots are present in tropics.
      •    The hot spots together occupy 1.4 per cent of the earth's land area. About 20 per cent of the human population lives in the hot spots.

Hot spots in India :
      •    Out of the 25 hot spots of the world, two are found in India. These are Western Ghats and Eastern Himalayas, and these extend to the neighboring countries also.
      •    These areas show high degree of endemism and are inhabited by a wide variety of flowering plants, swallow tailed butterflies, amphibians, reptiles and mammals.

(i)    Western Ghats :
      •    It lies parallel to the Western Coast of Indian peninsula for almost 1600 km, spread over in Maharashtra, Karnataka, Tamil Nadu and Kerala.
      •    The evergreen forests are found at low elevation (i.e. 500 m above mean sea level), whereas semi-evergreen forests occur at 500-1500 m height.
      •    The two main centres of biological diversity are :
               a.    The Agastryamalai hills and Silent valley
               b.    The new Amambalam Reserve.

(ii)    Eastern Himalaya :
     •    It extend to the north eastern India and Bhutan. Many deep and semi isolated valleys are found in this region.
     •    These valleys are exceptionally rich in endemic plant species. There occur temperate forests at altitudes of 1780 to 3500 m in this region.
     •    The eastern Himalaya is an active centre of evolution and exhibits a rich diversity of flowering plants.
   •    Numerous primitive angiosperm families (e.g., Magnoliaceae and Winteraceae) and primitive genera of plants like Magnolia and Betula and found in this region.

INTERNATIONAL EFFORTS FOR CONSERVING BIODIVERSITY :
     •    Earth summit of Rio de Janeiro (1992), Brazil, promoted Convention of Biological Diversity (CBD) which was signed by 152 nations.
      •    Its recommendations came into effect on 29th Dec. 1993. India became a party to this Convention on Biological Diversity in May, 1994.

The convention has three key objectives
       a.    Conservation of biological diversity
       b.    Sustainable use of biodiversity
      c.    Fair and equitable sharing of benefits arising out of the utilization of genetic resources.

A number of projects for the conservation and appropriate development of Biosphere Reserves, are being supported by the World Conservation Union and the World Wide Fund for Nature (WWF).

BIODIVERSITY CONSERVATION IN INDIA :
        •    India is a centre of rich biological diversity and has contributed significantly of the global biodiversity.
            •    India is a home land of 167 cultivated species and 320 wild relatives of crop plants.
           •    It is a centre of diversity of animal species (e.g. zebu, mithun, chicken, water buffalo, camel); crop plants (e.g. edible diascoreas, alocasia, colocasia); species and condiments (e.g., cardamom, black pepper, ginger, turmeric), bamboos, brassicas and tree cotton. India also represents a secondary centre of domestication for some animals (e.g. horse, goat, sheep, cattle, yak and donkey) and plants (e.g. tobacco, potato and maize).
       •    Because of the abundant diversity present in the country, its conservation is very important not only for the country but also for the rest of the world. Both in situ and ex situ conservation measures are being undertaken.
         •    The National parks, Wildlife sanctuaries and other protected areas maintained by the Ministry of Environment and Forests provide in situ conservation of biodiversity. 


            •    The joint forest management systems involve forest departments and local communities to enable tribal and local people to have access to non-wood forest products (such as lac, silk, honey, wax, tendu leaves, etc.) and at the same time protect the forest resources.
          •    Major ex situ conservation of biodiversity is being managed by National Bureau of Plant, Animal and Fish Genetic Resources.
          •    There is an International Crop Research Institute for Semi-Arid Tropics (ICRISAT) in Hydrabad for conserving germplasm of Groundnut, Pigeon Pea, Chick Pea, Pearl Millet and Sorghum.
        •    A number of other centres in India are maintaining hundred and thousands of present and past varieties of crop plants.
           •    Thus germplasms of plants and animals are being conserved in vitro in gene/seed banks, field gene banks, botanical gardens and zoological gardens.
           •    Being spread over different parts of the country, the various institutes are conserving regional variants of all types of important plants and animals.
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Bio-Diversity & Its Convervation - Part 4
January 09, 2020

Bio-Diversity & Its Convervation - Part 4

BIO – DIVERSITY & ITS CONSERVATION

PART 4


CONSERVATION OF BIODIVERSITY :
•    Conservation of biodiversity is protection, uplift and scientific management of biodiversity so as to maintain it at its optimum level and derive suitainable benefit for the present as well as future strategies.
•    Conservation strategies : There are two basic strategies of biodiversity conservation
            1.    in-situ (on site)
            2.    ex-situ (off site)

1.    In-situ conservation : It is protection and management of important components of biological diversity through a network of protected areas.

A.    Protected areas :
•    They are ecological/biogeographical areas where biological diversity alongwith natural and cultural resources are protected, maintained and managed through legal or other effective measures. National Parks and Wild life Sactuaries are the examples of protected areas.
•    The World Conservation Monitoring Centre (WCMC) has recognised 37,000 protected areas around the world.
•    As of September 2002, India has 581 protected areas (89 National parks and 492 Wildlife Sanctuaries).
•    These areas cover 4.7 per cent of the land surface as against 10 per cent internationally suggested norm. The protected areas provide following benefits.
            a.    Maintain viable populations of all native species and sub-species.
          b.    Maintain the number and distribution of communities and habitats, and conserve the genetic diversity of all the present species.
            c.    Prevent man made introduction of alien species.
        d.    Make it possible for species/habitats to shift in response to environmental changes.

B.    Biosphere reserves :
•    The Man and Biosphere (MAB) programme of UNESCO formulated the concept of Biosphere in 1975, which deals with conservation of ecosystems and genetic resources contained therein.
•    "The Biosphere Reserves are a special category of protected areas of land/or coastal environments, wherein people are an integral component of the system'.
•    These are representative examples of natural biomes and contain unique biological communities.
A biosphere reserve has three zones :
         a.    Core or natural zone : It comprises an undisturbed and legally protected ecosystem.
        b.    Buffer zone : It surrounds the core area, and is managed to accommodate a greater variety of resource use strategies, and research and educational activities.
           c.    Transitional zone or manipulation zone : It is the outer most part of the biosphere reserve. It serves as an area of active cooperation between reserve management and the local people, wherein activities like settlements, cropping, forestry and recreation and other economic uses continue in harmony with conservation goals.

Importance of biosphere reserve
I.    Restoration : Biosphere reserves help in restoration of degraded ecosystems and habitats.
II.    Conservation : Biosphere reserves ensure the conservation of landscapes, ecosystems, species and genetic resources. These reserves also encourage the traditional resource use.
III.    Development : The biosphere reserves promote culturally, socially and ecologically sustainable economic development.
IV.    Scientific research, monitoring and education : The biosphere reserves provide support for research monitoring, education and information exchange related to local, national and global issues of conservation and development.

C.    Sacred forests and Scared lakes :
•    Sacred forests are forest patches around places of worship which are held in high esteem by tribal communities.
•    They are the most undisturbed forest patches (Island of pristine forests) which are often surrounded by highly degraded landscapes.
•    They are found in several parts of India, e.g., Karnataka, Maharashtra, Kerala, Meghalaya, Temples built by tribals are found surrounded by Deodar forests in Kumaon region, Jaintias and Khasias in Meghalaya.
•    Not a single branch is allowed to be cut from these forests. As a result many endemic species which are rare or have become extinct elsewhere can be seen to flourish here.
•    Similarly aquatic flora and fauna is also protected in sacred water bodies. e.g. Khaeheopalri lake in Sikkim.

2.    Ex-situ conservation : It is conservation of selected rare plants/animals in places outside their natural homes. Ex situ conservation includes offsite collections and gene banks.

A.    Offsite collections :
      •    They are live collections of wild and domesticated species in botanical gardens, zoos, arboreta, etc.
      •    Currently, there are more than 1500 botanical gardens and arboreta (Gardens with trees and shrubs) having more than 80,000 species.
       •    Many of them have seed banks, tissue culture facilities and other ex-situ technologies. The number of zoos/zoological parks is more than 800.
      •    They have about 3000 species of mammals, birds, reptiles and amphibians. Most of them have well managed captive breeding programmes.

Therefore, offsite collections can be used to restock depleted populations, reintroduce species in the wild and restore degraded habitats.

B.    Gene banks :
       •    A gene bank or germ plasm bank is an institution where valuable plant material is preserved in a viable condition.
      •    These are stored either in the form of seeds or dormant vegetative organs or in the form of frozen gametes.
Seed banks :
      •    Plant germplasm in live state is the viable seed. In a seed the embryo is present in a dormant state. The moisture contents of seeds is kept low (5-15%) and they are stored at low temperature (10oC
     •    to20oC) with supply of little oxygen.
    •    With these conditions there is reduced enzyme activity and reduced respiration.
    •    From time to time at definite intervals these seeds are sown to produce new plants and fresh seeds are obtained.
    •    Such seeds are called Orthodox seeds as they can withstand the reduction in moisture and prolonged exposure to low temperature.
    •    Seeds of trees and shrubs usually get killed on drying and freezing. Such seeds are called Recalcitrant seeds e.g., tea, litchi.
    •    In such cases plants are kept in orchards and maintained through in-situ conservation.
   
Orchards :
    •    Plants with recalcitrant seeds are grown in orchards where all possible strains   and varieties are maintained, e.g., litchi, oil Palm, rubber tree, etc.

Tissue Culture :
    •    It is carried out through callus formation, embryoids, pollen grain culture and shoot tip culture for those plants which are either seedless, have recalcitrant seeds, variable seed progeny or where clone is to be maintained.
    •    The method is useful in maintaining a large number of genotypes in small area, rapid multiplication of even endangered species and for hybrid rescue. Shoot tip culture maintains virus free plants.
    •    It is used for international exchange of germplasm in vegetatively multiplied cultivars, e.g., banana, potato.

Cryopreservation :
   •    Preservation at 196oC (liquid nitrogen) can maintain tissue culture, embryos, animal cells/tissues, spermatozoa indefinitely. The cryopreserved material is revived through special technique when required.

To be Continued in Part 5
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January 09, 2020

Bio-Diversity & Its Convervation - Part 3

BIO – DIVERSITY & ITS CONSERVATION

PART 3

EXTINCTION OF SPECIES :
•    The most serious aspect of the loss of biodiversity is the extinction of species.
•    Once a species goes extinct, its chances for further evolution are lost.
•    A species is considered extinct, when no member of the species remains alive anywhere in the world.
•    If individuals of a species remain alive only in captivity or other human-controlled conditions, the species is said to be extinct in the wild.
•    In both of these situations, the species would be considered globally extinct.
•    A species is considered to be ecologically extinct, if it persists at such reduced numbers that its effects on other species in its community are negligible. Extinction is a natural process.

Types of extinction : Species become extinct through three types of extinction processes.

1.    NATURAL EXTINCTION :
•    It is the extinction of species slowly from the earth due to change in environmental conditions.
•    Some species disappear and the others which are more adapted to changed conditions, take their place.
•    Many species have lost in the geological past by natural extinction. The extinction of species in the geological past is also called background extinction.

2.     MASS EXTINCTION :
•    It refers to the extinction of large number of species due to catastrophe. There have been several periods in the earth's geological history, when large number of species became extinct because of catastrophes. Mass extinction occurred in millions of years.

3.    ANTHROPOGENIC EXTINCTION :
•    They are extinctions abetted by human activities like settlements, hunting, over exploitation and habitat destruction.
•    The World Conservation Monitoring Centre has found out that since 1600 A.D., the earth has lost 533 animal species (mostly vertebrates) and 384 plant species (mostly flowering plants).
•    75% of these extinctions are caused by direct human interference. It is almost documented that Dodo (Raphus cucullatus) and Taswania Wolf (Thylacinus cyanocephalus) have been hunted to extinction by humans.

SUSCEPTIBILITY OF EXTINCTION :
All species are not equally susceptible to extinction. The characteristics which make a species susceptible to extinction are listed below
     (i)    Large body size e.g. Bengal tiger, lion and elephant.
    (ii)    Small population size and low reproductive rate e.g. Blue whale and Giant Panda.
    (iii)    Feeding at high tropic levels in the food chain e.g. Bengal tiger and Bald eagle.
    (iv)    Fixed migratory routes and habit. e.g. Blue whale and whooping crane.
    (v)    Localized and narrow range of distribution. e.g. Woodland caribou and Island species.

RED DATA BOOK AND IUCN :
•    IUCN is International Union of Conservation of Nature and Natural Resources which is now called World Conservation Union (WCU).
•    It has its headquarters at Morges, Switzerland. It maintains a red data book or red list which is a catalogue of taxa facing risk of extinction.
•    Threatened species is the one which is liable to become extinct if not allowed to realise its full biotic potential by providing protection from exotic species/human exploitation/habitat deterioration/depletion of food. Red data book or red list was initiated in 1963.



Out of these, four categories of species are included threatened species - critically endangered, endangered, vulnerable and lower risk species.
Two more categories are also added to them.
        (i)    Rare Species (R): They are species with naturally small population, either localised or thinly scattered, which are always at risk from pests/pathogens/predators/exotic species. Clouded Leopard (Neofelis nebulosa). Hawaiian Monk Seal (Monochus schauinslandii). Great Indian Bustard (Ardeotis nigriceps).
         (ii)    Indeterminate Species : The species are in danger of extinction but the reason is not known, e.g., 3-banded Armadillo of Brazil, Short Eared Rabbit of Sumatra, Mexican Prairie Dog.

The main objectives of Red lists are listed below :
a.    Identification and documentation of endangered species.
b.     Providing a global index of the decline of biodiversity.
c.     Developing awareness about the importance of threatened biodiversity.
d.     Defining conservation priorities at the local level and guiding conservation action.


To be Continued in Part 4
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Tuesday, January 7, 2020

Bio-Diversity & Its Convervation - Part 2
January 07, 2020

Bio-Diversity & Its Convervation - Part 2

 BIO – DIVERSITY & ITS CONSERVATION

PART 2

GRADIENTS OF BIODIVERSITY :
•    Biodiversity is not uniform on the earth. It varies with change in latitude or altitude.
•    Biodiversity increase, when we move from high to low latitude (i.e. from the poles to the equator). The temperate region has severe climate with short growing period for plants.
•    On the other hand tropical region has favourable conditions for the growth throughout the year. The favourable environmental conditions favour speciation (i.e. origin of new species) and make it possible for a larger number of species to occur and grow.
•    Therefore, tropical regions are rich in biodiversity.
•    Similarly, the species diversity decreases from lower to higher altitude on a mountain.
•    The temperature drops about 6.5oC with increase in altitude by 1000 m. The drop in temperature and greater seasonal variability at higher altitudes are the two major factors that reduce diversity.
•    It should not be confused with complexity and heterogenecity of the physical environment which tends to increase complexity and diversity of flora and fauna of an area.

BENEFITS OF BIODIVERSITY :
•    Biodiversity provides numerous direct and indirect services to human beings, e.g., :
1.    Diversity of plants and animals provide a vast variety of foods and fabrics.
2.    Maintenance of ecological balance or ecosystems stability.
3.    Preserving biodiversity provides economic benefits which include improving the desirable characteristics of crops, making plants more pest resistant, providing medicines to treat and curve illness, supporting ecotourism and providing enjoyment to individuals.
4.    Biodiversity enriches the lives of people in industrialized world and developed countries provides the means of survival to people in developing countries.

THREATS TO BIODIVERSITY

1.    DESTRUCTION OF HABITATS :
•    Destruction of natural habitat is the primary threat to the biodiversity.
•    Natural habitats, which protect natural flora and fauna are being converted to human settlements, harbours, dams, reservoirs, crop-lands, grazing grounds and mining sites.
•    Deforestation deprive animal life of shelter and food.
•    This decreases the population of many species. Migratory animals are also affected by deforestation because of the disturbance in their routes.
•    Some of the dams are blocking, spawning and migration of fishes by inundating the habitats and by changing the physical environment.
•    Sometimes human cleanliness destroy the habitat of scavengers such as vultures, kites, etc.
•    The California condor (Cathartes californianus) a shy scavanger, which is the largest flying bird of today, has been severely affected by human cleanliness.

2.    DISTURBANCE AND DEGRADATION OF HABITATS :
•    They are of two types, natural and man-made. Natural disturbance and degradation are caused by spontaneous jungle fire, pest infestation, defoliation by insects, locust attack, etc. Man-made disturbance and degradation are more severe.
•    They include felling of trees, use of fire for clearing forest areas, collection of litter, and over-exploitation for other economically important products.
•    Disturbance and degradation result in loss of biodiversity.

3.    POLLUTION :
•    The most subtle form of habitat degradation is environmental pollution.
•    Pollution may reduce and eliminate populations of sensitive species.
•    The populations of fish eating birds and falcons have declined due to excessive use of pesticides in crop fields.
•    Lead poisoning is another major cause of mortality of many aquatic birds like ducks, swans and cranes.
•    These birds often swallow the spent shotgun pellets that fall into lakes and marshes. The nutrient enrichments (eutrophication) also drastically reduce biodiversity.

4.    INTRODUCTION OF EXOTIC SPECIES :
•    New species entering a geographical region are called exotic or alien species.
•    Introduction of exotic species may cause significant loss to the biological communities.
•    The great majority of the exotic species do not become established in the introduced new places.
•    However, some of the species are able to establish in new area. Such successful exotic species may kill or eat native species to the point of extinction, or may so alter the habitat that many natives are no longer able to persist.
•    Island ecosystems are most vulnerable due to small size and small number of species.

Examples of introduction of exotic species and their effects are :
•    Introduction of Nile perch (an exotic predatory fish) into lake Victoria (South Africa) threatened the entire ecosystem of the lake by eliminating several native species of the small Cichlid fish species that were endemic to this fresh water ecosystem.
•    In several tropical countries including India, water hyacinth (A free floating exotic water weed) clogs rivers and lakes, and threatens the survival of many aquatic species in lakes and rivers.
•    Lantana camara (An exotic shrub) strongly competes with the native species and eliminate many of them. The exotic shrub has invaded many forests in different parts of our country.

To be Continued in Part 3
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Bio-Diversity & Its Convervation - Part 1
January 07, 2020

Bio-Diversity & Its Convervation - Part 1

BIO – DIVERSITY & ITS CONSERVATION

PART 1

•    The term 'biodiversity' refers to 'the variety and variability among living organisms and the ecological complexes in which they occur'.
•    If you observe a patch of forest, you may find a wide variety of plant and animal life.
•    The plant life may range form a small herb to a large tree, and animal life may vary from a tiny insect to a large mammal.
•    Apart from plants and animals, numerous microorganisms, which cannot be seen with naked eyes also occur in the soil.
•    This shows biological diversity or biodiversity of a forest patch. Thus, biodiversity can be defined as 'the totality of genes, species and ecosystem of a region'.
•    Biodiversity differs from place to place as each habitat has its distinct biota.
•    However, many biologically rich and unique habitats are being destroyed, degraded and fragmented.
•    The major factors that tend to decrease biodiversity are increasing human population, higher resource consumption and pollution.
•    Loss of biodiversity reduces gene pool of species, number of interactions in the biota and ability of species to adapt themselves to changes in the environment.
•    It not only checks evolutionary advancements but also put the surviving species to dangers of extinction.

MAGNITUDE OF BIODIVERSITY:
•    Biologists are enganged in the identification and naming of species for the last 250 years.
•    Still, they are able to name and describe for less number of species than the actual number present. Presently, the known and described number of species of all organisms on the earth is between 1.7 and 1.8 million, which is fewer than 15% of the actual number.
•    It is predicted that the number of total species varies from 5 to 50 million. Approximately 61% of the known species are insects.
•    About 2,70,000 species of plants and only 4650 species of mammals are known to science.
•    Only fragmentary information is available about bacteria, viruses, protists and Archaea.
•    The major area where numerous species are believed to be unknown to science are tropics and coral reefs.
•    Presently, efforts are being made to discover and describe new species more rapidly.
•    The projects like 'Global Biodiversity Information Facility and the Species 2000’, are attempting to discover new species faster than ever before.

LEVELS OF BIODIVERSITY :
•    The biological diversity include three interrelated hierarchical levels, viz. Genetic diversity, Species diversity and Community and ecosystem diversity.

I.    Genetic diversity :
•    It is the diversity in the number and types of genes as well as chromosomes present in different species and the variations in the genes and their alleles in the same species.
•    For instance, the number of genes is about 450-700 in Mycoplasma, 4000 in Escherichia coli, 13000 in Drosophila melanogaster, 32000-50000 in Oryza sativa and 35000 to 45000 in Homo sapiens sapiens.
•    'The genetic variation existing within a species is called genetic diversity’.
•    The genetic variation may be in alleles (different variants of same genes), in entire genes (the traits determining particular characteristies) or in chromosomal structures.
•    Genetic diversity is useful in adaptation to changes in environmental conditions.
•    It helps in speciation or evolution of new species. Lower genetic diversity within a species or variety may be useful for uniformity in yield as well as higher yield.
•    However, it is liable to undergo degradation and prone to mass scale destruction at the hands of fungal or insect attacks.

II.    Species diversity :
•    It is the variety in the number and richness of the species of a region. The number of species per unit area is called species richness.
•    Number of individuals of different species represent species evenness or species equitability. Communities where species are represented by more or less equal number of individuals exhibit evenness.
•    Others where one or more species have more individuals than others show dominance or unevenness.
•    Species diversity is product of both species richness or evenness or equitability, i.e., species richness weighed by species evenness.
•    Odum et al (1960) calculate species diversity (d) as number of species per thousand individuals while Menhinick (1964) calculates it as number of species in relation to square root of total number of individuals.
•    Diversity index commonly used in ecological studies is Shannon index.

III.    Community and ecosystem diversity :
•    Community diversity refers to the variations in the biological communities in which species live.
•    There are three perspectives of diversity at the level of community. These are alpha diversity, beta diversity and gamma diversity.

       a)    Alpha diversity (a-index Diversity, Within-Community Diversity) : It indicates diversity within the community. It refers to the diversity of organisms sharing the same community or habitat. A combination of species richness and equitability/evenness is used to represent diversity within a community or habitat.

        b)    Beta diversity (b-index Diversity, Between-Community Diversity) : It is biodiversity which appears in a range of communities due to replacement of species with the change in community/habitat due to presence of different microhabitats, niches and difference in environmental conditions.

        c)    Gamma diversity (g-index Diversity) : It refers to the diversity of the habitats over the total land scape or geographical area.

•    Ecosystem diversity refers to the variation in the structure and functions of the ecosystem.
•    It describes the number of niches, trophic levels and various ecological processes that sustain energy flow, food webs and the recycling of nutrients.
•    It has focus on various biotic interactions and the role and function of keystone species (Species determining the ability of large number of other species to persist in the community).
•    Diversity helps in producing more productive and stable ecosystems/communities which can tolerate various stresses like prolonged drought.

To be Continued in Part 2
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January 07, 2020

Environment,Ecology & Hygiene - Part 3

ENVIRONMENT,ECOLOGY& HYGIENE

PART 3


HUMAN INTERACTION WITH THE ENVIRONMENT

Urbanisation and industrialisation
•    Urbanisation and industrialisation bring rural people into urban centres that may not be ready to handle the additional sanitary needs.
•    Ethiopia is at the stage of rapid development with priorities in agriculture and industry.
•    Currently small-scale industries that bridge agriculture and industrialisation are booming.
•    Large-scale industries, such as textiles, food and cement, are growing.
•    The need to improve and expand social infrastructures such as water supply, waste management and health services is obvious in order to handle the needs of the growing urban centres.
•    As a healthworker you need to understand that these developments have environmental health risks due to overcrowding, inappropriate waste management and a shortage of safe drinking water.

Development as a means of interaction
•    Assume for a minute that a textile factory is planned to operate in your woreda. Now, think what benefits and disadvantages may arise from the introduction of this factory.
•    In this diagram, the two arrows lying between ‘human activities’ and ‘environment’ indicate the relationship between them, i.e. that development requires resources from the environment (forward arrow) and, as a result, waste could be generated as a by-product (backward arrow). 
•    In fact, there are three possible types of interaction: humans can affect the environment, the environment can affect humans, and humans and the environment can co-exist (where they sustain each other).
•    The arrows indicate the negative effect if the generated waste is not properly handled. This affects the environment in the form of pollution of air, water, etc., and can have a negative influence on development.
•    Matters of development and health have been on the agenda in UN international conferences and meetings.
•    The issue of sustainable development is a key message for the friendly coexistence between development and the environment.
•    The World Commission on Environment and Development defined sustainable development as:
I.    development which meets the needs of the present without compromising the ability of future generations to meet their own needs.

THE ROLE OF ENVIRONMENTAL HEALTH IN PUBLIC HEALTH
•    Environmental health is a part of public health where the primary goal is preventing disease and promoting people’s health.
•    Environmental health is associated with recognising, assessing, understanding and controlling the impacts of people on their environment and the impacts of the environment on the public.
•    The role of the environmental healthworker, therefore, includes the following functions of public health:
      I.    Improving human health and protecting it from environmental hazards.
     II.    Developing liaison between the community and the local authority, and between the local and higher levels of administration.
     III.    Acting independently to provide advice on environmental health matters; designing and developing plans of action for environmental health.
     IV.    Initiating and implementing health/hygiene, sanitation and environmental  programmes to promote understanding of environmental health principles.
      V.    Enforcing environmental legislation.
     VI.    Monitoring and evaluating environmental health activities, programmes and projects.
•    You, as a healthworker, are very much involved in all of the above except (V) and (VI), which are mainly carried out by the woreda environmental healthworker. However, the kebele administrator may ask you to help with the enforcement of environmental legislation, if deemed apprioriate.

ENVIRONMENTAL HEALTH PLANNING
•    Environmental health planning refers to a systematic process by which goals are established, facts are gathered and analysed, alternative proposals and programmes are considered and compared, resources are measured, priorities are established, and strategies and activities are designed to meet the established goals or objectives within a specified period of time.
•    You, as part of kebele cabinet, will be requested to prepare an environmental health plan. The approach to planning is similar to that described in the Health Management, Ethics and Research Module. However, the primary focus is what makes it different. The following planning steps are suggested.

IDENTIFYING THE NEEDS AND GAPS
•    This is essentially an inventory (or list) of problems related to environmental health in your local context. You can use various tools in order to identify these problems.
•    Environmental health survey: This is a systematic survey using a questionnaire. The questionnaire contains basic indicators of environmental health such as latrine availability, source of drinking water, waste disposal systems, cleanliness of the community, etc.
•    You will need to do some statistical analysis (proportions and averages) to refine basic indicators of environmental health for your local context. You must be careful when designing a survey as it requires time, expertise and resources.
•    You can plan it in coordination with the woreda environmental healthworker.
•    Rapid/quick assessment: This is the usual method that helps you gain a quick overview of the range of problems.
•    The usual data collection tools that you can use for this are focused or group discussion, physical observation with checklists and interviewing people.

PRIORITY SETTING
•    It is difficult to handle all identified problems due to resource limitations.
•    You need to know in advance the available resources in the kebele.
•    Resources can be mobilised from government, community, private organisations and NGOs.
•    Do not rely too much on governmental resources as there are always limitations.
•    Mobilising community resources is the best option that could be sustained.
•    Priorities are then made on the basis of the depth and severity of the problem, the feasibility and the degree of community concern and willingness to be involved in the resource mobilisation.

SUMMARY
•    The historical perspectives show us that hygiene and sanitation have a deep-rooted origin. The practice of hygiene and sanitation is part of our daily life.
•    There are differences between hygiene, sanitation and environmental health. While hygiene focuses on individual personal hygiene/cleanliness, sanitation often refers to waste management, and environmental health has a broader meaning beyond hygiene and sanitation, referring to where we live, work and play. The focus of environmental health is on how environmental risk factors affect human health.
•    Environmental health plays a major role in the prevention and control of communicable diseases caused by pathogens, such as diarrhoea, and other diseases and conditions, such as chronic obstructive pulmonary disease caused through inhalation of air pollution.
•    There are various environmental health risks that affect our health. These include water and air pollution, food contamination and the disposal of wastes into our environment.
•    The interaction between humans and the environment has various forms. Urbanisation, industrialisation and development are the major forms of interaction. We should remember and try to control the disadvantages of development and not focus only on the benefits.
•    Environmental health planning requires you to gain knowledge of problems in your area and to identify needs and gaps, to set priorities and find resources to solve the problems.
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