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