Human Health And Disease

Plasmodium falciparum is the greatest killer of human beings over most parts of Africa and else where in tropics. It causes malignant (or pernicious or cerebral or tropical) tertian malaria. This malaria is most harmful. Plasmodium vivax causes benign tertian malaria. Plasmodium malariae causes quartan malaria. Plasmodium ovale is the rarest of the four species which infect man and it causes mild tertian malaria.

Filariasis also called elephantiasis is caused by Wuchereria bancrofti or filarial worm. It spreads by bite of Culex mosquito.

Ascaris has no intermediate host and man acquires infection by directly ingesting Ascaris eggs containing the infective second stage rhabditoid larva with contaminated food or water.

In passive immunity, antibodies from one individual are passed into another individual. They give immediate protection unlike active immunity which takes a few days or weeks to build up. However, it only provides protection against infection for a few weeks.

T- lymphocytes develop in bone marrow from lymphatic stem cells and then young lymphocytes migrate in the thymus. Afterwards, they pass on to all the lymphoid tissues of the body and get lodged there.

Immunoglobulin M (IgM) is the largest Ig and accounts for 5 - 10%ofthe total serum IgS- It is the first Ig produced in a primary response to an antigen and is frequently seen in the immune responses to andgenically complex organisms like viruses and bacteria.

Tuberculosis, commonly called TB is a very serious disease. About half a million people die of this disease each year in our country. It is caused by rod-shaped bacterium named Mycobacterium tuberculosis. It commonly affects the lungs, where small tubercles are formed but may attack any part of the body, including the brain, symptoms of pulmonary tuberculosis are fever, cough, blood containing sputum etc. BCG vaccine gives considerable protection against tuberculosis. Cholera is caused by Vibrio cholerae. It spreads through contaminated food and water. Typhoid is a bacterial disease and caused by Salmonella typhi. It spreads through contaminated water and food.

Typhoid fever is an infection of the digestive system by the bacterium Salmonella typhi. It is transmitted through food or drinking water contaminated by the faeces or urine of patients or carriers. Housefly carries the causative organism of typhoid on the legs and mouth parts from faeces or urine to food and drinks.

Answer (d) Both A and B

Humoral immunity is due to B-lymphocyte because it secretes antibody in the blood plasma.

Basophil is not a phagocytic cell. They accumulate at the site of allergic reactions and release histamine.

Carcinoma refers to the malignant tumours or cancer of epidermal/epithelial tissues. e.g., breast cancer, skin cancer, lung cancer, glands cancer etc. Sarcoma is the cancer of mesodermal or connective tissues such as cancer of bone (osteoma), cancer of adipose tissue (lipoma) cancer of lymph vessels (lymphoma). Blood cancer is also known as leukaemia.

The release of merozoites ofPlasmodium by the rupture of erythrocytes is accompanied by the liberation of toxic heamozoin or melanin panicles that produce shivering and then fever.

Wucherena or filarial worm is a diagenetic parasite. Its primary host is human and Culex mosquito is the intermediate host. When a mosquito bites an infected person, microfilarial or first stage juvenile are picked up. Inside the mosquito muscles, microfilariae transform into infectious parasite or third stage juvenile which are deposited near the site of mosquito. When this mosquito bites a healthy person, third stage juvenile or infectious parasite penetrates through the punctured skin and reach the human lymphatic system.

Sand fly takes a blood meal and injec s m crophages infected with amastigotes Amastigotes transform into promastigote stage in midgut Divide in midgut and migrate to proboscis Amastigotes again get transferred into the skin of host during taking blood as meal.

Human is considered as the intermediate host or secondary host because the parasite performs its asexual cycle within human in medicine. In zoology or biological science mosquito is the intermediate host

Fetus receives antibody from mother through the placenta so, it is naturally acquired passive immunity.

The slender microfilariae, 150-300 pm in length, are commonly found in the circulating blood or lymph of patients suffering from an infection with any of the filarial worms, e.g., Wuchereria. They mature into larvae, which are infective, within the body of a blood sucking insect, such as a Culex mosquito.

Yersinia pestis which is a gram negative bacterium that is responsible for causing plague. There are three forms of plague that are bubonic, septicemic and pneumonic. Of these bubonic plague is the most common form of plague that is transmitted through the bite of infected fleas.