Nutrition & Diseases — PPSC previous year questions

Silicosis is an occupational lung disease (a pneumoconiosis) caused by prolonged inhalation of fine crystalline silica dust, which scars the lung tissue and causes fibrosis and breathlessness. It is common among workers in mining, quarrying, stone-cutting, sand-blasting and glass and ceramic industries, and in India it has been reported widely among agate, slate-pencil and stone-crusher workers. It is incurable and increases the risk of tuberculosis, so prevention through dust control is key.

Rotavirus is the commonest cause of severe diarrhoea (gastro-enteritis) in infants and young children, and the oral rotavirus vaccine protects against it. India introduced the vaccine into the Universal Immunisation Programme in 2016, initially in four states, and expanded it nationwide by 2019. Malaria has a separate vaccine (RTS,S), tuberculosis is prevented by BCG, and there is no licensed HIV vaccine.

Malaria is caused by protozoan parasites of the genus Plasmodium (P. vivax, P. falciparum, P. malariae, P. ovale), transmitted by the bite of the female Anopheles mosquito, so it is neither bacterial, fungal nor viral. Ronald Ross identified the mosquito vector in 1897.

Mosquitoes transmit dengue fever, yellow fever and viral (Japanese) encephalitis. Aedes aegypti spreads dengue and yellow fever. Culex mosquitoes spread Japanese encephalitis. Each of the other groups holds a non-mosquito disease. Poliomyelitis spreads through contaminated food and water. Ancylostomiasis (hookworm) and ascariasis (roundworm) are soil-transmitted worm infections. Ringworm is a fungal skin infection.

Dental caries (tooth decay) is caused by bacteria such as Streptococcus mutans and Lactobacillus that ferment sugars on the tooth surface, producing acids which dissolve the enamel. It is not viral or hereditary, though diet and hygiene affect its severity.

Diabetes mellitus is a non-communicable (lifestyle/metabolic) disease caused by deficient insulin production or action — it does not spread from person to person. Tuberculosis is caused by the bacterium Mycobacterium tuberculosis, HIV/AIDS by the human immunodeficiency virus, and influenza by influenza viruses — all infectious. World Diabetes Day is observed on 14 November, the birthday of insulin co-discoverer Frederick Banting.

Vitamin K is essential for blood clotting — it is required by the liver to synthesise prothrombin and other clotting factors (II, VII, IX, X); its deficiency causes prolonged bleeding. It is fat-soluble and found in green leafy vegetables and is also made by gut bacteria. Vitamin C deficiency causes scurvy, vitamin D deficiency rickets/osteomalacia, and vitamin B12 deficiency pernicious anaemia.

Diphtheria is caused by a bacterium (Corynebacterium diphtheriae) and kala-azar by a protozoan (Leishmania), so pairs 1 and 4 are correct. Measles is a viral disease, not fungal, and cholera is caused by the bacterium Vibrio cholerae, not a virus.

Statement 1 is true: polio, rabies and influenza are viral, while diphtheria is caused by the bacterium Corynebacterium diphtheriae. Statement 2 is false: the NVBDCP covers malaria, dengue, chikungunya, Japanese encephalitis, lymphatic filariasis and kala-azar, so kala-azar is included and polio is the one left out. Statement 3 is true: diabetes is a non-communicable metabolic disorder, unlike TB, HIV/AIDS and influenza. That gives True, False, True.

Vitamin K is essential for the synthesis of prothrombin and other clotting factors, so its deficiency delays blood clotting. Xerophthalmia — drying of the conjunctiva and cornea that can progress to night blindness and keratomalacia — is caused by deficiency of vitamin A. Vitamin B12 deficiency causes pernicious anaemia, vitamin C deficiency scurvy and vitamin D deficiency rickets.