Human Health and Disease

Public health measures to safeguard against infectious diseases include:
- Proper disposal of waste and excreta
- Periodic cleaning and disinfection of water reservoirs, pools, cesspools and tanks
- Observing standard hygiene practices in public catering
- For air-borne diseases, avoiding close contact with infected persons or their belongings
- For vector-borne diseases, controlling or eliminating vectors and their breeding places by:
- avoiding stagnation of water around homes
- regular cleaning of coolers
- using mosquito nets
- introducing fishes like Gambusia in ponds
- spraying insecticides in ditches, drainage areas and swamps
- providing wire mesh on doors and windows
- Maintaining personal hygiene and clean food and water
- Vaccination/immunisation against infectious diseases

The study of biology has helped control infectious diseases by giving us knowledge of pathogens, their transmission, prevention and treatment. It has led to:
- development of vaccines and immunisation programmes
- discovery of antibiotics and other drugs
- better understanding of personal and public hygiene
- control of vectors like mosquitoes
- safer diagnostic techniques and newer vaccines through biotechnology
These advances have helped eradicate or control diseases like smallpox, polio, diphtheria, pneumonia and tetanus.

Amoebiasis is transmitted through food and water contaminated by faecal matter. Houseflies act as mechanical carriers and transfer the parasite from the faeces of an infected person to food and food products.

Malaria is transmitted when an infected female Anopheles mosquito bites a human and introduces sporozoites into the body.

Ascariasis is transmitted when a healthy person eats or drinks contaminated water, vegetables or fruits that contain the eggs of Ascaris from infected faeces.

Pneumonia spreads by inhaling droplets/aerosols released by an infected person, or by sharing glasses and utensils with an infected person.

To prevent water-borne diseases, one should:
- drink clean, safe water
- ensure proper disposal of waste and excreta
- keep water sources clean by periodic cleaning and disinfection of tanks, reservoirs and similar sources
- avoid contamination of food and water with faecal matter
These measures help prevent diseases such as typhoid, amoebiasis and ascariasis.

The chapter states that the primary lymphoid organs are bone marrow and thymus. The secondary lymphoid organs include spleen, lymph nodes, tonsils, Peyer's patches of small intestine and appendix.

MALT stands for mucosa-associated lymphoid tissue.

CMI stands for cell-mediated immunity.

AIDS stands for Acquired Immuno Deficiency Syndrome.

NACO stands for National AIDS Control Organisation.