Clean boiled water with sugar and salt added to it is given to avoid dehydration of body tissues. Our body loses excess of water during stomach and intestinal infection due to loose stools. This happens during gastrointestinal disorder. In brain, kidney and liver disorders, our body does not lose excess of water and hence, the above said water + sugar + salt does not need to be administered.

During any accident, wounds occur and they are exposed to air and soil. The air and soil may contain tetanus-causing microbes. Hence, the person is immediately given anti-tetanus injection. 

A person will be healthy if he eats a proper diet (option 3), lives in a hygienic environment (option 4) and keeps his body fit by exercising regularly (option 1). Thus, options (1), (3) and (4) help a person to be healthy as these habits keep the germs away and thus, reduce the chances of getting infected by diseases. But, drinking alcohol is not a healthy practice as it adversely affects the nervous system and its prolonged consumption adversely affects the liver and general body health. Thus, (2) is the correct answer because drinking alcohol is responsible for the ill health of a person.

Most of the skin infections are caused by fungi. For example, ringworms. Bacteria and viruses cause internal infections like TB, influenza, etc. Mosquitoes can cause rashes on skin (it is not a disease) and may also transmit other diseases (not related to skin). Thus, (1), (2) and (3) are not suitable. So, only (4) is correct.

Trypanosoma is responsible for sleeping sickness.

Penicillin is an antibiotic obtained from the fungus ‘Penicillium notatum’ and it works against bacteria. Quinine and chloroquine are drugs that are used to treat malaria. Anti-tetanus serum is a vaccine used to prevent tetanus.

  Japanese encephalitis is brain fever. In this disease, there is an inflammation in the brain tissue and hence, it is called “encephalitis” [“cephalic” refers to brain and “encephalitis” means swelling of brain tissues].

Viruses do not have defined body structures or body physiologies. They use the machinery of host cells and live life on that. Hence, it is difficult to control them because we cannot prepare drugs to arrest any step of their physiology because those drugs will actually affect our own (host) cells and harm us. Hence, it is very difficult to prepare drugs against viruses. On the contrary, the physiologies of bacteria, fungi and protozoa are well known and the reactions are different from host cells. We can easily prepare drugs to attack those specific reactions.

When water sources, including private wells, are contaminated with faeces from infected humans, the water will spread the hepatitis A virus to others who drink this water. The virus can enter water supplies through sewage overflows or from broken sewage systems. This virus cannot travel through air and also does not spread by physical contact. An infected mother also cannot pass it on.

AIDS stands for Acquired Immuno Deficiency Syndrome. It is a disease in which a person’s immune system becomes weak and is unable to fight infections. Hence, the concerned person finally dies due to other infections like common cold, sore throat, flu, etc. At the last stage, the person suffers from physical trauma due to infection and inability to treat it.

Headache and unconsciousness are ailments related to the nervous system, i.e. they are related to the brain. Also, the brain has a part called medulla, which controls the stimuli for vomiting.

Hepatitis is the swelling and inflammation of the liver, most commonly caused by a viral infection. It may lead to liver damage, liver failure or even liver cancer.

An active immune system recruits many cells to the affected tissue to kill off the disease-causing microbes. This recruitment process is called inflammation.

(a) Acute diseases: These diseases are severe, but short-spanned and get less time to cause prolonged poor health. (b) Chronic diseases: These diseases last for longer periods of time and take sufficient time to affect different parts of the body and lead to a poor health, which recovers after a long time. (c) Infectious diseases: These diseases spread from a diseased person to a healthy person due to the transmission of disease-causing organisms (for example, common cold). (d) Non-infectious diseases: These diseases do not spread from one person to another. For example, heart ailment, cancer, etc. They are not caused by infectious agents. The causative agents of these diseases are internal factors.