Pneumonia spreads through air. It is an inflammatory condition of the lung affecting primarily the microscopic air sacs known as alveoli. 

Haemophilia is a disease in which the blood does not clot whenever there is a wound/injury and it is a genetic disorder. It is not caused or spread by infectious agents. Thus, it is a non-infectious disease. Cholera, typhoid and malaria are caused due to microorganisms, which cause infection or disease in the digestive system, immune system and blood (also liver), respectively.

Penicillin blocks the bacterial processes that build the cell wall.

DDT is an insecticide (“insect” + “cidal” – killing). It is used to kill a variety of insects and pests, particularly mosquitoes. It should be noted here that though DDT is useful but at the same time, it is a pollutant and hence, its use must be limited. Apart from DDT, all other options given here are vaccines and hence, they cannot be used to kill mosquitoes because their function is to give immunity inside our body. BCG is a vaccine against TB; ATS is Anti Tetanus Serum and DPT is a triple vaccine against diphtheria, pertusis and typhoid.

The second time, our immune system has memory cells which quickly identify the problem and counter it and thus, eliminate it. This is called immunisation. Immunisation is a method of prevention of disease or infection and it also helps to avoid the spreading of a disease.

Disease-causing organisms, i.e. causative agents are transferred from a diseased person to a healthy person by an organism which itself does not get the disease. Such an agent is called “vector”.

AIDS is a viral disease caused by HIV. The human body cannot develop immunity against it. The antibodies that human immune system makes to fight HIV are not effective. HIV actually targets, invades and then destroys some of the most important cells in the immune system itself. So, no vaccine is effective in preventing AIDS.  

Anthrax is a bacterial disease and can be cured with antibiotics. All the other are viral diseases and antibiotics are not effective against viral diseases.

Tuberculosis is a chronic disease as it can last for a long time, even as much as a lifetime.

Malaria is caused by a protozoan.

Rabies virus is carried by vectors, which contain the virus and transmit it from a diseased person to a healthy person. The vectors for rabies are animals (dogs and cats usually).

Health is a state of being well enough to function well physically, mentally and socially. An individual can be in poor health without having any identifiable disease.

SARS is a respiratory disease caused by a virus. Symptoms usually occur about 2 to 10 days after coming in contact with the virus.

Edward Jenner created the vaccine for smallpox two centuries ago.