It is the time between infection and the first appearance of the diseases is called incubation period.

The reasons may be
i) Street foods are less hygiene, the conditions in which they are made are very bad.
ii) The worker who cooks and serve street food, do not wear gloves, do not wash hands and use the same hands to clean their sweat and wipe their body.
iii) Diseases spread through contaminated of food and water. Chaat may be contaminated by microbes due to its unhygiene preparation and handling.
This may be the reason Suresh fell ill and complained stomach ache.

1. In medical condition like diarrhoea the defecation process is increased. Whatever a body intakes, will be released out quickly.
2. Polio drops comprise of attenuated polio virus which when given, a large portion of !t needs to stay in the intestine for a long period to show its results.
3. If the patient is suffering of diarrhoea the transmit time in intestine becomes less and the opportunity for multiplication of virus is reduced. This leads to reduced efficacy of the polio vaccine is avoided to children suffering from diarrhoea.

Because Tuberculosis is a airborne disease and can spread through air when the patient coughs or sneezes if we stand close to him/her.

1. Yes, Chicken pox would not occur again for sanjay .
2. Because, once it occured, his body will derive immunity against that disease .
3. This kind of immunity is developed by our body, during the first infection of chicken pox pathogen .
4. The antibodies produced in the blood remain for a long period and kill the simile pathogens, whenever they enter the body.

Triple antigen is a combined vaccine for protection against Diphtheria, Pertussis (whooping cough) and Tetanus.

i) The vector of malarial parasite is female Anopheles mosquito.
ii) Malaria is caused by Plasmodium falciparum is malignant and fatal.

Possible causes: Infected by the virus through, contaminated food and water and oral route.
Possible solution: Proper sanitation and hygiene in the babies family.