a) Cholera
It can be prevented by Hygiene sanitary condition, intake of oral rehydration soulution. (ORS).
b) Typhoid
It can be prevented by preventing contamination of food by flies and dust improvement of basic sanitation, treatment with antibiotic drugs.
c) Hepatitis A:
It can be prevented by, prevention of food contamination drinking chlorinated boiled water, personal hygiene.

a) Common cold, Influenza.
b) Viruses exhibit both living and nonliving characters.
They can live on plants; animals, human being and even bacteria and can be easily transmitted from one host to another.

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.

Tuberculosis
Causative Agent: Mycobacterium tuberculosis
Mode of entry: Droplet infection from sputum of infected persons.
Organ affected in severe cases: Lungs
Symptoms: Persistent cough, Chest pain, Loss of weight and appetite.
Treatment: Infected person has to be treated with anti-tuberculosis drugs for a period of 6 months to one year.

1. Prevention of mosquito bites by using mosquito nets, mosquito screens, mosquito repellents and ointments.
2. Elimination of breeding places by providing adequate sanitation, underground waste water disposable system and drainage of stagnant water. 
3. Collection of water in any uncovered container such as water tank, pots, flower pots discarded tyres should be avoided.
4. Control of mosquito larvae by spraying oil on stagnated water bodies.
5. Adult mosquitoes can be killed by spraying insecticides.
6. Application of citronella oil or Eucalyptus oil on the exposed skin.

Endemic:
When the disease is found in certain geographical area affecting a fewer number of people. Eg. Occurance of goitre in Sub Himalayan regions.
Epidemic:
When the disease breaks out and affects large number of people in a particular geographical region and spreads at the same time. Eg. Influenza
Pandemic:
When the disease is widely distributed on a global scale.
Eg. Acquired Immuno Deficiency Syndrome
Sporadic:
When there is an occasional occurance of disease.
Eg. Malaria and cholera.