Summer is associated with an increased occurrence of food-borne infections, food poisoning and spoilage of food caused by bacteria. In infectious diseases germs enter the body through food or water and cause infection in the gut. Whereas in case of food poisoning the toxin (toxic chemical) secreted by bacteria is ingested with the food. Food poisoning often has a rapid onset, while the onset of infection depends upon the number of organisms ingested, immunological status of the individual and the potential of organisms to cause disease (virulence factor).

The most common organisms that cause food borne diseases are Salmonella, Campylobacter, Shigella, E.coli 0157:H7. Disease symptoms vary depending on the type of causative agent. Diagnosis is reached at with the help of laboratory test.

These organisms infect individuals with or without symptoms of disease and stay in the body even after recovery from the disease. They are secreted by anal route and may spread to food when the carrier of the organisms handles food without properly washing hands after defecation.

The pathogens present in the intestine of human beings or animals are shed in the faeces and spread through direct contact. They can spread through vegetables grown in improperly processed manure. If the sewage is not discarded properly, it may contaminate the drinking water.

Drinking or washing with such water without using a good soap, can cause the pathogen to spread to food and other animals and humans.

Slaughterhouses are a high-risk place, especially if the intestines of the slaughtered animals and their faecal material is not discarded properly and people working there do not maintain good personal hygiene, e.g. do not wear apron and gloves while working, there is a chance that pathogens from faecal sources can stick to meat or poultry surface and increase in number under optimum conditions. The meat of a healthy animal is sterile (free from all type of micro-organism) but after slaughtering the micro-organism present in the surrounding gather on the surface. Storing the meat in partially frozen form helps the pathogens present on the surface to grow and increase the risk, particularly when the meat is thawed at room temperature and is consumed without appropriate cooking.

There are more chances of food-borne infections and food poisoning in summer because the replication time of most food-borne pathogen is so short that occasionally present micro-organism turn into larger populations without any change in appearance within hours when the food is kept at room temperature especially in warm places.

Decreasing the risk of food-borne illness a) Avoid prolonged storage

One way to minimise the risk is to cook freshly picked fruit, vegetable and freshly slaughtered meat and poultry. This will reduce the risk associated with temperature variation that provides an opportunity for micro-organisms to grow during prolonged storage.

b) Store at appropriate temperature. The most important thing is to refrigerate vegetable and fruit prone to spoilage at temperature around 5C, whereas meat, poultry and fish should be stored frozen at -18C. Avoid thawing the frozen meat, etc. at room temperature, as the present micro-organisms will get an opportunity to grow in the presence of nutritionally rich drip (juice) and develop into huge populations of pathogens many of which may escape cooking temperature and cause infection when consumed. It is advisable to thaw under cold water or in microwave and quickly cook after thawing.

Eggs should preferably be stored in the refrigerator in a separate box rather than in the door as it is warmer near the door. Eggs are occasionally contaminated with Salmonella which has good chances to grow under warmer temperature.

c) Cooking If the pathogens are few in number, they are killed during cooking. However, if the number of pathogens is high some of them can escape the cooking temperature. It is advisable to avoid interrupted cooking.

It is also advisable not to leave the cooked food for more than an hour or so at room temperature, especially in summer when temperature is more than 32 C. It is recommended to refrigerate the food or freeze it within an hour from cooking till use.

The left-overs that are properly refrigerated can be consumed within four days after heating.

d) Handling of high-risk food items. Fruits and vegetables may carry food-borne pathogens. The risk is higher if the water used in cultivation is contaminated with human or animal faeces or manure/fertiliser based on animal faeces.

It is important to wash the vegetables and fruits carefully, preferably using boiled water. Removing the outer leaves of cabbage and lettuce would help to get rid of pesticides and micro-organism.

The other high-risk food items include raw meat, poultry and eggs. It is important to keep meat and poultry frozen and to keep eggs refrigerated till use. It is important to discard cracked eggs. Raw food should be kept separate from cooked food.

e) Cleanliness
It is important to wash hands with warm water and soap for at least 20 seconds before and after handling any food item. Similarly, it is important to clean the sink, counter top and drain preferably by using chlorine water (one tablespoon of bleach in around a litre of water). The cutting board for meat, poultry and fish should be kept separate from that used for cutting vegetables. They need to be washed with warm water and soap every time after use.

f) Personal measures People handling the food should wear apron, gloves and head covers. People with any food-borne disease should avoid handling food till complete recovery.