Food poisoning may be of the following two types:
Non–bacterial
It is caused by chemicals such as arsenic, certain plant and sea foods, etc. In recent years, there has been a growing concern about contamination of food by chemicals, eg. fertilizers, pesticides, cadmium and mercury.

Bacterial
It is caused by the ingestion of foods contaminated by living bacteria or their toxins. The conventional classification of bacterial food poisoning into toxic and infective types is becoming increasingly blurred with the knowledge that in some types, both multiplication and toxin production are involved.

Bacterial food poisoning may be of the following types:
Salmonella Food Poisoning
An extremely common form of food poisoning. The following reasons have been indicated for its increase in recent years:
An increase in communal feeding.

Source
Salmonellosis is primarily a disease of animals. Humans contract the infection from farm animals and poultry – through contaminated meat, milk and milk products, sausages, custards, egg and egg products. Rats and mice are another source; they are often heavily infected and contaminate foodstuffs by their urine and feces. Temporary human carriers can also contribute to the problem.

Incubation Period
About 12–24 hours, commonly.

Mechanism of Food Poisoning
The causative organisms, on ingestion, multiply in the intestine and give rise to acute enteritis and colitis. The onset is generally sudden with chills, fever, nausea, vomiting, and a profuse watery diarrhea which usually lasts for 2–3 days. The mortality rate is about 1 per cent. A convalescent carrier state lasting for several weeks may occur.