The term " Salmonellosis" refers to a complex group of food borne infection affecting both man and animals. It is also called as "Food Poisoning". If this disease is affected it causes even death in humans. This disease also creates large destruction in animal and food industries.
Salmonellosis or food poisoning is a global problem. Developed, developing and underdeveloped counties alike are affected by this disease. From the all reported cases, Human Salmonellosis represents 60-80 percent.
Problem of Salmonellosis:
The problem of other Salmonellosis infections had been reported in the developed counties while the incidence of typhoid fever has declined. The main cause of the problem is due to the widespread use of animal feeds containing antimicrobial drugs that favor drug-resistant salmonellae and their potential transmission to humans. The main source of this disease is food contaminated and it can be occurred sporadically or in small outbreaks in the main population. The extension of this problem is not found out yet in developing countries.
Agent factors:
According to research it is found out that Salmonellae comprise of a wide and important group of bacteria. It is now known to comprise more than 2200 serotypes capable of infecting humans. But in the case of most countries, only a few number of them are endemic at any one time.
Salmonellae are resistant to various environmental factors like drying, salting, smoking, and freezing even four years. This is why they can survive in many kinds of food. As a result of this, salmonellae have been isolated from divergent foods such as chocolates, biscuits, coconuts and spices. The bacterium is sensitive to heat and it cannot survive heat above 70 deg C.
Classification of salmonellae:
From an epidemiological side, salmonellae can be classified in to three main groups:
1) Salmonellae which infects only man- e.g.: S. typhi, S. paratyphi A and C.
2) Salmonellae that is host-adapted for particular species of animals, e.g.: S. cholera-suis in swine, S. Dublin in cattle, S. abortus equi in horses, S. gallinaum in paultry, etc.
3) Salmonellae with no particular host preference and can infect both man and animals. E.g.: S. typhimuium, S. Enteritidis. It can be exchanged from man to animals and vice versa. The responsibility of 50 per cent o more of all human salmonella infections all over the world goes to S. typhimurium.
Main sources of infection:
The main sources of the infecting agent could be contaminated food, animals, man or the environment. Let us examine them in detail:
a) Foods:
Foods that we receive from animals, especially commercially prepared foods such as meat, poultry and egg products are considered to be the primary sources of salmonellosis. Most of these foods, e.g.: meat and poultry become contaminated during slaughter. And every food that is produced in a contaminated situation may also become contaminated. Examples of such products are chocolates, spices, and coconut. And the cross- contaminated cooked foods from raw ingredients, kitchen utensils, or surfaces has also been described as cause of salmonellosis. Recent researches shows that salmonellae may penetrate the ovaries of egg-laying chickens. The food items which carries salmonellae is varied from county to country. For example, in USA, it is the beef act as the main source of salmonellae infection, but, at the same time in England and Wales the duty is undertaken by poultry. It is in poultry that more than 50 percent of Salmonellosis outbreaks.
b) Animals:
Animals are the principle vectors and hosts of zoonotic salmonellosis. Many animals like cattle, rodents, swine and fowl are naturally infected with a wide range of salmonellae and have the bacilli in their tissue (meat), eggs or excreta. Carriers occur among both man and animals.
c) Environment:
In the environment, dust, water, manure, sewage, sludge, vegetables, insects, birds, fish, rodents, and other mammals distributes Salmonellae. Man may be infected by these sources.
How Salmonellae is transmitted?
Salmonellae can be infected by the following ways:
1) By ingestion of contaminated food or drink.
2) By direct contract with domestic animals especially such as, dogs, pigeons, rats, mice and insects.
When man is infected by Salmonellae, he becomes source of the infection and in this way spread to others.
Prevention and control:
We should undertake the following steps to prevent Salmonellae.
1) Disease controls like immunization of farm animals against Salmonellosis
2) The use of hygienic animal feed
3) Ensuring a sanitary environment for the animals.
4) To take all other precautions to raise a "Salmonellae-free" animals.
5) Hygienic slaughtering and milking
6) Pasteurization of milk and eggs
7) Proper disposal of liquid and solid wastes
8) Health education and training.
Since the health sector alone cannot solve the problem of salmonellosis, responsibility for prevention and control measures may fall to agriculture, veterinary and other ministries, outside the health sector.
