Food-borne Disease

Food-borne Disease a disease acquired by the ingestion of food contaminated with pathogens, usually bacteria and their toxins. Incidence of food-borne diseases are common in many developing countries where public health and sanitation facilities are inadequate. Incidence of food-borne diseases may be grouped under three categories: parasitic infection, chemical contamination, and natural food poison. Microbiological agents, especially bacteria, are probably the most common cause of food borne diseases. Other agents of food borne diseases include parasitic worms (helminths), toxins in animals, chemical residues, environmental pollutants, cleaning agents, disinfectants, etc.

In Bangladesh, foods of animal origin are the primary sources of many pathogenic microorganisms. The diseases found in a live animal can be carried through and may persist through further processing and may ultimately appear in the final products if insufficient attention is paid to public sanitation, hygiene and process control. During laying, eggs may be contaminated by Salmonella. Milk may be contaminated from cow dung from dairy environment, and equipment. Incidence of contamination of country wine is very common and death rate from the intake of these contaminated wines is high. Fish and shellfish may become contaminated either from the water from where they are caught or from the environment during further processing.

Table Principal microorganisms associated with food-borne diseases.

Microorganism Food sources Incubation period (h) Duration Diseases
Salmonella species Raw meat, poultry, milk and egg 12-26 1-7 days D, Abp, V, F
Staphylococcus aureus Cold meats and dairy products 2-6 6-24 h N,V,D, Abp, dehydration
Clostridium perfringens Raw meat, poultry, dried foods, herbs, spices, vegetables 8-22 24-48 h D, Abp, N
C. botulinum Improperly preserved meat, fish,  vegetables 12-96 (Usually 18-36) Death in 24 to 8 days

Lassitude, fatigue, dizziness, D followed by C, CNS

Bacillus cereus and other Bacillus species Cereals, dried foods, dairy products, meat and meat products, herbs, spices vegetables 1-6 6-24 h N, V, D
Escherichia coli Many raw foods, particularly of animal origin 17-72 1-7 days D with blood and mucus, V, D, Abp, Dehydration
Vibrio cholera Water and under processed foods 2-48h 2-5 days D, Abp, V, F, dehydration
Vibrio parahaemolyticus Raw and cooked fish, shell fish and other seafoods 2-48 2-5 days D and enteritis Abp, V, D
Yersinia enterocolitica Raw meat and poultry, meat products, milk and milk products, vegetables 24-36 3-5 days F, headache, Abp, D with blood and mucus
Streptococcus species Raw milk, raw meat and poultry, food prepared by infected food handlers 3-22 24-48 h ---
Compylobacter jejuni Raw poultry meat, raw or inadequately heat-treated milk, untreated water 3-5 days Days or weeks Typhoid fever
Viruses Raw shellfish, cold foods prepared by contaminated food handlers, water, meat, poultry, soft cheese and other dairy products, vegetables, shellfish -- -- --
Listeria monocytogenes 1-70 days Days to years mortality rate 30% Mild, flu-like illness, septicemia, meningitis, abortion

[D- Diarrhoea, N- Nausea, Abp- Abdominal pain, C- Constipation, F- Fever, V- Vomiting, CNS- Central Nervous System.]

Most of the pathogens may be destroyed with heat treatment during cooking. But contamination after cooking may cause disorders. Spores of some microbes are extremely heat resistant. The toxins produced by bacteria vary in their ability to withstand heat. The toxins of Clostridium botulinum are heat labile and are readily destroyed by boiling, while some of the enterotoxins produced by Staphylococcus aureus and Bacillus cereus are very resistant to heat. Handling of food after heat treatment allows entry of a wide range of organisms, many of whom can multiply at refrigeration temperature. The food handler may also transfer organisms to food. The organism commonly carried by the nose and the skin can easily be transferred to food through handling.

Food poisoning by chemical agents and environmental pollutants are common in Bangladesh. The sources of chemical contamination include fungicides, herbicides, insecticides, and other agrochemicals. The main clinical manifestation of chemical contamination is vomiting within a few minutes to half an hour of ingestion of contaminated food. Environmental pollutants like lead and other heavy metals can cause long lasting effects on consumers. [M Kabirullah]

See also diarrhoeal diseases; malnutrition; typhoid.