Food Safety - Foodborne Viruses - Various types of virus have been reported to survive in food in a relatively long time span and cause disease in humans who consume them. Foodborne viruses typically measure 25-30 nm and the greatest reach 75 nm. Most viruses are transmitted through food contains genetic material, in the form of RNA. If foodborne viruses cause disease in humans, generally require long incubation time. This means that the range of consumption time and the onset of symptoms of the disease is long enough, so that the disease-causing food is quite difficult to trace.
Long time before pasteurization (heating at low temperatures to eliminate the bacteria Coxiella burnetti) was discovered and the application of good hygiene, humans may be hit by polio via polio virus that present in raw milk. Raw milk was first reported as polio virus carrier in the United States in 1914.
One of other important foodborne virus is hepatitis A virus. The virus that generally derived from human waste can contaminate water and sanitation if hygiene practices are not done properly, then the virus contaminate foods, particularly those not treated with heating or other cooking treatments. The incubation period of hepatitis A is 15-50 days, with an average of 28 days.
Shellfish is a kind of food most often associated with hepatitis A virus. Shellfish can contain this virus because (1) waters where the shellfish grow is contaminated by human fecal, (2) shellfish is a filter feeder, this leads virus to accumulate in the body of shellfish, (3) digestive tract of the shellfish is included to eat by human, (4) the shellfish is often not well cooked, (5) shellfish protects the virus during heating.
Norwalk-like viruses currently reported as the main cause of food poisoning due to foodborne viruses in the United States. Viruses, which exist in various serotypes cause gastroenteritis, characterized by diarrhea and vomiting with an incubation time of 18-36 hours. In the United States and Britain, salad is the food most frequently reported as a cause of food poisoning by Norwalk-like viruses.
Some viruses are zoonotic. The virus causes encephalitis, for example, can infect human who consume raw milk of goats, sheep or cows, that get the virus from insect bites. Therefore, the disease was then called tick-borne encephalitis.
In contrast to other microbes such as bacteria, viruses can not multiply in food. Therefore, the amount of virus in food will not increase, perhaps even decrease if the time span between contamination and the time when food consumed is long enough. This is because food is not a living thing that can support virus growth.