Common causes of foodborne illness
Common Sources of Foodborne Illness.
Raw foods of animal origin are the foods most likely to be associated foodborne pathogens. Foods of most concern include raw meat and poultry, raw eggs, unpasteurized milk, and raw shellfish.
Foods that mingle the products of many individual animals, such as bulk raw milk, pooled raw eggs, or ground beef, are particularly hazardous because a pathogen present in any one of the animals may contaminate the whole batch.
A single hamburger may contain meat from hundreds of animals. A single restaurant omelet may contain eggs from hundreds of chickens. A glass of raw milk may contain milk from hundreds of cows. A broiler chicken carcass can be exposed to the drippings and juices of many thousands of other birds that went through the same cold water tank after slaughter.
Raw shellfish can be hazardous because their method of filter-feeding strains microbes from the sea over many months. If there are any pathogens in the seawater these will be filtered out and stored inside the shellfish.
Fruits and vegetables consumed raw are of particular concern. Washing can decrease but not eliminate contamination. Recently, a number of outbreaks have been traced to fresh fruits and vegetables that were processed under unsanitary conditions. These outbreaks show that the quality of the water used for washing and chilling the produce after it is harvested is critical. Using water that is not clean can contaminate many boxes of produce.
Fresh manure used to fertilize vegetables can also contaminate them.
Alfalfa sprouts and other raw sprouts pose a particular challenge, because
the conditions under which they are sprouted are ideal for growing microbes
as well as sprouts, and because they are often eaten raw. A few bacteria
present on the seeds of sprouts can grow to high numbers of pathogens
on the sprouts. Unpasteurized fruit juice can also be contaminated if
there are pathogens in or on the fruit that is used to make it.