Don't pull the fire alarm before there's a fire. Read on before discounting the use of raw shrimp:
Listeria
Listeria is the common name for the pathogenic or disease-causing bacterium known as
Listeria monocytogenes. It is a foodborne illness that when ingested causes an infection known as listeriosis (Cossart & Bierne, 2001). Approximately 2,500 illnesses and 500 deaths are attributed to listeriosis in the United States annually (CDC, 2005).
Listeria is ubiquitous in the environment, and can be isolated from wild and domestic animals, birds, insects, soil, wastewater, and vegetation. The bacterium easily comes into contact with farm animals as it has been found to be present in grazing areas, stale water, and poorly prepared animal feed. In addition to being present in the environment,
Listeria can live in the intestines of humans, animals and birds for long periods of time without causing infection. Because
Listeria is present in nearly every environment - including in some food processing facilities - numerous opportunities for contamination exist during the food production process (Cossart & Bierne, 2001).
Healthcare providers frequently overlook
Listeria as a possible cause of illness due to its unusual growth capabilities. First, laboratories sometimes have a difficult time growing
Listeria. When it is grown,
Listeria can be confused with other less harmful contaminants and disregarded. Second, while most bacteria grow poorly when temperatures fall below 40°F,
Listeria survives at temperatures from below freezing to body temperature, and grows best at the 0°F to 50°F range, which includes the temperature range used for freezing and refrigeration.
Due to its unusual growth capabilities,
Listeria may be transferred in common ready-to-eat foods that have been kept properly refrigerated. Thus,
Listeria presents many challenges because of its ability to grow in diverse environments. These host factors, along with the amount of bacteria ingested and the virulence of the strain, determine the risk of disease.
Who is most susceptible to Listeria monocytogenes infection?
While the general public need not be especially concerned with preventing listeriosis, several segments of the population are at risk, and need to be informed of that risk so proper precautions can be taken to prevent listeriosis.
The bodys defense against
Listeria monocytogenes and other intracellular pathogens is called cell-mediated immunity because it depends on our cells (as opposed to our antibodies), especially lymphocytes called T-cells. Therefore, it is not surprising that individuals whose cell-mediated immunity is suppressed are more susceptible to the devastating effects of Listeriosis.
Pregnant women naturally have a depressed cell-mediated immune system; many think that this occurs so that the mothers immune system will not reject the fetus. In addition, the systems of fetuses and newborns are very immature; they are extremely susceptible to intracellular pathogens. Other adults, especially transplant recipients and lymphoma patients, are given necessary therapies with the specific intent of depressing immune T-cells, and these individuals become especially susceptible to
Listeria monocytogenes as well.
Pregnant women are about 20 times more likely than other healthy adults to contract listeriosis. About one-third of listeriosis cases happen during pregnancy. The incidence of listeriosis in the newborn is 8.6 per 100,000 live births (Tappero et al., 1995). There is no routine screening test for susceptibility to listeriosis during pregnancy, as there is for rubella and some other congenital infections. Newborns, rather than the pregnant women themselves, suffer the serious effects of infection in pregnancy.
In addition to pregnant women, fetuses, and newborns, persons with weakened immune systems due to treatment, particularly transplant recipients (Schuchat, et al., 1992) and persons receiving treatment for lymphoma, but also other cancer victims, are at significantly increased risk for
Listeria infection.
Further:
Epidemiology
Researchers have found L. monocytogenes in at least 37 mammalian species, both domesticated and feral, as well as in at least 17 species of birds and possibly in some species of fish and shellfish. Laboratories can isolate L. monocytogenes from soil, silage, and other environmental sources. L. monocytogenes is quite hardy and resists the deleterious effects of freezing, drying, and heat remarkably well for a bacterium that does not form spores. Most L. monocytogenes are pathogenic to some degree.
The more I read on this, the more I find that this pathogen is equally capable of being found in improperly handled boiled shrimp as it is in frozen raw shrimp. Increased risk exists in imported shrimp from Nigeria and Thailand. However, the demographic for this disease puts it at less cases than eye sores from birds dropping a load in someone's eye.
If you want to be completely safe, whether boiled or raw, boil the shrimp for a minute to reduce the risk of this pathogen (CDC test results).