Listeria monocytogenes is a food-borne pathogen of special concern for pregnant women, because infection increases the risk for adverse pregnancy outcomes such as preterm labor, spontaneous abortion, and stillbirth. Hormonal changes occurring during pregnancy decrease cell-mediated immune function, thus increasing the susceptibility of pregnant women to certain types of infections. Febrile gastroenteritis, central nervous system (CNS) symptoms, and bacteremia are possible clinical manifestations of listerial infection in pregnancy. In the past 20 years, epidemics of listeriosis have led to increased public awareness. Increased surveillance of potential sources of contamination has reduced the frequency of outbreaks of listeriosis; however, the incidence in pregnant women remains about 20 times higher than the general population. There are approximately 2500 cases of severe listeriosis reported each year in the United States, causing 500 deaths. Pregnant women represent one-third of all confirmed cases. The real incidence of listeriosis in pregnancy is likely to be higher, because the reported cases are confirmed invasive infections. The actual teratogenicity of listeriosis in pregnancy is unknown because most of the reported cases involve maternal or fetal death. The mortality rate of affected individuals is between 20% and 36%. Physicians have an important role in teaching preventive measures to pregnant women to reduce maternal, fetal, and neonatal morbidity and mortality.
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