According to the World Health Organization, salmonella bacteria are one of the most common causes of foodborne illness around the world. In the United States alone, 40,000 cases are reported to the Centers for Disease Control (CDC) each year, although many more go unrecognized. Pregnant women are considered a special risk group for foodborne illness because of potential risks to the health of both mother and child.
Infection in Pregnant Women
Most salmonella subspecies, including the two most common variants--Salmonella Enteridis and Salmonella Typhimurium--produce "salmonellosis" which is a mild, self-limited gastroenteritis. Symptoms including fever, stomach cramps, nausea, vomiting and diarrhea typically appear within 12 to 72 hours of ingestion and resolve within 4 to 7 days. Antibiotics are required in less than 2 percent of cases. However, pregnant women are more difficult to treat because fluoroquinolones--the antibiotic of choice in salmonella infection--are associated with birth defects.
In rare cases, salmonella escapes the intestine to enter the bloodstream. Bloodstream infection may itself be fatal and can produce longer-term complications when salmonella leaves the bloodstream to infect other areas of the body. Longer-term complications of salmonella infections include infection of the heart valves and lining of the heart (endocarditis), the bone (osteomyelitis), the kidneys (pyelonephritis), brain abcess and Reiter's Syndrome, an autoimmune disease that produces chronic joint pain, eye irritation and urination problems. These complications appear to be more common in pregnant women, compared to other healthy adults.
Salmonella infection crosses the placenta and may produce severe disease and death in the fetus, even when maternal symptoms are mild. In a 2004 report in the Scandinavian Journal of Infectious Disease, a pregnant woman admitted at 25 weeks gestation for salmonella gastroenteritis underwent cesarean section for abnormal fetal heartbeat. Despite intensive medical intervention, the infant died four hours later from culture-proven salmonella bloodstream infection and infection-induced multi-system organ failure. Similarly, the May 2008 issue of Archives of Obstetrics and Gynecology described a case of spontaneous abortion at 16 weeks gestation, 1 week after resolution of mild maternal salmonella infection.
Salmonella infection in infants is well-known known to be severe, compared with adults. In infants who survive the acute illness, the effects may be lifelong, as in a case described in February 2006 in the journal Obstetrics and Gynecology. In that case, the infant survived with intensive medical care, but now exhibits signs of severe developmental delay.
Preventing Salmonella Infections
Many salmonella infections can be prevented through careful attention to food preparation and handling, and the avoidance of certain kinds of pets (reptiles and amphibians). The United States government now offers a food safety information portal that pools the resources of several federal agencies, including the CDC, Food and Drug Administration (FDA), U.S. Department of Agriculture (USDA) and others. The FDA, in particular, offers a consumer-friendly food safety education module designed specifically for moms-to-be (see Resources).
- Scandinavian Journal of Infectious Disease. Fatal transplacental infection with non-typhoidal Salmonella. Schloesser RL, Schaefer V, Groll AH. October 2004.
- Archives of Gynecology and Obstetrics. Salmonella Mississippi: a rare cause of second trimester miscarriage. Gyang A, Saunders M. May 2008.
- Obstetrics and Gynecology. Alerting pregnant women to the risk of reptile-associated salmonellosis. Milstone AM. February 2006.