Listeriosis

Definition:

A disease caused by infection with the organism Listeria monocytogenes.

Causes, incidence, and risk factors:

Listeria monocytogenes is found commonly in wild animals, domesticated animals, and in people who have close association with domestic animals such as slaughterhouse workers and dairy farmers. L. monocytogenes causes disease in many animals and is a common cause of spontaneous abortion and stillbirth in domestic animals. L. monocytogenes also occurs as a food-borne contaminant that can cause disease.

In the human, L. monocytogenes most often causes a generalized blood infection (septicemia) or meningitis (inflammation of the covering of the brain). The fetus, newborn, and pregnant women are particularly susceptible to L. monocytogenes. The immunocompromised people such as those being treated for cancer, those with organ transplants, and those with AIDS are at increased risk.

Infection of a pregnant woman early in pregnancy generally leads to spontaneous abortion. The organism may be transmitted across the placenta. Infections in late pregnancy may lead to stillbirth or an infant who dies within a few hours of birth. About half of infants infected at or near term will die.

Listeriosis may become evident in the first week of life with a red papular skin rash, petechiae, whitish nodules on the mucous membranes, loss of appetite, lethargy, jaundice, vomiting, respiratory distress, and shock. The death rate is very high.

Late-appearing infection in the infant (symptoms appear at age 2 weeks or older) and infection in children is often seen as meningitis. There are no special clinical signs to differentiate listerial meningitis from other types of meningitis.

In adults, the disease may take many forms depending on what organ or organ systems are infected. It may occur as meningitis, pneumonia, septicemia, and endocarditis or in milder form as abscesses, skin lesion, and conjunctivitis.