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Disease Name: Listeria

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Please review the Idaho Reportable Disease Rules (IDAPA 16.02.10) for the most up-to-date information.

Listeria (Listeriosis): http://www.cdc.gov/listeria/diagnosis.html

Overview / Case Definition

Listeriosis is a relatively uncommon but important infection caused by Listeria monocytogenes, an aerobic, non-spore-forming, motile, gram positive bacillus. Most human infections (98%) are caused by serovar types 1/2a, 1/2b, 1/2c, and 4d. Listeriosis is most severe among neonates, the elderly, the immunocompromised, pregnant women, and those with other underlying medical conditions. Its principle clinical manifestation within these groups is bacteremia and CNS invasion (e.g., meningitis or meningoencephalitis). In individuals in which bacteremia occurs, the overall case-fatality rate among non-pregnant, untreated adults is approximately 30%; rates increase with age.

According to CDC, pregnant women are 20 times more likely and persons with AIDS are almost 300 times more likely to get listeriosis than other healthy adults. In pregnant women, infection may extend to the fetus; abortion or stillbirths are possible. The case fatality rate in newborns can be 20–30%. Within normal hosts, mild infection including febrile gastroenteritis is possible. There is little evidence of acquired immunity, even after a prolonged infection.

A person with listeriosis may experience fever, muscle aches, and sometimes gastrointestinal symptoms such as nausea or diarrhea. If infection spreads to the nervous system, symptoms such as headache, stiff neck, confusion, loss of balance, or convulsions can occur. According to CDC, manifestations are host-dependent. In elderly and immunocompromised persons, sepsis and meningitis are the main presentations. Pregnant women may experience a mild, flu-like illness followed by fetal loss or bacteremia and meningitis in their newborns. Immunocompetent persons may experience acute febrile gastroenteritis. A rare clinical manifestation is papular lesions.




Within 3 working days

Reportable by Healthcare and Labs:

Reportable by Food Service Facility:

Suspect Reportable:

Reporting Timeframe: Within 3 working days

Diagnosis / Testing

Though disease may be suspected from clinical findings, diagnosis can only be made through culture of the organism, typically from patient’s blood or CSF. Placental tissue and amniotic fluid may also be cultured in the case of spontaneous abortion or suspected neonatal infection. L. monocytogenes isolates should be sent to Idaho Bureau of Laboratories (IBL) for serovar determination.

IBL sampling and submission guide:  http://healthandwelfare.idaho.gov/Health/Labs/SamplingandSubmissionGuide/tabid/2223/Default.aspx


Additional Information

Listeria (Listeriosis): http://www.cdc.gov/listeria/diagnosis.html

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