For health professionals: Listeriosis (Listeria)
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What health professionals need to know about listeriosis
Listeria monocytogenes is divided into 11 serovars. However, most human and animal cases are caused by serovars 4b, 1/2b and 1/2a.
Invasive listeriosis is a national notifiable disease. All health professionals are to report cases to their provincial or territorial public health authorities.
Most commonly, Listeria causes a mild febrile illness. However, several types of listeriosis disease manifestations are recognized, including:
- listeriosis in pregnancy
- listeriosis of the central nervous system
- febrile gastroenteritis
- glandular listeriosis
- local listeriosis
- typhoid listeriosis
- atypical listeriosis
Listeriosis in pregnancy
This occurs mostly during the third trimester. It is characterized by a flu-like illness with symptoms such as:
- back pain
In many cases, the infection is subclinical or inapparent. However, intrauterine infection of the fetus can lead to:
- fetal death
- premature delivery
- spontaneous abortion
- birth of a fetus that dies shortly after birth
Surviving newborns with listeriosis are often classified as early onset or late onset.
Early onset neonatal listeriosis due to transplacental infection often presents as pneumonia and sepsis. Severe disease can result in widespread granulomas (granulomatosis infantisepticum).
Late onset neonatal listeriosis is said to occur from infection during birth. Neonates show symptoms of meningitis 1 to several weeks after birth. In both early and late onset neonatal listeriosis, the mortality rate ranges from 20% to 30%.
Listeriosis of the central nervous system
Meningitis is the most frequently recognized listerial infection. Common symptoms of listeriosis of the central nervous system include:
- high fever
- nuchal rigidity
- tremor or ataxia
The most common non-meningitic form of central nervous system listeriosis is encephalitis involving the brainstem (rhombencephalitis).
A non-invasive form of listeriosis that manifests as symptoms typical of gastroenteritis, for example:
This resembles infectious mononucleosis with swelling of the salivary glands and nuchal lymph nodes.
This can manifest as papules and pustules on the hands and arms following direct contact with infectious material. It can be accompanied by these constitutional symptoms:
This is characterized by high fever and is particularly frequent in immunocompromised individuals.
Rare cases of atypical listeriosis have been described with symptoms such as:
- purulent (mononuclear) pleural exudates
Listeriosis can be diagnosed in the laboratory by:
- cultivation of the organism
- demonstration of the infectious agent or its products in tissues or body fluids
Several commercially available kits exist for the detection of Listeria monocytogenes. These rapid procedures are based on enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR) technology. However, none have been validated for use as a diagnostic tool.
Antibiotics are the primary choice of therapy for treatment for human listeriosis.
Health professionals in Canada play a critical role in identifying and reporting cases of listeriosis. See the surveillance of listeriosis section for more information on surveillance in Canada.
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