Today, we will tackle a deadly food-borne disease that is sweeping South Africa, infecting 557 people and killing at least 36.
Our Disease In Focus Today is Listeriosis. - a bacterial infection most commonly caused by Listeria monocytogenes, although L. ivanovii and L. grayi have been reported in certain cases.
It is food-poisoning that can cause infections of the Central Nervous System (CNS) such as meningitis, meningoencephalitis, brain abscess, and cerebritis. In people with compromised immune system, Listeria can cause bacteremia or the presence of bacteria in the blood.
Listeriosis dates back approximately 60 years and is known for causing epidemics and isolated cases in some 50 species of animals but there has been increased frequency in human infections over the years. It mainly affects pregnant women, newborns, the elderly, and adults with impaired immune systems. In the US, about 1600 people gets infected annually resulting in 260 deaths.
Electron micrograph of a flagellated Listeria monocytogenes bacterium, Magnified 41,250X, by Elizabeth White, via Wikimedia
Symptoms and Transmission
Symptoms of listeria vary depending on the health condition of the patient. Pregnant women may experience fever and other flu-like symptoms such as fatigue and muscle aches. Infections during pregnancy can lead to miscarriage, stillbirth, premature delivery, or life-threatening infection of the newborn.
In other high risk groups excluding pregnant women (newborn, elderlies, and immunocompromised), symptoms include headache, stiff neck, confusion, loss of balance, and convulsions in addition to fever and muscle aches. Older adults with weak immune system my develop invasive infection such as sepsis, meningitis, and meningoencephalitis.
Healthy people usually have diarrhea and fever and may recover without major treatment as the symptoms will go away after few weeks.
Listeria can be found in the soil and water and it can be transmitted by vegetables and livestock. Crops can be contaminated from the soil or manure given as fertilizer and may carry and transmit the bacteria if not properly prepared or cooked. Livestock meat and milk can also be contaminated. Food that have high risk of contamination include unpasteurized or raw milk, cheese, processed meat, fruits, vegetables, and seafood.
Listeria usually transmitted by eating contaminated food. It can also be transmitted by mothers to babies during pregnancy. In rare cases, it is transmitted by direct contact to animals usually by veterinarians or farmers.
Diagnosis and Treatment
Listeriosis can be diagnosed following a review of medical history and by conducting a physical exam. A review of symptoms and recent food intake will be analyzed. In severe cases leading to Central Nervous System infection, a lab test that isolates Listeria from the blood or cerebrospinal fluid will be done.
Treatment varies depending on the severity of the infection. Healthy people generally recover without treatment although they might be given medicine for their fever or diarrhea.
Listeriosis is treated with antibiotics with Ampicillin as the generally preferred. In pregnant women, a high-dose (6g / day ) of intravenous Ampicillin for 14 days is the preferred treatment. This may be supplemented by gentamicin. Women who are allergic to ampicillin or penicillin or both are given trimethoprim with sulfamethoxazole for 14 days.
High-risk patients that developed invasive infections require specific treatment. Bacteremia requires 2 weeks of treatment and meningitis needs 3 weeks. Brain abscess requires at least 6 weeks of treatment.
Prevention
Since Listeria is naturally present in our environment, infection can be greatly avoided by basic hygiene and proper food preparation. Proper handwashing before and after preparing food will cut the risk. Separating meat, fish, and poultry from other food will lessen the transmission. Food should be stored, prepared and cooked properly. Food storages and kitchen utensils should be kept clean. Keeping refrigerators at 40°F (4°C) or colder is advised. Fruits and vegetables should be washed under running water.
For pregnant women, it is advised to avoid the following food: unheated hot dogs, luncheon meat, and deli meats; unpasteurized milk or cheese or any food made with unpasteurized milk; refrigerated pâté or meat spread; refrigerated smoked seafood including salmon, trout, whitefish, cod, tuna, and mackerel.
Previously on Disease in Focus:
Scarlet Fever
Norovirus
Sepsis
Gonorrhea
Disclaimer: Disease in Focus is written to provide general information but should not be used as basis for diagnosis and treatment. If you have symptoms of any disease discussed here, please seek advice from medical professionals.
Sources: Wikipedia | WebMD | CDC | About Listeria | NCBI | ACOG |
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