Listeriosis is a bacterial infection that can affect many animals, as well as people and birds. In adult sheep, goats, and cattle, it often causes a serious brain infection.
Listeriosis can be found all over the world, but it is more common in cooler climates. Many animals can carry the bacteria in their digestive tracts without looking sick.
The bacteria that cause listeriosis, Listeria monocytogenes, live in soil and in the digestive tracts of mammals. Soil, plants, and animal feed can become contaminated, and animals can get infected when they eat or breathe in the bacteria. Infections occur most often during winter and spring.
Animals usually get listeriosis from eating contaminated feed, especially silage (stored fermented green plant crops), or by breathing in the bacteria. Bacteria can also spread from one animal to another through feed contaminated with feces. After entering the body, the bacteria often attack the brain, digestive system, and placenta.
People can get listeriosis by eating unpasteurized dairy products, soft cheeses, or meat that has not been cooked well enough. Smoked or preserved meats and fish, such as smoked salmon, can also carry the bacteria. People can also become infected by handling dead animals that were infected.
Symptoms of Listeriosis in Animals
Brain Infection in Listeriosis
This form of listeriosis is common in sheep, cattle, goats, and pigs of any age. In sheep and goats, death can happen within 24–48 hours after infection. In cattle, the disease can develop more slowly. The infection often affects nerves on one side of the face, causing partial paralysis (inability to move). Animals can seem weak and might walk in circles.
Common signs include:
leaning to one side
walking in circles
drooping ear
facial paralysis
heavy drooling
unusual running movements while lying on one side
Body-Wide Infection in Listeriosis
This form of listeriosis occurs in pigs, dogs, cats, rabbits, and other small mammals. It can affect many bodily organs but most often damages the liver.
Uterine Infection in Listeriosis
All mammals can experience listeriosis with a uterine infection during pregnancy. It can lead to:
abortion
stillbirth
death of newborns
infection of the uterus or placenta
The bacteria can also be released through vaginal secretions or milk for a month or longer. These problems usually occur during the last part of pregnancy.
Diagnosis and Treatment of Listeriosis
Listeriosis is diagnosed by testing for Listeria bacteria, usually with a bacterial culture or a lab test.
If treatment starts early, antibiotics can cure listeriosis in both animals and people. If the disease has already progressed, animals are less likely to recover. Penicillin is usually the main antibiotic used in animals, and oxytetracycline can also work well. Some animals might also need fluids and electrolytes if they're not able to eat or drink normally.
Prevention of Listeriosis
To help prevent listeriosis:
Keep infected animals away from healthy animals.
Avoid contact with infected animals unless you're wearing protective clothing.
Stop feeding silage if contamination is suspected.
Vaccines have not worked very well in animals.
Important Human Health Points Regarding Listeriosis
Listeriosis can spread from animals to people. Any part of an infected animal, or anything it produces, can carry the bacteria, including milk, meat, and cheese.
Pregnant women are at greater risk because the infection can cause miscarriage or abortion. People with weaker immune systems are also at higher risk, including infants, children, and adults over 65. These people should avoid raw milk, soft cheeses, preserved meats and fish, and contact with farm animals or other animals that might be infected.
For More Information
Also see professional content regarding listeriosis in animals.
