Listeriosis: Disease that many think is witchcraft

Dear Daktari

I have a sheep ranch in Kisamis, Kajiado County. Due to the current drought, that has resulted in scarce pasture, I have been using silage which I prepared sometimes back on my farm using maize crops. About two weeks ago, two of my sheep started moving in circles in a confused manner. I was very scared when my farm hand told me about it. I was away but called in a vet who treated them and they recovered. Is this a case of witchcraft or what could have been the issue?

[Samuel Masankai, Kajiado County]

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Thanks Masankai for the question and for reading The Smart Harvest. When the central nervous system is hit by an infection, it will show clinical signs that you have described. No this is not witchcraft, but a normal animal disease and is treatable. So what could it be?

The right diagnosis

There are several diseases that manifest with central nervous signs. They include rabies, milk fever, ketosis in cattle, lead poisoning, brain abscesses and worms in the central nervous system. But your case looks like Listeriosis which is also called circling disease and can attack many animals including man.

What is Listeriosis?

Listeriosis is a bacterial disease that affects the central nervous system of ruminants. This bacterium is found in soils, animal intestinal tract and also in spoiled silage. In your case it is likely the source was from the silage which the sheep had just been fed on. Most likely it was spoiled hence the presence of Listeria monocytogenes. Listeriosis is common in feedlots or intensive systems.

How is the disease transmitted?

Listeriosis is easily transmitted from one sick animal to the other through inhalation of ingestion of the causative bacteria.

Sick animals shed the bacteria in urine and faeces and contaminate the drinking water, pasture, hay or silage. Once ingested, the bacteria goes through the membranes of the digestive tract and into the animal’s body system.

What are the clinical signs?

Listeriosis can attack cattle, sheep, poultry, pigs, dogs, cats, rabbits and each of this will display a wide range clinical signs.

Ruminants like cattle and shoats will show nervous signs while monogastrics like pigs, dogs and cats will suffer damage to the heart and liver. Abortions, newborn deaths will be observed in all susceptible species.

Typically, in sheep and goats the animals will go off feeds, will tilt their heads, appear disoriented and will move in circles hence the name circling disease.

If not treated, it will progress to facial paralysis.

The paralysis in most cases affects one side of the face causing the ear and eyelids to droop, the lip will also be out of shape due to muscle paralysis. Excess salivation due to muscle paralysis is often observed and the animal may struggle to stand. The progression of the disease can be dramatic hence the reason some assume it may be witchcraft.

Listeriosis can kill shoats within 24 to 48 hours following the onset of clinical signs. With quick treatment recovery rate is good.

Treatment and Prevention

When diagnosed early, listeriosis responds well to treatment with antibiotics supplemented with intravenous fluids and electrolytes and tender love and care. It is therefore critical that you call in the vet immediately you suspect listeriosis infection.

If your animals were feeding on suspected spoilt silage, immediately discontinue feeding them on it. Relatively young corn when ensiled has been shown to reduce multiplication of bacteria by creating acidic conditions.

Masankai might have ensiled corn that was mature hence predisposing it to bacterial growth. When an outbreak has been reported, don’t feed animals on rough feeds that will injure the mouth mucosa and make it easy for the bacteria to penetrate.

Quarantine

To avoid further spread in a flock, isolate the sick animals from healthy ones.

Most vets will treat the disease based on the clinical signs but a definitive diagnosis is through the analysis of cerebrospinal fluid, isolation and identification of the causative bacteria. The bacteria can also be isolated from nasal discharge, urine, faeces or milk of infected animal.

Finally, remember listeriosis is a zoonotic disease – it can be spread to people. Exercise extra caution when handling aborted foetus from suspected animals or dead animals.