Vet on call: Don’t mistake this sudden death cattle disease for deadly anthrax

Saturday January 6 2018

David Njuguna feeds his dairy cows in Elburgon.

David Njuguna feeds his dairy cows in Elburgon. You can protect your animals from black quarter if you vaccinate them once a year with the black quarter vaccine. PHOTO | JOHN NJOROGE | NMG 

By DR JOSEPH MUGACHIA
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Last week, a report in the Seeds of Gold on death of several cows in Tana River caught my attention. Farmers in the county, the story said, had been losing cattle in large numbers since the beginning of the month. They suspected they had an outbreak of anthrax.

While the County Director of Veterinary Services was unaware of the anthrax outbreak, he said that he could not rule out the disease because farmers had not vaccinated their animals in the year. Unlike with foot and mouth disease, the government does not routinely vaccinate for anthrax.

Farmers are expected to vaccinate the cattle annually at their own cost as part of the government’s privatisation of animal health services. However, in case of a confirmed anthrax outbreak, the government intervenes to control the disease and prevent it from spreading widely and also affecting humans.

After reading the report, I contacted the Tana River director of veterinary services for a professional discussion. I was lucky that he had just received a preliminary field investigation report from his staff.

“The disease is actually black quarter and not anthrax,” he told me. He said farmers had suspected anthrax due to the sudden death of their seemingly healthy cattle but his field team had diagnosed black quarter.

The diagnosis was preliminary as it was based on the clinical signs observed and the history of the outbreak given by the farmers and animal health service providers.

The veterinary directorate would carry out full investigations and make laboratory confirmation of the disease. He further said despite cattle being affected, no human case had been reported.

Anthrax outbreaks involving even small numbers of animals are usually accompanied by human cases because of the highly infectious nature of the bacteria to both humans and animals and the close contact of farmers with their animals.

Now, let us look at this disease with a mysterious name and capacity to suddenly kill many animals in a short time.

Black quarter has many more names such as quarter evil, quarter ill, gas gangrene, black leg and the tongue-twisting Latin name gangraena emphysematosa.

AFFECTS MAINLY HEAVY MUSCLES OF ANIMALS' BODY

The last name simply means dead tissue with gas accumulation, which medically is translated to gas gangrene. Gangrene is dead tissue in a portion of the live body.

The disease carries the name quarter because it affects mainly the heavy muscles of the animal’s body associated with its front quarters comprising the neck and shoulders and the hind quarters that include the back, hip and thigh muscles. Scientifically, black quarter is called Clostridial myositis.

Black quarter is mainly caused by the bacteria Clostridium chauvoei. Other species of the clostridium bacterial family may also be found present in black quarter infections.

This bacterial family is widely problematic to animals and humans. The most infamous of them all is Clostridium tetani, which causes the dreaded tetanus in humans and other warm blooded animals.

However, the bacterial family can claim its usefulness in human medicine and beauty. Clostridium botulinum is the source of the famous botulinum toxin marketed as Botox for removing wrinkles on the face. The toxin is also used in treating hyperactive nerve conditions.

The black quarter bacteria live in the environment where they persist for many years in the form of spores. They are widely spread throughout the world.

The bacteria are also naturally found in the intestines of ruminant animals without causing any disease. Their growth is kept in check by other micro-organisms and the normal environment of the digestive system.

In the environment, the black quarter bacteria thrive well in moist conditions as found in wet swampy areas. This makes the Tana Delta a good candidate for black quarter outbreaks. In fact, black quarter is a perennial problem in the Tana Delta.

Medical scientists are yet to fully understand how the apparently dormant bacteria cause very severe disease in seemingly healthy animals. The disease affects mainly cattle, sheep, goats, and buffalo. Horses and humans may also be infected.

PROGRESSES QUICKLY

Cattle ingest the bacteria from pastures. In some cases, the bacteria cross the intestinal wall and travel through the bloodstream to heavy muscles of the body mainly in the neck, shoulders, back, hips and thighs where they may remain dormant for many years until conditions are right for rapid multiplication.

One critical requirement for the bacterial growth is poor oxygen supply caused by such events as injury, reduced blood supply and exhaustion. The bacteria thrive in the absence of oxygen.

Cattle affected are normally in good body condition but may die suddenly. This is why farmers usually suspect the death is from anthrax. Sick animals have fever or raised temperature, may suddenly start limping and limbs are swollen starting with the upper areas with heavy muscles.

When the swollen areas are pressed, they are found to contain a lot of gas and they produce crackling sounds, described medically as crepitation. This is the same sound as the one produced by pressing air-filled plastic bag. It is produced by the air moving within the infected tissues.

Cattle that show signs of sickness die in 12 to 48 hours. The disease progresses quickly once the first signs are seen because the bacteria rapidly produce a lot of tissue-destroying toxins.

The dying tissues also generate poisons that kill more cells and get into the bloodstream as well. The toxins in the blood affect all the organs of the body and cause sudden death.

A veterinary doctor is able to quickly diagnose black quarter based on the observed signs, environmental conditions, the history of the disease and post-mortem findings.

The affected tissues are full of gas, they are dead and blackened.

Black quarter is normally seen in cattle that have not been vaccinated against the disease, in areas that have recently flooded or are wet and areas that have recently been excavated.

VACCINATE YOUR ANIMALS

The excavation exposes bacterial spores preserved in deeper soil layers and avails them for consumption by animals during grazing.
Incidentally, black quarter has many semblances with anthrax such as occurring in wet swampy soils, persistence in the environment and sudden death of seemingly healthy animals.

People fear anthrax more because it easily infects and kills humans. This is the main reason for confusion of anthrax, which I tackled on May 28, 2017, with black quarter.

Treatment of cattle suffering from black quarter is usually not effective because the disease progresses rapidly after onset of clinical signs.

Animals should, however, be removed from the suspect pasture and sick ones isolated from the healthy ones. The animal health service provider can minimise the chances of new cases developing by injecting all the animals, suspected to be exposed to the disease, with a suitable antibiotic.

There is good news though. You can easily protect your animals from black quarter if you vaccinate them once a year with the black quarter vaccine.

To make matters easier, use the combined vaccine of anthrax and black quarter generically known as blanthrax. Your animals will be safe from the deadly duo of anthrax and black quarter.