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Vet on call: Dealing with anthrax scare on your farm

Friday March 15 2019

A farmer in Kiambu burns the carcass of livestock that died of anthrax

A farmer in Kiambu burns the carcass of livestock that died of anthrax. The disease mostly occurs as sudden death to food animals. PHOTO | JOSEPH MUGACHIA | NMG 

DR JOSEPH MUGACHIA
By DR JOSEPH MUGACHIA
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There are three animal diseases that always raise my eyebrows whenever I am called to attend to an incident.

The diseases are anthrax, rabies and Rift Valley Fever (RVF).

While the latter is periodic, occurring during wet seasons and mainly in some mapped-out areas, it can come in mild forms and easily infect people through inhalation of the viruses from open carcasses or through mosquito bites before it is diagnosed in animals.

Anthrax mostly occurs as sudden death to food animals. People often get infected in large numbers, resulting in deaths when they consume meat from anthrax carcasses. Many are tempted to do so because the animals often die in very good body condition.

Rabies infection in animals shows up dramatically either by causing the animal to drool saliva, become aggressive, vocalise abnormally and seek to bite things and people or just go unusually dull and quiet with swaying of the hind quarters. People get infected from animal bites or contact with body fluids.

Last week, I got a call from one Njuguna of Kahawa Sukari at about 11am. “Doctor, please come and help my friends because a bull they were expecting to feast on has just collapsed and died,” he said.

He explained the friends were a church-run children’s home and he was concerned that they did not seem to understand the implications of a sudden death in a cow. “You see, I read your article on anthrax and I am concerned it could be the problem,” he concluded.

I arrived on the farm late afternoon accompanied by Jane, an animal health student attached to my practice. The situation was as Njuguna had described. The cow had been fed water and kitchen waste in the morning and let out to graze in a field. The bull soon walked back to the closed gate, attempted to push it open before it collapsed and died.

The owners were shocked because in 30 minutes, the carcass was heavily bloated.

The manager said their initial intention was to open up the carcass and freeze the meat for a feast during the Easter holiday.

INDICATIVE OF ANTHRAX

I told them to thank Njuguna for his knowledge on anthrax. The history of the case and the presentation of the carcass were highly indicative of anthrax.

The carcass lay at the edge of the plot close to the children’s home perimeter wall. Njuguna confirmed he had closely followed the instructions I gave on phone on removing the carcass from the gate to the current location. He had ensured nobody touched fluids from the carcass.

Jane and I proceeded to examine it. The skin was taut, making the legs stick out of the ballooned body. The carcass appeared fat.

There was dark blood oozing from the anus and the mucous membranes of the eyes were bluish. Greenish fluid oozed from the nose and mouth.

The bull had not been vaccinated against anthrax. Although the legs were sticking out, they were not stiff. I was able to fold the fore limbs at the carpal joint. This showed there was no rigor mortis — the stiffening that occurs after death. It is another good indicator of anthrax.

I was preparing to cut the nasal vein to observe the nature of blood when Jane urgently came to me and whispered, “Doctor, do you really want to open an anthrax carcass?” This was one of the days when she was required to observe cases, make her separate diagnosis and we compare notes before making the final diagnosis and intervention decision.

I explained to her that severing the nasal vein is a routine diagnostic procedure to either take a blood sample for laboratory analysis or observe the characteristics of the blood in the vessels.

Care must be taken when cutting the blood vessel for the doctor to minimise chances of inhaling anthrax spores. The spores are formed as soon as the anthrax bacteria come into contact with air. Therefore, the cut must be small and the doctor must face the direction of the wind.

Dark oily blood flowed from the cut vein and did not clot. I informed the manager that it was a case of anthrax.

Confirmation of the diagnosis is done in the laboratory but I could not take a sample as I did not have mercury chloride, the chemical used to kill the bacteria on the blood smear sample.

DISPOSE OFF THE CARCASS

The next course of action was to safely dispose of the carcass in a manner that would prevent further spread of the disease.

I opted for open burning and then burying the ash because the groundwater in the area was very close to the surface and it was also rocky. It would have been very difficult to bury the carcass the required two metres deep.

Using diesel, charcoal and hard wood, we incinerated the carcass in an open fire. Diesel is the fuel of choice because of its lower volatility and higher energy level compared to petrol. Petrol should never be used because it can spread fire through the wind or even burn the person lighting it.

We spread the charcoal all around the carcass. Hard wood was arranged over it in a triangular way. I then doused the wood, carcass and the charcoal with 20 litres of diesel.

Finally, I lit the stack using a fire torch from the top to the bottom. It is important to light this way to prevent anthrax spores from flying into the air with the rising hot hair.

I advised the people who had been exposed to the carcass to seek medical help from a hospital if they felt any signs of illness.

To conclude the exercise, the manager and I reported the incident and the action I had taken to the nearby police station.

The OCS was happy with the co-operation and promised she would ensure my instructions were followed for public safety.

I reported the case to the Kiambu County Director of Veterinary Services (CDVS) the following day and he started investigations immediately.

Even before he could complete the investigations, Njuguna’s cow also dropped dead suddenly and as bloated too.

Anthrax was again diagnosed and samples were taken to the National Veterinary Laboratories at Kabete for analysis. In the meantime, the CDVS team did anthrax vaccination in the outbreak area as recommended.