Five African countries are grappling with anthrax outbreaks, with nearly 1,200 people affected and 20 deaths so far, according to the World Health Organization. But the official count belies any confusion about the exact nature and scale of the outbreaks, which could complicate efforts needed to contain them.

Of the 1,166 suspected cases of anthrax in Kenya, Malawi, Uganda, Zambia and Zimbabwe, only 35 have been confirmed by laboratory tests. Experts say this is neither unusual nor unreasonable, especially in areas with limited resources.

But at least in Uganda, many suspected cases have resulted in negative anthrax tests, suggesting that a second disease is circulating.

“It could just be that diagnostic testing is inadequate, or it could be that you have a moderate number of cases of anthrax and simultaneously have an outbreak of something else that might look like that,” said Dr. Andrew Pavia, an infectious disease expert. at the University of Utah who advised the Centers for Disease Control and Prevention on anthrax treatment guidelines.

Anthrax does not typically spread between humans, so outbreaks are so far thought to be limited to people who have eaten meat from infected animals. Uganda now has prohibits the sale of beef products.

“Even if a person with cutaneous anthrax got off a flight in Washington, D.C., they wouldn’t infect anyone — as long as they didn’t have a gym bag full of contaminated meat to pass around,” Dr. Pavia said . .

Anthrax is caused by an extraordinarily resilient bacteria called Bacillus anthracis that can survive in soil and water for decades or even centuries. Cattle become infected when they ingest spores in the soil while grazing, and they can become ill and die just two or three days later.

Outbreaks in livestock are particularly likely after the type of heavy rains that countries in eastern and southern Africa have recently experienced.

In humans, anthrax can cause skin ulcers with a black center and swelling, which can suffocate the patient if they extend to the chest.

Sporadic outbreaks of anthrax in wildlife, livestock and humans are not uncommon in these countries. But having five outbreaks simultaneously “is probably a little strange, and that’s probably what’s getting the media attention,” said Dr. William Bower, an anthrax expert at the CDC.

In Uganda, the first suspicious livestock death occurred in June in Kyotera district, and the first sudden human death was reported in July, according to an internal report obtained by The New York Times.

By the end of October, at least 24 animals had died. Since then, infected animals and people have appeared in Kalungu district, about 45 miles north of Kyotera.

But it was only in mid-October, after reports of a mysterious illness among the population, that district authorities began testing the skin lesions of those affected. The first two samples tested negative for anthrax and several other diseases.

As of December 6, Uganda’s official count stood at 48 suspected cases. But of the 11 for which results were available, only three were positive for anthrax; the other eight tested negative, according to Kyotera officials.

That doesn’t mean patients are free of anthrax, said Dr. Jean Paul Gonzalez, a hemorrhagic fever expert at Georgetown University who has trained 250 Ugandan scientists on emerging infections.

Ugandan laboratories can reliably test for the presence of anthrax, but only if samples are properly collected and processed, Dr. Gonzalez said.

Dr. Jean Kaseya, director general of the Africa Centers for Disease Control and Prevention, said authorities were relying on patients’ symptoms, as well as known links to sick livestock or contaminated meat, to determine if they had anthrax.

“Because we have confirmed cases, because we have confirmed these deaths from anthrax, there is no doubt in our mind that it is indeed anthrax,” Dr. Kaseya said.

Patients in Kyotera district presented with itching on their hands and arms, swelling and numbness in affected limbs, and headaches. This was sometimes followed by swelling of the chest, difficulty breathing and death.

“It looks a lot like anthrax,” Dr. Bower said.

Although there is a vaccine against anthrax, Dr. Kaseya pointed out, it is not available in Africa, where the disease is a much more serious problem. “It’s an injustice and it’s not acceptable,” he said.

He added that Africa CDC was working closely with the Ugandan Ministry of Health to assist in the investigation. But Kyotera officials face numerous obstacles in their attempts to identify and diagnose cases, according to the internal report.

“Suspected cases do not want to show their skin lesions and allow samples to be taken,” the report said. Some people with symptoms have given authorities incorrect information or refused to provide information.

Authorities also lack enough cars and fuel to reach affected areas and evacuate seriously ill patients.

Convinced that witchcraft is responsible for this illness, many patients avoid the clinics of traditional healers. This led to at least one death at a sanctuary in Kalungu.

Paul Ssemigga, 68, a farmer, believes he fell ill after eating contaminated meat. He sought help from a traditional healer and took herbs for more than a month before seeking treatment at Kalisizo General Hospital in Kyotera.

It is not known whether Mr Ssemigga suffers from anthrax. Of the eight patients treated at the hospital, test results are only available for two; both were negative for anthrax.

But so far, Mr. Ssemigga appears to be responding to antibiotics and the swelling in his arms appears to be easing, said Dr. Emmanuel Ssekyeru, a doctor at the hospital.

It is possible that those who test negative for anthrax may have cellulitis, a generic term for any deep skin infection, Dr Ssekyeru said. Or they can suffer from many illnesses with similar symptoms: Rift Valley fever, a viral disease also seen in pets, for example, or infections by certain bacteria or by arboviruses such as West Nile virus. Western – or even tick bites.

Investigators should continue to consider these other possibilities, Dr. Pavia said.

“A rule in an outbreak is not to close your mind too early and always consider that there is a second pathogen or a second route of transmission,” he said.

Otherwise, managers could succumb to what’s called confirmation bias, where “you have a few cases of one thing and so you try very hard to lead others to that diagnosis, but you’re wrong.” “, did he declare.

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