Five African countries are grappling with anthrax outbreaks, with nearly 1,200 people infected so far and 20 deaths, according to the World Health Organization. But the official account belies confusion over the exact nature and scale of the outbreaks, which could complicate the 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. That’s not unusual or unreasonable, experts said, especially in resource-constrained areas.
But at least in Uganda, many of the suspected cases have resulted in negative tests for anthrax, raising the possibility that a second disease is circulating.
“It could just be insufficient diagnostic testing, or you could have a modest number of anthrax cases and at the same time have an outbreak of something else that could look like it,” said Dr. Andrew Pavia, an infectious disease specialist. at the University of Utah who has advised the Centers for Disease Control and Prevention on anthrax treatment guidelines.
Anthrax does not usually spread between people, so outbreaks so far are believed to be limited to people who ate meat from infected animals. Uganda now has banned the sale of beef products.
“Even if someone with cutaneous anthrax got off a flight in Washington, they’re not going to infect anyone — as long as they don’t have a bag full of contaminated meat coming through,” said Dr. .
Anthrax is caused by extremely hardy bacteria called Bacillus anthracis, which can survive in soil and water for decades or even centuries. Cattle become infected when they ingest spores on the ground while grazing and may become ill and die as little as two or three days later.
Cattle outbreaks are particularly likely after the kind of heavy rains that eastern and southern African nations have experienced recently.
In humans, anthrax can cause skin ulcers with a black center and swelling, which can suffocate the patient if it spreads to the chest.
Sporadic outbreaks of anthrax in wildlife, cattle and humans are not uncommon in these countries. But to have five cases at once “is probably a little strange, and that’s probably what’s getting the news attention,” said Dr. William Bauer, an anthrax expert at the CDC.
In Uganda, the first suspected cattle death was 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. A few infected animals and people have since turned up in the Kalungu district, about 45 miles north of Kiotera.
But it wasn’t until mid-October, after reports of a mysterious illness among the people, that local officials began testing skin lesions from those affected. The first two samples tested negative for anthrax and several other diseases.
As of December 6, Uganda’s official tally was 48 suspected cases. But of the 11 for whom results were available, only three were positive for anthrax. The remaining eight were negative, according to Kyotera officials.
However, this may not mean that patients are free of anthrax, said Dr. Jean Paul Gonzalez, an expert on hemorrhagic fevers at Georgetown University, who has trained 250 Ugandan scientists in emerging infections.
Ugandan lab facilities can reliably test for anthrax, but only if the samples are taken and processed properly, Dr. Gonzales said.
Dr. Jean Kaseya, director general of Africa’s Centers for Disease Control and Prevention, said officials rely on patients’ symptoms, as well as known connections to sick cattle or contaminated meat, to determine whether they have had anthrax.
“Because we have confirmed cases, because we have confirmed these anthrax deaths, there is no doubt for us that it is anthrax,” Dr Kaseya said.
Patients in the Kyotera area had itching of the hands and arms, swelling and numbness of the affected extremities, and headache. Chest swelling, difficulty breathing, and death sometimes followed.
“It sounds a lot like coal,” Dr. Bauer said.
Although there is a vaccine for anthrax, Dr. Kaseya noted, it is not available in Africa, where the disease is a much bigger problem. “This is inequality and it is not acceptable,” he said.
He added that the Africa CDC is working closely with the Ugandan Ministry of Health to assist in the investigation. But officials at Kyotera face several obstacles in their efforts to identify and diagnose cases, according to the internal report.
“Suspected cases were reluctant to show their skin lesions and allowed samples to be taken,” the report said. Some people with symptoms have given officials incorrect information or refused to provide information at all.
Officials also lack enough cars and fuel to travel to affected areas and evacuate critically ill patients.
Convinced that witchcraft is responsible for illness, many patients avoid clinics for traditional healers. This led to at least one death at a shrine in Kalungu.
Paul Ssemigga, 68, a farmer, believes he fell ill after eating contaminated meat. She sought help from a traditional healer and took herbs for over a month before seeking care at Kalisizo General Hospital in Kyotera.
It is not clear whether Mr Szemiga has anthrax. Of the eight hospitalized patients, test results are available for only two. both were negative for anthrax.
But so far, Mr Ssemigga appears to be responding to antibiotics and the swelling in his hands appears to be going down, said Dr Emmanuel Ssekyeru, a medical doctor at the hospital.
It is possible that those who test negative for anthrax have cellulitis, a general term for any deep skin infection, Dr Ssekyeru said. Or they may have one of a number of diseases with similar symptoms: Rift Valley fever, a viral disease also seen in domestic animals, for example, or infections with certain bacteria or with arboviruses such as West Nile virus — or even tick bites.
Researchers should continue to look at these other possibilities, Dr. Pavia said.
“A rule of thumb in outbreaks is that you don’t close your mind too early and always consider that there is a second pathogen or a second route of transmission,” he said.
Otherwise, officials can succumb to so-called confirmation bias, where “you have a few cases of one thing and so you try really hard to put others on that diagnosis, but you turn out to be wrong,” he said.