Five African countries are battling an anthrax outbreak, with nearly 1,200 people affected so far and 20 dead, according to the World Health Organization. But the official tally belies confusion about the exact nature and scale of the outbreaks, which could complicate the efforts needed to contain them.
Of the 1,166 presumed cases of anthrax in Kenya, Malawi, Uganda, Zambia and Zimbabwe, only 35 have been confirmed with lab tests. That’s neither common nor unreasonable, experts said, especially in regions with limited resources.
But at least in Uganda, many of the presumed cases have resulted in negative tests for anthrax, raising the possibility that there is a secondary disease spread.
“Diagnostic testing may not be adequate, or you may have a moderate number of anthrax cases and at the same time you have an outbreak of something else that may look similar,” 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 usually spread between people, so outbreaks so far are thought to be confined to people who eat meat from infected animals. Uganda now has banned the sale of beef products.
“Even if someone with cutaneous anthrax gets off a flight in Washington, DC, they can’t infect anyone — as long as they don’t have a duffel bag full of contaminated meat they’re passing on,” said Dr. Pavia.
Anthrax is caused by an unusually resilient bacterium called Bacillus anthracis that can survive in soil and water for decades or even centuries. Cattle become infected when they ingest spores on the ground while grazing, and they can become sick and die after only two or three days.
Outbreaks in cattle are particularly likely after the kind 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 it reaches the chest.
Sporadic outbreaks of anthrax in wild animals, cattle and humans are not uncommon in these countries. But having five outbreaks at once “is probably a little unusual, and that’s probably what’s getting some attention in the news,” Dr. William Bower, an anthrax expert at the CDC
In Uganda, the first suspicious 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 appeared in Kalungu District, about 45 miles north of Kyotera.
But it was only in mid-October, after reports of a mysterious illness among people, that district officials began examining skin lesions from those affected. The first two samples came back negative for anthrax and for several other diseases.
As of December 6, Uganda’s official tally reached 48 suspected cases. But of the 11 for which results were available, only three were positive for anthrax; the remaining eight tested negative, according to Kyotera officials.
However, that may not mean the patients do not have anthrax, said Dr. Jean Paul Gonzalez, an expert on hemorrhagic fevers at Georgetown University who has trained 250 Ugandan scientists on emerging infections.
Uganda’s lab facilities can reliably test for anthrax, but only if the samples are properly taken and processed, said Dr. González.
Dr. Jean Kaseya, director general of the Africa Centers for Disease Control and Prevention, said officials rely on patients’ symptoms, as well as known links to sick cattle or contaminated meat, to determine whether they have anthrax.
“Because we’ve confirmed the cases, because we’ve confirmed these deaths from anthrax, there’s no doubt for us that it’s anthrax,” said Dr. It’s good.
Patients in Kyotera District have itchy lesions on the hands and arms, swelling and numbness of the affected limbs and headaches. Sometimes it is followed by swelling of the chest, difficulty breathing and death.
“That’s like anthrax,” said Dr. Bower.
Although there is a vaccine for anthrax, Dr. Unfortunately, it is not available in Africa, where the disease is a bigger problem. “This is inequality, and it is unacceptable,” he said.
He added that the Africa CDC is working closely with Uganda’s health ministry to assist in the investigation. But officials at Kyotera faced many obstacles in their attempts to identify and investigate the 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 gave false information to officials or refused to provide information.
Officials also lack sufficient vehicles and fuel to travel to affected areas and evacuate critically ill patients.
Convinced that witchcraft is to blame for illness, many patients avoid clinics for traditional healers. That led to at least one death at a shrine in Kalungu.
Paul Ssemigga, 68, a farmer, believes he fell ill after eating contaminated meat. He sought help from a traditional healer and took medicinal herbs for over a month before he sought care at Kalisizo General Hospital in Kyotera.
It is not clear whether Mr. Ssemigga has anthrax. Of the eight patients treated at the hospital, test results were available for only two; they were both anthrax negative.
But for now, Mr. Ssemigga seems to be responding to antibiotics, and the swelling in his arms seems to have subsided, Dr. Emmanuel Ssekyeru, the hospital’s medical officer.
It’s possible that those who test negative for anthrax have cellulitis, a general term for any deep skin infection, Dr. Ssekyeru. Or they can have any of several 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 a tick bite.
Investigators should continue to consider these other possibilities, said Dr. Pavia.
“A rule of thumb in outbreaks is that you don’t close your mind too early and you always consider that there is a second pathogen or a second route of transmission,” he said.
Otherwise, officials may succumb to so-called confirmation bias, where “you have several cases of something and so you try hard to shoehorn others into that diagnosis, but you wrong,” he said.
