Excruciating chest pain. Night sweats so severe he could ring out his sheets in the morning. A worsening cough. Getting out of breath when he walked his dogs — or tried to complete his regular 6-mile run.
Those were some of the symptoms that veterinarian Jonathan Cranston was feeling six weeks after returning home to England from a trip to South Africa, where he'd been involved in a project that examined the stress level of wildebeests.
At first he blamed the night sweats on his mattress.
"It was getting slightly hotter in England, I'd just gotten a new mattress and I thought the mattress wasn't breathing — so much so that I was going to ring up the company and ask if I could send it back," the 35-year-old says, acknowledging how ridiculous the thought was in hindsight.
Turns out it was probably the wildebeests who were responsible for his symptoms.
Wildebeests are one of 21 animal species in South Africa's Kruger National Park known to carry zoonotic tuberculosis. (A zoonotic disease can be transmitted from animals to humans.) And zoonotic TB is what Cranston had.
But it took a while for doctors to make the diagnosis — even though they'd drained 10 cups of fluid next to one of his lungs. They viewed Cranston as an unlikely candidate for TB. He was young and healthy and didn't have risk factors — like serving time in an overcrowded prison. The doctors figured he just had "a really nasty pneumonia," he says.
Each year, some 149,000 people come down with zoonotic TB. It's caused by Mycobacterium bovis rather than Mycobacterium tuberculosis, the usual culprit for TB in humans.
Zoonotic TB can affect any warm-blooded animal but is most frequently found in livestock and wild animals. It's also been linked to circus animals like elephants because they live in close confinement. Dogs and cats rarely get it, so pet owners don't need to worry much. But farmers, vets, slaughterhouse workers and butchers are at risk. Animals can not only carry the disease but can be sickened by it as well.
The most common routes of transmission are through unpasteurized milk, raw or undercooked meat, airborne infection and direct contact with infected animals. That's different than the TB we're familiar with, which spreads from human to human when a person infected coughs, speaks or sings.
The disease, which kills 13,000 people every year, is only now beginning to gain attention. "If we're going to end TB, we need to deal with this very neglected area," says Dr. Paula Fujiwara, scientific director of the International Union Against Tuberculosis and Lung Disease.
To that end, public health, veterinary and food safety experts gathered in Geneva this past April to draft an action plan. The World Health Organization and the Union came up with a ten point program. "Zoonotic TB: Defining Key Priorities For Action" calls for efforts to increase global awareness, improve surveillance and develop new diagnostic tools as well as pasteurization and cooking strategies to improve food safety.
The program is meant to complement the World Health Organization's End TB Strategy, seeking to reduce the total number of yearly TB-related deaths — estimated at 1.8 million — by 95 percent and to cut new cases by 90 percent by 2035. The ultimate goal is full elimination by 2050.
"The number of people who die of zoonotic TB every year is higher than the number of people who died of Ebola," says molecular epidemiologist Adrian Muwonge from the Roslin Institute at University of Edinburgh.
After doctors drained the fluid from Cranston's lung, it took another ten days for doctors to get biopsy results to find out he in fact had TB. But they were adamant he hadn't contracted it from being in close quarters with wildebeests.
"I was seen by one of the top respiratory consultants in Oxfordshire, which is an academic hub, and in his mind, [zoonotic] TB was completely off his list," Cranston recalls.
"A lot of people don't know about [zoonotic TB]," agrees Dr. Fujwara. "We don't have good surveillance and we don't have good diagnostic tools."
Cranston began the usual six-month treatment regimen for human TB. He did a culture test, which Cranston thought would prove his TB was from M. bovis, but the first test failed and it was another three months before doctors got the positive result.
One of the major challenges in treating M. bovis is its resistance to one of the four medications used to treat human TB. That was a problem Cranston encountered. One of the four drugs he was given was ineffective for zoonotic TB. So he had to take antibiotics for a year instead of the usual six months.
Cranston finished treatment in August 2014 and was officially given the all clear in November — but not before he went back to South Africa to work again with wildebeests. It can't be proven that the wildebeests infected him but they're considered the likeliest source.
"It definitely hasn't scared me off. I love Africa and just being able to work with those animals is an incredible privilege," says Cranston, whose veterinary practice is at the Cotswolds in south central England. But now he's careful to wash his hands after contact with the animals, cover any cuts he has and minimize time spent in close confinement with the wildebeests.
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