UK Veterinary surgeon's battle with bovine TB

Shobha Shukla, Citizen News Service - CNS
Dr Jonathan Cranston, UK
[Listen or download this podcast] Have you ever heard of animals transmitting TB to humans? I am sure many of us have not. And yet in 2015 there were an estimated 149,000 such new human cases of zoonotic (bovine) TB globally and 13,400 deaths. Unlike conventional TB, which is caused by Mycobacterium tuberculosis (M. tuberculosis), zoonotic TB in humans is caused by the bacterial strain Mycobacterium bovis (M. bovis) which belongs to the M. tuberculosis complex. M. bovis causes bovine TB in cattle and zoonotic TB in people. At the 47th Union World Conference on Lung Health in Liverpool, I met a 35 year old veterinary doctor Jonathan Cranston from UK, who is a survivor of zoonotic TB.

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Dr Cranston graduated from Royal Veterinary College, London in 2006, and for the last 4 years he has worked at a mixed practice in Cheltenham doing a mixture of farm, equine and small animal work.

Here is what Cranston shared in an exclusive interview with CNS:

Since August 2011, Cranston had been going to South Africa for a couple of weeks every year to help with research, veterinary work and student training around wildlife conservation, working with Wildlife Vets, based very close to Kruger National Park. It was there that he contracted bovine TB in 2013, while working on a study to look at the stress levels in the wildebeests (also called gnus) who were moved from one area to another and also quarantined in enclosures— taking their blood samples and putting monitors on them. He returned to England in May 2013 and, about 6 weeks later in June 2013, started showing clinical signs of TB.

Symptoms:

“The first symptom that I can recall is waking up suddenly in the middle of the night with a severe chest pain, as if I was being stabbed and struggling for breath. This lasted for about half an hour and then disappeared. A couple of nights later I woke up with severe night sweats, so much so that I could actually wring out the sweat from my night clothes and bedding. I was also developing exercise intolerance, finding it more and more difficult to take out my dogs for walks. I was also coughing a lot, especially if I bent down to pick up something. One Sunday I did a 10 km run with my brothers, which I would normally be able to do without any problem. But this time I really struggled.”

Diagnosis and treatment

“My housemate at that time was a doctor and he suspected I had pneumonia and he put me on some antibiotics. But the antibiotics did not work. My doctor father arranged for me to have a chest X-Ray. I was to get the results after 1 week. But in that 1 week my condition deteriorated. One morning while swimming I struggled in the pool and just managed to crawl out of it. I went to work and collapsed there with severe headache and fever. When I went to see the doctor the next day he diagnosed it as a case of pleural effusion. I was in hospital for 3 days to get 2.5 litre of fluid drained out.”

“At that point I was pretty convinced that I had TB. But the doctors still thought it was a complicated case of pneumonia and put me on antibiotics for pneumonia. But they did agree to do a pleural biopsy. 10 days later the biopsy result confirmed that I had TB. The consultant was convinced that I had human TB, even though I raised my doubts that it was more likely to be bovine TB, as I had been working with animals in Africa where TB is quite prevalent. I was put on the 4 drug (HRZE) regimen and meantime the pleural fluid was sent for culture. As the first culture test (that takes 6 weeks) failed, they had to re culture it—a wait of another 6 weeks. So it was after 3 months into my TB treatment that doctors finally confirmed bovine TB. At that point they had to change the medication as bovine TB is resistant to pyrazinamide. I was found resistant to isoniazid as well. So they stopped the two medicines and added moxifloxacin. I was on medication for another 9 months. I was given the all clear sign in November 2014 after 12 months of medication”.

Possible modes of transmission

“We do find many cases of bovine TB in UK. But with the TB testing in cattle that we do, we pick up the disease quite early, much before the clinical signs manifest. So the vets working in this country have a very low risk of contracting the disease. It is speculation, that while I was working with the wildebeests in Africa, I could have got it through a cut in my hand while putting my hand in its mouth, or its saliva, or by inhaling some of the bacteria. We are not entirely sure as to how animal to human transmission occurs. But we certainly know that bovine to bovine transmission is through close contact, through aerosol, and also through body fluids like saliva and blood.”

Who are at greater risk of getting bovine TB?

“In Africa 21 species have been identified as been carrying TB or susceptible to TB and wildebeest is one of them. Lions are also susceptible to it and so are cattle, including buffaloes. There have also been a few reported cases of TB in cats in UK. Any human being working closely with animals it at threat—vets, farmers, game rangers.”

Lack of awareness

“I was seeing a senior respiratory consultant and his perception was that bovine TB does not present in the way it did in my case. It is a disease that doctors often do not really know about. So there is need for more awareness in medical professionals to know how the disease presents itself, who is at risk and what are the risk factors”.

The way forward 

“Firstly, awareness about the disease and its symptoms is very important. One has to be aware that it is a zoonotic disease and any animal you are working with is a potential carrier. When I was at the vet school it was a disease that was never looked upon as a risk for humans. Bovine TB should be put on a differential list, particularly for people working in close contact with animals and developing respiratory symptoms”.

“Secondly, practice basic general hygiene when working with animals—wash hands, wear gloves to cover up any wound/cuts on the hands, wear a mask when close to the head of the animal. If one is aware that it is a condition one can potentially catch, while dealing with any animal, then one will be more cautious. I still work In Africa for conservation of wildlife but I am more careful now and take precautions. I am also aware that I could catch it again.”

“Thirdly, we need to have better diagnostic tools, as diagnosing bovine TB is not easy. Quite often with the human TB treatment, they drop some of the drugs after the first phase of treatment. But luckily in my case they decided not to do so because the culture results had not come by then. I was already resistant to 2 of the 4 drugs. Had they dropped 1 more drug, it would have increased my risk of getting drug resistant TB. Protocols need to be put in place to ensure that people do not suffer unnecessarily”.

While speaking with CNS, Dr. Paula Fujiwara, Scientific Director at the International Union Against Tuberculosis and Lung Disease, agreed that, “Unless we address zoonotic TB, we cannot end TB. If it goes unheeded, there will be an enormous number of cases in the next 15 years. We need to have better data too. The true burden of zoonotic TB is underestimated due to lack of routine surveillance data. USA is the only country that does systematic surveillance of it. Other challenges are lack of diagnostic tools as only a culture can confirm its diagnosis. As symptoms for bovine and regular TB are the same, it may often lead to misdiagnosis and delay proper treatment initiation. All that we know is that it is resistant to pyrazinamide, and sometimes to other drugs too. As most people are put on HRZE regimen for TB treatment, so for people with zoonotic TB, it means they are taking only 3 drugs, which may impact treatment outcomes. Communities that consume unpasteurised milk and raw meat could be at greater risk of it, but we do not know for sure.” Human health and animal health are inter-related and require a coordinated response by working together in collaboration with veterinarians and doctors to understand more about zoonotic TB and the risks that it poses, if we are aiming for a TB free world by 2030.

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Shobha Shukla, Citizen News Service - CNS
1 November 2016
(Shobha Shukla provided thematic coverage from the 47th Union World Conference on Lung Health, Liverpool, United Kingdom, with kind support from TB Alliance (Global Alliance for TB Drug Development). Follow her on Twitter @Shobha1Shukla) 

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