Wednesday, October 7, 2015

Should veterinarians advise human patients about zoonoses?

Humans and animals can share diseases. Should they share doctors?

Should veterinarians play a formal role in advising human patients about zoonotic diseases? It’s an interesting question, addressed in a fascinating paper by Emeritus Professor Rick Speare and colleagues. Professor Speare is a veterinarian and medical doctor, and has worked with humans and non-human patients, so he has a fairly unique perspective. He’s also committed to ensuring that “OneHealth” isn’t just a buzzword.

Zoonotic diseases are those acquired by humans from non-human animals (for example, rabies may be transmitted from animals to humans in some circumstances, and dog bites remain a major source of rabies transmission in endemic countries). Humanoses are those diseases acquired by animals from human sources (for example, H1N1 influenza was spread from humans to pigs and poultry; Mycobacterium tuberculosis has been transmitted from humans to cattle). Some diseases travel both ways, so they’re both.

The argument the authors make in this paper is interesting. Previous surveys have established that, in general, doctors feel that vets know more about zoonoses – perhaps more in terms of how to reduce the risk of being exposed to the bugs that cause them and less about their treatment in human patients.
However, in the main – aside from a few exceptions (and they are around, for example a number of prominent veterinarians are involved with the Australasian Society for Infectious Diseases) – doctors don’t talk to vets and vets don’t talk to doctors.

“The outcome is that the profession thought to be the most expert on zoonoses is not involved in the management of individual patients.”

The paper does not suggest that vets open our doors to non-human patients and start treating them (not that we don’t get the odd request, which is always politely redirected). But it does suggest that veterinary expertise could help in a number of ways:

  • Vets could provide accurate, comprehensive information about the epidemiology of the disease a patient has, which may be useful in differentiating between human, animal or environmental sources of a disease (for example, ringworm in a patient);
  • Vets could help evaluate specific risk factors for zoonotic disease exposure – for example advising animal caretakers how to decrease risks of infection of their animal with zoonotic diseases (for example, there has been a spike in cases of Brucella suis in pig hunters and their dogs in Northern New South Wales this year);
  • Vets could advice on the management of affected animals, including vaccination strategies (for example, for leptospirosis in a dairy herd);
  • Vets could provide advice to patients at increased risk of zoonotic disease or at increased risk of catastrophic effects from zoonoses – for example, people undergoing immunosuppressive treatment, those with an immunodeficiency disorder, or pregnant women.
  • If vets and doctors worked together, it would be much easier to determine in the source of the infection or reinfection is the animal, the environment or human. The way I read the article was that the doctor would still be in charge of treating the human in the equation, but the veterinarian involved would treat (if required) affected animals and ensure that risks of further exposure or reinfection are minimised.

Professor Speare and colleagues analysed survey data and found that, in Queensland at least, the majority (79.8 per cent) of respondents would be willing to seek advice from a vet about zoonotic disease if their doctor recommended it. That proportion climbed to 90.7 per cent if the bill was funded by Medicare.

Is this a case of vets trying to encroach on medical turf? Not at all. Doctors in Australia refer to a range of allied health professionals and Medicare provides rebates if patients are referred to eligible providers (for example, dieticians, physiotherapists, speech pathologists, psychologists, osteopaths and so forth).

The authors argue that, just as these allied health professions have expertise in their areas, “Veterinarians have multi-species training and experience and are more familiar than physicians in considering management strategies involving more than one species.”

Not all of my colleagues agree that this argument is compelling. Some feel that many veterinarians do not have the level of expertise and training around human patients that would be required. One colleague argued vehemently that a good infectious disease physician knows more than any vet OR doctor about zoonoses.

Certainly if such a model were adopted, and one could be referred to a veterinarian as PART of the management of a zoonotic disease, additional training of a select group of veterinarians would be required. Perhaps these veterinarians should undertake postgraduate training in public health (as many already do) or maybe they should be specialists.

Personally I think this is an idea worth exploring. As a veterinarian I am often asked for advice by clients about zoonoses in general, often because they have been misinformed. For example, I have counselled pet owners who have been advised to euthanase their cat if they are pregnant due to what their doctor believes is an unacceptably increased risk of catastrophic consequences from infection with Toxoplasma gondii during pregnancy. Often the doctor involved does not realise that people are more likely to acquire the infection from other sources (unwashed fruit and vegetables, undercooked meat) and that the risks of feline transmission can be minimised by simple hand and litter tray hygiene.

I do give general advice about reducing risk of exposure when animals have an infection (for example, a kitten or puppy with ringworm). I always, always recommend that humans consult a doctor about medical issues that may affect them. But it would be helpful to establish a more formal path of communication between veterinarians and doctors.