Wednesday, July 30, 2014

Brucellosis in dogs and people

Hunting dogs on the back of a ute.

Today’s blog continues SAT’s focus on zoonotic diseases (i.e. pathogens that humans and animals can share), and the topic is brucellosis. I was fortunate enough to graduate after Brucellus bovis was successfully eradicated from Australia (officially in July 1989), thanks to a massive,multi-decade vaccination program.

Lots of the older vets, however, did contract brucellosis and it was a nasty, relapsing disease that caused all kinds of awful signs. But Dr Jenny Robson, Microbiologist and Infectious Diseases Physician with Sullivan Nicolaides Pathology in Queensland, told the conference that we haven’t seen the last of brucellosis yet.

There have been recent cases of Brucellus suis in humans and dogs, with exposure to feral pigs the common link. That is, usually the dogs and humans go pig hunting, and are exposed that way. Domestic (i.e. pet and farmed) pigs in Australia have so far been spared, with one exception being a free range piggery in Queensland where a spillover infection occurred.

A wild pig and pet dog inspect the trash together.
Dr Robson quoted sources estimating the number of feral pigs in Australia to sit at around 23 million, which works out at almost one for every person in Australia. Walk down the street in Sydney on a busy day and that’s a lot.

Humans are most likely infected when B suis enters cuts and abrasions in the skin, or during the process of butchering. Dogs may be infected the same way or through inhalation of aerosolised pathogen or eating meat from infected pigs.

So what has this got to do with you if you aren’t a pig hunter? Well, potentially a bit. Let’s say you adopt a dog from a shelter who happens, in a former life, to have been taken pig hunting. That dog may have relapsing signs. Dr Robson spoke about a dog who developed orchitis (I used to think this had something to do with orchards but it’s actually – I am told by sources who know these things – excruciatingly painful inflammation of the testicles [our physiology lecturer, who had happened to have a bout of orchitis, claimed it was "worse than childbirth"]) due to brucellosis, long after humans had stopped taking the dog hunting.

B suis can also cause infection in other parts of the body including bones (osteomyelitis), fever, pain, abscesses on organs, endocarditis, meningitis etc. etc. Certainly not a benign disease you just get over by having a couple of days off and keeping up the fluids.

There is a question about whether sufferers can ever be truly cured, as relapses are not uncommon even with “successful” treatment. There is a risk that infected dogs can infect other dogs, pigs and people.

It would certainly be useful, as Dr Robson pointed out, to know more about the distribution of this pathogen around Australia and to have a better treatment for affected dogs (and people of course!).

One thing that is KNOWN to contribute to spread of the pathogen is illegal relocation of pigs by those who hunt them. There are a million reasons why this practice should be stopped, and the spread of a nasty disease like brucellosis is one of them.

Thank you, keen readers, for the ongoing stream of small animal likes. Rachel, again, gets a nod for this footage of an Armadillo playing with a toy pig. This is the kind of video that justifies the entire existence of the internet (aside from SAT of course!!!)

And then Deb chipped in with this tear-jerker compilation of good news compiled by Animals Australia.

Meanwhile if you want to read a bit more about the occupational exposure of vets to zoonoses, check our previous post here - which includes some links to very helpful guidelines about preventing infection with a range of hideous pathogens.