When I talk about infection control (or infectious diseases, in general), I emphasize the need to avoid tunnel vision. Sometimes, we run into situations where someone says “that animal tested negative for [name your bug], so we don’t have anything to worry about.”

Well, no.

It means you (probably) don’t have to worry about that particular pathogen. It doesn’t mean you don’t need to worry about various other known pathogens.

And then there are the unknown pathogens to consider.

One thing that makes infectious diseases challenging (and interesting) is the continued emergence of new problems. Academically, they’re fascinating. However, if you or your animal is the index case, that wouldn’t be the first descriptor you’d use.

That’s my long-winded introduction to an interesting story out of Australia about a parrot-associated bacterium causing abortions in horses and horse-associated infections in vets. There’s been talk about this for a few years now, ever since a cluster of Chlamydia psittaci infections was identified in staff and students at the vet school in Wagga Wagga. This bacterium is most often associated with birds of the parrot family (psittacines) and while it usually causes flu-like illness, it can cause severe disease too. There wasn’t a parrot (or other bird) source identified in the vet school cases, though. Cases were ultimately tracked back to contact with fetal membranes from a mare that had given birth to a near-term but sick foal (that ultimately died).

This unusual finding led to broader screening for C. psittaci in association with equine reproductive losses, and they found evidence of the bacterium in ~21% of samples from fetal and placental tissues and 24% of samples from foals. This clustered in an area “~170 km inland for the mid-coast of New South Wales.”

Genetic evaluation of the bacteria showed they were related to the common Australian parrot strain, suggesting this started as a spillover from parrots. Whether that means there is continual spillover (all parrot-to-horse transmission) or whether it’s now being passed around within the horse population isn’t clear, and that’s an important factor to sort out.

It’s an interesting equine infectious disease story and another reminder of the need for good routine infection control measures like handwashing and wearing protective equipment and clothing.  While these measures won’t prevent all infections, and C. psittaci creates some additional challenges because it’s potentially aerosol-spread, they should reduce the risk of most known (and many unknown) disease threats.

To read the complete report about the incident, click on the link below:
Jenkins et al. An epizootic of Chlamydia psittaci equine reproductive loss associated with suspected spillover from native Australian parrots. Emerging Microbes and Infections 2018