I’ve had this paper from One Health (Chan et al 2017) on my “to blog” pile for a while, since it’s an interesting story. Like any case report, it’s a bit of an oddball infection, and not likely indicative of a major or new risk. However, there are often a few good general take-home messages from reports like this.
The paper describes five human cases of psittacosis (Chlamydophila psittaci infection) linked to contact with fetal membranes of a horse. Psittacosis is a potentially nasty bacterial infection that is usually linked to psittacine birds (parrot family). This bacterium can be found in other species periodically, but it’s rare, and horse contact doesn’t trigger much thought about psittacosis.
The mare foaled on a stud farm, where two people were in attendance and a 3rd examined the fetal membranes after foaling. That’s a common procedure to make sure they are intact, since any membranes left behind in the mare can cause serious complications. The membranes appeared abnormal and the foal died a week later (but testing of the foal was not performed).
The fetal membranes were taken to the local vet school by one of the farm personnel (who was also a vet student), and they were examined by two staff and three students.
Five of the nine people that had contact with the fetal membranes developed psittacosis, and the timing of when they got sick was consistent with exposure at the time of fetal membrane contact. Risk factor analysis was performed and direct contact with the membranes was the only thing that was significant, and no other reasonable sources (e.g. bird contact) were identified.
Two of the five affected individuals were hospitalized, but everyone recovered.
Anytime there’s an outbreak, it’s good to look back and see what could be done differently. It doesn’t make much sense to look at psittacosis-specific prevention measures around horses since this is such a rare problem. There has to be a balance between what’s practical, what people will actually do, and what might help (e.g. farms aren’t going to have biosafety cabinets to examine fetal membranes, so looking to recommendations for handling infected bird tissues has some limitations). Therefore, we’re left focusing on more general practices that could potentially protect people in a scenario like this, but that are also more broadly useful. A lot of it comes down to attention to hygiene, especially hand washing. Wearing routine personal protective equipment or dedicated clothing to reduce contamination and tracking around of microbes, handling items in a manner to reduce splashes (e.g. gentle handling, not tossing the placenta around), cleaning and disinfecting equipment and areas that might be contaminated, and hand washing would go a long way.