The woman was admitted to hospital with a fever, headache, neck stiffness, confusion, difficulty speaking and nausea. These signs are suggestive of meningitis and a spinal tap was supportive of that presumptive diagnosis. Blood samples were also taken, and the same bacterium, Streptococcus zooepidemicus, was isolated from both blood and spinal fluid, confirming a diagnosis of S. zooepidemicus meningitis. She was treated and improved, but did not fully recover.
Streptococcus zooepidemicus is primarily associated with horses, although it can occasionally be found in other species such as dogs. After the diagnosis, the woman’s family was questioned about her hobbies and it was revealed that she was an avid horsewoman. Further, she had been bitten by her horse the previous week. That was the presumed source of infection, but it doesn’t appear that any further investigation was undertaken.
Associating the meningitis with the bite is reasonable, but it’s not definitive. Streptococcus zooepidemicus infections in people have occurred in the absence of bites or other clear sources of exposure to horses, so the bite wasn’t necessarily the problem. Regardless, it indicates the need to be proactive and properly treat any horse-associated wound, be it a bite or any another wound that gets contaminated with bacteria from the horse or its environment.
This was a very unusual case. People shouldn’t be overly concerned about getting S. zooepidemicus meningitis from their horse. However, it should serve as a reminder that bad things can happen periodically and that proper attention to general hygiene practices and bite wound care is always important.
On a side-note, I thought the title "A horse bite to remember" was a bit crass, since the woman is now unable to live independently because of severe amnesia (memory problems) as a result of the infection. Maybe they were trying to be ironic, but it seems below a journal such as Lancet.
This Worms & Germs blog entry was originally posted on equIDblog on 10-Oct-10.