I recently had a patient a 42 yo dairy farmer who had not been right for a week. Flu like symptoms, headache and lethargy.
He was a “good keen man” a deer hunter who brought home steaks with respectable frequency. His partner had bullied him to the clinic. He had been unwell enough to take to bed which his partner reported was most unusual. Usually fit and well with ono PmHx. Being summer and his symptoms he earned a leptospirosis serology test.
Which came back as positive with a significant titre.
Treatment for symptomatic cases here is oral doxycycline and follow up to see if symptoms resolve.
#FOAMed and Leptospirosis
After looking around I found the Excellent talk from Dr Lane (ICU Queensland) http://www.intensivecarenetwork.com/index.php/icn-activities/icn-podcasts/393-39-lane-on-tropical-microbiology But his experience didnt fit with mine. Are kiwis just tougher than those weak australian soldiers he sees? or is there some other factors effecting the cases we see?
Also the Adventure doc blog had an article: http://adventuredoc.net/2008/12/29/leptospirosis/
Firstly what the hell is leptospirosis?
To quote professor wikipedia Leptospirosis (also known as Weil’s syndrome, canicola fever, canefield fever, nanukayami fever, 7-day fever, Rat Catcher’s Yellows, Fort Bragg fever, black jaundice, and Pretibial fever) is caused by infection with bacteria of the genus Leptospira
Have I heard of that?
Leptospirosis was in the news in 2010 when british olympic rower Andy Holmes passed away after contracting the disease.
How does it present?
“Lepto” can present like just about anything from a mild flu like illness to a severely sick patient with hepato-renal syndrome and meningitis.
Natural history of leptospirosis
Usually patients will have the initial phase with flu like symptoms For many this is all the patient will experience but for some this is resolves and they then have a second phase of illness. This is more severe and may include hepatic failure (Weil’s disease) and renal involvement.
So how common is it?
Worldwide it is one of if not the most common zoonotic disease.
Leptospirosis is a notifiable disease in NZ so we have good records of when lab tests come up positive.
New Zealand has between 80-140 confirmed cases a year, this is about three quarters of the positive lab serology results. (more on this later)
Making leptospirosis not common but not rare. So it falls into that BS category of “Maintain a high index of suspicion” Now im pretty sure there isnt a suspicion index but you will see it from time to time. (if you look)
Meat workers, esp those who “pull kidneys” or work the offal line. Deer hunters and farm workers are other high risk groups.
Risk in NZ
Over the years there has been a number of vaccination campaigns in cattle, pigs and now they are trialing deer vaccines to reduce the carriage of leptospira in herds. Despite this amongst herds some animals remain positive/carriers. Around 70% of beef herds, 40% of sheep and 80% of deer herds have leptospira. This is highest amongst farms which graze both cattle and deer.
These figures lead to an estimated exposure of 8-25 leptospirosis carrying carcases per day for a meatworker.
Why is it not everywhere? Are we missing cases?
Waikato epidemiologists feel it is likely we have significant underreporting. The serological evidence that many people are infected and clear the leptospira without significant illness. Currently the ELISA has a low sensitivity and it is felt that serology is better for clinical diagnosis. The culture may take a number of weeks to become positive. To be eligible in NZ for Accident compensation corporation funding/payments you must have appropriate symptoms and a rise in your serology titer of 4 fold. It seems a safe bet that we are missing a number of cases.
In contrast to Dr Lanes Queensland experience deaths from leptospirosis are quite rare in New Zealand with one every few years. New Zealand appears to have slightly different endemic strains of leptospira. Also the soldiers are likely exposed to rodent urine vs that of bovines. Rat urine is more commonly infected with the more virulent strains of leptospira. A final thought from me about deaths from Leptospirosis: As deaths are reduced by immunomodulation perhaps the soldiers who are often being exposed for the first time to these antigens vs the meat workers who have a chronic exposure simply do not have the same immune overreaction?
So how did the patient do?
My patient improved over the following few days but took a couple of weeks to “come right” This was defined as being able to spend a couple of days staking deer in rough terrain and delivering me some venison steaks!
Paul Lane, ICU (Queensland) http://www.intensivecarenetwork.com/index.php/icn-activities/icn-podcasts/393-39-lane-on-tropical-microbiology
A new dawn of leptospirosis in New Zealand“Turning prevalence to incidence”
C Heuer et al. http://epicentre.massey.ac.nz/acvsc/scwk_08/Heuer_050708.pdf
Professor Wikipedia et al. http://en.wikipedia.org/wiki/Leptospirosis