Meliodosis

This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American

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Meliodosis is currently poking its head above the surface in Australia and is causing a few problems. This nasty little disease is caused by the bacterial species with my favorite name, Burkholderia pseudomallei.

 

B. pseudomallei is a soil and water dwelling gram negative organism that spends most of its time not doing much, but, if it gets into a body it can cause a wide range of symptoms including chest joint and bone pain, coughs, pneumoniae and lung nodules and even skin infections if the skin remains wet enough. While it remains of concern to humans, meliodosis was originally observed in livestock such as horses and donkeys. In fact meliodosis roughly translates as “a distemper of asses” from greek which just gets funnier the more I think about it. There are many people who I wish would contract this (only a mild case of course) just so I could state this fact then make smart-arse comments for the rest of the night.

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Infection with B. pseudomallei is often resolved at the acute stage but the timing of the acute stage can be another matter entirely. Acute infections arise within days to hours of acquiring the micro-organism and result in fever, generalised pain, coughs which left untreated can develop into pneumonia and a few other things. If left untreated long-term patients start to get a host of other problems, particularly if the infection spreads into the abdomen such as abscesses on liver and/or spleen. Less common and apparently regional observations include parotid (salivary gland) abscess in Thai patients and prostatic (prostate gland) abscesses in Australian men.

I mentioned the timing of the acute stage could be important earlier. It turns out B. pseudomallei infections have an incubation time (time between infection and the onset of symptoms) that range wildly. Incubations of as little as a day have been observed and most are 1-21 days but some cases have developed after 60+ years of incubation!

Chronic meliodosis is declared if any of the symptoms last more than 2 months and, of course, during that time everything ramps up. Rashes become full blow skin infections and skin ulcers, that cough becomes pneumonia, lung nodules and even pathology that mimics tuberculosis can be detected.

Treatment for this little nasty takes about 20-22 weeks with at least the first 2 weeks spent in a hospital. During those 2 weeks intravenous antibiotics are fed into the system until the fever passes at which point a bacteriostatic drug (one which doesn’t kill the bacteria but simply stops it from growing) is prescribed for 20 or so weeks.

Even if treatment is successful 10-20% of patients develop recurrent meliodosis and start the treatment cycle over again.

So all in all it’s a pretty nasty bug, which is why attempts have been made to weaponise it. Both the US and the Soviet Union apparently tried but as far as I could tell it remains a ‘potential’ rather than ‘actual’ biological weapon.