The Aftermath of the Western Australian Melioidosis Outbreak.
The 1997 outbreak of septicaemic melioidosis in a remote northwestern Australian community marked a watershed in public health microbiology response to bacterial infections in regional WA. This was the first time we attempted to put a scratch team together to provide immediate disease control measures, on-site environmental microbiology assessment and follow up with molecular epidemiology. This post looks at the aftermath of the melioidosis outbreak.
Much has been learned in almost a decade and a half since the event; most notably the role of the drinking water supply as a means of distribution of the causal agent, Burkholderia pseudomallei. Though we still don’t know exactly what the final means of exposure was, the disease control measures introduced in a hurry just before Christmas 1997 and the additional measures rolled out when we identified contamination of the water treatment installations a year later appear to have worked. There have been no further septicaemic cases attributable to exposure after the original outbreak in the last decade. It therefore looks like we may have stumbled upon an unexpected method of melioidosis control. Certainly not the only effective method, but at least it’s a start.
The other big insight has been the potential for occasional long distance movement of the causal agent, B. pseudomallei as a result of severe weather events. We’ve known for some time that severe weather in northern Australia coincides with an increased occurence of melioidosis cases, but the incidental observation that peak years for the infection in WA are when tropical cyclones approach the state from a landward direction. At this point the association is based on 10 years’ data generated as a result of disease notification in WA. It will be interesting to see how this shapes up over a longer period.
Disease notification has already alerted us to possible effects of climate change on the epidemiology of melioidosis. It should also allow monitoring of the results of agricultural and mining development in the State’s north. Clearly we need to keep a close eye on the impact of industrial cultivation of rice in the Kimberley, since melioidosis is a disease of rice farmers in Southeast Asia. Mine sites and other large scale industrial developments significantly alter soil conditions and bring workers into contact with the soil. This may also change the melioidosis risk in tropical WA.
Carefully organised and effectively targeted surveillance will help pin-point the risk and deliver disease workable control measures. Lessons learned in the aftermath of the 1997 melioidosis outbreak may bring wider benefits to the booming norther part of the State.