Ecology of zoonotic diseases

Figuring out the what, where and when of disease outbreaks By Nadine Lymn, ESA director of public affairs Plague, Lyme disease, Hantavirus, West Nile Virus—these bacteria and viruses are zoonotic diseases that can be transmitted to people from animals like ticks, mosquitoes and rodents and were the subject of a recent Ecological Society of America (ESA) congressional briefing. Disease transmission is an environmental issue–understanding the ecological dynamics at play is crucial.  Ecology can help sleuth out the source of new diseases and help predict where and when new outbreaks are likely to occur. That was a key message Robert Parmenter and Gregory Glass had for the congressional, federal agency and scientific society staff attending ESA’s briefing on April 23, 2013. Parmenter directs the Scientific Services Division of the US Department of Agriculture’s Valles Caldera National Preserve in New Mexico.  He has years of experience with zoonoses, especially plague and Hantavirus. Glass is a professor at Johns Hopkins School of Public Health and directs the Global Biological Threat Reduction Program of the Southern Research Institute. His work has included a focus on Lyme disease and Anthrax, along with hantaviruses.  Between the two of them, Parmenter and Glass painted a vivid picture of the dynamics of these diseases and how collaborations between ecological and medical research can solve disease mysteries, such as that of the first hantavirus outbreak in the Four Corners region of the US. In May of 1993, people were coming down with flu-like symptoms that rapidly filled their lungs with fluid, killing some of them. Others just as quickly recovered. A sense of panic gripped the area and scientists from the Centers for Disease Control arrived and, within 19 days, identified the disease as Hantavirus Pulmonary Syndrome for which there is neither a vaccine nor a cure. But where had it come from and why now? Enter the ecologists who began field surveys and discovered that the source for the disease was the deer mouse, whose aerosolized urine and feces can infect humans with Hantavirus if inhaled. An unusually wet winter had led to a boom in the deer mouse population, which resulted in many of them descending from higher elevation forested areas to lower elevation areas where people tend to live, increasing the likelihood of mouse-human encounters. Since 1993, there have been other Hantavirus outbreaks, but now, with a much better understanding of the ecological factors in play, people can be notified ahead of time that conditions are right for increased chances of exposure and take appropriate precautionary steps. It turns out that different varieties of Hantavirus are present in a variety of rodents across North and...

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