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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Pest control resources fell as anti-terrorism efforts rose

The United States “war on terrorism” mobilized the federal government to take action to prevent a recurrence of the events of 9/11/01. Ten years and just over a month later, efforts that span two presidential administrations have led to a country that is more secure against one of Earth’s most dangerous species: humans. Unfortunately, an unwanted side effect has been a jump in the infiltration into the U.S. of countless other species that pose an entirely different kind of threat. A recent analysis by the Associate Press (AP), found that in the years since 9/11, scientists that were once responsible for curbing the entry of invasive species at U.S. borders have been reassigned to anti-terrorism efforts after the formation of the Department of Homeland Security (DHS), established under the Homeland Security Act of 2002 (P.L. 107-296). In 2003, as laid out in the bill’s provisions, many APHIS agricultural border inspectors were transferred from the Department of Agriculture to U.S. Customs and Border Protection, a unit of the U.S. Department of Homeland Security. As a result, the number of pest cases intercepted at U.S. ports of entry fell from over 81,200 in 2002 to less than 58,500 in 2006. The numbers have since steadily risen again after complaints from farm industry and lawmakers. As highlighted in a recent EcoTone post, invasive species can be serious burden on the economy as clean up costs for individual species can number anywhere from hundreds of thousands to millions of dollars. The AP article notes that the most problematic overseas imports are fruits, vegetables and spices, which can carry insects, their larvae or contagions capable of decimating crops. The article states that crop-threatening species has spiked from eight in 1999 to at least 30 in 2010. The Center for Invasive Species Research (CISR) reports that since 1991, the silver-leaf whitefly has cost an estimated $500 million to California agriculture, translating to “roughly $774 million in private sector sales, 12,540 jobs and $112.5 million in personal income.” Nationally, the fly’s damage has been estimated to be in excess of $1 billion.  CISR also found that the red palm weevil, first identified in the United States in August 2010, poses a “serious threat” to ornamental palm tree sales, which contribute $70 million to the California economy and $127 million to the Florida economy each year. A recent study found that wood boring insects, such as the Asian long-horn beetle, reportedly cost more than $3.5 billion in losses, including $1.7 billion to local governments, $1.59 billion to homeowners, $130 million to forest landowners and $92 million to the federal government. The same study concluded there is a 32 percent...

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From the Community: Pika population sees a boost, birds not spreading West Nile and five women honored for their role as environmentalists

Pika found to be flourishing in the Sierra Nevada region, bird migration patterns suggest mosquitoes are to blame for spreading West Nile and mice courtship rituals could shed light on autism. Here are news stories and studies on ecological science from the first week in March.

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Nutrient enrichment linked to diseases in humans and wildlife

Scientists have provided a rather grim prognosis for global health: the recent increase in nutrient enrichment due to human activities, such as nitrogen pollution through fossil fuel combustion, is likely contributing to several varieties of infectious diseases in humans and wildlife.

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