Zika: Are outbreaks in U.S. cities avoidable?
Mar09

Zika: Are outbreaks in U.S. cities avoidable?

A guest commentary by Shannon LaDeau, a disease ecologist at the Cary Institute of Ecosystem Studies and a Baltimore Ecosystem Study NSF LTER co-principal investigator and Paul Leisnham, an associate professor of ecology and health at the University of Maryland’s Department of Environmental Science and Technology. When it comes to addressing emerging infectious disease, we have a short attention span. Forces are mobilized when we’ve crossed a tipping point, and demobilized when the immediate threat has passed. In the case of Zika, the World Health Organization (WHO) declared a public health emergency based on a strong association between Zika infection and a rise in congenital malformations and neurological complications – mainly microcephaly in newborns and a spike in Guillain-Barré syndrome. President Obama requested $1.8 billion in emergency funding to combat the Zika outbreak in the US and abroad. His request was bold; the US is not one of the 52 countries and territories in the Americas with local Zika transmission. Less surprising was House Appropriations Committee Chairman Hal Rogers’ (R-Ky) suggestion that Health and Human Services allocate $1.4 billion in ‘left over’ Ebola funds to contain Zika virus. We still don’t know what environmental conditions triggered the Ebola epidemic, which was the deadliest to date. Zika is not new. The mosquito-borne virus has been on our radar since 1947, when it was discovered in Uganda. For decades, it was seen as a milder form of dengue and was primarily a nuisance in places with poor infectious disease surveillance. In 2012, the pathogen of concern was chikungunya. In another three years it will likely be something else. Because our public health and funding infrastructure are reactive, instead of understanding the roots of these epidemics, we are left trailing human infection. This mindset has to change. Infectious disease emergence is a social and ecological issue. While there are many benefits to a connected global community, we are moving pests and pathogens around the world at an unprecedented rate. The two mosquitoes species that transmit Zika, Aedes albopictus and Aedes aegypti, are imports from Southeast Asia and Africa respectively, and are now active on nearly every continent. Adapted to breed almost exclusively in cities, they bite people during the day and breed in small containers of water – a bottle cap will suffice.  As long as cities support large numbers of Aedes mosquitoes, urban residents are at risk from not just Zika but chikungunya, dengue, and emerging diseases that aren’t even on our radar. There is an environmental justice overlay to this (and many) environmental problems: poorer neighborhoods have larger mosquito populations and their residents have fewer resources to take the actions necessary to...

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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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Global economic pressures trickle down to local landscape change, altering disease risk

by Liza Lester, ESA communications officer The pressures of global trade may heighten disease incidence by dictating changes in land use. A boom in disease-carrying ticks and chiggers has followed the abandonment of rice cultivation in Taiwanese paddies, say ecologist Chi-Chien Kuo and colleagues, demonstrating the potential for global commodities pricing to drive the spread of infections. Their work appears in the September issue of ESA’s journal Ecological Applications. After Taiwan joined the World Trade Organization in 2001, active cultivation of rice paddies fell from 80 percent to 55 percent in just three years. The government of Taiwan subsidized twice-yearly plowing of abandoned fields to reduce the spread of agricultural pests into adjacent fields still in cultivation. Compliance has been spotty. Kuo found that, while plowing did not suppress rodent populations, it did inadvertently reduce the presence of the ticks and chiggers that use rodents as their primary hosts. “The government considers only agricultural pests such as insects and rodents. They don’t think about the disease factors,” said Kuo. But land use policy can have complex and unexpected reverberations in the ecology of the landscape. Chiggers, the larval stage of trombiculid mites, spread scrub typhus (Orientia tsutsugamushi), a bacterium that gets its name from the scrubby, dense vegetation that often harbors its flesh-loving host. Scrub typhus is a common culprit underlying visits to Southeast Asian hospitals for flu-like symptoms. It is one of the rare bacterial infections that develop into hemorrhagic fever. Without antibiotics, the infection is often fatal. Ticks (Ixodidae) transmit bacteria spotted fever group rickettsiae, causing fever, aches and rash similar to Rocky Mountain spotted fever. Neither pest prefers to live underwater. Hualien, Kuo’s study area, is one of the least populous of Taiwan’s counties, yet had nearly the highest incidence of scrub typhus from 1998-2007. The county is a smattering of small villages surrounded by a patchwork of flooded, plowed, and abandoned rice paddies. Flooded paddies are poor habitat for ticks and chiggers, and so cultivation of rice, which locally means carefully managed flooding of fields to drown agricultural pests, likely suppresses ticks and chiggers as well. Even the seemingly unkillable ticks die after a few weeks of submersion, and chiggers are similarly terrestrial. Though studies are few, limited data indicate that most chiggers die after a month under water. This study did not assess flooded paddies due to the difficulty of finding and collecting rodents, ticks, and chiggers underwater. Instead, Kuo trapped rodents in fallow and plowed fields and examined their tick and chigger passengers, testing the arachnids for presence of disease-causing rickettsial bacteria. He found 6 times as many ticks on the rodents living...

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Northwest leaders: coal export proposal deserves environmental review

This post contributed by Terence Houston, ESA Science Policy Analyst A proposal to develop new marine coal export terminals in Oregon and Washington, which could ship between 75 million and 175 million tons of Powder River Basin coal annually to Asia, has drawn concern from environmentalists in the region. The National Wildlife Federation and the Association of Northwest Steelheaders have released a report outlining various environmental concerns to local communities brought on by coal production in the region. The six export terminals would be located in Cherry-Point, Grays Harbor, Longview, Port of St. Helens, Port of Morrow and Coos Bay. In the report, entitled “The True Cost of Coal,” the authors state that the proposed projects would pose threats to public health and set back decades of successful environmental recovery efforts in the region.  Among the detriments cited in the report are air pollution from coal dust, noise pollution and congestion from increased train traffic, increased risk of invasive species from tanker traffic as well as mercury deposition and ocean acidification, which could lead to the loss of salmon and steelhead, critical to the regional economy. A number of local communities and organizations, including Oregon Physicians for Social Responsibility and Oregon’s Environmental Justice Task Force and the American Indian Yakama Nation tribe, have called upon Governor John Kitzhaber (D-OR) to delay any coal-export projects until a comprehensive health impact assessment is completed. The effort is being pushed by mining corporations, including Peabody Energy, Arch Coal, Cloud Peak Energy and Ambre Energy North America. The Alliance for Northwest Jobs and Exports, which advocates for the aforementioned entities, contends that “the proposed terminals would create thousands of new jobs and generate tens of millions in additional tax revenue for schools and other services in Washington and Oregon. The group’s website further maintains that the six proposed coal export terminals “can be built in a safe and environmentally responsible way.” The issue has garnered attention from lawmakers on Capitol Hill. Rep. Jim McDermott (D-WA) has introduced H.R. 6202, the True Cost of Coal Act. The bill imposes a $10 per ton tax on coal and establishes a Coal Mitigation Trust Fund to mitigate potential negative environmental impacts of coal transportation. The bill is unlikely to advance in the Republican-controlled House. Reps. Cynthia Lummis (R-WY) and Denny Rehberg (R-MT), both supporters of Powder River Basin coal production, have been joined by leading Republicans and some Democrats in calling on the Obama administration to initiate project-specific permit reviews rather than the broad environmental impact assessments environmental advocates endorse. Sen. Jeff Merkley (D-OR) has issued a letter requesting that the Bureau of Land Management and...

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Solutions for a nitrogen-soaked world

Overabundance of an essential nutrient is not always a good thing. – by Liza Lester, ESA communications officer. A tractor spreads manure. Excess fertilizer seeping out of fields has a host of consequences for ecological systems and human health. Credit, flickr user eutrophication&hypoxia, 2010.   NITROGEN is both an essential nutrient and a pollutant, a byproduct of fossil fuel combustion and a fertilizer that feeds billions, a benefit and a hazard, depending on form, location, and quantity. Agriculture, industry and transportation have spread nitrogen liberally around the planet, say scientists in the latest edition of ESA’s Issues in Ecology series, with complex and interrelated consequences for ecological communities and our dependence upon the resources they provide, as well as for human health. Nitrogen is a basic component of life’s most famous molecules: proteins, RNA and DNA. Though nitrogen fills 78.1 percent of the air we breathe, energy is required to convert (or ‘’fix”) it into biologically accessible forms, a process that some species of bacteria can accomplish, but other organisms cannot. Consumers like humans, cows, birds and mosquitoes get nitrogen by eating other live things. For plants, lack of nitrogen in their immediate environment can be a serious limitation. In many ecosystems, the limit of available nitrogen is the limit of growth. We have removed that limit for our food crops by supplying them with fertilizer in the form of manure, nitrogen-“fixing” bacteria symbiotic with legumes like soybeans, and synthetic nitrogen fertilizers. Pulling from a broad pool of expertise in air quality, agronomy, ecology, epidemiology and groundwater geochemistry, the sixteen authors track nitrogen through its different chemical forms and biological incarnations as it progresses across economic, environmental and regulatory bounds. They argue for a systematic, rather than piecemeal, approach to managing the resource and its consequences. “We’re really trying to identify solutions,” said lead author Eric Davidson, a soil ecologist and executive director of the Woods Hole Research Center. “This is a paper about how much we <em>do</em> know, not about what we don’t know. We know about nitrogen cycles, and sources, and we know problems can be addressed in economically viable ways.” In the mid-twentieth century, widespread adoption of the Haber-Bosch industrial process for “fixing” nitrogen from the air using fossil fuels (natural gas, usually) changed agriculture in the US, and there is no going back. There are seven billion people on Earth. Without synthetic nitrogen, author Jim Galloway, a biogeochemist at the University of Virginia, estimates we could feed about four billion. “There are a variety of impacts due to the human use of nitrogen. The biggest is a positive one, in that it allows us to...

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Chickenpox sweeties and the social ecology of infectious disease

This post contributed by Liza Lester, ESA communications officer   No one speaks for the endangered poliomyelitis. No one raises money to protect the last survivors, as health workers stalk the virus through its last redoubts in India, Pakistan, Nigeria and Afghanistan. On the contrary, the WHO spends billions on hunting it to extinction. But the virus has held out longer than expected. Joshua Michaud, policy analyst at the Kaiser Foundation, thinks the polio fighters are falling behind. Guinea worm will be the next scourge to fall, he said on an AAAS panel engaged to discuss Infectious Disease: Challenges to Eradication on Monday. Why have efforts with guinea worm been so successful? a precocious Georgetown student wanted to know. Biology was on our side. There is no vaccine for guinea worm, and no medicine to cure infection. To extract the worm, you must wind it slowly around a stick as it emerges through a sore in your leg (an oft-repeated story holds that the treatment has not changed since the Egyptians of the XVIII dynasty described it in 1550 BCE, though the source appears to have been exaggerated). The process is excruciating, and it takes weeks. But we know key details of the worm’s biology that the ancient Egyptians did not. Basic technology and careful hygiene can defeat the worm. Larvae harbor in the bodies of invisible copepods, “water flies” tiny enough to swallow. Once swallowed, female larvae nestle against the long limb bones of their hosts, growing up to a meter in length over the course of a year. They surface inside a burning ulceration that sends their victims running for a dip in a cool pond—and the next generation of larvae escape to start the cycle of life anew. The good news, said Michaud, is that guinea worm does not have another host. It has no environmental bolt hole to hide in while under siege, only to emerge when health forces are not looking. It needs humans. And affected people are visibly affected. Break the cycle for one year, and you can free a communal water source, and its community, from the worm. Copapods may be microscopic, but a simple nylon strainer on the end of a drinking tube saves you from swallowing them (although not bacterial and viral parasites that might also lurk there, interjected Dennis Carroll, in charge of avian flu and other emerging threats at USAID). Help the infected, persuade them to stay out of drinking water sources when their worm breaches, and you break the cycle. Success requires the help and good will of village elders. The Carter Foundation has been courting good...

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New grants promote greater understanding of infectious disease

This post contributed by Lindsay Deel, a Ph.D. student in geography at West Virginia University and Intern with ESA’s journal Frontiers in Ecology and the Environment Infectious diseases won’t know what hit them. A massive new collaborative effort between funding sources in the United States (US) and United Kingdom (UK) takes aim at infectious diseases from ecological and social perspectives, reported the National Science Foundation (NSF) in a recent press release. The overall goal of the suite of eight projects is to improve understanding of the factors affecting disease transmission, said NSF, but a major focus will also be on building models to help predict and control outbreaks. Each of these projects examines different themes within the global context of infectious disease. For example, Tony Goldberg (Professor of Epidemiology, University of Wisconsin–Madison) and colleagues will investigate the spread of HIV from its origin in monkeys to humans by examining similar viruses that are currently impacting wild monkeys in Uganda. This project will also study human social factors – such as awareness, beliefs, and behaviors – surrounding the transmission of such diseases. Another project helmed by David Rizzo (Professor of Plant Pathology, University of California–Davis) will explore how interacting forest disturbances – such as fire and drought – may control the emergence, persistence, and spread of invasive pathogens using the case of sudden oak death – a disease caused by a non-native pathogen, Phytophthora ramorum. “Over the past 10 years, potentially millions of trees in California and Oregon coastal forests have died as a result of this emerging disease,” explains Rizzo. “The goal of this new grant is [to] link this new disturbance agent (sudden oak death) with pre-existing disturbance agents (fire, drought) in coastal forests.” Samantha Forde (Professor of Ecology and Evolutionary Biology, University of California – Santa Cruz) will lead a project using a simplified laboratory system of E. coli bacteria and its viruses as a model to study why some viruses have evolved the ability to infect multiple host species, while others can only infect one.  “This will further a general understanding of the dynamics of disease in natural systems and help to improve public health initiatives,” she says. From the modeling perspective, Armand Kuris (Professor of Biological Sciences, University of California at Santa Barbara) and colleagues will delve into the complexity of ecological systems and how the level of complexity might influence disease dynamics.  Kuris and colleagues hope to bring the role of infectious diseases into the core of ecological thinking, comparable to the roles of predation, competition, disturbance and resource quality. Joseph Tien (Professor of Mathematics, Ohio State University) will examine the recent cholera epidemic in Haiti. ...

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Weighing the long-term implications of mountaintop removal mining

The practice of mountaintop removal mining has spurred a great deal of research and policy debate since January of this year, when the Environmental Protection Agency (EPA) vetoed a federal permit for the 2,278 acre Spruce No. 1 mine in Logan County, West Virginia. The veto of the permit was EPA’s 13th use of its veto authority, granted under the Clean Water Act (Public Law 92-500). In the practice of mountaintop removal mining, upper elevation forests are cleared and stripped of topsoil and explosives are used to break up rocks to access buried coal. Excess rock (“mine spoil”) is pushed into adjacent valleys where it buries existing streams. Surface mining is currently the dominant driver of land-use change in the Appalachian region. Industry advocates and regional lawmakers describe the practice as having important economic benefits for the region. At the same time, a great deal of scientific research has called into question whether the long-term ecological and human health consequences of mountain top removal mining outweigh the short-term economic benefits. A recent study by West Virginia University and Washington State University scientists found a correlation between areas of mountain top removal mining and birth defects of local residents. The researchers used government data on almost two million birth records from mining sites in Kentucky, Tennessee, Virginia and West Virginia. The study notes that, even after accounting for socioeconomic risks, the correlation persists—making it increasingly likely that water and air pollution were dominant factors. The study specifically found that areas with the most substantial environmental disturbances corresponded with the greatest incidents of birth defects. The study does concede a number of other factors may play a role, such as underreporting of maternal smoking and drinking. In May, EPA also released two studies on the effects of mountain top removal mining in Appalachian states. The first study found that streams were “permanently lost with the removal of the mountain and from burial under mining waste.” It also found increased levels of selenium and other pollutants near mining sites that can have detrimental impacts on wildlife in the area. The second study, focusing on water conductivity, found that high levels of conductivity are associated with a loss of aquatic life. On Capitol Hill, EPA’s veto has been met with sharp criticism among senior congressional Republicans, the mining industry and West Virginia lawmakers (among both political parties). Mining advocates claim EPA’s actions serve to stifle job creation in the region amidst an already fragile economy. Both of the West Virginia Senators, Joe Manchin (D) and Jay Rockefeller (D) are opposed to EPA’s action—the latter having sent a letter to the President criticizing the...

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