The USGS One Health Approach to Wildlife Disease and Environmental Change

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One Health is a collaborative approach – working at the local, regional, national, and global levels – with the goal of achieving optimal health outcomes recognizing the interconnection between people, animals, plants, and their shared environment.  USGS researchers conduct surveillance and research to support a One Health approach to respond to zoonotic diseases and environmental change.   

Many emerging human infectious diseases, such as COVID-19, are zoonotic meaning they are shared between animals and humans. Of emerging human infectious diseases that are zoonotic, 70% originate in wildlife[1].  The effects of emerging wildlife diseases are global and profound, often resulting in economic and agricultural impacts, declines in wildlife populations, and ecological disturbance.  One Health is a collaborative approach – working at the local, regional, national, and global levels – with the goal of achieving optimal health outcomes recognizing the interconnection between people, animals, plants, and their shared environment. 

One Health connections

One Health is the idea that the health of people is connected to the health of animals and our shared environment.  More at Centers for Disease Control and Prevention (Public domain.)

USGS Wildlife Disease Science Supporting the One Health Framework  

USGS wildlife disease research capabilities have been utilized to conduct surveillance and research to support a One Health approach to respond to zoonotic diseases.        

Following the 2016 Joint External Evaluation the Centers for Disease Control and Prevention, USDA and DOI planned and implemented the first USA One Health Zoonotic Disease Prioritization Workshop. Eight diseases were selected as priority at the workshop and include: Zoonotic influenza; Salmonellosis; West Nile virus; Plague; emerging coronaviruses; Rabies; Brucellosis; and Lyme disease. 

Of the eight prioritized zoonoses, USGS conducts work on seven including emerging coronaviruses. Below we highlight the most recent USGS research from the field. 

 

Avian Influenza Viruses: 

Scientist swabbing hunter-harvested ducks in western Alaska

Lindsay Carlson swabbing hunter-harvested ducks in western Alaska as part of USGS research to investigate the persistence of avian influenza viruses in North American wetlands.  USGS scientists and colleagues found that influenza A viruses may remain infectious in surface waters of northern wetlands for more than seven months.  (Credit: Andrew Reeves, U.S. Geological Survey. Public domain.)

The emergence of highly pathogenic strains of avian influenza (HPAI), commonly referred to as bird flu, is a serious threat to our global economy and human health. HPAI may result in high mortality rate in domestic and sometimes wild birds, which can cause significant economic losses. The secondary threat from HPAI is the possibility of human infection. Although instances of HPAI becoming lethal to humans are rare, such infections are possible, such as when the Asian H5N1 virus evolved to incur a 60-percent case-fatality rate in humans. 

Recent USGS research has resulted in a risk model and associated visualization tool for the spread of HPAI based on the ability of domestic birds to encounter wild fowl across space and time. USGS is also advancing understanding of the migratory ecology of Blue-winged Teal and how this may impact the ability of this species to transmit HPAI or other pathogens across the wild bird – domestic poultry interface. 

As avian influenza viruses are sometimes detected in the environment outside the avian host and may persist in the aquatic environment, USGS scientists have performed biosurveillance for detection of these viruses along the Delmarva Peninsula, on the East Coast of the United States, among potential aquatic reservoirs including water, sediment, and filter-feeding biota such as bivalve mollusks. Future efforts throughout waterfowl habitat along Delmarva or elsewhere could be used to determine the significance of avian influenza viruses detected from different reservoirs related to site-specific habitat variables such as water quality, land use, or biological components. 

Additional research provided baseline data on HPAI occurrence in groundwater underlying poultry farms and documented the challenges for conducting a pathogen transport study during a disease outbreak. Results indicated that that viruses associated with poultry can be transported to groundwater underlying poultry operations.

 

Coronaviruses: 

image of SARS-CoV-2, CDC

CDC graphic on coronavirus disease 2019 (COVID-19). (Public domain.)

COVID-19 Effects on Fisheries: The One Health approach has been especially useful during the COVID-19 pandemic, allowing researchers to explore the effects of global public health measures on fish, wildlife, and ecosystems. For example, a study co-authored by the USGS found that uneven COVID-19 responses have had correspondingly uneven effects on inland fisheries around the globe. Fish populations in some regions thrived as commercial fisheries shut down, while other fisheries became over-burdened as seafood became an increasingly important food source in strained markets. In another study, USGS found that COVID-19 also affected recreational anglers in the United States, with many reporting fishing as an important social outlet and source of stress relief during tough pandemic times. These studies emphasize the complex relationship between human health, natural resources, and human’s relationship with nature.  

Development of SARS-CoV-2 vaccine to support black-footed ferret conservation: The SARS-CoV-2 virus is known to infect and cause severe disease, such as respiratory distress and death, in mustelids, including farm-raised mink and domestic ferrets. This raised concern that the virus may also pose a threat to endangered black-footed ferrets managed in captivity for breeding and recovery purposes. Although to date no evidence of exposure in captive or wild black-footed ferrets has been observed, detection of SARS-CoV-2 in zoo animals and documented cases of transmission from farm workers to farm-raised mink demonstrates the risk of human to animal viral transmission in captive settings. In addition to enhanced use of personal protective equipment by caretakers and other procedures to reduce risk of transmission to black-footed ferrets, a small study was conducted by the U.S. Fish and Wildlife Service (USFWS) and the USGS to assess whether immunization of black-footed ferrets using commercially available viral proteins could elicit a protective immune response against the virus. Vaccinated animals had higher antibody levels, including virus neutralizing antibodies, compared to unvaccinated animals. It is still unknown whether vaccination is protective against the disease or reduces its effects; nevertheless, due to the importance of this captive population, approximately 2/3 of the black-footed ferrets at USFWS National Black-footed Ferret Conservation Center were vaccinated as a precautionary measure. 

Little Brown Bat and Indiana Bats

A single Myotis lucifugus (little brown bat; black nose) in a cluster of M. sodalis (Indiana bats; pink noses).  (Credit: Riley Bernard, University of Tennessee. Photo by Riley Bernard, University of Tennessee)

Examining the susceptibility of North American bats to SARS-CoV-2: The USGS led assessments on the likelihood for scientists and wildlife managers to transmit SARS-CoV-2, which is the type of coronavirus that causes COVID-19 in humans, to North American bats during fieldwork. The studies found that if no protective measures are taken, less than two in 1,000 bats are likely to become infected during summer fieldwork and one in 1,000 are likely to become infected during winter fieldwork. That risk is reduced with the proper use of personal protective equipment or if individuals test negative for COVID-19 prior to conducting research.  To more directly assess the potential for bats to become infected by SARS-CoV-2, the USGS conducted an infection trial in big brown bats and found that big brown bats are resistant to infection. To determine the potential susceptibility of other North American bat species, researchers began an experimental challenge trial examining the susceptibility of Mexican free-tailed bats to SARS-CoV-2. This species was selected because it resides in large colonies, often in urban settings, thereby increasing potential risk of exposure to the virus from infected humans. The reservoir potential of these bats for the virus is currently unknown and will be assessed in this study. 

 

Lyme Disease: 

Image: Catching Ticks for Research

A University of Tennessee scientist examines a drag cloth used to catch ticks in the field for research purposes. (Credit: Graham J. Hickling, The University of Tennessee. Public domain.)

Cases of tick-borne diseases in humans, particularly Lyme disease, have been increasing for decades in the United States. A new article led by the USGS summarizes what’s happening in Rhode Island, where the major tick of concern is the blacklegged tick, also called the deer tick. It transmits the pathogens that can cause diseases such as Lyme, babesiosis and anaplasmosis, all of which have rising cases and are expected to continue to increase.

In previous research, the USGS and partners found a few significant factors that contribute to the higher infection rates from blacklegged ticks in the north. Northern blacklegged ticks abundantly seek food sources, known as hosts, on top of the leaf litter and twigs where they can frequently encounter people. Research suggests that the climate and host associations may play a part in this pattern, as warmer temperatures in the south may cause ticks to stay below the leaf litter surface. Research has also found that black-legged ticks in the north attach to and feed off mammals, such as rodents and shrews, that are efficient at carrying and spreading the bacteria that cause these diseases. 

 

Plague: 

Plague is a zoonotic, primarily vector-borne disease caused by a bacterium that was moved to North and South America and elsewhere by human commerce in the early 20th century. This bacterium infects a wide variety of host mammals and plague circulates in free-ranging rodents through transmission by fleas. Plague poses a substantial threat to the highly endangered black-footed ferret. The USGS works with the U.S. Department of Health and Human Services and the Centers for Disease Control and Prevention (CDC) on an ongoing One Health approach to investigate1) plague maintenance and circulation that cause ecosystem alteration, 2) the factors that lead to devastating “spillover” which can result in wildlife extinctions and increased human health risks, and 3) methods for managing plague. USGS science on plague ecology, flea ecology, and management tools have contributed to our one health understanding of ecological and human health impacts of this re-emerging disease. 

Adult female black-footed ferret with her prey

Adult female black-footed ferret with her prey, a juvenile prairie dog, in Conata Basin, South Dakota. (Credit: David Eads, USGS. Public domain.)

The black-footed ferret is one of the most endangered mammals in North America and plague is a major obstacle to ferret recovery. In a joint effort to combat plague, USGS scientists have developed an oral vaccine to protect prairie dogs. Ferrets are heavily dependent on prairie dogs as a food source, and they use prairie dog burrows for shelter. Extensive laboratory experiments and field trials have been conducted to determine the vaccine’s efficacy in preventing plague in prairie dogs. The vaccine, which is mixed with a peanut butter-flavored bait and placed in selected prairie dog colonies, has been designed to provide better protection against plague with less labor, lower costs, and reduced risk for ecological impacts on nontarget species than current control methods involving broad application of insecticides. Ultimately, the vaccine has great potential to improve recovery efforts for the black-footed ferret, sustain prairie dog populations, reduce human exposure to this zoonotic disease, and protect grassland ecosystems of the American West. 

 

A One Health Approach to Assessing Environmental Impacts to Fish, Wildlife, and Human Health:  

The USGS and partners have also applied a One Health framework to climate change, funding a national synthesis looking at how changing temperature and precipitation patterns are affecting fish and wildlife health across North America. The researchers have found that climate change has both direct and indirect effects on animal health, increasing exposure to pathogens and parasites while also causing physical stress (such as overheating and dehydration) that lowers immune functions. They are currently developing a searchable database of these health impacts, creating an important resource for managers and scientists and helping to identify knowledge gaps in the literature.   

The USGS is focused on understanding the exposure of wildlife and humans to contaminants and pathogens in the environment. This is accomplished by studying sources and movement of chemicals in the environment, which informs human and wildlife exposure followed by ecotoxicological studies to understand effects on wildlife. In this way the science is at the intersection of wildlife, humans, and the environment within a One Health context.   

USGS scientists use a One Health approach on scientific investigations that determine how contaminants such as PFAS bioaccumulate in fish and wildlife that are harvested by the public to the monitoring of contaminant mixtures (PFAS, lead, algal toxins, pesticides, pharmaceuticals, etc.) found in tap water. These investigations are led through the Environmental Health Program

 

CDC One Health graphic connecting human, animal, and environmental health.

CDC One Health graphic connecting human, animal, and environmental health. More at Centers for Disease Control and Prevention

(Public domain.)