Science Center Objects

The USGS National Wildlife Health Center (NWHC) works on developing various disease management tools, including the development of vaccines. Our current work focuses on vaccines for sylvatic plague, white-nose syndrome, and rabies as disease control strategies.

Sylvatic Plague Vaccine

Field Efficacy Trials with Sylvatic Plague Vaccine

Image: Sylvatic Plague Vaccine-Laden Bait

Over 30 organizations and agencies are testing a USGS-developed oral vaccine to prevent the spread of plague in prairie dogs. If successful, the sylvatic plague vaccine could help protect endangered black-footed ferrets in the western U.S. because the ferrets rely on prairie dogs for food.

The vaccine is placed in peanut butter-flavored bait (pictured), which is then scattered throughout the test areas for consumption by prairie dogs. (Credit: Tonie Rocke, U.S. Geological Survey. Public domain.)

Plague, caused by Yersinia pestis, is widespread throughout the western US and frequently occurs in wild rodents.  All four species of prairie dogs in the US are particularly susceptible to plague, suffering high mortality rates during outbreaks (> 90%) and resulting in local extirpations.  As a keystone species of grassland ecosystems, prairie dog losses significantly impact numerous other species that depend on them for food or shelter, including black-footed ferrets, burrowing owls, mountain plovers, and several canine and avian predators.  Currently, plague is managed in prairie dogs through manual application of insecticides to burrows to kill the fleas that transmit Y. pestis. However, this process is labor intensive and recent evidence suggests that fleas can develop resistance to the most frequently used pesticide. 

The NWHC, in conjunction with others, has developed and tested a sylvatic plague vaccine (SPV), deliverable to prairie dogs via palatable bait that offers an additional approach for plague management.  From 2013-15, the NWHC conducted a large, collaborative field study to test the effectiveness of SPV in reducing mortality from plague in four species of prairie dogs in 7 western states.  This study involved state, federal, tribal and non-government agencies organized under the Black-footed Ferret Recovery Implementation Team (BFFRIT), a multi-agency effort led by the US Fish and Wildlife Service.  Vaccine treatment had an overall positive effect on prairie dog abundance on our study plots compared to placebo plots and also increased survival of prairie dogs on plots where plague was detected.  Although some plague losses occurred on vaccine plots, our results provide evidence that consumption of vaccine-laden baits can protect prairie dogs against plague.  However, further evaluation and refinement is needed to optimize SPV use as a management tool and to determine if its use will provide benefits to other species, like black-footed ferrets, or whether it could be used to protect public health.

Conservation and Public Health Applications of the Sylvatic Plague Vaccine on National Park Service Lands

Prairie dog and SPV bait

A Gunnison's prairie dog eats a bait laden with the sylvatic plague vaccine. Prairie dogs in the wild are less likely to succumb to plague after they ingest peanut butter-flavored bait that contains a vaccine against the disease. (Credit: Tonie Rocke, USGS. Public domain.)

Plague, caused by Yersinia pestis, has devastated human and animal populations throughout history.  The United States has 5-10 human cases of plague, including some deaths, every year. The disease is also deadly for endangered black-footed ferrets, considered one of the rarest mammals in North America, and their prey, prairie dogs. Reintroduction of black-footed ferrets has occurred at Badlands National Park as part of the national recovery effort.  Despite initial successes, plague is considered to be the biggest impediment to the full recovery of the black-footed ferret.

Current efforts to manage plague in ferrets are labor intensive and include capture and vaccination of released ferrets and pesticide treatment of prairie dog burrows to reduce fleas that carry Y. pestis.  However, fleas are developing resistance to pesticides in some locations. Therefore, the NWHC is examining the effectiveness of sylvatic plague vaccine to protect not only prairie dog populations, but the ferrets that depend on those populations for prey. 

 

 

 

 

 

 

 

 

White-nose Syndrome Vaccine

Testing the Feasibility of Vaccination for White-Nose Syndrome and other Bat Diseases

Bats are important for protecting human health and the U.S. economy by controlling insects that carry diseases (e.g., West Nile and Zika Viruses) or cause damage to agricultural crops (estimated $3.5 billion in savings annually). Unfortunately, North American bats are experiencing devastating population declines from an emerging fungal disease, white-nose syndrome (WNS).

Little brown bat with white-nose syndrome

Little brown bat with white-nose syndrome (Credit: Marvin Moriarty, U.S. Fish and Wildlife Service. Public domain.)

To help safeguard North American bat populations, the NWHC is developing a vaccine against the fungus that causes WNS that can be applied topically to wild bats. Currently, several vaccine candidates are being tested to determine which provides the best protection to hibernating bats. Once developed, the goal is to confer disease resistance to vulnerable bats and safeguard their populations. This project was requested by the U.S. Fish and Wildlife Service and is jointly funded by the USFWS, USGS Ecosystems Mission Area, and the National Fish and Wildlife Foundation (NFWF).

Exploring the Potential for Transdermal Immunization of Bats

The U.S. Fish and Wildlife Service and numerous state agencies and conservation organizations have solicited assistance with identifying and implementing strategies for conserving at-risk bat populations. Therefore, the NWHC is testing and developing novel methods of vaccination (transdermal – through the skin) against the fungus that causes WNS.  This project is funded by the Ecosystems Mission Area Wildlife Disease Cyclical and is in collaboration with the University of Wisconsin School of Veterinary Medicine.

Project Documents

 

Rabies Vaccine

Image: Bats in a Texas Evening Sky

Bats in a Texas evening sky. (Credit: Paul Cryan, USGS. Public domain.)

Oral Delivery of Vaccine to Control Rabies in Vampire Bats (Desmodus rotundus)

Rabies, transmitted by vampire bats to cattle or people, is a tremendous economic burden in Central and South American countries. Additionally, vampire bats are moving north and are expected to disperse into southern Texas in the next decade. Currently, managers cull vampire bats to reduce vector populations by applying a pesticide to the skin of captured bats. Therefore, the NWHC is developing an effective and practical oral vaccine for rabies that can be applied to the skin of vampire bats.  To accomplish that goal, laboratory challenge trials in vampire bats are necessary to confirm vaccine efficacy, and a vehicle for delivering the vaccine must be developed and tested through field trials.  The intended goal of this project is to find better ways to manage rabies in bats, reducing risks to humans and domestic animals. This work is being conducted in close collaboration with USDA-APHIS in Mexico.