Amount of soil (about 200 mg) from which Geomyces destructans was cultured. This shows the small amount of soil needed to harbor live fungus and the threat that humans might pose in moving it around from cave to cave on their gear, boots, and clothing.

The fungus that has killed millions of bats in eastern North America since 2006 can survive in the environment for long periods of time, according to new research conducted by the USGS National Wildlife Health Center and collaborating partners at the University of Wisconsin-Madison, Wisconsin Veterinary Diagnostic Laboratory, and U.S. Forest Service.

What is White Nose Syndrome?

White-nose syndrome (WNS) is a disease that has resulted in large-scale population declines for many species of North American bats. It is caused by Geomyces destructans, a fungus that is only capable of growing at cool temperatures; for this reason, the pathogen can only grow on bats when they are hibernating and have a depressed body temperature.

The WNS Causing Fungus Can Survive for Years

Scientists were previously unsure of how the fungus survived during the summer months when a bat’s body temperature is above that which is permissible for the growth of G. destructans. A new study published in Applied and Environmental Microbiology sheds light on this mystery, demonstrating that the fungus can survive over the summer in the soil of the caves and mines where bats hibernate.  Researchers at the USGS National Wildlife Health Center used culture techniques to analyze soil samples collected from 14 caves and mines in which bats with white-nose syndrome had been previously observed. The scientists found that G. destructans remained viable in the soil of these sites over the summer when bats were absent.  The findings reveal that caves and mines, which remain cool year-round, can serve as reservoirs for the fungus and that bats entering previously infected sites may contract white-nose syndrome from the environment.

In addition, the researchers found that G. destructans could persist in caves and mines for periods of time much longer than several months. At one site, the fungus was still surviving in soil two years after bats had been excluded from the mine. Similar species of fungi that are not pathogenic to bats appear to play out their entire life cycles in the soil of caves, and it is plausible that G. destructans is capable of doing the same. Once G. destructans arrives at a cave or mine, it is possible the site could remain contaminated indefinitely.

What these Findings Mean for Bats and Humans

This research has important implications for managing WNS and vulnerable bat species by revealing the important role that the environment plays in the disease. For example, the findings suggest that susceptible bats may not be able to effectively re-colonize caves and mines that have been previously contaminated and that the reintroduction of certain bat species to such sites may not be a sound strategy for reestablishing lost populations. Although bats likely play a major role in transporting the fungus, the work additionally highlights the potential for humans entering contaminated caves and mines to come into contact with G. destructans years after bats have disappeared from those sites.

The same study also used molecular techniques to examine the distribution of G. destructans in eastern North America and provided new evidence that the fungus is not native to the continent. These findings support a previous hypothesis that G. destructans may have been introduced from Europe where bats do not appear to die from infection by the fungus.  Using these molecular techniques, the scientists  looked for the fungus in the soil of 55 caves and mines where bats hibernate in the eastern U.S. They found that G. destructans was limited to caves and mines within the range of the disease, but the fungus could not be detected in sites that remained disease-free. In addition, the investigation found that the fungus’ presence correlated with the arrival of white-nose syndrome at sites sampled before and after the disease was observed. These results indicate that a pre-existing form of the fungus was not present prior to the manifestation of disease and argues against G. destructans being native to parts of eastern North America prior to the emergence of white-nose syndrome.

Early Detection of WNS

Amount of soil (about 200 mg) from which Geomyces destructans was cultured. This shows the small amount of soil needed to harbor live fungus and the threat that humans might pose in moving it around from cave to cave on their gear, boots, and clothing.

The molecular techniques used in the study represent the first successful attempt to use high-throughput screening, a method to rapidly test large numbers of environmental samples, for G. destructans and accurately distinguish it from the large number of similar fungi that occur in caves and mines. Such a technique has great utility in monitoring sites for the fungus and could serve as a means by which the disease agent can be detected prior to the disease itself being observed. This could allow for proactive management strategies that may reduce the number of bats lost and prevent or slow the spread of the fungus across the landscape.

USGS scientist Thierry Work takes a sample from diseased coral at Tunnels Reef on the north shore of Kauai, Hawaii

A coral disease epidemic is killing unusually large numbers of coral on the north shore of the Hawaiian island, Kauai, and USGS scientists, in collaboration with researchers from the University of Hawaii Institute of Marine Biology, are investigating the cause.

Coral reefs cover less than 0.5 percent of the earth’s surface, but provide habitat for an estimated 25 percent of all marine species. Second only to tropical rainforests in size and complexity, more than one million species of plants and animals may be interlinked with coral reefs.

“Coral reefs are important to Hawaii’s underwater environments and the financial well-being of its tourism industry,” said USGS scientist Thierry Work. “Like it or not, ecosystem health is closely intertwined with human and animal health.”

What is Causing the Disease?

Scientists have collected coral samples from the diseased areas, which are referred to as lesions, and examined them in the laboratory. The lesions are closely associated with a mysterious cyanobacterial infection. Cyanobacteria, a type of blue-green algae, often cause visible blooms in freshwater lakes; however, many cyanobacteria are also present in the ocean. Some species of cyanobacteria produce toxins that can sicken wildlife, domestic animals, and humans. The effects of this current outbreak appear limited to corals.

This coral disease outbreak is the first instance where a cyanobacterial disease has been documented in Hawaii on such a large scale. Scientists are trying to figure out what is promoting the outbreak. An unusually large amount of sediment is present on two affected reefs, and this is known to adversely affect corals in other areas.  However, what role sediment or other land based pollution has in driving this disease remains unclear.

Cyanobacteria-affected coral taken at Makua, Kauai on August 5, 2012. The green dots indicate macroalgae; the red dots indicate cyanobacteria-associated tissue loss; and the blue dots indicate live coral.

Why Study this Outbreak? You Can’t Manage What You Don’t Measure and You Cannot Measure What You Don’t Know

Wildlife disease outbreaks are indicators that something is awry in the environment. Understanding causes of disease and what drives those causes is important because this information helps management agencies make informed decisions to prevent further spread of the disease or minimize impact of disease.  Like many other places, coral reefs in Hawaii are adversely impacted by global climate change, land-based pollution, overfishing, and disease. Understanding the role and causes of disease in corals and their prevention may contribute to prevention of additional outbreaks and aid in their recovery.

Coral Reefs are Important

Coral reefs are not only essential for other marine species, they are also economically important. Reefs shelter and provide nursery grounds for many commercially and culturally important species of fish and invertebrates, they protect the islands’ harbors, beaches, and shorelines from erosion and wave damage by storms, and they are vital to the Pacific’s marine tourism industry. Globally, these diverse ecosystems may provide valuable goods and services worth about $375 billion each year to communities around the world.

Coral reefs are sensitive indicators of the health of marine environments. Yet coral reefs are in decline in many parts of the world. It is estimated that 30 percent will be destroyed or seriously degraded in the next 10 years. Disease has played a major role in the decline of coral reef cover in certain parts of the globe such as the Caribbean. In many cases, the causes of mortalities of marine invertebrates are unknown. USGS is collaborating with state, territorial, and other federal agencies to develop tools to assess health of corals and other marine organisms and to determine causes of coral mortality to preserve this unique and valuable natural resource.

For more information on coral disease, see this publication:

Dr. Greta Aeby (left), a coral expert with the Hawai‘i Institute of Marine Biology at the University of Hawai‘i, and Dr. Thierry Work, wildlife disease specialist for the USGS National Wildlife Health Center exit the water at ‘Anini after more than six hours of documenting and photographing diseased rice corals.

Work, T.M., Russell, Robin, & Aeby, G.S. (2012). Tissue loss (white syndrome) in the coral
Montipora capitata is a dynamic disease with multiple host responses and potential causes. Proceedings of the Royal Society B-Biological Sciences, 279(1746), 4334-4341.

http://rspb.royalsocietypublishing.org/content/279/1746/4334.long

Bat with white-nose syndrome.

As Halloween approaches and bats prepare for winter hibernation, these iconic animals of the night sky face an uncertain future because of white-nose syndrome (WNS). USGS scientists and others continue to make progress in understanding this deadly bat disease. WNS has killed over 5 million bats since it first appeared in New York in 2007, and the disease, caused by the fungus Geomyces destructans, has spread at an alarming rate to 19 U.S. states and four Canadian provinces (view map).

USGS Science and White Nose Syndrome

USGS science is providing the foundation for informed decisions to manage this devastating wildlife disease.

“The USGS research to combat white nose syndrome lies in what scientists call ‘Pasteur’s Quadrant’: it is not only of immediate and intense need because of the havoc that this disease is causing to an economically important animal, but it also advances the frontier of understanding of how fungi thrive in the environment,” said USGS Director Marcia McNutt. “The race is on: scientist versus fungus, with the survival of several important species of bats at stake.”

Partnerships among agencies – federal, state, tribal, academic, and NGOs – have been essential to combating WNS. In particular, the U.S. Fish and Wildlife Service (FWS) has funded multi-agency studies that address priorities of the WNS National Plan for assisting states, federal agencies, and tribes to manage WNS. Over the past three years, USGS scientists have published over 30 scientific articles contributing to the ever increasing understanding of this deadly disease.

“The partnership with USGS has provided a solid framework for science-based management of the disease,” said the U.S. Fish and Wildlife Service’s National White-Nose Syndrome Coordinator Jeremy Coleman. “Working cooperatively with our agency partners provides an opportunity to more efficiently and effectively address priorities in working toward containment of white-nose syndrome.”

WNS Fungus Findings

Scientists are currently searching for weak links in WNS disease processes to break cycles of infection and to slow the spread of this disease. In one of these studies, recently published in the journal PLoS ONE, scientists at USGS National Wildlife Health Center have carefully defined the effects of temperature on the growth of the WNS causing fungus, G. destructans. In the laboratory, scientists have shown that small changes in temperature, consistent with those found in bat caves, affect the overall growth rate and physiology of the fungus. Within caves or mines, localized variations in microclimates provide different environments for bats to hibernate. Different species of bats prefer different microclimate conditions for hibernation, which has been proposed as one of the reasons why some bat species may be more susceptible to WNS than others.

USGS scientists, in collaboration with EcoHealth Alliance and other agencies, have recently initiated a two-year study to build upon the knowledge gained in this laboratory study. They will measure variations in microclimates within actual bat caves and compare these conditions to the presence and abundance of G. destructans in the environment and on bats at those locations. Information from this study will then be used to predict the distribution of G. destructans within bat caves and to estimate the potential for progression of WNS at hibernation sites across the landscape.

Hibernating bats showing signs of infections with Geomyces destructans, the fungus that causes white-nose syndrome.

In two additional studies, published in the journal Mycologia , USGS and U.S. Forest Service  scientists  teamed up with others to learn more about the fungal ecology of bat hibernation sites and developed an improved diagnostic test for the fungus. Researchers examined G. destructans within the broader group of related Geomyces fungal species, most of which do not cause disease in bats, but are common in bat caves. This information is helping scientists to understand more about the diversity of related fungi in bat caves as well as the delicate ecology of these underground ecosystems. These findings were then used in the second study to develop a new highly sensitive and specific test that can differentiate between G. destructans and similar fungal species. This new test provides a valuable and reliable tool for enhanced diagnosis and surveillance of WNS.

More information on white-nose syndrome in bats can be found at:

USGS National Wildlife Health Center, WNS page

U.S. Fish and Wildlife Service, White-Nose Syndrome.org

USGS Fort Collins Science Center, WNS page

Culex species mosquito biting a human hand.

A deadly disease spread by the bite of infected mosquitoes continues to afflict people and wildlife in the United States.

Human deaths from West Nile virus (WNV) are alarmingly high for 2012, as this year is on track to become the worst West Nile virus epidemic ever in the United States. The Centers for Disease Control and Prevention  reports that more than 120 people this year have died from a fatal inflammation of the brain (encephalitis) caused by WNV, and the disease has been diagnosed in more than 2,630 people.

Wildlife also suffer from the disease, which is transmitted by infected mosquitoes (primarily members of the Culex species) to more than 100 species of birds and to nine mammal species including humans and horses. Evidence of infection has also been reported in amphibians and in reptiles such as alligators.

The virus was first discovered in the West Nile area of the east African nation of Uganda in 1937. From 1950 onward, it spread throughout the Mediterranean and Europe. In 1999 the first North American case was diagnosed in wildlife in Queens, N.Y., and that’s when the USGS became involved.

USGS Science and West Nile Virus

For nearly 40 years, the USGS National Wildlife Health Center  (NWHC) has been working to advance wildlife and ecosystem health by identifying, understanding and responding to disease threats to our native wildlife, as well as sharing that information with public health and domestic animal health agencies.

Screenshot of the USGS West Nile Virus website

In the case of West Nile virus, on Sept. 2, 1999, the NWHC was contacted by New York state officials regarding sick, dying and dead American crows. After the disease was identified as West Nile virus, the USGS also provided diagnostic and technical assistance to state health departments to test dead birds as part of an emerging WNV surveillance effort. This assistance eventually expanded to include 25 states until local public health departments began to develop their own surveillance and testing capabilities. The CDC provided funding for this effort.

The USGS Eastern Geographic Science Center began collaborating with the CDC in 2000 to use the surveillance data to produce weekly national maps depicting surveillance efforts by counties within U.S. states and the presence of WNV. As a result of the development of these disease maps, USGS now produces GIS mapping and graphic products that show the occurrence and distribution of West Nile virus and other wildlife diseases by county, state and by week of occurrence.

West Nile Research at USGS Now

Emerging pathogens such as WNV pose a major threat to conservation efforts in maintaining the health of wildlife, in particular birds. Wild birds are the principal hosts of WNV, and many birds die from WNV infections. Greater sage-grouse, American white pelicans, and species groups such as corvids (crows, jays, ravens, and related species), and raptors are quite susceptible to WNV and continue to be the focus of research on WNV at NWHC.

USGS scientists are involved in laboratory studies of WNV, and research on free-living wild birds is on-going at many USGS science centers. Resource managers and scientists are especially concerned about the effect of this virus on greater sage-grouse and American white pelicans. Both species were imperiled prior to the arrival of WNV; because they are highly susceptible to this disease they have experienced widespread mortality.

Thus far WNV has never been reported in Hawaii. However, resource managers and others are greatly concerned that if WNV becomes established in that state, it could devastate the native Hawaiian bird community. Hawaiian forest birds, some species of which are among the most endangered birds in the world, would be at risk from the disease in the event WNV spreads to the islands. The USGS is working with the U.S. Fish and Wildlife Service in Hawaii as well as the U.S. Department of Agriculture to conduct WNV surveillance.

Sage-grouse have declined throughout their entire range, largely due to the loss and fragmentation of sagebrush habitat.

One Health: The Connection between Global Health and Domestic Animal, Wildlife, and Human Disease

The USGS is vigilant for newly emerging and re-emerging wildlife diseases, as well as monitoring existing wildlife health concerns. Virulent Newcastle disease in cormorants, avian influenza in waterfowl, and white-nose syndrome in bats are just a few of the diseases USGS tracks. The Eastern Geographic Science Center is mapping the occurrence of arboviral diseases that have a wildlife- mosquito cycle: West Nile virus, St. Louis encephalitis, eastern equine encephalitis, western equine encephalitis, and La Crosse encephalitis. In addition to the maps displayed on USGS web pages, at the county level these pages also provide epidemiological information including a histogram of disease cases per week over time, tables of disease cases by state, and other related information. The USGS has been producing West Nile virus surveillance maps since 2000 and plans to continue this highly valued partnership with CDC into the future.

Studying diseases in wildlife is obviously important work for the health and welfare of wildlife, but it is also important for the health of humans and domestic animals—70 percent of recent emerging human diseases originated in wildlife or domestic animals, including West Nile virus, plague, AIDS, SARS and avian influenza. The health of humans, animals — wild and domestic — and ecosystems are all inter-related; this is the concept of “One Health,” which advocates understanding and appreciating the links among human, animal and ecosystem health, and the importance of and commitment to working together to address health challenges.