In March 2016, two hikers on a trail east of Seattle, WA, found a little brown bat lying on the ground in obviously poor condition. The bat was taken to an animal shelter where it died two days later from White-Nose Syndrome (WNS).
This bat was the first case of WNS found west of the Rocky Mountains. It represented a jump in the spread of WNS, and a troubling one. WNS was first detected in a cave in Albany, New York, and since then it has been moving slowly westward at a rate of about 200 miles per year, according to David Blehert of the United States Geological Survey, the laboratory that confirmed the WNS diagnosis for the Washington bat. Before this year’s discovery outside of Seattle, the westward-most case detected was in eastern Nebraska.
WNS, caused by a cold-loving fungus, Psuedogymnoascus destructans (Pd), can kill 100% of the hibernating bats in a colony, and in the ten years since it has been detected and monitored has killed over 6 million bats in the United States and Canada. As of July 2016, bats infected with the fungus have been found in 29 states and 5 Canadian provinces.
According to Blehert, this is probably the “most significant epizootic of wildlife” ever observed; never before have we seen hibernating mammals specifically affected by a skin fungus. What does that mean? Are we looking at extinction for some bat species? What are the ecological consequences of rapidly losing so many individuals to disease so quickly? And, what, if anything, can be done to combat the disease and help bat populations recover? Continue reading “An Epizootic for the Ages: Revisiting the White-Nose Syndrome Story”
A lot has happened since I first wrote about White-Nose Syndrome, the fungal disease that has devastated bat populations in North America. The disease, caused by the cold-loving fungus Geomyces destructans (now renamed Psuedogymnoascus destructans), has been identified in many more places, including most recently confirmed cases in Georgia, South Carolina, Illinois and Missouri in the United States and Prince Edward Island, Canada.
Controlling the spread of this disease is a tremendous problem, because as I indicated in a previous blog post, keeping a hardy fungus from spreading among a population of densely packed small animals in tiny, cold damp areas is not a simple task.
Since the first photograph of bats with white muzzles in Albany, NY, was published, hibernating bat populations in the northeastern U.S. have been devastated by an emerging disease, White-Nose Syndrome (WNS), which continues to spread throughout the United States and now has been found in two Canadian provinces. Bats suffering from WNS are emaciated with little or no body fat and have a characteristic white fungal growth on their wing membranes, ears and muzzles. Instead of hibernating all winter, these bats can be seen active in the snow, when there is virtually no food available.
The infectious agent that responsible for WNS is a new species of the cold-loving fungus, Pseudogymnoascus destructans (formerly, Geomyces destructans) . Currently, WNS is confirmed either through histological analysis or by fungal culture. Both of these techniques have significant limitations. First, they have turnaround times of at least one week. Secondly, they require large amounts of tissue sample from affected bats, more than can be reasonably taken from live bats. Histological analysis is a laborious process that requires highly skilled and trained personnel. Fungal culture can be difficult because bats harbor many bacteria and fungi, and getting a pure culture of a causative organism is not simple. Furthermore, researchers need a quick method for assessing spread of the disease that can provide results quickly.
Polymerase Chain Reaction (PCR), already used for a host of diagnostic tests in humans, plants and animals, is a logical choice. In a paper published in the Journal of Veterinary Diagnostic Investigation, Lorch and colleagues design and evaluate a PCR-based diagnostic method for WNS. They compare the PCR method to a fungal culture method and the “gold standard” traditional histological analysis. Continue reading “PCR-Based Diagnosis Wins by a Mile In the White-Nose Syndrome Race”