Quarterly Wildlife Mortality Report
Written and compiled by members of the U.S. Geological Survey National Wildlife Health Center - Wildlife Epidemiology & Emerging Diseases Branch.
Bisgaard Taxon 40-Associated Mortality
Between August and October 2016, the U.S. Geological Survey’s National Wildlife Health Center (NWHC) received a number of avian cases in which a Pasteurella-like bacterium, Bisgaard taxon 40, was associated with mortality. The most significant of these was a mortality event involving rhinoceros auklets (Cerorhinca monocerata) that occurred in the Salish Sea area of Washington State. At this location approximately 420 dead adult and juvenile auklets washed ashore and were observed by volunteer beach survey teams. Ten adult auklet carcasses were submitted to the NWHC for diagnostic evaluation. In seven of these birds, bacterial septicemia associated with Bisgaard taxon 40 was determined to be the cause of death. Following this event, the NWHC continued to isolate this bacterium from dead birds collected from various locations in the Great Lakes region and the mid and north Atlantic coast of the U.S. (including Wisconsin, Maryland, Massachusetts, and Maine). These mortalities involved birds of the order Charadriiformes and included common tern (Sterna hirundo), roseate tern (S. dougallii), laughing gull (Leucophaeus atricilla), herring gull (Larus smithsonianus), and great black-backed gull (L. marinus). The NWHC also received similar reports and diagnostic results on 44 birds examined by the Canadian Wildlife Health Cooperative in British Columbia. Bisgaard taxon 40 was first recognized in 2003 in gulls, but has not previously been associated with mortality in wildlife. The NWHC is currently reviewing previous instances where Bisgaard taxon 40 was identified in the laboratory, as well as trying to determine the extent of this bacterium’s occurrence among apparently healthy gulls.
Gulf Coast Sanderlings Infected with Livestock Skin Bacteria
During regular surveys of over-summering sanderlings (Calidris alba) on a Gulf Coast barrier island in Louisiana in 2016, U.S. Geological Survey (USGS) biologists with the USGS Wetland and Aquatic Research Center (Gainesville, Florida) observed eye and beak lesions on an estimated 20%-30% of individuals in foraging flocks. The lesions ranged from barely noticeable to severe with roughed and matted feathers, scab formation, and yellow waxy growths around the top of the bill, eyes, and head. Individuals with small lesions foraged and acted apparently normally. Those with severe lesions foraged lethargically and were less likely to stay with the foraging flocks. In the most severe cases, infected birds allowed biologists to approach them likely due to severe morbidity and probable blindness from the lesions. Sanderlings were the only species observed with lesions among mixed flocks of foraging shorebirds, with one exception: A single dunlin (Calidris alpine) showed similarly ruffled facial feathers, and photos appeared to show the same waxy growth on the face.
The USGS National Wildlife Health Center (NWHC) received several specimens with severe lesions and diagnosed dermatophilosis caused by a gram-positive, non-acid fast facultative anerobic bacterium, Dermatophilus congolensis. Overproduction of keratin (hyperkeratosis) resulted in waxy growths on the most severely affected sanderlings. Growths were evident on the wings, the side and the front of the head, and extended over the surface of the eyes of some individuals, although the cornea and conjunctiva were not infected. The D. congolensis infection was microscopically apparent and confirmed by sequencing PCR-amplified DNA extracted from the lesioned skin.
D. congolensis has rarely been described in wild birds and is considered an opportunistic infection of livestock associated with prolonged rainy periods, high humidity, high temperature, and conditions that damage skin (such as ectoparasite infestation; Moriello 2013). Disease caused by D. congolensis is most often reported in hoofed livestock and can be zoonotic if people have direct contact with lesions on infected animals. As with any observation of clinical signs of unknown disease origin, people handling or coming into contact with potentially infectious wildlife should follow their institution’s biosafety protocols and may wish to consider the following:
Wear protective clothing including aprons, coveralls, rubber boots, rubber or latex gloves, eye protection, and face shields that can be disinfected or discarded to prevent skin and mucous membrane contact with biological materials and movement of biological materials among sites.
Work in well-ventilated areas or upwind of animals to decrease the risk of inhaling airborne particulate matter such as dust, feathers, or dander.
A particulate respirator (NIOSH N95 respirator/mask or better) is recommended when working in confined spaces or conditions that promote aerosolization of debris. Check with your agency policies for specific respirator guidance while handling sick and dead wildlife.
Wash hands often and thoroughly for at least 30 seconds with soap or alcohol-based hand sanitizer.
Do not eat, drink, or smoke while handling animals.
Decontaminate work areas and properly dispose of potentially infectious material including carcasses before moving on to a new area.
New World Screwworm Myiasis in Endangered Key Deer
In late September 2016, the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (USDA APHIS) National Veterinary Services Laboratories confirmed New World screwworm (Cochliomyia hominivorax) infection in Key deer (Odocoileus virgineanus clavium) from National Key Deer Refuge on Big Pine Key, Florida. New World screwworms had not been reported in the State of Florida in over 50 years due to an extensive and successful eradication program initiated by USDA during the 1950s-1960s in response to the parasite’s significant economic impact on livestock production. Adult screwworms typically posit eggs in open wounds. Developing larvae feed on the living host and cause severe tissue damage which can quickly result in death. As of December 29, 2016, a total of 133 Key deer, >10% of the estimated population of approximately 1000 individuals, have been found dead or euthanized due to severe infestation. Peak mortality occurred in October and affected predominantly males, attributable to infestation of injuries sustained during the rut. A small number of cases have also been detected in other wildlife species, including raccoon (Procyon lotor), and domestic animals, including dog, cat, and pig. In all, 13 islands are known to be infested between No Name Key and Sugarloaf Key, Florida. The origin of the outbreak remains uncertain.
Since the initial detection, the Florida Department of Agriculture (FDACS), USDA APHIS, U.S. Fish and Wildlife Service (FWS), and other partner agencies have implemented multiple management strategies to eradicate screwworms from Florida and to conserve the remaining Key deer population. Increased surveillance by agency personnel, local veterinarians, and pet owners has been implemented to detect cases in wildlife and domestic animals from the resident populations. Inspection stations at Key Largo, the entrance to mainland Florida, to screen animals leaving the affected region have been instituted. Free-ranging Key deer are being treated both orally and topically with the anti-parasiticide, Doramectin. Sterilized male screwworm flies are being released in high numbers in the region to unproductively mate with female flies in order to eradicate the local screwworm population. Furthermore, sperm banking from all deceased male deer is underway in collaboration with the Southeast Zoo Alliance for Reproduction and Conservation. Ongoing monitoring efforts suggest that the combination of management efforts being implemented has been effective to date. For additional information on New World screwworm in North America and the current outbreak, please visit USDA-APHIS, FWS Wildlife Health Office, FDACS, or the Center for Food Security & Public Health at Iowa State University. Contributions to this summary were provided by Dr. Samantha Gibbs, FWS and Dr. Sherrilyn Wainwright, USDA-APHIS.
To view, search, and download historic and ongoing wildlife morbidity and mortality event records nationwide visit the Wildlife Health Information Sharing Partnership event reporting system (WHISPers) online database: http://www.nwhc.usgs.gov/whispers/
To request diagnostic services or report wildlife mortality: http://www.nwhc.usgs.gov/services/