Penn Vet | Fact Sheets
Green Frog

Disease Fact Sheets

These disease fact sheets have been created for use by wildlife biologists, researchers, and the public.

The diseases include those that affect wild animals in the Northeast (e.g. White-nose Syndrome), and some that are shared between wild and domestic animals (e.g. Canine Distemper Virus), and between wildlife and humans (e.g. West Nile Virus).

Characteristics of each disease are described including cause, species affected, geographic distribution, transmission mode, clinical signs, and management. The sheets are intended to be concise and easy to navigate quickly; for those interested in delving into more detail, additional readings are listed.




Anthrax is an infectious disease of animals and humans caused by the spore forming bacteria Bacillus anthracis. Anthrax spores can cause disease in humans when they are inhaled, are consumed in under-cooked meat, or enter open wounds. 

WF-white-tail-deer-Bovine Tuberculosis

Bovine Tuberculosis

Tuberculosis (TB) is a zoonotic disease of the respiratory (or gastrointestinal tract, depending on the route of exposure) system. Of the three major types of TB (human, avian, and bovine), bovine TB has the greatest host range and is known to infect many species of mammals including humans. Bovine TB (BTB) is caused by the bacteria Mycobacterium bovis.

WF-white-tailed-doe-Brain Abscess

Brain Abscess Syndrome

Brain abscess syndrome is a naturally occurring disease described primarily in white-tailed deer in which abscesses (enclosed pockets of pus) form within the brain. Several species of bacteria including, ActinomycesStaphylococcus and Streptococcus, can be responsible for these abscesses, but the most common cause is Trueperella pyogenes.

Brain worm

Brain Worm

Parelaphostrongylus tenuis, commonly known as brain worm, is a nematode (roundworm) parasite of several species of hooved mammals, both wild and domesticated. The white-tail deer is the definitive or natural host.



Brucellosis is a zoonotic disease of mammals and humans. There are many species of brucellosis bacteria that infect different animals. Brucella abortus infects cattle and bison and this is the greatest concern for potential human infections. 

WF-Ferret-Canine distemper

Canine Distemper

Canine distemper is one of the most significant diseases of domestic and wild carnivores. It is caused by the highly contagious canine distemper virus (CDV) and can infect a variety of species. 


Chronic Wasting Disease - CWD

Chronic wasting disease (CWD) is caused by a prion, which is a protein that can behave like an infectious agent. These infectious proteins cause a degenerative neurological disease of domestic and wild members of the deer family (deer, elk, reindeer, and moose) otherwise known as cervids.

WF-white-tailed deer-Deer Liver Fluke

Deer Liver Fluke

Deer liver flukes, a parasitic flatworm found within the livers of infected deer and other ruminants, rarely cause clinical illness in free-ranging deer and do not seem to have a major impact on wild deer populations. These flukes present more of a problem when they infect domestic cattle and sheep. 

Fox-Echinococcosis multilocularis-Wildlife Futures

Echinococcosis multilocularis

There are two main forms of Echinococcosis, a zoonotic disease caused by tapeworm larva; cystic echinococcosis (CE) caused by Echinococcosis granulosus and alveolar echinococcosis (AE) caused by Echinococcosis multilocularis. Control and prevention of E.multilocularis is difficult due to the wildlife cycle between foxes and small mammals.  



Ehrlichiosis is a tick-borne disease of mammals caused by multiple species of bacteria from the group Ehrlichia that infect white blood cells. This disease has been recognized in domestic animals since the 1930’s and was fist reported in humans in 1954. Ehrlichiosis is considered an emerging infectious disease because there has been an increase in its occurrence.



Fibromas are wart-like growths most commonly confined to the skin. These types of lesions, found in both domesticated animals and wildlife, result from viral infections which are largely species-specific. 

WF-white-tailed-doe-Hemoragic Disease

Hemorrhagic Disease

Hemorrhagic disease is the most common infectious disease of white-tailed deer in the eastern United States and can cause a significant number of deaths during an outbreak2. While endemic in the eastern US, it is considered an emerging disease in other parts of North America.



Leptospirosis is a potentially fatal, zoonotic disease, meaning humans can contract the disease from infected domestic or wild animals. Leptospirosis is a reemerging disease and the incidence in people and animals is increasing worldwide. 

WF-deer-Lice in deer

Lice in Deer

There three types of lice reported in deer; one sucking louse (Solenopotes binipilosus) and two chewing lice (Tricholipeurus lipeuroides and T. parallenus). The sucking louse feeds on the blood of the animal and the chewing lice feed on the skin.



Listeriosis is a disease of domestic and wild animals and occasionally humans, caused by bacteria from the Listeria group. Listeria monocytogenes is the species typically responsible for causing clinical illness.

WF-red fox from pixabay-Mange and Mites

Mange and Mites

Mange is a highly contagious skin disease of mammals caused by burrowing skin mites. There are three main types of mange, each caused by a different type of mite. A fourth form of mange, psoroptic mange, is caused by Psoroptes cuniculi and affects rabbits and deer. 



Pseudorabies is a major concern in the swine industry. Infected feral swine can potentially spread the virus to domestic swine resulting in significant economic losses.

WF-Snowshoe, courtesy John Brown-Rabbit Hemorrhagic Disease

Rabbit Hemorrhagic Disease

Rabbit hemorrhagic disease virus (RHDV) is a highly contagious and deadly calicivirus that affects some species in the larger group (Order) of Lagomorphs, which includes all rabbits, hares and pikas.



Rabies is an acute and progressive nervous system infection caused by viruses from the Lyssavirus genus, or group. Rabies is of great public health concern because it can be transmitted to humans by the bite of infected animals and once clinical signs occur is nearly 100% fatal.

WF-racoon-Raccoon Roundworm

Raccoon Roundworm

Raccoon roundworms (Baylisascaris procyonis) are common large parasitic worms known as ascarids that inhabit the small intestines of raccoons. Baylisascaris causes disease in humans.

Rumen Acidosis, Wildlife Futures

Rumen Acidosis

Rumen acidosis occurs in wild or domestic ruminants (deer, elk, moose, cattle, sheep etc.) when they ingest large quantities of readily digestible and highly fermentable carbohydrates such as grain. Corn, wheat, and barley are most commonly responsible for rumen acidosis, though apples, bread, carrots, and sugar beets can also cause this disease.



Most mammals are susceptible to trichinosis, but it is primarily a disease of carnivores. In North America, Trichinella has been detected in black bears, coyotes, cougars, gray wolves, skunks, bobcats, raccoons, wolverines, fishers, lynxes, walruses, red foxes, grizzly bears, polar bears, and more. 

WF-Tularemia-eastern cottontail


Tularemia is a highly infectious, zoonotic disease caused by the bacterium Francisella tularensis. In North America, the two most common subspecies are called Type A, which is the more virulent type and is associated with rabbits and squirrels, and Type B, which is associated with aquatic rodents such as muskrats and beavers.

WF-muskrat-Tyzzers Disease

Tyzzer's Disease

Tyzzer’s disease is a significant disease of muskrats and rabbits that can cause major mortality events, particularly in young animals under stressful conditions.

WF-lucifugus bat-White Nose Syndrome

White-Nose Syndrome (WNS)

Since its discovery in 2006, WNS has caused unprecedented mortality in North American bat populations. Over six million bats have died from this disease in the United States and Canada. 

WF-moose-Winter Ticks

Winter Ticks

Winter ticks (Dermacentor albipictus) are one-host ticks that rely on moose, elk and caribou for sequential blood meals in order to complete their 8-9 month life cycle. In all areas in which the two occur together, winter ticks are having a significant impact on North American moose populations.




Aspergillosis is an infectious disease of birds and mammals caused by the fungi in the Aspergillus group. While this disease can affect wild mammals, it is more common in birds.

WF-mourning-dove-Avian Chlamydiosis

Avian Chlamydiosis

Avian chlamydiosis is an infectious disease of birds that is caused by the bacteria Chlamydophila psittaci. Humans usually contract avian chlamydiosis from pet birds, pigeons, and domestic poultry.

WF-herring-gull-Avian Cholera

Avian Cholera

Avian cholera is an infectious disease of domestic and wild birds caused by the bacteria Pasteurella multocida. There are many strains of P. multocida that infect different species of birds and mammals and cause varying degrees of disease.

WF-Avian Influenza-canada-geese

Avian Influenza

AI is a global disease with the potential to threaten wildlife, agriculture and human health. In nature Avian influenza (AI), most commonly found in waterfowl and some shorebird species, is caused by various strains of the influenza A virus. These strains are subdivided into two categories based on the severity of disease they cause in poultry.

WF-house-finch-Avian Mycoplasmosis

Avian Mycoplasmosis

Of the 23 species of Mycoplasma bacteria known to infect birds, Mycoplasma gallisepticum (MG) is the most significant to wild species. Until recently, MG was only known to cause disease in domestic poultry and occasionally wild turkeys. 

WF-wild-turkey-Avian Pox

Avian Pox

 Avian pox is an infectious disease of birds caused by a poxvirus. There are many different species and strains of avian poxvirus that preferentially infect different species of birds.

WF-autumn-wild turkeys-Blackhead Disease

Blackhead Disease

Blackhead is a parasitic disease of gallinaceous birds (ground-feeding, chicken-like birds) caused by the protozoan named Histomonas meleagridis.

WF-mallard duck-Botulism


Botulism is caused by a toxin that affects the nerves, thus it is a non-infectious disease. The botulism toxin is produced by the bacteria Clostridium botulinum, and is one of the deadliest known toxins.

WF-male wood duck-Duck Plague

Duck Plague

 Duck plague is a highly contagious infectious disease of ducks, geese, and swans caused by a herpes virus. This disease was first described in domestic waterfowl in the Netherlands in 1923. 

Great Blue with fish-Jacob Dingel


Eustrongylidosis is a parasitic disease caused by nematodes in the Eustrongylides genus, including E. tubifexE. ignotus, and E. excisus. The parasites have a complex multi-stage life cycle that requires two intermediate hosts and a definitive host.  Wading birds, including herons and egrets, are common definitive hosts of E. ignotus, the species most prevalent in the US. 

WF-Bald Eagle-Lead Poisoning FS

Lead Poisoning

Waterfowl and other birds are particularly susceptible to lead poisoning because they often consume shotgun pellets, bullet fragments, and fishing tackle made of lead while feeding. 

WF-turkey-Lymphoproliferative Disease

Lymphoproliferative Disease

Lymphoproliferative Disease (LPDV), caused by a retrovirus, results in tumor formation in internal organs and the skin in several species of fowl.

WF-double-crested-cormorant-Newcastle Disease

Newcastle Disease

Newcastle disease (ND) is a viral disease of wild and domestic birds. There are many different strains of the ND virus that cause different degrees of disease in different bird species.

WF-house sparrow-Salmonellosis


Salmonellosis is caused by bacteria from the Salmonella genus, or group. There are more than 2,000 different species or subspecies of Salmonella that have been found across many species of animals, including pets, livestock, captive reptiles, fish and birds, and wildlife.



Trichomoniasis is an infectious disease of birds caused by the single-celled protozoan Trichomonas gallinae and Trichomonas stableri. The parasite inhabits the upper digestive tract, mainly the crop and esophagus.

WF-Eider-sm dresseri-IanGereg

Wellfleet Bay Virus

After investigating several recent severe mortality events among common eiders in the Cape Cod Bay town of Wellfleet, Massachusetts, scientists have isolated a new virus. (image: Ian Gereg)

Raven-West Nile Virus-Wildlife Futures

West Nile Virus

West Nile Virus (WNV), of the genus or group, called Flaviviruses is a mosquito-borne zoonotic disease that primarily aff­ects birds by attacking their central nervous system. The virus was first isolated from a human patient in the West Nile region of Uganda in 1937.

Reptiles & Amphibians

WF-box-turtle-Aural Abscesses

Aural Abscesses

An aural abscess, or ear abscess, is the internal swelling of the tympanic (middle ear) cavity caused by a bacterial or viral infection. Such abscesses frequently affect reptiles, particularly box turtles. 

WF-spotted salamander-Salamander Chytridiomycosis

Bsal Salamander Chytridiomycosis

Batrachochytrium salamandrivorans (Bsal) is an infectious fungus that causes the skin disease Bsal chytridiomycosis in some amphibians.

WF-green frog-Chytridiomycosis

Chytridiomycosis (Bd)

Chytridiomycosis is considered an emerging disease that significantly impacts amphibian populations across the globe. Over 700 species of amphibian are affected by Bd.


Frog Deformities

Over the past two decades, increasing observations of frogs with severe deformities, including extra limbs, missing limbs, and misshapen limbs, have garnered widespread attention and concern.


General Guidelines for the Intake, Quarantine, and Release of Reptiles and Amphibians in Rehabilitation Facilities in Northeastern States, USA

These guidelines are provided to help reduce the risk of pathogen and disease transmission in reptile or amphibian cases brought into rehabilitation facilities.

WF-Eastern_Milk_Snake_Ophidiomycosis Snake Fungal Disease

Ophidiomycosis (Snake Fungal Disease)

Ophidiomycosis is an emerging disease that affects wild and captive snakes across North America. The incidence of ophidiomycosis is thought to have increased in some snake populations over the last few years.



Ranavirus (family Iridoviridae), is a double stranded DNA virus that can cause severe infections in a number of cold-blooded taxa, including amphibians, reptiles, and fish.


Sea Turtle Mass Mortality

Harmful algal blooms (HABs) are an emerging concern for mass stranding and mortality of sea turtles.


Snake Lung Parasite

Pentastomes are wormlike crustaceans that parasitize the lungs of reptiles and mammals.

Multiple Species Groups



Anaplasmosis is a tick-borne disease caused by the bacteria Anaplasma phagocytophilum. Rodents, like the white footed mouse, deer and birds are considered the main reservoirs of A. phagocytophilum.

WF-adorable rabbit-Bots and Warbles

Bots and Warbles

The larval stage (maggot or bot) of different species of flies, known variously as bot fly or warble fly, parasitize mammalian hosts to complete their development into adult flies. 

WF-turkey-Capture Myopathy

Capture Myopathy

Capture myopathy (CM) is a non-infectious disease of wild and domestic animals in which muscle damage results from extreme exertion, struggle, or stress. 



Dermatophilosis is a bacterial skin infection of many animal species, and sometimes humans, caused by the spore-forming bacterium Dermatophilus congolensis.

WF-white-tail-deer-Eastern Equine Encephalitis

Eastern Equine Encephalitis

Eastern Equine Encephalitis (EEE) is a zoonotic viral disease that is maintained in bird reservoirs, transmitted by mosquitoes, and sometimes causes fatal neurological disease in mammals.

WF-Adult_deer_tick-Lyme Disease

Lyme Disease

Lyme disease is a tick-borne disease of humans and certain domestic mammals caused by the bacteria Borrelia burgdorferi and rarely, Borrelia mayonii.

WF-Opossum_3-Sarcocystosis-By Cody Pope - Wikipedia User Cody pope, CC BY-SA 2.5


Sarcocystosis is a disease of birds and mammals caused by several species of single-celled coccidian protozoa from the Sarcocystis group.



Toxoplasmosis is a disease of wild animals, domestic animals, and humans caused by the single-celled protozoan parasite known as Toxoplasma gondii