Common Diseases and Parasites

of Furbearing Animals

Although it’s beyond the scope of this page to discuss specific diseases in detail, some general comments and examples are appropriate. All animals should be considered capable of transmitting disease and should be treated with caution. Be especially wary of animals that appear sick or have died of unknown causes. A basic precaution is to wear disposable surgical gloves before skinning and wash hands frequently.

Many of the signs and symptoms of such illnesses as plague, tularemia, and leptospirosis, to name a few, are non-specific and mimic the flu or common cold - fever, aches, rash, swollen glands. Not many health practitioners are familiar with these unusual diseases. Therefore, it is a good idea to alert your physician to the fact that you are a trapper and may have contracted a zoonotic disease (an animal illness communicable to humans).

VIRAL DISEASES

Rabies is caused by a virus, which grows in nervous tissue of warm-blooded mammals. Once inoculated into the skin or mucous membranes the virus travels up the nerve to the brain. Most cases of rabies in North America are caused from bites by non-immunized dogs and cats but many wild animals harbor the disease. The more common of these animals are skunks, foxes, raccoons and bats. The virus is found in the salivary glands and saliva, nervous tissue and spinal fluid of infected animals. Transmission to humans occurs through a bite from the infected animal but can occur if infected saliva or spinal fluid gets into an open cut or is splashed into the eyes or mouth.

If a suspected inoculation or exposure occurs, wash the cut with soap and water and apply an antiseptic and dressing. Call your physician. Do not discard or destroy the carcass of the animal. It may be needed for testing. With appropriate immunization even after exposure, rabies is preventable, but once symptoms of the disease occur, it is fatal.

Rabies virus can be become airborne and some cases of human rabies have occurred from people exploring caves where infected bats live. Theoretically rabies could be contracted from the dens of infected skunks and raccoon in the same manner.


Hanta virus includes a group of viruses, which cause a feverish illness in humans. If severe it can be fatal. Small rodents, especially the deer mouse, are the reservoir for this virus. The virus is shed in saliva, urine, and feces of infected animals. Humans can contract the virus directly from a bite or indirectly by inhalation of airborne excrement containing the virus.

Canine Distemper, although this virus is not a threat to humans, it can be transmitted to your pets via carcass consumption of affected animal, or virus carried into your home on shoes or clothing. It is very difficult to treat if your pet has not been vaccinated against it. It can display the same symptoms as rabies and is sometimes mistaken for rabies. If you have a pet it is wise to vaccinate it for rabies and distemper, to prevent infection.

TICK BORNE DISEASES

Several diseases can be transmitted to humans through tick bites.

  • Colorado Tick Fever is caused by a virus. Symptoms are usually relapsing fever, headache, and muscle aches. The disease is usually self-limited.
  • Rocky Mountain Spotted Fever is caused by a rickettsia. Symptoms again are fever, headache and muscle aches at first but later a rash consisting of red spots occurs.
  • Lyme Disease is caused by a spirochete. Once again early symptoms are fever, headache and muscle aches. An expanding red rash starting at the sight of the tick bite is characteristic of the disease but rarely recognized.
  • Any symptom of high fever, headache, muscle aches and a rash several days after a tick bite should be reported to your doctor.

BACTERIAL DISEASES

Tularemia is caused by a bacteria. The most common animals infected are rabbits and hares but a variety of rodents and carnivores or birds can harbor the illness. Transmission to humans is through tick bites usually, but can also occur through ingestion of poorly cooked meat, inhalation of airborne excrement, or bites. The liver of an infected animal is often covered with white spots. Human symptoms include a painful ulcer at the sight of exposure with painful swollen glands and fever.

Plague is caused by bacteria. It is most often transmitted to humans through fleas. The disease is carried by many small rodents especially rats There are three types of plague, each having their own particular symptom.

  • Bubonic Plague - Enlargement of the lymph nodes, fever, headache, drainage at exposure site.
  • Pneumonic Plague - Symptoms make their presence known in the lungs and plural cavity, which can cause death if not treated.
  • Septicemia - Bacteria is present in the blood and affects the heart, liver and other body organs. Most late stages of bubonic and pneumonic plague will progress to septicemia if not treated.

Salmonella is a bacterial disease caused by the accidental ingestion of the bacteria through contamination of water, food and hands. This disease is infectious with a significant threat to humans. All mammals are susceptible to this disease. Symptoms include cranipy, abdominal pain, nausea, vomiting, diarrhea and fever.

Shigella is a bacterial disease caused by the accidental ingestion of bacteria through contamination of water, food and hands. Symptoms include abdominal pain, nausea, vomiting, diarrhea and fever.

Leptospirosis is a bacterial disease evident in beaver and muskrats and is prevalent throughout the United States. It is highly infectious and dangerous to humans. It is transmitted through direct contact with contaminated fur, internal organs, body fluids, water, blood and insect bites. The symptoms include flu-like headache, fever, in addition to white spots on liver, spleen, lymph nodes and kidneys upon medical examination


Tuberculosis is a bacterial disease which occurs worldwide and is common in weasels, badger, skunk, cattle, and deer. It is transmitted through inhalation of bacterial droplets from infected animals. Symptoms are a productive cough, fever and enlarged lymph nodes.

INTERNAL PARASITES

Giardia is caused by a parasite. It is carried by many rodents and water dwelling mammals, especially the beaver. Hence the name "beaver fever." It is contracted by drinking contaminated water. Symptoms in humans are mainly diarrhea and abdominal cramps.


Echinococcosis (larval stage of the tape worm) occurs in plant-eating and meat- eating mammals of the Western United States. It is transmitted through the accidental ingestion of eggs of tapeworms. There are no clinical symptoms in animals, but with humans it varies, depending on where the cysts are located, i.e. lungs, liver or heart.

Visceral Larva Migrans (toxocara roundworms - cat and dog)) occur in raccoons, fox, coyotes and bobcats, living in the intestines of infected animals. Transmission occurs through accidental ingestion of eggs. Symptoms may include abdominal pain, diarrhea, weight loss.

Cutaneous Visceral Migrans (hookworms) are common in young of raccoons, fox, coyotes and bobcats. Transmission is through direct contact of the skin, with a raised, itchy area and hemorrhage under the skin. Symptoms include hemorrhage and swelling of the area where the parasite entered the skin.

Trichinellosis is found worldwide in carnivores. It is a larva which invades the muscle and other tissue causing muscle aches, diarrhea, and myocardial failure if in the heart. Transmission is accidental ingestion of the larva in undercooked meat of the infected animal.

EXTERNAL PARASITES

Lice: There are two types of lice, sucking and biting. High populations of infected animals lead to hair loss, irritability, poor body condition and susceptibility to secondary infection and disease. They are transmitted by direct contact with the lice "jumping" onto the human. They cause intense itching, especially in areas where there is a considerable growth of hair.

Fleas: Fleas irritate the host animal by constantly biting and secreting toxic allergenic products in their saliva. Infected animals will often break the skin creating a "hot spot" which can be infected by bacteria. They are also a carrier of the bacterial disease, the Plague. They are transmitted to humans by direct contact with infected animals by "jumping" onto the human. On humans they leave a red, itchy, swollen spot which may form a "white head" of pus.

Sarcoptic Mange is caused by sarcoptic mites which are obligate parasites with all life cycle stages able to burrow and tunnel in the skin. It is common in many areas of North America and infect domestic swine, dogs, foxes, coyotes and wolves. Transmission is through direct contact between animals or by contact with objects that infected animals may have rubbed. It causes intense irritation as the mites burrow in the skin resulting in inflammation, weeping of fluid onto the skin, thickening of the skin and hair loss. Severely infected animals die from secondary infection, hypothermia and exposure. In humans the infection is called "Scabies".

This is a description of some of the more notable zoonotic diseases and was not meant to be an in-depth review but rather a brief introduction to make the student aware that animals can carry a variety of illnesses that can be transmitted to humans either directly through bites or contamination of cuts and mucous membranes with excrement, or directly from fleas and ticks. Likewise the signs and symptoms of these illnesses are similar and can mimic the flu or common cold.

GENERAL PRECAUTIONS TO PREVENT INFECTION

  • Recognize the problem in the animals by observation
  • Cover all open cuts on hands and exposed skin before starting to work on all animals
  • Consider wearing disposable rubber gloves. Clean your tools and work area well when finished.
  • Wash thoroughly with warm, soapy water after working with animals
  • Never skin an animal found dead with no obvious cause, i.e. tooth marks, road kill, etc. Turn in suspicious specimens to the proper authorities
  • Observe strict hygiene when working with all wild species
  • Seek medical attention immediately if you suspect you have been exposed to any disease carried by animals or if you exhibit any symptoms of disease
  • Most bacterial and viral diseases in animals present flu-like symptoms in humans. Be cautious if you become ill after handling animals.
  • Use common sense out on the trapline when dealing with wild animals which may carry disease.
  • Common chlorine bleach is an effective anti-viral and anti-bacterial agent for a disinfectant and can be used to wash hands and surfaces.

IF YOU'RE BITTEN BY A WILD ANIMAL

1. If it is a wild animal, attempt to kill the animal without damage to the skull.

2. If the animal is domestic, insist that the offending animal be penned and observed for at least 10 days to see if it gets sick or dies.

3. Cleanse the wound as quickly as possible with soap and water.

4. Keep the dead animal cool, but do NOT freeze it.

5. Always call your Doctor! He or she will make a decision as to what treatment and/or shots may be necessary based on the type of animal; whether or not the animal escaped; whether or not the animal might have felt provoked; the type and location of the bite; and whether rabies is likely in the area. You may be required to deliver the animal carcass to a veterinarian for processing and shipping to a laboratory for analysis.