Distemper

Distemper

Causative Agent

Distemper is an infectious and contagious viral disease of many domestic and wild carnivores caused by infection with Canine Distemper Virus (CDV) of the genus Morbillivirus.

Distribution

Geographic:

Seasonality:

Most cases occur in spring involving young animals not previously exposed to the virus.

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Raccoons are often diagnosed with distemper.

Hosts, Transmission and Life Cycle

Hosts:

Carnivores, wild and domestic, can be infected with CDV: dogs, cats, foxes, mustelids, raccoons, and bears.
In North America, coyotes and wolves are common hosts of CDV.

Transmission:

Transmission of CDV is primarily through contact with body fluids containing the virus or through inhalation of fine mists containing the virus (e.g., from an infected animal coughing).
Because CDV is so fragile in the environment, close association between affected and non-affected animals is necessary for transmission. As such, dense populations of susceptible animals are necessary to sustain an epidemic of canine distemper.

Life Cycle:

Inhaled virus enters the upper respiratory tract or ingested virus enters and is spread via the lymph nodes throughout the body, causing damage to the immune system.
Following spread in the lymph nodes, the virus is then often found in parts of the digestive system and liver.
Widespread infection begins about 1 week after infection and virus may be shed in the environment for several months after the animal recovers.
CDV is relatively fragile and quickly inactivated in the environment by ultraviolet light, heat, drying and common disinfectants.

Signs and Symptoms

Signs of canine distemper will vary depending on the species, age and immune status of host, the strain of virus, and environmental conditions.
Young animals are the most susceptible.
The incubation period for CDV ranges from 1 week to greater than a month, while the duration of the disease ranges from 1 to 4-6 weeks ending in either recovery or death.
Classic signs of infection include:
- depression and crusting or “pus-like” discharges from the eyes and nose.
- coughing, fever, vomiting, diarrhea, lack of appetite and thickening of skin of the nose, lips, eyelids, ears, anus and foot pads, particularly in mustelids.
Signs of infection of the central nervous system in several species include:
- abnormal behaviour, convulsions, seizures, paralysis, incoordination, “aimless wandering”.

Meat Edible?

Meat from carnivores is rarely consumed; however, DO NOT consume meat from an animal that is suspected to have CDV.

Human Health Concerns and Risk Reduction

CDV is not believed to be a public health concern for humans.
Domestic dogs are a more likely source for CDV than wild carnivores.
To prevent spread of CDV and other diseases to domestic dogs, they should be vaccinated and not be allowed to roam free in areas where they may encounter wild carnivores.
CDV has been examined as a cause of multiple sclerosis in humans. There is at present no evidence to prove this theory.

Similar Diseases

Some of the neurological signs observed in CDV infection are similar to those seen in animals with rabies.
However, CDV infection is caused by inhaling virus particles, rabies is transmitted through bites.
Because of the similarity and the potential for human infection with rabies, follow the protocols outlined in the description of rabies in this manual for how to handle an animal or carcass that is suspected of being rabid.

Samples for Diagnosis

Submission of the whole animal is necessary as a variety of tissues must be examined to confirm the disease.