Contagious Ecthyma

Contagious Ecthyma

or Orf

Causative Agent

A viral disease of sheep and goats (wild and domestic) caused by infection with the parapoxvirus or orf virus.
Disease is also called soremouth.

Distribution

Geographic:

Present in areas of southern BC in some populations of bighorn sheep and mountain goats.

Seasonality:

Usually reported during the rut when these species are in more close association. Also reported during the winter when these animals are using road salt or salt blocks. Contagious ecthyma is also likely to be reported during the hunting season when humans see animals more closely.

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Typical signs of contagious ecthyma include extensive scabbing of the face and lips.

Hosts, Transmission and Life Cycle

Hosts:

Contagious ecthyma may be more likely to be transmitted when there is contact with domestic sheep and goats.
Endemic in some populations of bighorn sheep and mountain goats in BC.
Experimental infection observed in moose, white-tailed deer, and elk – effects were considered mild. Not observed in these species in the wild.

Transmission:

Likely following a similar pattern in domestic animals, transmission occurs as a result of direct contact with infected animals or when cuts and abrasions are in contact with contaminated objects, such as salt blocks.
The virus can survive outside of the host for extended periods, perhaps years – scab material lying in places of habitual use may serve as recurring “reservoirs of infection”.

Life Cycle:

Presence of contagious ecthyma in bighorn sheep and mountain goats is most likely as a result of transmission of orf virus from domestic sheep or goats.

Signs and Symptoms

Animals may appear restless, nervous and show excessive licking on the lips and nostrils, and scratching of the head.
Scabby lesions of this disease are most commonly found on the lips, skin of the face, udder, within the mouth and above the hooves.
Lesions range in size from tiny crusts to large merging scabs that may cover the lips.
If mouth lesions are severe enough, animals will not feed and lameness may ensue due to lesions on the foot – in young animals, both scenarios may lead to loss of condition or death by starvation.
Generally, affected animals recover uneventfully; however, in severe outbreaks, death may occur in younger animals.
Initial scabs form 7 days after infection followed by 10 days of a cycle of pustules to scabs
After 3 weeks, lesions begin to subside and typically do not scar.
Short-term immunity (up to 5 months) is thought to occur following an infection.

Meat Edible?

Meat from an infected animal is suitable for consumption, however, trim off affected parts.
Meat from severely affected animals may be of inferior quality due to the poor condition of the animal.

Human Health Concerns and Risk Reduction

Orf or contagious ecthyma is a zoonosis and as such, appropriate precautions should be taken when handling an animal suspected of having this disease.
Orf is an occupational hazard of those who handle domestic goats and sheep.
Lesions similar to those in animals including swollen/painful lymph nodes and mild fever may occur – skin lesions usually subside within 6 weeks without scarring. Most likely to be contracted by humans during the hunting season when hunters are in direct contact with infected animals.

Samples for Diagnosis