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Orf (disease)
Encyclopedia
Orf is an exanthemous disease
caused by a parapox virus and occurring primarily in sheep and goat
s. It is also known as contagious pustular dermatitis, infectious labial dermatitis, ecthyma contagiosum, and sheep pox, thistle disease and scabby mouth. Orf virus is zoonotic - it can also infect humans.
, meaning humans can contract this disorder through direct contact with infected sheep and goats or with fomites carrying the orf virus. It causes a purulent-appearing papule
locally and generally no systemic symptoms. Infected locations can include the finger, hand, arm, face and even the penis (caused by infection from the hand during urination). Consequently it is important to observe good personal hygiene and to wear gloves when treating infected animals. The papule may persist for 7 to 10 weeks and spontaneously resolves. It is an uncommon condition and not easily identified by most doctors. This affliction can be contagious (passed from one human to another).
While orf is usually a benign self-limiting illness, it can be very progressive and even life-threatening in the immune-compromised host. One percent topical cidofovir
has been successfully used in a few patients with progressive disease. Serious damage may be inflicted on the eye if it is infected by orf, even among healthy individuals. The virus can survive in the soil for at least six months.
It has been recorded since the late 19th century and has been reported from most sheep- or goat-raising areas including those in Europe, the Middle East, the United States, Africa, Asia, Alaska, South America, Canada, New Zealand and Australia. Orf is spread by fomite
s and direct contact. In some environments infection is injected by scratches from thistle
s of both growing and felled plants. Symptoms include papule
s and pustules on the lips and muzzle, and less commonly in the mouth of young lambs and on the eyelids, feet, and teats of ewes. The lesions progress to thick crusts which may bleed. Orf in the mouths of lambs may prevent suckling and cause weight loss, and can infect the udder of the mother ewe, thus potentially leading to mastitis
. Sheep are prone to reinfection. Occasionally the infection can be extensive and persistent if the animal does not produce an immune response.
A live virus vaccine
(ATCvet code: ) is made from scab material and usually given to ewes at the age of two months, but only to lambs when there is an outbreak. The vaccine can cause disease in humans.
In sheep and goats the lesions mostly appear on or near the hairline and elsewhere on the lips and muzzle. In some cases the lesions appear on and in the nostrils, around the eyes, on the thigh, coronet, vulva, udder and axilla. In rare cases, mostly involving young lambs, lesions are found on the tongue, gums, roof of the mouth and the oesophagus. It has also been reported a number of times to cause lesions in the rumen. In one case it was shown that a severe form of orf virus caused an outbreak involving the gastrointestinal tract, lungs, heart, as well as the buccal cavity, cheeks, tongue and lips. Another severe case was reported pharyngitis, genital lesions and infection of the hooves which led to lameness and, in some cases, sloughing of the hoof.
More typically sheep will cure themselves of orf within a week or so as the disease runs its course. Sheep custodians can assist by applying antibiotic sprays on to large scabs, ensuring infected lambs receive sufficient milk and separating out the infected stock to slow down cross-transmission to healthy animals. It is advisable for those handling infected animals to wear disposable gloves to prevent cross-infection and self-infection. Vets need to be contacted if there is a risk of misdiagnosis with other, more serious conditions.
s, steenbok
and alpaca
s, chamois
and thar, reindeer
, musk ox
, the dog
, the cat
, the mountain goat
, bighorn sheep
, dall sheep
, and the red squirrel
.
Disease
A disease is an abnormal condition affecting the body of an organism. It is often construed to be a medical condition associated with specific symptoms and signs. It may be caused by external factors, such as infectious disease, or it may be caused by internal dysfunctions, such as autoimmune...
caused by a parapox virus and occurring primarily in sheep and goat
Goat
The domestic goat is a subspecies of goat domesticated from the wild goat of southwest Asia and Eastern Europe. The goat is a member of the Bovidae family and is closely related to the sheep as both are in the goat-antelope subfamily Caprinae. There are over three hundred distinct breeds of...
s. It is also known as contagious pustular dermatitis, infectious labial dermatitis, ecthyma contagiosum, and sheep pox, thistle disease and scabby mouth. Orf virus is zoonotic - it can also infect humans.
In humans
Orf is a zoonotic diseaseDisease
A disease is an abnormal condition affecting the body of an organism. It is often construed to be a medical condition associated with specific symptoms and signs. It may be caused by external factors, such as infectious disease, or it may be caused by internal dysfunctions, such as autoimmune...
, meaning humans can contract this disorder through direct contact with infected sheep and goats or with fomites carrying the orf virus. It causes a purulent-appearing papule
Papule
A papule is a circumscribed, solid elevation of skin with no visible fluid, varying in size from a pinhead to 1 cm.With regard to the quote "...varying in size from a pinhead to 1cm," depending on which text is referenced, some authors state the cutoff between a papule and a plaque as 0.5cm,...
locally and generally no systemic symptoms. Infected locations can include the finger, hand, arm, face and even the penis (caused by infection from the hand during urination). Consequently it is important to observe good personal hygiene and to wear gloves when treating infected animals. The papule may persist for 7 to 10 weeks and spontaneously resolves. It is an uncommon condition and not easily identified by most doctors. This affliction can be contagious (passed from one human to another).
While orf is usually a benign self-limiting illness, it can be very progressive and even life-threatening in the immune-compromised host. One percent topical cidofovir
Cidofovir
Cidofovir is an injectable antiviral medication for the treatment of cytomegalovirus retinitis in patients with AIDS. It suppresses CMV replication by selective inhibition of viral DNA polymerase and therefore prevention of viral replication and transcription...
has been successfully used in a few patients with progressive disease. Serious damage may be inflicted on the eye if it is infected by orf, even among healthy individuals. The virus can survive in the soil for at least six months.
In sheep and goats
Fomite
A fomite is any inanimate object or substance capable of carrying infectious organisms and hence transferring them from one individual to another. A fomite can be anything...
s and direct contact. In some environments infection is injected by scratches from thistle
Thistle
Thistle is the common name of a group of flowering plants characterised by leaves with sharp prickles on the margins, mostly in the family Asteraceae. Prickles often occur all over the plant – on surfaces such as those of the stem and flat parts of leaves. These are an adaptation that protects the...
s of both growing and felled plants. Symptoms include papule
Papule
A papule is a circumscribed, solid elevation of skin with no visible fluid, varying in size from a pinhead to 1 cm.With regard to the quote "...varying in size from a pinhead to 1cm," depending on which text is referenced, some authors state the cutoff between a papule and a plaque as 0.5cm,...
s and pustules on the lips and muzzle, and less commonly in the mouth of young lambs and on the eyelids, feet, and teats of ewes. The lesions progress to thick crusts which may bleed. Orf in the mouths of lambs may prevent suckling and cause weight loss, and can infect the udder of the mother ewe, thus potentially leading to mastitis
Mastitis
Mastitis is the inflammation of breast tissue. S. aureus is the most common etiological organism responsible, but S. epidermidis and streptococci are occasionally isolated as well.-Terminology:...
. Sheep are prone to reinfection. Occasionally the infection can be extensive and persistent if the animal does not produce an immune response.
A live virus vaccine
Vaccine
A vaccine is a biological preparation that improves immunity to a particular disease. A vaccine typically contains an agent that resembles a disease-causing microorganism, and is often made from weakened or killed forms of the microbe or its toxins...
(ATCvet code: ) is made from scab material and usually given to ewes at the age of two months, but only to lambs when there is an outbreak. The vaccine can cause disease in humans.
In sheep and goats the lesions mostly appear on or near the hairline and elsewhere on the lips and muzzle. In some cases the lesions appear on and in the nostrils, around the eyes, on the thigh, coronet, vulva, udder and axilla. In rare cases, mostly involving young lambs, lesions are found on the tongue, gums, roof of the mouth and the oesophagus. It has also been reported a number of times to cause lesions in the rumen. In one case it was shown that a severe form of orf virus caused an outbreak involving the gastrointestinal tract, lungs, heart, as well as the buccal cavity, cheeks, tongue and lips. Another severe case was reported pharyngitis, genital lesions and infection of the hooves which led to lameness and, in some cases, sloughing of the hoof.
More typically sheep will cure themselves of orf within a week or so as the disease runs its course. Sheep custodians can assist by applying antibiotic sprays on to large scabs, ensuring infected lambs receive sufficient milk and separating out the infected stock to slow down cross-transmission to healthy animals. It is advisable for those handling infected animals to wear disposable gloves to prevent cross-infection and self-infection. Vets need to be contacted if there is a risk of misdiagnosis with other, more serious conditions.
In other animals
Primarily, orf is a disease of sheep and goats although it has been reported as a natural disease in the following: humanHuman
Humans are the only living species in the Homo genus...
s, steenbok
Steenbok
The Steenbok, Raphicerus campestris, is a common small antelope of southern and eastern Africa. It is sometimes known as the Steinbuck or Steinbok.- Description :...
and alpaca
Alpaca
An alpaca is a domesticated species of South American camelid. It resembles a small llama in appearance.Alpacas are kept in herds that graze on the level heights of the Andes of southern Peru, northern Bolivia, Ecuador, and northern Chile at an altitude of to above sea level, throughout the year...
s, chamois
Chamois
The chamois, Rupicapra rupicapra, is a goat-antelope species native to mountains in Europe, including the Carpathian Mountains of Romania, the European Alps, the Tatra Mountains, the Balkans, parts of Turkey, and the Caucasus. The chamois has also been introduced to the South Island of New Zealand...
and thar, reindeer
Reindeer
The reindeer , also known as the caribou in North America, is a deer from the Arctic and Subarctic, including both resident and migratory populations. While overall widespread and numerous, some of its subspecies are rare and one has already gone extinct.Reindeer vary considerably in color and size...
, musk ox
Musk Ox
The muskox is an Arctic mammal of the family Bovidae, noted for its thick coat and for the strong odor emitted by males, from which its name derives. This musky odor is used to attract females during mating season...
, the dog
Dog
The domestic dog is a domesticated form of the gray wolf, a member of the Canidae family of the order Carnivora. The term is used for both feral and pet varieties. The dog may have been the first animal to be domesticated, and has been the most widely kept working, hunting, and companion animal in...
, the cat
Cat
The cat , also known as the domestic cat or housecat to distinguish it from other felids and felines, is a small, usually furry, domesticated, carnivorous mammal that is valued by humans for its companionship and for its ability to hunt vermin and household pests...
, the mountain goat
Mountain goat
The Mountain Goat , also known as the Rocky Mountain Goat, is a large-hoofed mammal found only in North America. Despite its vernacular name, it is not a member of Capra, the genus of true goats...
, bighorn sheep
Bighorn Sheep
The bighorn sheep is a species of sheep in North America named for its large horns. These horns can weigh up to , while the sheep themselves weigh up to . Recent genetic testing indicates that there are three distinct subspecies of Ovis canadensis, one of which is endangered: Ovis canadensis sierrae...
, dall sheep
Dall Sheep
The Dall sheep , Ovis dalli, is a species of sheep native to northwestern North America, ranging from white to slate brown in color and having curved yellowish brown horns...
, and the red squirrel
Red Squirrel
The red squirrel or Eurasian red squirrel is a species of tree squirrel in the genus Sciurus common throughout Eurasia...
.