UNP-0063 Contagious Ecthyma (Orf/Sore Mouth) in Sheep and Goats
Contagious Ecthyma (Orf/Sore Mouth) in
Sheep and Goats
Introduction
Contagious ecthyma, also known as orf
or sore mouth, is a zoonotic disease, which means that
it is easily transmitted from animals to humans. It induces acute
pustular lesions in the skin of goats, sheep, and wild ruminants
worldwide. Young animals are the most susceptible to contracting
the disease. Kids and lambs can contract sore mouth after a few
weeks of birth. However, sore mouth outbreaks in young animals
are most frequent during postweaning.
Sore mouth is caused by a poxivirus related
to the pseudocowpox and bovine papular stomatitis virus family.
The virus is epitheliotropic, which means that it has an affinity
for the skin; infection occurs by direct contact. The period of
incubation is relatively short. Susceptible animals usually develop
the first signs of the disease 4 to 7 days after exposure that
persists for 1 to 2 weeks or for longer periods. The disease affects
sheep and goats; it is marked by an increase in incidence and
severity if not controlled among small ruminant herds.
Sore mouth outbreaks occur more frequently
during periods of extreme temperatures such as late summer and
winter. The disease initially presents itself as papules (elevation
of the skin) that progresses to blisters (fluid-filled pouches)
or pustules before encrusting. These lesions are found in the
skin of the lips. They can spread around the outside and inside
of the mouth, face, lips, ears, vulva, lets, scrotum, teats, and
feet, usually in the interdigital region. Extensive lesions on
the feet can lead to lameness in adults and young animals. The
infection is spread by direct and indirect contact from infected
animals or by contact with infected tissue or saliva containing
the virus.
During the course of the disease, blisters
eventually break down to release more of the virus and later develop
into wet pus-like (suppurative) scabs. These lesions can persist
for 3 weeks and can become a site for the development of secondary
bacterial infections. Scab tissues are extremely painful, to the
point of preventing sick animals from eating. Because infected
kids present lesions on their gums and lips, does and ewes can
acquire lesions on their udder. The lesions on the udder are due
to direct contamination during nursing that causes mastitis (inflammation
of the mammary gland) in does and ewes. Severe to moderate enlargement
of the lymph nodes, arthritis, and pneumonia resulting from sore
mouth has been reported. Most animals acquire immunity after contracting
the disease; however, subsequent outbreaks in herds are common
with a less severe form of the disease.
Diagnosis
Diagnosis is based on the characteristics
and location of the lesions, as well as a herd history of previous
outbreaks. A definitive diagnosis is based on viral isolation
and an immunologic test.
Treatment
Lesions can be treated with a single application
of 3 percent iodine solution. Animals are cured spontaneously
in most cases. In severe cases of secondary bacterial infection,
the usage of a systemic antibiotic is recommended. It is important
to treat the lesions on the teats (nipples) of the does to prevent
the development of mastitis. For infected kids, be sure they are
fed artificially.
Prevention and Control
- Minimize transportation stress.
- Always quarantine new animals before
introducing them to the rest of the herd.
- In case of an outbreak, separate sick
animals in a pen for treatment.
- Always feed and treat sick animals after
feeding the herd.
- Incinerate gloves and all tissues that
come in contact with lesions extracted from sick animals. The
virus can persist in animal tissue for a long period of time,
becoming a source of contamination.
- Always wear gloves when handling sick
animals and vaccines as humans can contract the disease.
- Avoid the consumption of milk from does
that present lesions on the teats and udder.
- A systematic vaccination of the entire
herd is recommended only during outbreaks. There are two vaccines
available for use in sheep. The vaccines are modified versions
of live viruses and are administered topically. A small dose
of the vaccine is brushed over light scarifications of the skin
on the inside of the thigh. These vaccines will induce a mild
form of the disease. In sheep flocks where there is a prevalence
of the disease, lambs should be vaccinated at the age of 1 month
with a booster 2 to 3 months later. There is currently no recommended
vaccination protocol for goats since the sheep vaccine is not
FDA-approved for use in goats.
Consult your
local veterinarian for disease treatment and prevention.
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References
Merck Veterinary Manual. (2006). Contagious ecthyma (orf, contagious
pustular dermatitis, sore mouth). Whitehouse Station, NJ:
Merck & Co., Inc.
de la Concha-Bermejillo, A., Guo, J.,
Zhang, Z., and Waldron D. (September 2003). Severe persistent
orf in young goats. Journal of Veterinary Diagnostic Investigation,
15(5), 423-31.
Haig, D. M., and Mercer, A. A. (1998).
Ovine diseases. Orf. Veterinary Research, 29(3-4), 311-326.
Haig, D. M., McInnes, C. J. (2002). Immunity
and counter-immunity during infection with the parapoxvirus orf
virus. Virus Research, 88(1-2), 3-16.
Key, S. J., et al. (2007). Unusual presentation
of human giant orf (Ecthyma Contagiosum). The Journal of Craniofacial
Surgery, 18(5), 1076-1078.
Zamri-Saad, M., Roshidah, I., al-Ajeeli,
K. S., Ismail, M. S., and Kamarzaman, A. (1993). A severe complications
induced by experimental bacterial superinfection of orf lesions.
Tropical Animal Health and Production, 25(2), 85-88.
UNP-0063, April 2008, Maria
Lenira Leite-Browning, DVM,
Extension Animal Scientist, Alabama A&M University
For more information, contact your county Extension office. Visit http://www.aces.edu/counties or look in your telephone directory under your county's name to find contact information.
Issued in furtherance of Cooperative Extension work in agriculture and
home economics, Acts of May 8 and June 30, 1914, and other related
acts, in cooperation with the U.S. Department of Agriculture. The Alabama
Cooperative Extension System (Alabama A&M University and Auburn
University) offers educational programs, materials, and equal
opportunity employment to all people without regard to race, color,
national origin, religion, sex, age, veteran status, or disability.
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