Soremouth in Sheep

Fred M. Hopkins, DVM, MS
College of Veterinary Medicine
and
Warren Gill, PhD
Extension Animal Science-Beef, Sheep, Horse
University of Tennessee

        Soremounth is a highly contagious viral disease of sheep and is also known as contagious ecthyma and orf. This disease occurs world-wide and is very common in the U.S. Sine the disease is so contagious, active infections should exclude animals from shows and sales.

The Soremouth Virus

        Soremouth is caused by a Pox virus of which many types exist. This virus can persist for months in dried scabs in the environment and up to 7 years at 45EF. The virus can transmitted to susceptible animals by direct contact with other animals having signs of this disease. Carrier animals, which spread the virus but don't show signs are also important in the transmission of soremouth.

        The Soremouth virus can also be spread by contact with equipment, fences, feed and bedding that has previously be in contact with infected sheep. The virus requires breaks in the skin to gain entry and produce infections. This skin breaks are though to be the result of eating course, tough forage briars.

Signs of Soremouth

        A Soremouth infection normally runs its course in an individual in 1-4 weeks. Infections are seldom fatal. The disease spreads rapidly and may infect up to 90% of a susceptible flock in two months. A recovered animal can be immune to this disease for as little as two months or as long as a year. Both sexes and all breeds of lambs are equally susceptible. Most new cases occur in lambs less than one year of age. Sites of infection are most commonly the lips or nose, but the udder, teats and junction of the hoof and lower legs may also be infected. About 3 days after coming into contact with the soremouth virus, a small (1/4" diameter) raised, reddened area can be seen. These areas become blisters or pustules for a short period of time and may run together to produce larger areas of infection. Over a one week period of time, scabs form over infected areas. These scabs fall off after about 3 weeks, revealing rough reddened areas of granulation tissue. Once all scabs have fallen off, the infection is considered inactive. Affected lambs are depressed and reluctant to nurse or eat. Ewes with udder or teat lesions may not allow nursing and their lambs may spread the disease by attempting to nurse young lambs. Ewes with udder or teat lesions are also much more susceptible to Staphylococcal mastitis which often results in loss of the udder half or death of the ewe. The diagnosis of soremouth is generally based on clinical signs alone and laboratory testing of animals is usually not of much use or not available.

Human Infections with the Soremouth Virus

        The Soremouth virus is spread to people by contact with infected sheep. The infection in usually is seen on the hands or face. Symptoms include raised reddened area and enlarged lymph glands. Rarely, human deaths due to the soremouth virus have been reported.

Treatment of Soremouth in Sheep

        Treatment of soremouth infection in infected flocks is of limited use. Recovery may occur a few days quicker when individuals are treated topically. A solution of 50% strong iodine and 50% glycerine applied to affected areas with a soft brush is believed to be useful. This treatment needs to be applied daily. Rubber or vinyl gloves should always be used when treating infected sheep to prevent spread to humans.

Control of Soremouth in Sheep

        The control of soremouth in sheep should include thorough cleaning followed by disinfection of areas and equipment in contact with infected sheep. Most common disinfectants work well and specific ones such as iodophors have been recommended. Isolation of infected animals until the scabs fall off should help prevent this disease. A inexpensive vaccine is available but is sometimes hard to find and only comes in 100 dose vials. The vaccines is made of live, unaltered virus and should never be used unless the infection is known to already exist in a flock. Gloves should always be worn when administering the vaccine as human infections may result. The vaccine can be given as early as one week of life and should be repeated in 2-3 months. Immunity should last one year, though the effectiveness of the vaccine varies with which sub-type of soremouth virus exists in the flock. Vaccination is generally done on the inside of the thigh in lambs and behind the elbow in ewes. The area is scratched to make a raw, but not bleeding area. The vaccine is applied to the raw area and a raised reddened area should result in a few days.

        Soremouth is a very contagious viral disease that results in very significant losses in the sheep industry. Treatment of affected individuals of little value but control measures can be effective in limiting economic losses