Contagious Ecthyma/Sore Mouth

Contagious ecthyma also known as sore mouth is a zoonotic disease (it is easily transmitted from animals to humans). The disease forms 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 post weaning. The disease affects sheep and goats, it is marked by an increase in incidence and severity if not controlled.

Sore mouth is caused by a poxivirus. The virus is epitheliotropic (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 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, scrotum, teats, and feet, usually in the inter digital region. Extensive lesions on the feet can lead to lameness in adults and young animals.

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.

Transmission

  • The infection is spread by direct and indirect contact from infected animals
  • By contact with infected tissue or saliva containing the virus.
  • Sore mouth outbreaks occur more frequently during periods of extreme temperatures such as late summer and winter.

Symptoms

  • Early in the infection sores appear as blisters and then become crusty crabs. Sores are typically found on the lips, muzzle and mouth.
  • Sheep and goats get similar sores on the lower leg and teats especially when ewes or does are nursing infected lambs or kids.
  • Young animals may have difficulty in nursing/feeding and may require bottle or tube feeding

Treatment control and prevention

  • 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. NB: 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.
  • 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 theinside 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.