The disease is spread by the poxvirus and usually occurs during the dry seasons, especially when there are high insect populations. In addition, certain ticks can carry the disease.
Most infected animals show no visible clinical signs. The disease is spread through the saliva of infected animals and by infected animals rubbing against healthy animals, transferring it through skin lesions.
Infected animals will not eat. Small sores will develop on the inside of an animal(s) mouth, nose, and sexual organs. If the disease is present in a herd, a large number of animals will suddenly abort. An outbreak usually affects 1% to 2% of a herd, but rarely more than 3% of infected animals will die.
Lumpy skin disease can be prevented and controlled effectively through annual vaccination, but animals vaccinated during the disease’s incubation period still become infected.
Dairy cattle in peak production are often the most severely affected with a marked decrease in milk production. Depression, anorexia, rhinitis, conjunctivitis, and excess salivation may also be observed. In severely affected animals, necrotic lesions can also develop in the respiratory and gastrointestinal tract. The disease can be subclinical (up to 50% of cases in an outbreak) or may be very severe or even fatal. Morbidity varies between 5 to 45% and the mortality rate usually remains below 10% but both rates can be considerably higher when an outbreak occurs in a naïve cattle population.
Unfortunately, there are no specific antiviral drugs available for the treatment of lumpy skin disease. The only treatment available is supportive care of cattle. This can include treatment of skin lesions using wound care sprays and the use of antibiotics to prevent secondary skin infections and pneumonia
Lumpy skin disease is primarily spread between animals by biting insects (vector), such as mosquitoes and biting flies. Less commonly, the virus may be spread by direct contact to the skin lesions, saliva, nasal discharge, milk, or semen of infected animals
The incubation period is between 4 and 14 days post-infection.
After an initial period of high fever (41°C) and swollen lymph glands, the animal may develop large, firm nodules that are up to 5 cm in diameter in the skin. These can be found all over the body, but particularly on the: Head, neck, udder, scrotum, perineum.
The nodules may become necrotic and ulcerate, leading to an increased risk of flystrike.
