Lumpy skin disease occurs frequently in many cattle herds throughout Africa. The disease does not affect humans, but the The Food and Agriculture Organization of the United Nations (FAO) considers lumpy skin disease "economically important." The disease is significant because cows with the disease can become so skinny that they produce no milk or meat. Scars that form after cows recover can make their hides unsellable. Efforts to control the spread of lumpy skin disease have proven somewhat successful.
Scientists have positively identified the lumpy skin disease virus as a member of the Poxviridae family and the Capripoxvirus genus of poxviruses. It infects only cows and Asian water buffaloes. While the virus also appears in the blood of some flies and mosquitoes, it does not sicken the insects. Bites from virus-carrying insects appear to spread infection, as does physical contact been sick cows and uninfected ones.
A United Kingdom Department for Environment, Food and Rural Affairs (DEFRA) factsheet on lumpy skin disease explains that cows with the disease show few symptoms for the first 10 days to two weeks. Adult females will give less milk, and all cows will develop a fever and eat less. When lumpy skin disease's telltale 3 mm high and nearly 1 mm diameter lumps do develop, they can spread over a cow's entire hide and produce large scabs that then burst. In addition to the lumps, cows will generally develop swollen and tender udders or testicles, sores on their tongues and nasal discharges. The DEFRA document goes on to state, "Sterility in bulls and abortion in cows may occur, and the disease can affect almost all organs. There are nodules in lungs at postmortem examination. Bronchopneumonia may be present. Hemorrhages may occur in the spleen or the liver and rumen. Raised nodules may occur on the mucous membrane of the three stomachs. Ulcers form in the abomasum, as well as inflammation and hemorrhages in the intestines."
No Treatment, High Survivability
Lumpy skin disease has no specific treatment, but, according to the Food and Agriculture Organization, about 95 percent of adult cows that get the disease typically recover over the course of weeks to months. Cattle younger than 12 months have the highest mortality rate from the disease.
Prevalent in Sub-Saharan Africa
To date, lumpy skin disease has been found primarily in most of the countries south of the Sahara Desert in Africa, Madagascar and Egypt. The only outbreak that occurred outside of Africa took place in Israel during 1989. Since 1996, all countries in the European Union and North America have required cattle producers to screen for and report any suspected cases of lumpy skin disease.
Some Prevention Possible
The best way for cattle producers to stem the transmission of lumpy skin disease is to slaughter cows positively diagnosed with the disease and then burn the carcasses. Separating sick animals from healthy ones and keeping the sick animals completely isolated until they die or recover can be considered when destruction is not economically feasible. In either event, cattle producers need to thoroughly disinfect surfaces and equipment that have come into contact with sick cows because the lumpy skin disease virus can survive outside of a living host for up to 18 days. A brochure prepared by an Iowa State University on lumpy skin disease states that injecting chloroform or formalin solutions into sick cows' scabs has prevented some transmission of the virus. Further, sheep pox and goat pox vaccines have shown some effectiveness against the closely related lumpy skin disease virus.