Lumpy Skin Disease

Also known as

Neethling virus,  pseudolumpy skin disease

Description

Lumpy skin disease is a highly contagious disease of cattle caused by a virus. There are two forms—mild and severe.

The severe form of the disease was originally confined to South Africa and Kenya but has spread north and west to other parts of Africa and into the Middle East. The mild form (often called pseudolumpy skin disease) occurs in cattle in the United Kingdom.

In the past decade, since 2012, lumpy skin disease has spread from Africa and the Middle East into southeastern Europe, affecting European Union countries (Greece and Bulgaria) and several other countries in the Balkans, and in 2013 was confirmed in Turkey. It has since spread into Eastern Europe and Russia.

Mortality rate from either disease is low, but damage to hides, loss of milk production and loss of weight during the long course of the disease can have an economic impact on cattle producers. Secondary bacterial infection often aggravates the condition.

This disease is very contagious; up to 50% of a herd may become infected, with spread to neighboring farms. An insect vector is suspected as the route of transmission from one animal to another, due to the rapid spread of this disease over fairly long distances.

All ages of cattle are susceptible, but young ones are more seriously affected. Animals that have recently recovered have immunity for about 3 months.

Incubation time of about 1 to 4 weeks is common. In severe cases there is fever, weeping eyes, nasal discharge, drooling, and lameness. About a week after these early signs, the skin nodules suddenly appear, usually first on the perineum (the area between the anus and the vulva on females, and between the anus and scrotum on males).

Then nodules may appear on the muzzle and other areas of the body. Some animals are covered with lumps.

The nodules are round and firm, about 1 to 4 centimeters (1/4 to 1 ½ inches) in diameter and slightly raised, with the hair on these lumps standing straight up. Thr lumps are very painful. The enlargements are between the layers of the skin, and there may be just a few or several hundred on the affected animal.

The lesions are often deep enough to expose tissues under the skin if they ulcerate. The nodules may seep fluid and have an ulcerated center.

These skin nodules contain a firm, creamy-gray or yellow mass of tissue. Secondary infection sometimes occurs and causes extensive discharge and sloughing. The animal may become extremely emaciated.

Eventually the nodules either regress, or necrosis of the skin results in hard, raised areas that are separated from the surrounding skin. These areas slough away to leave ulcers, which eventually heal with scarring.

Some affected animals are lame due to swelling in the legs (affecting the tendons) and brisket. There may be permanent damage to tendons and joints due to secondary bacterial infection, or permanent damage to teats and udder from a secondary mastitis.

Nodules inside the nostrils may obstruct breathing and the animal breathes with a snoring sound. Nodules on the inner surfaces of the nasal passages and mouth are flat plaques that later ulcerate. If they develop on the conjunctivae of the eye and eyelid they cause severe irritation and weeping.

Nodules on the prepuce (foreskin of the penis) or vulva (external tissues surrounding the vagina) may spread to surrounding inner tissues.

Usually the nodules disappear quickly but may persist as hard lumps for a longer time or become moist and draining, with necrotic (dead) tissue that sloughs away.

Surrounding lymph nodes may become enlarged, with local swelling around those areas. It may take 4 to 12 weeks for the animal to recover, and pregnant cows may abort. There may be uterine infection, and sometimes temporary or permanent infertility in cows. Bulls may also become infertile due to secondary infections.

There may be lesions inside the mouth, and in the throat, trachea, lungs (and some of these animals develop pneumonia) and stomachs (especially the abomasum). The animals in which the infection/lesions spread into the respiratory or digestive tracts often die.

Signs

• Fever,
• Watering eyes,
• Nasal discharge,
• Drooling,
• Lameness,
• Skin inflammation
• Firm round nodules
• Reluctance to eat

Causes

The severe form of the disease is caused by the Neethling poxvirus which is similar to the sheeppox and goatpox viruses (all three of these viruses are capripoxviruses). The virus is present in the blood during the early stages (when the animal has a fever) and is possibly spread from one animal to another by biting insects, since the incidence is highest in wet summer weather.  

The disease is most prevalent along water courses and on low ground. Quarantine restrictions (in attempts to limit the spread of infection) have failed, so biting insects have been suspected as vectors. Some outbreaks have occurred under conditions in which there are no insects present, however.

Three species of hard ticks found in Africa have been shown to be biologically able to transmit the virus. Since this disease can be experimentally transmitted by infected saliva, contact between animals is thought to be another route of infection. African buffalo are suspected as hosts of this virus in Kenya.

Prevention

A vaccine against the Neethling virus has been available for a number of years and can be given to cattle over 6 months of age. Vaccination of cattle with a sheeppox virus vaccine is also affective for prevention.

Treatment

There is no specific treatment for lumpy skin disease except to use antibiotics to help prevent secondary infection in ulcerating nodules, and this is important to prevent or keep these infections from becoming worse.