Lumpy skin disease (LSD) is a devastating disease of cattle and buffalo caused by a Capri pox virus. It is transmitted between animals by direct contact, via arthropod vectors and iatrogenically. The virus is highly hosted specific and does not cause disease in humans.
The disease has never been recorded in Australia, but internationally it has been spreading rapidly and the World Organisation for Animal Health (the OIE) is encouraging Members in at-risk areas to initiate vaccination campaigns ahead of virus entry and to continue timely reporting of all outbreaks [1].
The presence of LSD leads to restrictions on international trade in live animals and their products and, in the European Union, there has been a very intensive (and expensive) vaccination and culling program implemented to halt the spread of the disease.
Request for samples
With the heightened awareness internationally of LSD, it is important that Australia, with large dairy and beef export markets, is able to confidently and credibly demonstrate on-going freedom from this disease. Equally, it is important that veterinary practitioners are aware of the disease and are able to recognize it quickly if an incursion should occur.
To assist with both of these objectives, from 1 June 2018 the Victorian Significant Disease Investigation (SDI) program [2] will support sample collection and submission from cases where it is appropriate to consider LSD as a potential differential diagnosis
Background
What is lumpy skin disease?
Lumpy skin disease (LSD) is a disease of cattle and buffalo caused by a Capri pox virus.
Since 2012, LSD has spread from Africa and the Middle East into south-eastern Europe, affecting the European Union (EU) Member countries (Greece and Bulgaria) and several other countries in the Balkans.
Although the risk of these diseases entering Australia is low, the potential economic impact of an incursion would be considered due to the disruption of trade in livestock and livestock products, as well as costs associated with disease control and eradication.
How is the virus spread?
It is not fully understood how lumpy skin disease virus is transmitted between animals. It is believed that arthropod vectors, direct contact, contaminated feed and water and iatrogenic means (e.g. repeated use of needles on different animals) can all spread the disease.
The virus is present in high concentrations in the skin nodules and scabs on affected animals and can be isolated from blood, saliva, ocular and nasal discharges, and semen.
Lumpy skin disease virus can be found in the blood for up to 21 days post-infection but shedding in semen may continue for at least 42 days post-infection.
What are the clinical signs of lumpy skin disease?
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, and perineum. The nodules may become necrotic and ulcerate, leading to an increased risk of flystrike.
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 mortality rate usually remains below 10% but both rates can be considerably higher when an outbreak occurs in a naïve cattle population.
What samples should I collect to rule out lumpy skin disease?
Collect:
- Skin lesions (duplicate samples by excision or biopsy) in saline and formalin
- Blood samples – one each of clotted blood/serum (red/gold top tube) and EDTA blood tubes
What diseases of cattle could look like lumpy skin disease?
- Ringworm and infection with other dermatophytes
- Dermatophilus infection
- Cutaneous leucosis
- Parapox (bovine popular stomatitis)
- Bovine herpes mammalians
- Pseudo lumpy skin disease (bovine herpesvirus 2)
- Photosensitisation
- Insect bites
- Urticaria
- Demodectic mange
- Trauma, including burns