About lumpy skin disease

 Lumpy skin disease (LSD) is a devastating disease of cattle and buffalo caused by a capripox virus.

The disease has never been recorded in Australia but is spreading rapidly internationally.

Since 2012, LSD has spread from Africa and the Middle East into south-eastern Europe, affecting European Union (EU) Member countries (Greece and Bulgaria) and several other countries in the Balkans.

LSD was first reported in Asia and the Pacific region in 2019 in north west China, Bangladesh and India. During 2020, LSD continued to spread across continental Asia with many countries including Bhutan, Hong Kong, Myanmar, Nepal, Taiwan, Vietnam and Sri Lanka, reporting outbreaks. In 2021, the disease was confirmed in Vietnam, Thailand, and Malaysia. Indonesia reported confirmed cases in March 2022.

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 European Union has implemented an intensive (and expensive) vaccination and culling program to halt the spread of the disease.

Victorian Significant Disease Investigation program

With LSD moving through Asia, the risk of this disease entering Australia is increasing. The potential economic impact of an incursion would be considerable due to the disruption of trade in livestock and livestock products, as well as costs associated with disease control and eradication.

With the heightened awareness internationally of LSD, it is important that Australia, with its 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 recognise it quickly if an incursion should occur.

To assist with these objectives, the Victorian Significant Disease Investigation (SDI) program supports sample collection and submission from cases where it is appropriate to consider LSD as a potential differential diagnosis.

To be eligible for investigation under the SDI program, cases must be:

• cattle or buffalo of any age
• resident in Victoria
• showing multiple, cutaneous skin lesions.

Samples from single animals are eligible, but cases involving several cattle on the same property are preferred.

Samples to collect:

• Skin lesions (excision or biopsy) – One sample in saline and a duplicate in formalin,
• Blood – One each of clotted/serum (red/gold top) tube and EDTA blood tube.

Submission, documentation and approvals process will be as per usual for a SDI investigation. Always discuss the case with your local department veterinary officer before submission.

Understand the signs of lumpy skin disease

The incubation period for lumpy skin disease 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.

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.

Other diseases of cattle that could look like lumpy skin disease

• Ringworm and infection with other dermatophytes
• Dermatophilus infection
• Cutaneous leucosis
• Parapox (bovine popular stomatitis)
• Bovine herpes mammilitis
• Pseudo lumpy skin disease (bovine herpesvirus 2)
• Photosensitisation
• Insect bites
• Urticaria
• Demodectic mange
• Trauma, including burns
• Actinobacillosis (cutaneous form due to infection with Actinobacillus lignieresi)

Lumpy skin disease – information for veterinarians

Lumpy skin disease is caused by a Capripoxvirus that affects cattle and buffalo.  The disease has never been recorded in Australia, but internationally it is spreading rapidly.

The heightened risk of an incursion in Australia

Although lumpy skin disease is not present in Australia, its recent detection in Indonesia and ongoing spread throughout neighboring Asian countries is very concerning.

Lumpy skin disease would be costly and challenging to control or eradicate should it reach Australia, with wide-ranging and significant long-term impacts for our livestock industries.

Like Japanese encephalitis and other vector-borne diseases, unless an incursion is detected early, its eradication or elimination (eradication in a defined geographical area) would be difficult.

Australia’s current response policy for lumpy skin disease is to eradicate it in the shortest possible time, by the destruction of infected animals and contaminated products, quarantine and movement controls, insect vector control and other activities.

A vaccine is not currently available (or its use permitted) in Australia, although vaccines are in use internationally with varying success in terms of disease control.

The economic impact of an incursion in Australia would be considerable due to the disruption of trade in livestock and livestock products (including products from sheep and goats, not just cattle), as well as costs associated with disease control and eradication.

Continued vigilance is essential in order to detect an incursion as quickly as possible, and thereby protecting the health of the Australian cattle herd, as well as Australia’s export trade in livestock and livestock products.

Clinical signs

Clinically, disease may range between subclinical disease to severe illness or death.

Initial clinical signs may include fever (40-41.5 0C), depression, anorexia, and reluctance to move. Rhinitis, conjunctivitis and excess salivation may also be apparent.

Cattle may develop large, firm nodules (up to 5 cm in diameter) in the skin. These can be found over the entire animal, but are found particularly on the head, neck, udder, scrotum and perineum. The nodules may become necrotic and ulcerate, leading to an increased risk of secondary bacterial infections and flystrike. In severe cases, the nodules can fall away leaving full-skin thickness holes in the animals hide.

Affected bulls may not work due to painful lesions on their prepuce, and cows may abort or become anestrus. Live neonates or aborted fetuses from infected cows may also present with skin lesions.

In severely affected animals, lesions can also develop in the respiratory and gastrointestinal tract. Pneumonia is a common, and often fatal, complication.

Bos taurus cattle are generally more susceptible than Bos indicus cattle. Jersey, Guernsey, Friesian and Ayrshire breeds are particularly susceptible.

Morbidity rates vary greatly, ranging between 1-95%. Mortality rates are usually 1-5%, but have been reported as high as 75%.

Disease transmission

Lumpy skin disease virus is spread primarily by biting insects such as flies and mosquitoes, and possibly ticks. It can also be transmitted by fomites, and in some cases, from animal to animal.

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.

Virus can be found in blood for up to 21 days post-infection. Shedding in semen may continue for at least 42 days post-infection.

Lumpy Skin Disease is not Zoonotic

The virus is highly host specific and does not cause disease in humans.

There is no risk from consuming beef or dairy products.

Differential diagnoses

Differential diagnoses include:

• urticaria
• pseudo lumpy skin disease (bovineherpes mammalitis; herpesvirus 2)
• bovine papular stomatitis (parapoxvirus)
• dermatophytosis (Trichophyton spp., Microsporum spp.)
• pseudo cowpox (parapoxvirus)
• vaccinia virus and cowpox virus (orthopoxviruses)
• streptothricosis (Dermatophilus congolensis)
• demodicosis (Demodex bovis)
• insect or tick bites
• onchocercosis (Onchocerca spp.)
• besnoitiosis (Besnotia besnoiti)
• cutaneous actinobacillosis (Actinobacillus lignieresi)
• rinderpest
• Hypoderma bovis infection
• photosensitization
• skin tuberculosis.

Suspicion of Lumpy Skin Disease

Lumpy skin disease is a notifiable disease. All suspected cases must be reported to Agriculture Victoria on the Emergency Animal Disease Hotline on 1800 675 888 or to local Agriculture Victoria Animal Health and Welfare staff immediately.

Sample collection

Diagnosis of lumpy skin disease is based primarily on detection of the virus in lesions. Detection of antibody in serum may also aid diagnosis.

Specimens that should be collected from live animals include:

• blood (from animals with fever)
• serum
• nodular fluid
• skin biopsies of suggestive lesions
• scabs, and
• skin scrapings from lesions.

At necropsy, a range of samples, both fresh and fixed, should be taken from skin lesions, lesions in the respiratory and gastrointestinal tracts, and other internal organs.

Following the initial diagnosis of lumpy skin disease, a more restricted sample set, still based on sampling lesions, may be defined