In March 2022, cases of lumpy skin disease (LSD) were detected in Sumatra and the disease has the potential to spread across the rest of Indonesia over time.
If containment efforts fail and LSD reaches the island of Timor — less than 800km from mainland Australia — it presents a very real threat for our beef and dairy industries.
LSD is a pox virus affecting cattle and water buffalo. Originating in Africa in the 1970s, it has gradually spread since the 2000s across the Middle East, south-eastern Europe and Asia (as shown in the map).
The virus transmission is still not fully understood.
Biting insects such as flies, mosquitoes and ticks have been proven experimentally to transmit the disease via their saliva. Infected bulls can also excrete the virus in semen. Transmission via direct contact, contaminated feed, and iatrogenic methods (such as repeated use of needles between animals) are also suspected.
LSD has an incubation period of up to 28 days, with peak outbreaks during wet summer weather, although infections can still occur during winter.
Clinical signs include discharge from the eyes and nose, salivation, enlarged lymph nodes, persistent high fevers, depression, loss of appetite, and the appearance of characteristic painful, raised, firm skin lumps, 1cm to 5cm in diameter, especially around the head, brisket, neck, udder, limbs and genitals, which can become ulcerated and infected (the number of lumps can vary greatly with severity of disease).
Lesions can also be found in the mouth, nose, trachea and lungs on post-mortem. Pneumonia, lameness, mastitis and abortions can also result from LSD infection.
About one third of infected animals will show no signs of the disease, one third will show mild to moderate signs and one third will show severe signs.
European breeds and high-producing dairy cattle are more susceptible and usually more severely affected, with sharp drops in milk yield and body condition commonly reported.
There are no effective treatments for LSD, and supportive care or humane euthanasia is necessary for badly affected animals. Mortality rates in naive herds are reportedly as high as 10 per cent, and recovery is generally slow in surviving infected animals.
Ringworm, mange, hives and several other viral and bacterial infections can cause skin lesions similar to LSD, so diagnosis is essential via tissue samples, virus isolation or PCR.
Outbreak controls include vaccinating, restricting movements and culling.
Australia currently has no vaccine approved for use, but this is under discussion as part of our biosecurity plan with a threat so close to home. Recent government funding boosts to northern Australian biosecurity and surveillance efforts are also a welcome addition.
Overseas, containment and vaccination programs supported by the Australia-Indonesia Health Security Partnership and the Food and Agriculture Organisation of the United Nations (UN FAO) are also under way, and ongoing funding for these programs is vital.
Should LSD arrive in Australia, controlling the spread across northern Australia would be almost impossible even with a vaccine due to the extensive nature of our cattle enterprises, and the sheer distance biting insects can potentially travel when climactic conditions allow.
An incursion would have substantial implications for our international trade and exports.
Economic impacts for dairy and beef farmers alike would be felt through mortalities, reproductive losses, drops in body condition, reduced milk production, processor rejection due to hide and muscle damage, export restrictions (including genetic material, dairy products and live animals), and potentially forced culling to manage an outbreak.
Not to mention the social and environmental ramifications that would undoubtedly result from such losses.
At home — regardless of where, how or what we farm in Australia — it’s important that we are all aware of the signs of exotic diseases such as LSD, support surveillance, biosecurity and quarantine efforts (especially if visiting farms while travelling overseas) and know who to contact if needed.
LSD is considered exotic to Australia, notifiable and an emergency animal disease. For further information, contact your state department veterinarian or in the case of a suspected outbreak call the Emergency Animal Disease Watch Hotline on 1800 675 888 (24 hours a day, every day of the year).
Lucy Collins is completing her Dairy Residency with The University of Melbourne. She works as an on-farm veterinarian for Apiam Animal Health, and alongside her partner on his family’s dairy farm in south-west Victoria. She is a 2021 Nuffield Scholar supported by Gardiner Dairy Foundation.