Dr Mark Schipp on lumpy skin disease

Image: Australian Chief Veterinary Officer Dr Mark Schipp visiting a cattle feedlot in Lampung Indonesia. (Credit: DAWE)

 

At the end of March, I had the great privilege of travelling to Indonesia and Singapore to meet with my counterparts there very soon after they began responding to outbreaks of lumpy skin disease in their countries. I would like to take this opportunity firstly to thank my hosts who were exceedingly gracious and welcoming at what was a very busy time for them, and secondly to pass on to you some observations and lessons learnt. 

 

Image: Dr Schipp visits lumpy skin disease affected farm in Singapore. (Credit: DAWE)

 

Lumpy skin disease is not present in Australia. If there was to be an outbreak of the disease here, it would have devastating consequences for our cattle industry and export trade. Lumpy skin disease is an extremely challenging disease to detect and combat, and early recognition is key to an effective response. 

Maintaining awareness and gathering intelligence are important, and we need to be aware of the animal health status of countries in our region as they change. Both Indonesia and Singapore saw lumpy skin disease move into Malaysia last year and so were able to train and prepare animal health and biosecurity staff in advance. 

To be aware of changing animal health status we need countries to promptly report new disease information to the World Organisation for Animal Health (OIE). To do this, countries need to be able to undertake surveillance and diagnosis of disease. Luckily, both Indonesia and Singapore were actively seeking out likely incursions of lumpy skin disease and were quick to recognise it when it arrived. 

Private veterinarians and animal industry participants play a vital role in passing on concerns or suspicions to authorities so that these can be investigated. Please report any suspicious or unusual pests and diseases and other biosecurity concerns to the Emergency Animal Disease Watch hotline on 1800 675 888. 

In Australia we need everyone who interacts with cattle and buffalo to be aware of the signs of lumpy skin disease, who to tell if they suspect the disease and the urgency of doing so. There will be some false alarms but that is okay – it means that the message is getting through and being taken up. Disease exclusions also help us to demonstrate to our trading partners that we are looking and have no evidence that the disease is present in our national herd. 

 

Clinical signs of lumpy skin disease 

When we have a new disease in a novel environment there is uncertainty as to how the disease will express itself. Lumpy skin disease was for many years associated with Africa, and when it moved to Asia we wondered how native cattle in the region would be affected. The clinical course of lumpy skin disease in Indonesia and Singapore has been typical – animals show a range of clinical signs from a few mild lumps to being severely affected and unable to walk or feed. Animals already in poor or weak condition are more severely affected. After a two-week illness these severely affected animals will recover if they have been supported and are able to stand. 

 

Image: Lumpy skin disease in a cow overseas (Credit: Michael Patching)

 

The economic consequences of a disease are often due to the domestic and international trade impacts brought about by movement restrictions rather than disease outcomes per se. In Indonesia the disease struck in the lead up to Ramadan, a time of heightened cattle sales and movement. The movement restrictions imposed to keep the disease in one province soon had food affordability and security consequences as supply lines were cut or disrupted. Having pre-agreed approaches to permitted movement of animals to and from affected areas will greatly assist industry, remove uncertainty and reduce the potential for illicit activity. Australia’s AUSVETPLAN has such nationally agreed response plans, including movement of animals and animal products.

Part of the reason for restricting movement is to protect zones free of disease but this can be unrealistic at the local level. In terms of exports, countries usually trade on the basis of their national status, although free zones may be recognised in some circumstances and often only after protracted negotiation and assessment. Zoning recognition is very difficult if not impossible for lumpy skin disease as it is vector borne and a large number of vectors are able to carry and transmit the virus. 

In Australia’s case, movement restrictions would assist to contain the virus so that control and eradication could be achieved more quickly, with the objective to return our national animal health status to being lumpy skin disease-free as quickly as possible. 

 

Insect vectors do not respect borders 

The vector-borne nature of lumpy skin disease is its greatest challenge. Insects do not respect borders. The movement of insects is thought to be the means of entry of lumpy skin disease into both Indonesia and Singapore. Australia is famous for our biosecurity efforts at the border, but our typical approaches of X-rays, biosecurity detector dogs and inspection activities are no match for insects blown in or carried in the hold of returning livestock vessels or aircraft. 

These insect vectors are also the greatest challenge in combatting the disease when it arrives. The temptation is to vaccinate in the area immediately surrounding a known infected property, but this approach has been shown to fail on a number of occasions overseas. The insect vectors move faster than the vaccinators and new infections are found outside the vaccinated zone. 

A better approach is to vaccinate in an area well in advance of the vectors so that when they move from the infected herds, they are only encountering vaccinated (and hopefully immune) cattle. This requires vaccination to be used preventatively in free areas rather than just as an emergency response in infected areas. 

Vaccination is the only effective response to lumpy skin disease. Neither Indonesia, nor Singapore, nor indeed Australia had a vaccine registered and approved for use. The conundrum is that the only effective lumpy skin disease vaccines are live vaccines using attenuated forms of the virus. Vaccinated animals cannot be distinguished from infected animals, and indeed sometimes vaccine strains can become more virulent and be spread by biting insects. 

It also means that for a lumpy skin disease-free country to maintain its free status under international standards, preventative vaccination ahead of the disease being detected in the country must be prohibited. So, Australia cannot embark upon a preventive lumpy skin disease vaccination campaign without trading partners considering us to be already lumpy skin disease affected. However, potential vaccine candidates are currently being reviewed for emergency use so that we are well prepared. Ideally, at some point, an effective vaccine will be developed that uses newer technologies, similar to what has been seen in response to the COVID-19 pandemic. However, this may be some time away. 

Having the vaccine is in itself insufficient, you must also be able to deliver it to the cattle in a comprehensive and efficient manner. If lumpy skin disease were to enter northern Australia, we would have the challenge of large numbers of cattle on extensive holdings as well as large numbers of unmanaged cattle and water buffalo. In Indonesia, delivery of the vaccine has been hampered by a range of factors including lack of capacity in cold chains, inability to catch, corral and vaccinate cattle that are free ranging on roadsides or under palm oil plantations, and inability to rapidly release national emergency funds to provincial and district levels. 

 

Everyone has a role to play in preventing lumpy skin disease 

Through the Emergency Animal Disease Response Agreement (EADRA) Australia has pre-agreed mechanisms to cost share and release funds for emergency response. Livestock industries are part of that agreement and would play a large and important role in any response in ensuring cattle are rapidly vaccinated. Obviously, an enormous amount of coordination is required to deliver such a comprehensive response. Australian biosecurity officers and livestock industry participants regularly exercise responding to a range of emergency animal diseases and such exercises also include use of control centres and liaison with other agencies and bodies that would support such a response with logistics, accommodation, meals and the like. 

Lumpy skin disease is a very serious disease that we want to keep out of Australia. We can do this by monitoring disease spread in our region, assisting our near neighbours to keep the disease out or under control, maintaining strong biosecurity controls at the border, practicing our own emergency response arrangements and ensuring that we have effective diagnostics and plans for how a vaccine would be used if the disease were to arrive in Australia. All our efforts in preparation and response need to involve everyone in Australia’s great cattle industry. 

Please follow my social media channels on LinkedIn and Twitter for the latest updates.