核衍生技术帮助亚洲农民应对牛病暴发

Named after the characteristic lesions that form on the skin of cattle infected by the virus, how lumpy skin disease is spread is only partially understood. Previous outbreaks in Africa and the Middle East have identified different species of flies as vectors, but the movement of infected animals and contaminated animal products, such as semen or milk, are also transmission suspects.

“We need to carefully re-look at what the vectors are for this disease. We have some understanding of how it has spread in Africa. We have a weak idea of what the vectors are in Europe, but we are at a total loss at what vectors are causing its spread in Asia,” said Giovanni Cattoli, Head of the  Animal Production and Health Laboratory of the Joint FAO/IAEA Centre of Nuclear Techniques in Food and Agriculture. The laboratory team is in direct contact with laboratories, researchers and veterinary authorities in Bangladesh, Bhutan, Cambodia, Indonesia, Nepal, Mongolia, Myanmar, Sri Lanka, Thailand and Viet Nam, trying to help them understand the origins and spread of the virus using the nuclear-derived polymerase chain reaction technique — the same method that is used worldwide to identify and analyse COVID-19.

Based on the list of countries most affected, the virus may have travelled from North Africa into the Middle East and Europe, including Russia. It then unexpectedly emerged in China and Southern Asia. Overall, the virus has spread across numerous climates and it is unclear how such a spread could happen over such a short period.

“The virus is spreading very fast — much faster than could be expected. It emerged in China for the first time in 2019 and after just a year, we already have more than one strain of the virus in Asia,” explained Cattoli.

Global travel restrictions imposed under the pandemic, however, have affected the IAEA’s ability to support the response to the outbreak. When lumpy skin disease first appeared in Bulgaria in 2016, experts were able to travel there to conduct outbreak investigations. This time, Cattoli and his team collaborate online with counterparts in affected Asian countries to give emergency support in the form of equipment, reagents and consumables, and to investigate the outbreaks and analyse the samples submitted to the FAO/IAEA laboratory in Austria. Through the Veterinary Diagnostic Laboratory (VETLAB) network, laboratories in Asia can share data and results in near real-time, and the FAO/IAEA laboratory team can provide comments and suggestions immediately on how countries can improve their procedures.

A quick response to the virus is critical to getting its spread under control, methods of which include culling, vaccination and movement restriction. When the virus broke out in Europe, culling was initially used but this was not popular with farmers. Vaccination and restrictions ultimately managed to eliminate it in the region, but it needs to be confirmed how effective existing vaccines would be against the emerging Asian strains.

“Making sure you have the best vaccine is very important for saving money and being effective — a wrong vaccine could exacerbate the problem,” said Cattoli, explaining that an ineffective or less than optimal vaccine could lead to new strains evolving and furthering the duration and spread of the disease. The IAEA is working with the FAO’s regional office in Thailand to support Asian countries with quality assurance and ensure the vaccine is effective against their virus strains.

Inaction could lead to dire economic consequences. Lumpy skin disease is a listed disease with the World Organisation for Animal Health (OIE), so if there is an outbreak in one country, then export of cattle could stop. Furthermore, it is a disease that compromises rural societies and villages the most. “They have few animals and can be especially dependent economically and for nutrition, on animal products like milk. In these already difficult times, this additional virus is a heavy burden to bear,” said Cattoli.