Border controls in China need strengthening over African horse sickness risk – study

Herders in the Altai Mountains in China. Thailand's 2020 outbreak of African horse sickness was worryingly close to China's southern borders, the researchers noted.
Herders in the Altai Mountains in China. Image by mingchen J

Horse controls at China’s borders should be strengthened immediately because of the risk posed to its equine industry by African horse sickness, according to researchers.

The introduction of the devastating infectious disease has the potential to deliver a fatal blow to China’s large horse industry, they say.

Shan Gao, Zan Zeng and their fellow researchers set out to predict the possibility of African horse sickness being introduced to China.

They used spatial risk analysis in their modeling of both climate and non-climate variables, and examined the habitat connectivity of the Culicoides biting midges that spread the virus.

The disease, they noted, kills up to 90% of infected horses, half of infected mules, and around 10% of infected donkeys.

In February 2020, Thailand reported a case of the disease – the first in Southeast Asia – which led to a major outbreak. Although China has no direct border with Thailand, the distance between China’s western border and Thailand’s border is only 110km, and the nearest cases were only 600km away.

The density of the horse population in the southern part of China is the highest in the country, they noted – far greater than that in Thailand and neighboring countries.

Their modeling showed that there is a high-risk area in the southern part of China for the disease. Furthermore, the habitats of Culicoides up through South East Asia are connected. “Therefore, the risk of introducing African horse sickness into China is high and control of the border area should be strengthened immediately,” they said.

Discussing their findings, the researchers, from a range of Chinese institutions, described African horse sickness as a truly devastating disease in terms of animal welfare and the economic damage that it causes.

Although China is currently free of the disease, the cases near its border show the risk presented by the disease.

China, they said, is a big horse breeding country. In 2019, the country had an estimated 3.671 million horses, accounting for 6% of the world’s total, ranking fifth among nations. The country horse industry’s annual output is estimated at about 70 billion yuan ($US1.1b).

“In southern China, there are a large number of horses and a large number and variety of African horse sickness vectors.

“Once the African horse sickness virus vectors enter China, it will cause a fatal blow to China’s horse industry.”

The disease would also pose a serious risk for wild equines, which include endangered Przewalski’s horses.

“Therefore, the prevention and control of the introduction of African horse sickness are of great significance not only to the protection of the equine breeding industry in China, but also to the prevention of the spread of wild endangered species.”

China should bolster its early warning systems, strengthen its monitoring of insect vectors in border areas, and improve its supervision of border horse trade, they said.

If an outbreak occurs, timely preventive measures should be taken to prevent a huge impact on the national horse industry.

The study team comprised Gao, Zeng, HaoNing Wang, FangYuan Chen, LiYa Huang and XiaoLong Wang.

Gao, S., Zeng, Z., Wang, H. et al. Predicting the possibility of African horse sickness (AHS) introduction into China using spatial risk analysis and habitat connectivity of Culicoides. Sci Rep 12, 3910 (2022).

The study, published under a Creative Commons License, can be read here

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