Researchers in China have identified 22 strains of African Swine Fever (ASF) during an epidemiological survey carried out from June to December 2020.

The National African Swine Fever Specialty Laboratory identified the country’s first ASF case in 2018 and was responsible for the latest study.

The lab which is based within the Harbin Veterinary Research Institute identified new strains (genotype II) with low fatality rates in some provinces and regions.

The results of the study were published in the ‘emergence and prevalence of naturally occurring lower virulent African swine fever viruses in domestic pigs in China in 2020’ paper on 26 February.

New worry

The study found that there are at least four natural variants of the low-fatality strain in the field in China.

Although the pathogenicity is significantly lower than that of typical virulent strains, it still presents a threat and has a strong transmission ability.

Researchers are worried about the concealment aspect of the new strains. In other words, infected pigs may appear healthy, while continuing to spread the virus throughout the population.

World picture

At present, at least 24 variants of ASF have been identified worldwide.

Among them, genotype II is mainly prevalent in Asia. Currently, there is no commercial vaccine or effective treatment.

Early diagnosis and culling of infected pigs are the main strategies for prevention and control.