Detection of African swine fever virus in free‐ranging wild boar in Southeast Asia

Abstract

African Swine Fever (ASF) is a highly contagious and fatal viral disease affecting both domestic and wild suids. The virus was introduced to Southeast Asia in early 2019 and has since spread rapidly throughout the region. Although significant efforts have been made to track and diagnose the disease in domestic pigs, very little is known about ASF in free‐ranging wild boar and their potential role in maintaining the disease within Southeast Asia. Through a collaboration between government and non‐government actors in Laos, Viet Nam, and Cambodia, investigations were conducted to (a) characterize the interface between domestic pigs and wild boar, (b) document risk factors for likely ASF spillover into wild boar populations by way of this interface, and (c) determine whether ASF in wild boar could be detected in each country. An extensive overlap between wild boar habitat and domestic pig ranging areas was found around villages bordering forests in all three countries, creating a high‐risk interface for viral spillover between domestic pig and wild boar populations. Fifteen and three wild boar carcasses were detected through passive reporting in Laos and Viet Nam, respectively, in 2019 and early 2020. Four of five carcasses screened in Laos and two of three in Viet Nam were confirmed positive for African swine fever virus using real‐time PCR. There were no confirmed reports of wild boar carcasses in Cambodia. This is the first confirmation of ASF in wild boar in Southeast Asia, the result of a probable viral spillover from domestic pigs, which highlights the importance of early reporting and monitoring of ASF in wild boar to enable the implementation of appropriate biosecurity measures.

The impact of African swine fever virus on smallholder village pig production: An outbreak investigation in Lao PDR

“…Wild boar and feral pigs are a possible source of the ASFV outbreak described, as in European outbreaks, however current literature suggests this to be unlikely in Lao PDR (Denstedt et al., 2020 ). Spread of this nature would require prior evidence of ASFV circulating in wild boar populations over enough time for the disease to spread over large distances (Boklund et al., 2020 ; Schulz et al., 2019 ).…”

African Swine Fever, the forgotten pandemic

“…The most important transmission routes for ASFV introduction from the wild reservoir to pig holdings in Belgium, and between holdings, have been identified based on questionnaire surveys (Mauroy et al, 2021). As reported in this Special Issue, ASFV infection in wild boar in Southeast Asia has been confirmed for the first time, the result of a probable viral spillover from domestic pigs (Denstedt et al, 2021). In another article, O'Neill et al (2021) investigate whether ASFV can potentially regulate wild boar density.…”

The Role of the Wild Boar Spreading African Swine Fever Virus in Asia: Another Underestimated Problem

“…A recently published study has found several ASFV-positive wild boar carcasses in Laos and Vietnam ( 26 ). These results suggest that these two countries are likely to have a large ASFV-infected wild boar population, which coincides with our results as they are also medium-risk countries (see Table 1 ).…”