The contribution of insects to African swine fever virus dispersal: data from domestic pig farms in Lithuania

Abstract

Outbreaks of African Swine Fever (ASF) in domestic pig farms in Lithuania typically begin in June and are detected through October, suggesting that insects might be involved in the transmission of the virus. Entomological collecting was performed to obtain two data sets: from farms with ASF outbreaks, and from farms without ASF outbreaks but in an ASF‐infected area. Target insects from the families Muscidae, Calliphoridae and Tabanidae were analysed for the presence of ASF Virus (ASFV) DNA. Musca domestica L., Calliphoridae flies and Stomoxys calcitrans (L.) collected by entomological net during ASF outbreaks were confirmed to be ASFV positive. Viral DNA detected in insects collected by Nzi traps from farms with no ASFV outbreaks indicate that Culex, Lucilia, M. domestica and S. calcitrans are likely to play a role in spreading the ASFV mechanically. This finding could suggest contamination from outside of the farms: from infected wild boar or their carcasses. The role of Stomoxys flies as mechanical vectors could be accidental, because we did not find a significant correlation between the activity of S. calcitrans and the number of ASF outbreaks in pig farms, whereas temperatures positively correlated to the number of ASF outbreaks during 2018–2019.

African Swine Fever in Wild Boar in Europe—A Review

“…This is also in agreement with a study from Estonia, where various groups of blood-feeding arthropods were collected in ASFV-affected wild boar habitats but tested negative for the presence of the ASFV genome [ 144 ]. However, mechanical transmission on a laboratory scale was reported with the stable fly (Stomoxys calcitrans ) [ 145 ] and two studies from Eastern Europe have reported the detection of a low amount of ASFV genome on insects collected on domestic pig outbreak sites [ 146 , 147 ].…”

Biosecurity Levels and Farm Characteristics of African Swine Fever Outbreak and Unaffected Farms in Estonia—What Can Be Learned from Them?

“…The second reason may be that with applied biosecurity measures not all transmission routes are controlled. Due to the strong seasonal pattern in the occurrence of ASF outbreaks in domestic pigs (the summer season) the role of blood-sucking insects in virus transmission has been discussed [ 30 , 31 , 32 ]. In Estonia, pig stables are not insect-proof and this has not been considered as necessary to date.…”

A Systematic Review on Viruses in Mass-Reared Edible Insect Species

“…M. domestica has also been reported to mechanically transmit several types of viral pathogens to livestock including: avian influenza virus (AIV), both high and low pathogenic strains [46,[212][213][214][215][216], turkey coronavirus (TCV) [217], Newcastle disease virus (NDV) [218][219][220][221][222], reticuloendotheliosis virus (REV) [223], porcine reproductive and respiratory syndrome virus (PRRSV) [224][225][226][227][228], porcine circovirus genotype 2 (PCV2b) [229], porcine epidemic diarrhea virus (PEDV) [230], African swine fever virus (ASF) [231,232], Aujeszky's virus (PRV-1) [233], senecavirus A (SVA) [234], Rift Valley fever virus (RVFV) [235], Aleutian mink disease virus (AMDV) [236,237], and lumpy skin disease (LSDV) [238,239].Viruses detected in dipteran edible species are listed in Table 4. The lesser wax moth, Achroia grisella, is a species closely related to Galleria mellonella [241].…”