Midges, mosquitoes and flies and their role in ASFv spread

Source: Vincent ter Beek, Pig Progress, 14 April 2021, photo credit: The Conversation/Shutterstock

That stable flies could theoretically transmit African Swine Fever virus under experimental conditions was already known, yet conclusions like those trigger curiosity. Could it be confirmed on larger farms too? And how about mosquitoes?

Stable flies and midges formed the key components of a Romanian study that was published in the EFSA Journal, a publication of the European Feed Safety Authority. The study briefly referred to earlier reports where the stable fly (Stomoxys calcitrans) was detected in various body parts for 3 days after infection.

ASF virus in blood-feeding arthropods

The Romanian study was carried out by scientists from the University of Agricultural Sciences and Veterinary Medicine of Cluj-Napoca, the Romanian National Sanitary Veterinary and Food Safety Authority and the Romanian Institute for Diagnosis and Animal Health.

The team noted that no field evidence had yet been found demonstrating the presence of viral DNA in blood‐feeding arthropods, which is why they visited 30 Romanian farms positive for ASF and took samples. On 9 farms, they wrote, pigs were still present at the time of sampling, whereas on the other outbreak farms pigs were culled maximum 24 hours prior to sampling. The team mostly caught Culicoides species (midges) and the abovementioned S. calcitrans (stable flies).
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