A Japanese study found that blowflies may be able to acquire the HPAI virus from deceased wild birds directly or from faecal materials from infected birds, according to a scientific paper from Kyushu University. 

The study focused on blowflies, in particular Calliphora nigribarbis, which are attracted to decaying animals and faeces, and migrate to lowland areas of Japan from northern or mountainous regions in early winter, coinciding with HPAI season.

"Our investigation aims to delineate the role of blowflies as HPAI vectors by conducting a virus prevalence survey in a wild bird HPAI-enzootic area," the paper's summary said. 

In December 2022, researchers collected 648 Calliphora nigribarbis. Influenza virus RT-PCR testing identified 14 virus-positive samples, with the highest occurrence observed near the crane colony (14.9%). 

Subtyping revealed the presence of H5N1 and HxN1 in some samples. 

Subsequent collections in December 2023 identified one HPAI virus-positive specimen from 608 collected flies in total, underscoring the potential involvement of blowflies in HPAI transmission. 

"Our observations suggest C. nigribarbis may acquire the HPAI virus from deceased wild birds directly or from faecal materials from infected birds, highlighting the need to add blowflies as a target of HPAI vector control," the paper concluded.