The researchers collected 648 blowflies and discovered that 14 blowflies were carrying the  https://phys.org/tags/bird+flu+virus/ - bird flu virus . The majority of virus-positive blowflies were collected from the sample site closest to the crane colony.

"While 14 blowflies may seem like a low number, this represents a prevalence in blowflies of 2.2%, which is a huge percentage compared to other diseases spread by insects," explains Fujita. The research team also used  https://phys.org/tags/genetic+testing/ - genetic testing  to confirm that the blowflies were carrying the same virus strain that has been infecting the crane colony.

Unlike birds and mammals which the virus infects and replicates inside, blowflies instead ingest the virus from infected dead birds or their waste, with the virus maintaining infectivity for up to two days. Blowflies are capable of flying at least 2 kms per day, so the researchers estimate that it is feasible for them to reach nearby  https://phys.org/tags/poultry+farms/ - poultry farms  or other wild bird populations within a 4 km range.

The researchers believe that as the blowfly moves from place to place, it could contaminate surfaces, food sources and  https://phys.org/tags/water+sources/ - water sources , with healthy birds becoming infected through direct contact with these contaminated sources, or by ingesting adult or larval blowflies.