Blowflies are potential vector for avian influenza virus at enzootic area in Japan
Researchers from Kyushu University have discovered that blowflies, a family of flies strongly attracted to decaying flesh and feces, are carrying the bird flu virus in southern Japan. Their findings, published in Scientific Reports, introduce a potential new route of transmission for bird flu and highlight the need to develop new countermeasures to prevent and control the disease in poultry farms.
In this research, the scientists studied a wild crane colony in Izumi city, Kagoshima Prefecture, in southern Japan. In winter, the prime season for avian influenza, thousands of cranes migrate to this area, with their dense numbers making them vulnerable to infection. During winter 2022-2023, 1,600 cranes out of colony of 10,000 cranes died from bird flu. The researchers collected 648 blowflies and discovered that 14 blowflies were carrying the bird flu virus. The majority of virus-positive blowflies were collected from the sample site closest to the crane colony. The research team also used 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 is it feasible for them to reach nearby 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 water sources, with healthy birds becoming infected through direct contact with these contaminated sources, or by ingesting adult or larval blowflies.
