Blowflies are considered a potential vector of avian influenza virus in areas endemic for avian influenza in Japan

 

Professor Dr. Salah Mahdi Hassan

Consultant and expert in poultry health and production

28/8/2024

 

Blowflies, like other true flies, have only one pair of wings, short antennae, and large compound eyes. To distinguish them from other fly species, blowflies are often shiny, metallic, blue, green, or black, and have hair-like bristles. Blowflies do not bite humans, however, they can pose a serious health threat to humans and animals, by positioning themselves on feces, dead animals, garbage, and other decaying and contaminated organic matter, often carrying dangerous bacteria and parasites with them.

 

Researchers from Kyushu University in Japan have discovered that blowflies carry the avian influenza virus in southern Japan. Their findings, published in the journal Scientific Reports on 4/5/2024, indicate a potential new route of transmission for avian influenza, highlighting the need to develop new measures to prevent and control the disease in poultry farms.

In this research, scientists studied a colony of wild cranes in Izumi city, Kagoshima Prefecture, southern Japan. During winter, the peak season for bird flu, thousands of cranes migrate to this area, and their dense populations make them vulnerable to infection.

During the winter of 2022-2023, this area witnessed avian influenza infections in cranes, which led to the death of 1,600 birds out of 10,000 birds. The researchers collected 648 swollen flies for the purpose of viral isolation, and the presence of the avian influenza virus was found in only 14 flies, with the confirmation that most of the swollen flies that were positive for the virus had been collected from areas very close to the location of the infected cranes. The study also used genetic tests to confirm that the swollen flies were carrying the avian influenza virus with a genetic strain identical to the strain of the virus that infected the cranes.

It is known that when the avian influenza virus infects birds and mammals, it leads to infection and multiplication of the causative virus in the affected tissues. As for the case of the bloated fly, when it swallows the bird flu virus from birds that died as a result of infection with the avian influenza virus or their droppings, the virus remains capable of infectivity for two days without multiplying (biological vector).

Scientific sources indicate that the puffer fly has the ability to fly a minimum distance of 2 kilometers per day. Therefore, the researchers’ calculations for the current study they conducted indicated that it is easy for the puffer fly carrying the avian influenza virus to reach areas where chicken farms or wild birds are located, within a range of four kilometers.

 

Researchers believe that as flies move from one place to another, they contaminate surfaces, food sources, and water sources, and thus healthy birds become infected through direct contact with these contaminated sources, or by eating the adult fly or larvae.