Blowflies carrying bird flu have been found in southern Japan, raising concerns about a potential new transmission route by which the virus can spread.
In a new study published in the journal Scientific Reports, researchers from Kyushu University collected 648 blowflies, which are known for their attraction to decaying flesh and feces, from a wild crane colony in Izumi City. They discovered that 14 of these blowflies were carrying the virus.
"While 14 blowflies may seem like a low number, this represents a prevalence in blowflies of 2.2 percent, which is a huge percentage compared to other diseases spread by insects," Ryosuke Fujita, the study's first author and an associate professor at Kyushu University's Faculty of Agriculture, said in a statement.
In winter, the peak season for bird flu, thousands of cranes migrate to the Izumi City area, where their dense populations make them particularly vulnerable to infection. During the winter of 2022–2023, 1,600 cranes out of a colony of 10,000 died from bird flu.
Scientists deployed traps at various locations around Izumi City to capture blowflies, and genetic testing confirmed that they carried the same virus strain infecting the crane colony.
"We were notified about the cranes being infected and we had to act quickly," Fujita said.
"We were particularly interested in one species of blowfly, Calliphora nigribarbis, as, unlike other fly species, they are active in winter, coinciding with the peak season of bird flu. This, along with their attraction to the flesh and feces of animals, makes them a prime suspect for spreading the virus."
The researchers believe that as blowflies move from place to place, they could contaminate surfaces, food sources and water sources. Healthy birds may then become infected through direct contact with these contaminated sources or by ingesting adult or larval blowflies.
Since 2020, bird flu has spread rapidly across the globe, resulting in the deaths of millions of wild birds and the culling of over half a billion farmed birds worldwide.
This news follows troubling reports indicating that bird flu has made a significant leap from birds to dairy cattle across several U.S. states, marking the beginning of mammal-to-mammal transmission.
The virus has not only spread among cows but has also been detected in other animals, including cats and even a raccoon.
To date, there have been 11 reported human cases of bird flu in the U.S., the first in April 2022. All cases have been mild, with four associated with cattle farms and seven with poultry farms, including a recent cluster of four cases in Colorado.
"Bird flu has been causing substantial damage to wildlife and the poultry industry, and also holds great risk for humans who work closely with livestock. It's therefore vital to understand how the virus spreads and its potential routes of transmission to control and prevent outbreaks," Fujita said in the statement.
Unlike birds and mammals, which the virus infects and replicates inside, blowflies ingest the virus from infected dead birds or their waste. The virus maintains infectivity for up to two days.
Blowflies are capable of flying at least 2 kilometers per day, so the researchers estimate that it is feasible for them to reach nearby poultry farms or other wild bird populations within a 4-kilometer range.
The authors note that implementing measures to eliminate blowflies could be relatively straightforward in Japan, where farmers typically use closed farming systems to control infections and boost production. This approach would help shield farmers from significant financial losses.
"By keeping areas clean and using fly control methods, such as fine nets or insecticides, we can reduce the risk of virus spread to indoor poultry farms. However, in outdoor farms in other countries, and in wild bird populations, controlling blowflies may be logistically impossible," Fujita said.
Having determined that blowflies carry the virus, Fujita and his team are working with the Japanese government to capture blowflies from quarantined areas around infected poultry farms. Their goal is to find conclusive evidence linking blowflies to these outbreaks.
Additionally, they are developing AI-based tools to assess and predict the risks posed by vector insects. "By combining advanced technologies with field research, we aim to enhance our understanding and control of bird flu and other insect-borne diseases, thereby protecting both animal and human health," Fujita said.
Is there a health problem that's worrying you? Do you have a question about bird flu? Let us know via health@newsweek.com. We can ask experts for advice, and your story could be featured in Newsweek.
Disclaimer: The copyright of this article belongs to the original author. Reposting this article is solely for the purpose of information dissemination and does not constitute any investment advice. If there is any infringement, please contact us immediately. We will make corrections or deletions as necessary. Thank you.
