# 1692
There have been rumors, of course. Vague references in news reports of concerns over flies and mosquitoes as possible carriers of the H5N1 virus. Even some scientific speculation.
But until recently, little actual research on the subject, and most of that has been on flies.
In 2006, in the paper entitled DETECTION AND ISOLATION OF HIGHLY PATHOGENIC H5N1 AVIAN INFLUENZA A VIRUSES FROM BLOW FLIES COLLECTED IN THE VICINITY OF AN INFECTED POULTRY FARM IN KYOTO, JAPAN, 2004 , researchers isolated detectable levels of the bird flu virus in the gut of two blowfly species.
The possibility that flies might serve as a mechanical vector of the virus was raised.
Last summer I reported on this story from North Carolina State University.
Houseflies can transmit the bird flu
// 13 Jul 2007
The common housefly feeds and breeds on all kinds of organic matter, including food, animal feed, garbage, faeces and animal carcasses. Could these creatures transmit bird flu?
On farms, houseflies constantly move between dirty areas with pathogens and clean areas, such as feed storage and animal housing. Due to this nature of movement, houseflies have been implicated in the transmission of different types of diseases caused by bacteria, protozoan and viral parasites.
Bird flu is no exception
Research conducted at North Carolina State University in the US shows that these houseflies can indeed transmit the AI virus . According to the researchers, “more than one-third of the adult Musca domestica sampled contained AI virus particles”.
Led by Wes Dawson and James Guy, the researchers said adult flies carried an infectious dose in their gut for more than three hours after feeding. “This might be important for spread of the virus when fly populations are high and in contact with highly virulent strains,” they explained.
Now comes word from researchers that blood samples, isolated from mosquitoes collected in Thailand near outbreaks of H5N1 in poultry, have tested positive for the virus.
A Hat tip to ProMed Mail, which alerted me to this article late last night.
The reader should note, however, that this study did not evaluate whether these mosquitoes could pass the virus on to another host.
There are previously raised questions about viral load (number of virus particles required to convey infection) and enzymes in the mosquito's digestive system that may inactivate the virus sufficiently to disable transmission. More research is needed.
Vector-Borne and Zoonotic Diseases
Philippe Barbazan, Arunee Thitithanyanont, Dorothee Misse, Audrey Dubot, Priscille Bosc, Natsuang Luangsri, Jean-Paul Gonzalez, Pattamaporn Kittayapong. Vector-Borne and Zoonotic Diseases. February 1, 2008, 8(1): 105-110. doi:10.1089/vbz.2007.0142.
Abstract: (reparagraphed for readability)
Blood-engorged mosquitoes were collected at poultry farms during an outbreak of highly pathogenic avian influenza in Central Thailand during October 2005. These mosquitoes tested positive for H5N1 virus by reverse transcription-polymerase chain reaction (RT-PCR). Results were confirmed by limited sequencing of the H5 and N1 segments.
Infection and replication of this virus in the C6/36 mosquito cell line was confirmed by quantitative real-time PCR.
However, transmission by mosquitoes was not evaluated, and further research is needed. Collecting and testing mosquitoes engorged with the blood of domestic or wild animals could be a valuable tool for veterinary and public health authorities who conduct surveillance for H5N1 virus spread.
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