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AVIAN INFLUENZA (36): THAILAND, MOSQUITOES
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A ProMED-mail post
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International Society for Infectious Diseases
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Date: Fri 1 Feb 2008
Source: Vector Borne Zoonotic Dis. 2008 Feb;8(1):105-110 [edited]
<http://www.liebertonline.com/doi/abs/10.1089/vbz.2007.0142>
Avian influenza H5N1 virus in mosquitoes collected from Thai poultry farm
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The abstract reproduced below is from a paper published in the
current issue of Vector-borne and Zoonotic Diseases. The paper is
titled: "Detection of H5N1 Avian Influenza Virus from Mosquitoes
Collected in an Infected Poultry Farm in Thailand. The authors are
Barbazan P, Thitithanyanont A, Misse D, Dubot A, Bosc P, Luangsri N,
Gonzalez JP, Kittayapong P.; at the Center of Excellence for Vectors
and Vector-Borne Diseases, Faculty of Science, Mahidol University at
Salaya, Nakhonpathom, Thailand, and Institut de Recherche pour le
Developpement, IRD-UR 178, Paris, France.
"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."
--
Communicated by:
Shamsudeen Fagbo
<oloungbo@yahoo.com>
[The relevance of this paper is difficult to evaluate as arthropod
vectors have not previously been implicated in the epidemiology and
transmission of seasonal or avian influenza viruses. This research
demonstrates that avian H5N1 influenza virus can be taken up by
blood-feeding mosquitoes in a form retaining infectivity long enough
to infect susceptible C6/36 mosquito cell cultures. The experiments
leave open the question whether the virus surviving in the insect
vector will be competent in vertebrate cells and in a form that may
be infectious on transmission to live susceptible poultry and/or mammals.
There is no clear precedent for involvement of mosquitoes in the
transmission of influenza, but recently Sawabe et al. (Am J Trop Med
Hyg. 2006 Aug;75(2):327-32);
<http://www.ajtmh.org/cgi/content/abstract/75/2/327>), demonstrated
that 2 species of blow flies (_Calliphora nigribarbis_ and _
Aldrichina grahami_) collected within a radius of 2.5 km (1.55 miles)
from an infected poultry farm in Japan had H5N1 virus in gut,
intestinal organs and crop that was infectious for embryonated
chicken eggs. They concluded that blow flies might play a role as
mechanical transmitter of H5N1 virus.
These experiments, while far from conclusive, deserve to be pursued. - Mod.CP]
....................arn/cp/ejp/mpp
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