Houseflies can spread bird flu virus: Study

[Snowy Owl]

Houseflies can spread bird flu virus: Study

http://www.asianage.com/presentation/leftnavigation/news/india/houseflies-can-spread-bird-flu-virus-study.aspx

Delhi, Mumbai, Kolkata, Bangalore, London
Wednesday, July 11, 2007

By ASIT JOLLY
Chandigarh, July 10:

Recent North American research has made the startling conclusion that several insects, particularly Musca domestica or the common housefly, are capable of carrying and transmitting the New Castle Disease Virus as well its more deadly, highly pathogenic strain, H5N1, which is transmittable from animals to humans.

British scientist, Terry Mabbett, reporting in a recent issue of Poultry International, says the new research findings must come as a big wake up call for the world?s poultry industry.


"That the avian influenza (AI) virus can be spread by winged insects as well as wild birds underlines the need for efficient fly control on poultry farms along with other strict biosecurity measures," he says.

According to him, studies recently carried out at the North Carolina State University, adult houseflies were seen to carry infectious doses of the Newcaslte Disease Virus in their guts for up to three hours after feeding.

This he says, "might be important for the spread of the virus when fly populations are high and in contact with highly virulent NDV strains."

The scientist has also cited earlier reported instances of houseflies carrying avian influenza virus. A 1985 study based on a serious 1983/84 outbreak of H5N2 in Lancaster County Pennsylvania (USA) where nearly 90 per cent of the affected poultry stocks died.

More than a third of the housefly samples collected from the vicinity of the outbreak contained bird flu virus particles.

Similarly, blow flies caught near a Kyoto poultry farm in Western Japan following an H5N1 outbreak in 2004 also carried doses of the virus.

Dr Mabbett says the presence of avian influenza virus in Musca domestica or other flies has opened up a whole new dimension on this virus disease.

Indian poultry experts told this newspaper that "at the very minimum, poultry farm owners need to put their house in order. Our poultry farms could be particularly susceptible to insect-borne transmissions of the virus because of the abysmal sanitation maintained."

A senior, Punjab-based veterinarian, who has requested anonymity because he does not wish to jeopardise his business relationship with local poultry owners, said, "These people must realise that if flies can be carriers, none of the temporary precautions deployed during suspected disease outbreaks would work. Poultry workers would invariably become the first and most susceptible targets of the infection."

He said, "The only way transmission of the bird flu virus through houseflies can be prevented would be to ensure complete sanitation on our poultry farms. Both the owners and the health authorities must wake up to this unshakeable fact. They must clean up!"

[gsgs]

Re: Houseflies can spread bird flu virus: Study

why to examine H5N1 and not normal flu, which is much easier ?

[Coleman]

Re: Houseflies can spread bird flu virus: Study

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 <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p>

Here is the referred study re. Kyoto

[Ganseerpel]

Re: Houseflies can spread bird flu virus: Study

Thanks Coleman, we had it already several times here.
Might be an interesting issue.

Does anybody know if american housflies (or subpopulations) bite? There are rumors they do so.

@ snowy: The link seems not to work.
I can't find the original paper. We should have it full text.

[Ganseerpel]

Re: Houseflies can spread bird flu virus: Study

Another good reason to control houseflies: they carry bird flu virus
Dr Terry Mabbett

Avian influenza has taken a great toll on the human population and on the poultry industry over much of the world. One aspect that has occupied scientists is the possible methods of transmission, of which there appear to be many. Wild birds have received much of the attention until now but studies shows that flies can be virus carriers too.



Poultry farms and houseflies need no introduction. Universal infestation by Musca spp. and close relatives is part and parcel of livestock production, especially in hot climates. Musca domestica (common housefly) is a dipterous insect of cosmopolitan distribution and versatile within its environment, feeding and breeding on all kinds of organic matter including food and animal feed, garbage, faeces, sewage and animal carcasses. Houseflies constantly move between dirty' areas of putrefaction teeming with pathogens and clean' areas including feed storage and animal housing. As such they are a major source of disease and implicated in the transmission of over 30 different diseases caused by bacterial, protozoan and viral parasites.
Adult flies carry disease

Houseflies breeding in media brimming with bacteria, including pathogens, might be expected to convey at least some from the larval (maggot) stage to the adult fly emerging from the pupa case. But early research showed the hostile chemical nature of the larval gut and antagonism by gut microflora maintained a generally low level of pathogens. More than one-fifth of houseflies and almost two-fifths of green bottle blowflies (Lucilia spp) were sterile on emergence.
The main risk of disease spread is from adult houseflies contaminated with bacteria, protozoa and virus particles. Houseflies could theoretically transmit pathogens on their feet but opportunities for attachment to such small surface areas are considered tiny and microbes are susceptible to desiccation.
Hazards are focused on housefly feeding, sucking up liquid from putrefying food and faeces supporting high concentrations of pathogens. Transmission via vomit drops presents risks, but adult housefly vomit originates from sugary fluids stored in the crop and presents a correspondingly lower risk than excretory deposits. Research which showed Salmonella typhimurium multiplying in the mid- and hind-gut and passing out intermittently over an interval of at least one week lent huge weight to these arguments.
Houseflies are well established vectors of food poisoning bacteria like Salmonella spp. and Escherichia coli harboured by birds. More recently, transmission of poultry virus diseases like Newcastle disease and avian influenza (AI) by houseflies is considered, in addition to spread by direct contact by contaminated faeces and bird secretions.
Houseflies carry virus disease particles

Recent research at North Carolina State University has shed new light on the role of Musca domestica in the potential transmission of Newcastle disease virus (NDV). Adult flies carried an infectious dose in the gut for three hours after feeding and researchers Drs Wes Dawson and James Guy considered this might be important for spread of the virus when fly populations are high and in contact with highly virulent velogenic NDV strains.
<TABLE cellSpacing=0 cellPadding=0 width=275 border=0><TBODY><TR><TD></TD></TR><TR><TD></TD></TR></TBODY></TABLE>
Newcastle disease virus is a dedicated disease of poultry but AI is now under the spotlight because the H5N1 highly pathogenic strain is a zoonosis transmitted to humans from animals. The march of H5N1 has been far and fast leaving precious little time to study infection and spread in detail. H5N1 virus spread by wild birds is a relatively recent focus since the Qinghai strain of H5N1 appeared in wild fowl in western China during May 2005 and subsequently sped all the way to Western Europe and West Africa in just six months.
There are several reported instances going back 20 years of houseflies carrying the AI virus and suspected as a mode of transmission. In 2005, they were highlighted and summarised by scientists from Novartis Animal Health as part of an article reinforcing the importance of good fly control on poultry farms.
Following reports in 1985 of house flies in poultry houses contaminated with AI, a detailed study was presented at a conference in Australia in the following year. The study was based on a serious 1983/4 outbreak of H5N2 in Lancaster County, Pennsylvania, USA. Up to 90&#37; of affected flocks died and various modes of transmission, including direct contact between birds, mechanical vectors and vector insects and especially houseflies, were considered.
Fifteen different insect species mainly flies and beetles were collected in 300+ species-specific samples, each containing 10-60 insects. More than one-third of the adult Musca domestica samples contained AI virus particles, as did one-third of samples comprising less abundant fly species like Ophyra (dump flies) and Coproica (dung flies).
During the 2004 H5N1 outbreak, Asian scientists identified the virus in blowflies caught near a poultry farm in Kyoto in western Japan, which had experienced a disease outbreak in the preceding months.
Parallels with West Nile virus

If the AI virus is present in Musca domestica or other flies, it does not necessarily mean transmission to poultry, let alone extra risk of human infection. However, the possibility of spread by flies does open a whole new dimension on this virus disease. A comparison can be drawn with West Nile virus (WNV), a flavivirus causing disease in wild birds, horses and humans and transmitted amongst these three groups by the blood-sucking activity of mosquitoes, mainly Culex spp.
WNV is a zoonosis and an arbovirus, a virus particle transmitted by an arthropod animal such as an insect, mite or tick. This efficient means of WNV transmission between humans, wild birds and horses by airborne blood-sucking insects has facilitated a breathtaking speed of spread. From a single case in the West Nile region of Uganda in 1937, the virus now threatens many parts of the world and spread right across North America from New York State to California in just three years (1999-2002).
That the AI virus can be spread by winged insects as well as wild birds underlines the need for efficient fly control on poultry farms, along with other strict biosecurity measures.



Dr Terry Mabbett, Potters Bar, UK

Updated: May 16, 2007

http://www.wattpoultry.com/PoultryInternational/Article.aspx?id=12172

[Ganseerpel]

Re: Houseflies can spread bird flu virus: Study

If it refers to Musca domestica, they don't bite :

http://creatures.ifas.ufl.edu/urban/flies/house_fly.htm

[AlaskaDenise]

Re: Houseflies can spread bird flu virus: Study

Poultry biosecurity info from 2005 was indicating flies as vectors.

However, they may have considered it mechanical (feet, etc.)

Flies that DO bite - horse flies and deer flies! They can create an open large bleeding sore on a horse's belly.

.

[Ganseerpel]

Re: Houseflies can spread bird flu virus: Study

It is clear that among different kinds of fomites, many insects can be mecanical carriers for a whole set of pathogens. The question is, if additional traits in certain species play a major role in spread.

[Ganseerpel]

Re: Houseflies can spread bird flu virus: Study

<TABLE cellSpacing=0 cellPadding=0 width="100%" summary="This table is for layout of the contents and right sidebar columns" border=0><TBODY><TR vAlign=top><TD width="100%">Research Project: NEWCASTLE DISEASE EPIDEMIOLOGY, PATHOGENESIS, AND CONTROL
Location: Exotic and Emerging Avian Viral Diseases Research Unit
Title: Detection and isolation of exotic Newcastle disease (ENDV) from field collected flies
Authors

<TABLE cellSpacing=0 cellPadding=3><TBODY><TR><TD vAlign=top></TD><TD vAlign=top align=left background=/incme/images/spacer.gif>Chakrabarti, Seemanti - UNIV CALIFORNIA, RIVERSID </TD></TR><TR><TD vAlign=top></TD><TD vAlign=top align=left background=/incme/images/spacer.gif>King, Daniel - jack </TD></TR><TR><TD vAlign=top></TD><TD vAlign=top align=left background=/incme/images/spacer.gif>Afonso, Claudio </TD></TR><TR><TD vAlign=top></TD><TD vAlign=top align=left background=/incme/images/spacer.gif>Swayne, David </TD></TR><TR><TD vAlign=top></TD><TD vAlign=top align=left background=/incme/images/spacer.gif>Cardona, Carol - UNIV CALIFORNIA, DAVIS </TD></TR><TR><TD vAlign=top></TD><TD vAlign=top align=left background=/incme/images/spacer.gif>Kuney, Douglas - UNIV CALIFORNIA, RIVERSID </TD></TR><TR><TD vAlign=top></TD><TD vAlign=top align=left background=/incme/images/spacer.gif>Gerry, Alec - UNIV CALIFORNIA, RIVERSID </TD></TR></TBODY></TABLE>

<TABLE cellSpacing=2 cellPadding=0 width="100%" border=0><TBODY><TR><TD vAlign=top>

<SCRIPT> <!-- function showinfo(){ window.open('_pubinfo.js', 'pubinfo', 'height=150,width=150') pubinfo.document.write('hi

'); } // --> </SCRIPT>Submitted to: Journal of Medical Entomology
<!--Publication type added 03-02-06 -->Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 3, 2007
Publication Date: N/A
<!--Removed abstract only flag 03-02-06 when pub_type_code was added to display --><!-- --><!-- To appease ARIS/NPS folks, the publisher's url that links to reprints hosted at ars.usda.gov were not displayed, as per PVL March 2006. We await the reprint field in ARIS --><!-- Reprint URL field added to ARIS June 1, 2006, file modified June 6, 2006 --><!-- June 6, 2006: To capture good data stored in the publisher's url field that links to a reprint uploaded in SP, the following clause is inserted to display that information as the 'reprint url' -->
Interpretive Summary: The primary mode of transmission of exotic Newcastle disease virus (ENDV) is from infected to healthy birds. Identifying other potential modes of transmission is important for the establishment of policies and procedures that will contribute to disease control. Samples of flies were collected at two premises that contained ENDV infected backyard chickens during the 2002-2003 END outbreak in California. Virus was isolated from three fly species, the first report of ENDV isolation from two of those species. Characterization of the recovered ENDV isolates confirmed their identity to isolates from commercial poultry and other birds that were being depopulated to control the outbreak. Although the amount of virus recovered per fly was very low and possibly below the dose required to infect a bird that might consume individual flies, the potential dispersal of infectious virus by flies moving from a premises with infected chickens to a nearby premises with uninfected poultry is a biosecurity concern. Fly control should be included as a component of depopulation of a premises containing infected birds during an eradication program. Technical Abstract: Flies were collected by sweep net from the vicinity of two small groups of "backyard" poultry (10-20 chickens per group) that had been identified as infected with exotic Newcastle disease virus (ENDV) in Los Angeles County during the 2002-2003 END outbreak in California. Collected flies were subdivided into pools, homogenized in brain-heart infusion broth with antibiotics, and the separated supernatant tested for the presence of ENDV by inoculation into embryonated chicken eggs. Exotic Newcastle disease virus was isolated from pools of Phaenicia cuprina, Fannia canicularis, and Musca domestica. The isolated viruses were identified by hemagglutination inhibition (HI) with Newcastle disease virus (NDV) antiserum. Isolated viruses demonstrated identical monoclonal antibody binding profiles as well as 99% sequence homology in the 374 bp fusion gene sequence when compared to ENDV recovered from infected commercial egg layer poultry during the 2002 outbreak.

</TD></TR></TBODY></TABLE></TD><TD> </TD><TD vAlign=top><TABLE cellSpacing=0 cellPadding=0 border=0><TBODY><TR><TD> </TD></TR><TR vAlign=bottom><TD><TABLE cellSpacing=0 cellPadding=0 width=179 align=center bgColor=#e7eee6 summary="This table is for layout of the right navigation" border=0><!-- BEGIN RIGHT NAV TABLE --><TBODY><TR><TD class=grayBackgroundColor colSpan=3 height=1 alt=""></TD><TR class=rightNavBackground><TD class=grayBackgroundColor width=1></TD><TD><TABLE cellSpacing=0 cellPadding=0 width=179 summary="This table is for layout of the right navigation links" border=0><TBODY><TR><TD class=rightNav_label align=middle colSpan=2>Project Team</TD></TR><TR><TD colSpan=2 height=5></TD></TR><TR><TD vAlign=center align=middle width=17></TD><TD style="PADDING-BOTTOM: 6px" vAlign=top align=left>King, Daniel - Jack</B> </TD></TR><TR><TD vAlign=center align=middle width=17></TD><TD style="PADDING-BOTTOM: 6px" vAlign=top align=left>Suarez, David </TD></TR><TR><TD vAlign=center align=middle width=17></TD><TD style="PADDING-BOTTOM: 6px" vAlign=top align=left>Yu, Qingzhong </TD></TR><TR><TD vAlign=center align=middle width=17></TD><TD style="PADDING-BOTTOM: 6px" vAlign=top align=left>Afonso, Claudio </TD></TR><TR><TD vAlign=center align=middle width=17></TD><TD style="PADDING-BOTTOM: 6px" vAlign=top align=left>Kapczynski, Darrell </TD></TR><TR><TD colSpan=2 height=3></TD></TR></TBODY></TABLE></TD><TD class=grayBackgroundColor width=1></TD></TR><TR><TD class=grayBackgroundColor colSpan=3 height=1></TD></TR></TBODY></TABLE></TD></TR><TR><TD> </TD></TR>
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http://www.ars.usda.gov/research/publications/publications.htm?seq_no_115=209076

[Ganseerpel]

Re: Houseflies can spread bird flu virus: Study

Here is another one:

stable fly [Stomoxys calcitrans]

http://www.icb.usp.br/~marcelcp/stomoxys.htm (English)
http://de.wikipedia.org/wiki/Stechfliegen (German)

[cartski]

Re: Houseflies can spread bird flu virus: Study

"Although the amount of virus recovered per fly was very low and possibly below the dose required to infect a bird that might consume individual flies,.."

How does dose-response work here? Would not a micro amount of viral material incubate over time to cause a clinically noticeable infection? And if the normal infection defences of the host are impaired or already overloaded, would not a micro amount of viral material be able to gain a foothold? If these ideas are reasonable, the vector cannot be dismissed as being a trivial source.

J.

[Ganseerpel]

Re: Houseflies can spread bird flu virus: Study

I don't know the details of the study.

If the viral dose is beneath a treshold, infection does not occure. Doses beyond this treshold will give an infection rate x < 100% (median infection dose: MID x) untill it reaches 100 %. In many infection experiments in animals doses are about 10<SUP>4 to</SUP><SUP>7</SUP> x EIC 50 or TCID 50.