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Avian flu: NIV survey gives clean chit to migratory birds

While the country had reported outbreaks of the highly pathogenic avian influenza (bird flu) from 2006-08 and experts had questioned the role of migratory birds in the transmission of the virus...

Written by Anuradha Mascarenhas | Pune | Published: September 29, 2009 1:31:43 am

While the country had reported outbreaks of the highly pathogenic avian influenza (bird flu) from 2006-08 and experts had questioned the role of migratory birds in the transmission of the virus,a latest study by the National Institute of Virology (NIV) and city-based Ela Foundation has given a clean chit to these birds,as none of them had tested positive for H5N1.

India had reported outbreaks of the avian influenza H5N1 in poultry in the states of Maharashtra,Gujarat and Madhya Pradesh (February-April 2006); Manipur (July 2007); West Bengal (January 2008) and Tripura (April 2008). Since the role of migratory birds in the transmission of avian influenza was not clear,an Avian Influenza (AI) surveillance in wild migratory,wild resident,domestic birds and poultry was undertaken by the NIV and Ela Foundation in 2006¿07.

The study did not report any H5N1 or any other AI viruses from sampled birds during the study period. Although AI virus has been reported earlier in the species/families of birds elsewhere,the screened population in the present study was free from any AI infection. No convincing evidence has yet shown that infected,asymptomatic wild birds can or do carry influenza virus along established,seasonal long-distance migration routes,said Dr Satish Pande,trustee of Ela foundation who,along with NIV and other ornithologists,has published the findings in the August issue of the journal Science.

Considering the lower rate of virus isolation,it is justified to screen larger sample sizes for AI surveillance,over a longer period of time and to cover more species. About 1,298 avian species have been recorded from the Indian subcontinent of which about 1,001 species are resident and 159 (12 per cent) species are winter migrants. We tested 36 wild bird species,which represent 31 per cent and 41.2 per cent of the species and families respectively,found AI positive globally,said Pande.

A total of 1,968 faecal specimens (1,369 droppings from wild migratory and wild resident birds; 474 droppings from poultry and 125 cloacal swabs from chickens and ducks) were collected from eight districts of Maharashtra and two districts of Manipur (July 2007) during the avian migratory season between December 2006 and April 2007 . Samples representing 10 avian families of wild migratory birds,four families of wild resident birds totalling 36 species,were screened for AIV from among 20 water bodies in Maharashtra.

The samples were screened for AI viruses by reverse transcriptase polymerase chain reaction (RT-PCR),real-time PCR and were processed for virus isolation in embryonated chicken eggs and cell culture. Two samples from wild ducks were positive for viruses other than AI,newcastle disease virus (NDV) and infectious bursal disease virus (IBDV).

During the study period no sample was positive for Influenza A viruses,Influenza A (H5N1) or any other strain of HPAI by RT-PCR and virus isolation. In view of the recent H5N1 outbreaks in poultry in India,continued and more widespread AI surveillance is necessary to elucidate the role of wild migratory,resident,domestic birds and poultry in the transmission of AI viruses,said NIV director AC Mishra.

Swine flu: 17 more positive cases
Seventeen more were detected with H1N1 virus on Sunday and no deaths were reported in the past two days,Dr Ashok Mehta,joint director of health,said. However,25 people in serious condition are admitted to the Intensive Care Units of various hospitals. Of this,six are on artificial ventilation.

Meanwhile,two more inmates from the Yerawada Central Prison suspected with swine flu symptoms were administered Tamiflu. On Sunday,a total of 1,677 were screened for swine flu and 304 people with symptoms were given Tamiflu,Mehta said.

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