Karachi, April 10: The latest outbreak of bird flu in the poultry estate located in Gadap Town of Karachi, which killed thousands of layer birds in the last fortnight, has so far not cast an adverse affect on human health.

Information gathered from different sources on Tuesday gave to understand that the national poultry disease reference laboratory had confirmed the presence of deadly form of avian influenza (H5N1 virus) in the birds of Karachi in the first week of April.

Prior to the confirmation from Islamabad about four to seven thousand birds died due to viral infection while almost 28,000 birds were culled at three poultry farms in Gadap till Monday, said a poultry a poultry farmer and official of the provincial livestock department.

The concerned town health officer, Dr Khalil Ansari, told Dawn that on Tuesday he visited the affected farms located in Poultry Estate 1 of Gadap Town, which housed about 40 poultry forms and water recreation facilities, off Super Highway, and found the farms locked or non-operational. Mr Ansari said that he did not find any probable case of the feared infection in human being so far.

According to experts H5N1 strain of influenza in birds was different from and more dangerous than any other outbreak of avian influenza. Birds infected with the virus in question could shed large amounts of virus in faeces and other bodily secretions that could under rare circumstances, resulted in human infection. Public health officials as well as livestock department personnel are scheduled to update the provincial health minister at a meeting on Wednesday, said a source in the health department.

In the meantime, when the secretary of the provincial livestock and fisheries department, Mohammad Siddiq Memon, was contacted by this scribe, he mentioned that he was not aware that the virus has been confirmed as H5N1 as the specimen had recently been sent for testing at Islamabad.

However, he admitted the incidence of casualties in birds, saying though he was not in position to give an exact figure about casualties of birds except that it may be sizable. He said no culling had been done so far.

Referring to the virus outbreak, he remarked it could be attributed to various factors, including poor coverage of relevant vaccinations in farm birds and substandard or spurious vaccines.

Another source in the poultry industry said that vaccinations against bird flu were being done since 2004 and samples were also drawn from poultry farms on weekly basis. It was the en bloc deaths of the birds that samples from some farms of Gadap were dispatched to Islamabad. And about ten days ago the Islamabad laboratory informed that samples drawn from birds of three birds were found positive for the avian influenza virus, following which culling was required. Doubting that virus were carried in the chicken feeds is not appropriate, the source added and about 47,000 birds killed after detection of the virus had been buried safely, leaving little chances of any further transmission of virus.

A senior health official said hospitals and all town health officers had been cautioned to take measures and careful handling of patients brought with symptoms and history similar to those infected with the virus.

President Pakistan Poultry Association, Sindh Chapter, Sohail Chaudhry, said the three different flocks (about 30,000 birds) had been eliminated after emergence of the virus last Monday.