FAISALABAD, Jan 28: Poultry experts of the University of Agriculture who are investigating the outbreak of avian influenza (AI H7) in Karachi , are of the opinion that the source of infection may be water supplied to the city from a reservoir which harbours migratory waterfowl during winter.

This was revealed by the Vice-Chancellor, University of Agriculture, Dr Riaz Hussain Qureshi, while talking to Dawn here on Wednesday. He said a special team had collected AI-infected birds and after detailed examination and investigation reported that this disease could be prevented or at least minimized by improved biosecurity and chlorination of water, proper awareness and timely measures.

According to him, avian flu is a highly contagious viral disease - ranging from mild upper respiratory ailments to reproductive failure to acute, highly fatal generalized diseases.

He said the first known outbreak of avian influenza occurred in Pakistan in 1994. The disease was caused by subtype H7N3 which does not affect humans. The subtype H9N2, widespread in Pakistan, is of low pathogenicity and does not cause heavy losses. Subtype H5 has not been confirmed from poultry in Pakistan so far.

About the transmission of the disease, he said the AI virus was generally introduced into domestic poultry through contaminated water or the spread of sewage in an area. Live-bird markets are a reservoir of infection.

Answering a question about ways of prevention and control of the disease, Dr Qureshi said that prevention required a high level of preparedness. Biosecurity is a first line of defence - bird-proof buildings to avoid contact between poultry and wild birds, in particular waterfowl, discouraging live bird markets, placing movement restrictions on affected holdings and on all farms in a radius of at least 10km around such holdings and eradicating by slaughter and destruction.