KARACHI, Feb 24: Since heat destroys the H5N1 virus that causes bird flu, threat to birds and humans is expected to diminish with a rise in mercury level as the summer comes closer.

These views were expressed by Dr Faisal Mehmood, Assistant Professor at Infectious Diseases Department of Aga Khan University Hospital, in his presentation at the PMA House on Saturday.

He said that avian virus did not affect humans until 1997 when an outbreak of bird flu infected 18 people and caused six deaths in Hong Kong. Since then, human cases of bird flu had been reported in different parts of the world, including Asia and Europe, he added.

“Most cases were traced to be in contact with infected poultry or bird-contaminated surfaces,” he said, adding that avian influenza virus often originated in areas where people live in close proximity to chickens.

Dr Mehmood observed that an outbreak of bird flu was not as big a risk for general public as for the poultry workers. It could be controlled by culling the infected birds. However, he warned that available research did hint that the virus could mutate at some point in the future and trigger a lethal human flu pandemic.

He elaborated that H5N1 mutated quickly and was able to incorporate large blocks of genetic code from viruses that infected other species, a process called re-assortment.

For that reason, he said, H5N1 had particular potential to combine with a human flu virus, creating a new viral strain that was feared to spread rapidly from person to person.

Under all conditions the most practical precaution effective at preventing a repeat of the dreadful bird flu history of the past could be hand hygiene, he stressed. “Over 90 per cent of viruses like bird flu enter our bodies through contact between the mucous membranes of eyes, nose and finger nails,” he said.

The speaker mentioned that the exact incubation period of bird flu in humans was not clear though illness appeared to develop within one to five days of exposure to the virus. People fell sick after direct contact with infected birds or bird-contaminated surfaces and not from contact with other animals, he added.

He regretted that a very few people were aware of the possible risk factors though the reported human cases of avian influenza included people from all ages.

When asked about its treatment, he said no effective vaccine could be developed till bird flu virus mutated and the patients were prescribed antiviral drugs and antibiotics.

He stressed that improved public amenities like running water and improved hygiene could be the first and most practical line of defence against killer viruses like the bird flu.

Earlier, PMA Karachi General-Secretary Dr Samreena Hashmi introduced the speaker and highlighted the objectives of the session.—APP