Mexican official denies rumor of bird flu on northern border with U.S.

Mexico's Agriculture Department on Thursday denied rumors that a case of high-pathogenic avian flu had been found in a town on the U.S. border.

Photo: Mexican official denies rumor of bird flu on northern border with U.S.

"Mexico is totally free of bird flu," Jose Angel del Valle, the department's head of animal health, said in a telephone interview.

A supposed news item posted on a Web site on Wednesday said there had been a case of H5 bird flu in a duck found dead in the town of Nogales, on the U.S. border.

The U.S. Department of Agriculture said earlier Thursday that the report was a hoax, but the rumor affected Chicago Board of Trade grain prices overnight Wednesday.

Last year, Mexico reported several isolated cases of low-pathogenic bird flu, which doesn't affect humans. The most recent case was in the southern state of Chiapas, near the Guatemalan border, reports AP.

According to ABC News, virologists say they understand why bird flu in its present form does not spread among humans. The finding suggests the world may have a precious breathing space to prepare for any flu pandemic.

The reason lies in minute differences to cells located in the top and bottom of the airways, the team reports in today's issue of the journal Nature. To penetrate a cell, the spikes that stud an influenza virus have to be able to bind to the cellular surface.

The virus spike is like a key and the cell's docking point, called a receptor, is like a lock. They both have to be the right shape for the connection to happen.

Scientists in the US and Japan, led by Professor Yoshihiro Kawaoka of the University of Wisconsin at Madison, found that avian influenza viruses and human influenza viruses home in on slightly different receptors.

The receptor preferred by human flu is more prevalent in cells in the mucous lining of the nose and sinus as well as the throat, trachea and bronchi.