A strain of swine flu that is resistant to treatment with the drug Tamiflu has been discovered near the U.S.-Mexican border, the Pan-American Health Organization said on Monday.

"We have found resistance to Tamiflu on the border. We have observed some cases, few to be sure, in El Paso and close to McAllen, Texas," said Maria Teresa Cerqueira, head of the organization's local office.

Cases of A(H1N1) that were resistant to the anti-viral medicine have now been found in the United States, Canada, Denmark, Hong Kong, and Japan.

Experts gathered in La Jolla, Calif., on Monday to discuss the response to the outbreak, said the resistance probably is because of overusing anti-virals such as Tamiflu.

"In the United States, Tamiflu is sold with a prescription, but in Mexico and Canada, it is sold freely and taken at the first sneeze. Then, when it is really needed, it doesn't work," Cerqueira said.

Roche, the manufacturer of Tamiflu, has said it expects a 0.5 percent rate of case resistance based on clinical trials.

Cerquiera said one patient diagnosed with a Tamiflu-resistant strain had been treated with Zanamivir — an anti-viral made by GlaxoSmithKline — and another was given no alternative medication. Both survived.

Since the swine flu outbreak emerged this year, it has killed 353 people in the United States and 146 in Mexico, according to authorities from each country.

A vaccine against the disease is being tested for safety and effectiveness and is expected to be ready in the next two to four months, although the precise date is unclear.

U.S. officials have recommended that children and pregnant women be among the groups first in line for swine flu shots, but said they were unlikely to have enough vaccine for everyone once the drug is ready to be rolled out.
Copyright AFP