(Updates with details, background)
LA JOLLA, Calif. (AFP)--A strain of swine flu that is resistant to treatment with the drug Tamiflu has been discovered near the U.S.-Mexico 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 local PAHO 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 was likely due to over-use.
"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," said Cerqueira.
Roche Holding AG (ROG.VX), the manufacturer of Tamiflu, has said it expects a 0.5% rate of case resistance based on clinical trials.