Mexico's Health Minister Jose Angel Cordova, 02 May 2009

Mexico's health minister says the country's swine influenza A-H1N1 flu epidemic has reached its peak and is declining.

Jose Angel Cordova said Sunday the outbreak appeared to have peaked in Mexico between April 23 and April 28, and that the number of severe cases is declining. But Cordova cautioned against lowering one's guard against the disease.

An official from the U.S. Centers for Disease Control and Prevention said she is heartened by the reports, but that it is too soon to be certain that Mexico's outbreak is leveling off.

Dr. Anne Schuchat told reporters that scientists still do not know how virulent the virus will be, and she expects more severe cases and more deaths.

Police officers, wearing mask as a precaution against the swine flu, patrol a street in Mexico City, Sunday, 03 May 2009

Mexico is the epicenter of the international outbreak. It has reported 19 deaths and another 487 infections. The neighboring United States has confirmed 226 cases nationwide and one death.

At least 18 other countries have confirmed cases. The first case in South America was confirmed Sunday in Colombia. El Salvador also reported its first two cases.

The acting director of the U.S. Centers for Disease Control, Dr. Richard Besser expressed cautious optimism about the outbreak Sunday. He said (on Fox News) there are encouraging signs that swine flu does not appear more severe than a viral strain found in the typical flu season.

The World Health Organization announced Sunday that it is not raising its alert level to the pandemic stage. Still, it has sent 2.4 million anti-viral treatments to 72 developing countries to prepare for a possible pandemic.

Scientists have yet to determine the strength and lethality of the previously unknown strain, which is a mix of swine, avian and human flu strains. 

The new strain has raised concerns because it is spreading outside the normal flu season, and has been deadly among young healthy adults.

Health experts are concerned the new strain could become a more serious threat during the northern hemisphere's winter flu season, when typical influenza viruses cause widespread respiratory illness.

Some information for this report was provided by AP and Reuters.