Hemorrhagic variant of dengue fever rising in Mexico, moving closer to US border after floods

By Mark Stevenson, AP
Wednesday, July 21, 2010

Mexico worried by rise in hemorrhagic dengue

MEXICO CITY — Mexico is facing a sort of perfect storm of floods that breed mosquitoes, prompting a big increase in the number of hemorrhagic dengue cases, the country’s top epidemiological official said Wednesday.

The disease’s Type 2 strain, which makes people who have already had the Type 1 variant more vulnerable to developing the hemorrhagic form, is now in the Gulf coast state of Veracruz and moving north toward the region on the U.S. border.

Type 1 is already present in border states like Tamaulipas, which suffered extensive flooding in the weeks after Hurricane Alex made landfall June 30.

“It is possible, if not this year then next, for (Type 2) to reach Tamaulipas,” said Miguel Angel Lezana, director of the National Epidemiological Center.

Veracruz borders Tamaulipas to the south.

Cases of the milder, classic form of dengue fever in Mexico have declined slightly since 2009. But the more serious hemorrhagic form has spiked to about 1,900 cases this year, compared with about 1,430 in the same period of 2009.

Only 16 people have died this year from the hemorrhagic form, but the seriousness of the disease makes it a concern.

Lezana said the recent flooding in border areas created ideal conditions for the Aedes aegypti mosquitoes that spread dengue fever.

“Now that temperatures are rising, that is the ideal combination — heat and humidity,” Lezana said.

He said state and federal government workers are fighting the mosquitoes with control programs.

Lezana also noted the mosquitoes have adapted to living in Mexico at altitudes up to 1,850 meters (6,105 feet) above sea level — at least 350 meters (1,155 feet) higher than previously recorded.

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