Zika outbreak: Puerto Rico's response beset with problems

Zika is spreading rapidly in Puerto Rico and is expected topeak in late summer and early fall. By year's end, public healthofficials estimate, hundreds of thousands of people will havebeen infected.

Health officials from across the United States are gatheringtoday at the headquarters of the Centers for Disease Control andPrevention in Atlanta to outline a national strategy forcombating Zika. In a measure of the concern surrounding theoutbreak in Puerto Rico, CDC director Tom Frieden toured theisland, meeting with top health officials and local experts lastmonth to assess the situation first-hand.

Puerto Rico is beset with problems already hampering theresponse: abundant mosquitoes, high levels of insecticide

"We don't have good surveillance" here, Frieden said in aninterview at the Puerto Rican health department in San Juanduring his tour. "We don't have good control measures."First detected in Brazil last year, the Zika outbreak isspreading through the Americas.

The World Health Organizationdeclared a global health emergency last month because of growingevidence that Zika can cause microcephaly, a rare birth defectdefined by an unusually small head. In adults, the virus hasbeen linked to the typically rare autoimmune disorder,Guillain-Barrsyndrome.

Early lessons

"Here in Puerto Rico, we're really starting from squareone," said Audrey Lenhart, a CDC vector control expert in aninterview at the CDC's Emergency Operations Center in San Juan.

In its latest report, the Puerto Rican health departmentsaid there are now 350 confirmed cases of Zika infection,including 40 pregnant women.

"We have a very serious combination of problems," said Dr.Alberto de la Vega, an obstetrician specializing in high-riskpregnancies at San Juan's University Hospital at the Puerto RicoMedical Center.

To mitigate the risk of microcephaly among newborns, the CDCand the Puerto Rican government are distributing Zika protectionkits to pregnant women that include condoms to prevent sexualtransmission from an infected partner, insect repellent, bednets and larvicide tablets for standing water that cannot bedrained.

No vector control

Lluberas, who advises the WHO and the World Bank on vectorcontrol programs, said there are a few municipalities that sprayinsecticide once every seven to 10 days or once every few weeks.Spraying "needs to be done a lot more frequently" to beeffective, he said.

Eliminating Zika will require spraying insecticide indoorson walls, under beds, behind furniture and inside closets, whereAedes aegypti hide. So far, only two insecticides deltamethrinand bifenthrin are approved for indoor residual spraying, andresearchers have found high levels of resistance to bifenthrinin Puerto Rico.

"You find resistance in mosquitoes in one locale, and 20miles away they are not resistant," said Joseph Conlon,technical advisor for the American Mosquito Control Association,which represents researchers, public health officials andpesticide makers.

"People would not really be coming into direct contact withthose surfaces," McAllister said.

Given the urgency of the outbreak, health officials need tofocus on known methods of curbing mosquitoes "rather than doingresearch on things that may or may not work," she said.