Zika outbreak: Puerto Rico's response beset with problems
Lack of money to buy mosquito repellent or sleep with air conditioning raises risk of infection, doctor says
Zika is spreading rapidly in Puerto Rico and is expected to peak in late summer and early fall. By year's end, public health officials estimate, hundreds of thousands of people will have been infected.
Health officials from across the United States are gathering today at the headquarters of the Centers for Disease Control and Prevention in Atlanta to outline a national strategy for combating Zika. In a measure of the concern surrounding the outbreak in Puerto Rico, CDC director Tom Frieden toured the island, meeting with top health officials and local experts last month to assess the situation first-hand.
Puerto Rico is beset with problems already hampering the response: abundant mosquitoes, high levels of insecticide
"We don't have good surveillance" here, Frieden said in an interview at the Puerto Rican health department in San Juan during his tour. "We don't have good control measures." First detected in Brazil last year, the Zika outbreak is spreading through the Americas.
The World Health Organization declared a global health emergency last month because of growing evidence that Zika can cause microcephaly, a rare birth defect defined by an unusually small head. In adults, the virus has been linked to the typically rare autoimmune disorder, Guillain-Barré syndrome.
"Here in Puerto Rico, we're really starting from square one," said Audrey Lenhart, a CDC vector control expert in an interview at the CDC's Emergency Operations Center in San Juan.
In its latest report, the Puerto Rican health department said 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-risk pregnancies at San Juan's University Hospital at the Puerto Rico Medical Center.
To mitigate the risk of microcephaly among newborns, the CDC and the Puerto Rican government are distributing Zika protection kits to pregnant women that include condoms to prevent sexual transmission from an infected partner, insect repellent, bed nets and larvicide tablets for standing water that cannot be drained.
No vector control
Lluberas, who advises the WHO and the World Bank on vector control programs, said there are a few municipalities that spray insecticide once every seven to 10 days or once every few weeks. Spraying "needs to be done a lot more frequently" to be effective, he said.
Eliminating Zika will require spraying insecticide indoors on walls, under beds, behind furniture and inside closets, where Aedes aegypti hide. So far, only two insecticides — deltamethrin and bifenthrin — are approved for indoor residual spraying, and researchers have found high levels of resistance to bifenthrin in Puerto Rico.
"You find resistance in mosquitoes in one locale, and 20 miles away they are not resistant," said Joseph Conlon, technical advisor for the American Mosquito Control Association, which represents researchers, public health officials and pesticide makers.
"People would not really be coming into direct contact with those surfaces," McAllister said.
Given the urgency of the outbreak, health officials need to focus on known methods of curbing mosquitoes "rather than doing research on things that may or may not work," she said.