A July 14 letter titled “Pesticide cautions” warns against the use of pesticides for mosquito control. The writer repeats claims by a small minority of research scientists that microcephaly may be due to the mosquito-control pesticide pyriproxyfen rather than infection with the Zika virus.
This despite the approved use of pyriproxyfen for decades in South America and only recent increases in the incidence of microcephaly (since the arrival of the Zika virus in early 2015).
Certainly integrated pest management is important in mosquito control — and judicious use of pesticides is part of integrated pest management.
The mosquito repellents listed by the writer have been shown in many trials to have limited or no effectiveness. Garlic rubbed on the skin, not ingested, decreases mosquito bites for 20 minutes to 40 minutes only; Vitamin B1 has no significant effect in controlled trials.
Much more effective are well-studied and safe repellents such as DEET or picaridin and, in prolonged outdoor exposure situations, permethrin-treated clothing. For those who desire a natural alternative, oil of lemon eucalyptus may be used, though it must be reapplied every one to two hours or so.
The United States has much better systems for mosquito control than many parts of the world, but Zika is on its way or already here in limited areas. Most Zika infections produce no symptoms, but infections in pregnancy may lead to devastating neurologic injury in a very small group of newborns, justifying bite-prevention efforts and integrated pest management.
William Simpson Jr., M.D.
Emeritus Professor, MUSC
Public Health Committee