The US Centers for Disease Control and Prevention (CDC) strongly recommends that pregnant women use the approved insect repellants - N,N-diethyl-meta-toluamide (DEET) and the pyrethroid permethrin - as a key element in a multipronged approach for avoiding mosquito bites in the fight against Zika virus infection.
A new review of the safety and toxicity of these two insect repellants supports this recommendation, say Boston-based researchers in a commentary online August 19 in Obstetrics & Gynecology.
"Women and their doctors often worry about what they are exposing their baby to during pregnancy. We have heard lots about the dangers of Zika and we wanted to help women and obstetrics providers understand the basis for the recommendations of the CDC and our professional organizations for recommending DEET and permethrin for protection against Zika," said first author Dr. Blair Wylie of Massachusetts General Hospital.
Specifically, "our group wanted to provide the data behind the recommendations to use these specific products," she told Reuters Health by email.
The authors note in their report that reviews assessing the safety and toxicity of DEET conducted by the U.S. Environmental Protection Agency and the Canadian Pest Management Regulatory Agency find that DEET has "low acute toxicity and does not appear to pose a significant health concern to humans when used as directed."
As for permethrin, some animal and limited epidemiologic data suggest that prenatal pyrethroid exposure may adversely affect learning and behavior, "but this level of evidence pales in comparison to the known risks of Zika virus to the fetal brain," they write.
The take-home message, Dr. Wylie told Reuters Health, is "use of recommended insect repellants as directed is recommended without reservation for the protection against Zika virus infection during pregnancy."
Dr. Wylie believes Zika "should be discussed with all reproductive-aged people, both women and men."
"Unfortunately, personal avoidance measures alone, which include application of insect repellants, will not prevent 100% of mosquito bites," the authors note in their article, meaning that governments and affected communities will have to consider wider issues of vector control for Zika prevention.
They add, "Even when a vaccine becomes available for Zika virus, it is hard to imagine a world free of vector-borne disease. With more than 725,000 human deaths per year, the mosquito remains the world's deadliest animal. In this ever-changing world, obstetrician-gynecologists will continue to field questions from their pregnant patients about vector-borne disease and the use of insect repellants."