New observational research has found that people with high exposure to common “pyrethroid” insencticides were 56% more likely to die during a study period than others. Cardiovascular disease was the leading cause of death in the exposed.
CGRER member Wei Bao, assistant professor of epidemiology in the University of Iowa College of Public Health, is an author of the study, published Jan. 30 inJAMA Internal Medicine.
Pyrethroid insecticides are used in most household insecticides and some pet products and head-lice shampoos. The study followed a sample of 2,116 adults who took the United States National Health and Nutrition Examination Survey between 1999 and 2002, representative of the U.S. population as a whole. The researchers noted levels of pyrethroid-associated chemicals in their urine and found death records to determine how many had died by 2015, as well as their cause of death.
While those with higher pyrethroid exposure were more likely to die overall, the highly exposed were three times more likely to suffer cardiovascular deaths than others as well. Bao said in an Iowa Now feature that the study does not prove that the insecticides are the cause of death, only that death and exposure are correlated.
Zika virus spread rampantly throughout the Americas in 2014 and 2015. While the infection itself presents with few noticeable symptoms, it has been linked to an increased number of babies born with microcephaly and Guillain-Barré syndrome, which can result in paralysis.
In a study published recently in the journal Frontiers in Microbiology, researchers developed a way to predict Zika outbreaks before they happen. The scientists used climate data from Zika-prone areas to build computer models for Aedes mosquito populations.
One of the study’s authors, Dr. Ángel Muñoz of Princeton University, said, “Both the mosquitos that transmit Zika and the virus itself are climate-sensitive.” He continued in an interview with E & E news, “High temperatures, like the ones observed during the record-breaking years 2015 and 2016, generally increase the virus replication rates and also the speed of mosquito reproduction. The overall effect of high temperatures is an increase in the potential risk of transmission.”
The researchers used their computer model to test how well their projections of the virus spreading matched with what actually occurred in 2014 and 2015. They found that their model could consistently predict a Zika outbreak one month before it occurred. In some areas, the model predicted an epidemic three months in advance.
Their computer model is not without its limitations. First, the study notes that scientists can only confidently make predictions for entire countries and regions, not cities or towns. Second, Aedes mosquitos also carry dengue and chikungunya, so the model does not distinguish whether the mosquitos are carrying Zika or another vector-borne disease. It simply indicates when conditions for disease transmission are highly suitable.
Dr. Benjamin Beard is deputy director of the Centers for Disease Control and Prevention’s Division of Vector-Borne Diseases. Referring to the changing climate and increased international travel, he said in an email, “We are seeing an accelerated threat from mosquito-borne diseases overall. Over the past few decades, we have seen a resurgence of dengue and the introduction of West Nile, chikungunya, and now Zika virus into the Western Hemisphere.”