Researchers use climate data to predict Zika outbreaks


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The Aedes aegypti mosquito transmits many diseases including Zika. (Sanofi Pasteur/flickr)
Jenna Ladd| July 25, 2017

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.

So far, there have been 5,932 cases of the virus reported in the U.S. and nearly 40,000 in U.S. territories such as Puerto Rico. Zika is transmitted by the Aedes mosquito and human sexual contact.

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.”

Millions of honeybees slain after Zika eradication effort went awry


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Authorities are still tallying the dead pollinators in Dorchester County, South Carolina after Sunday’s aerial pesticide spraying. (Jason Riedy, flickr)
Jenna Ladd | September 2, 2016

Millions of honeybees were exterminated in South Carolina this week after an attempt to kill mosquitoes possibly carrying the Zika virus went wrong.

Dorchester County officials aerially sprayed a pesticide called naled early Sunday morning, resulting in the death of millions of honeybees and other pollinators. Due to concern regarding four travel-related cases of Zika reported in the county, the chemical was sprayed over 15 square miles in order to eradicate mosquitoes that may further spread the virus. Naled has been used in the United States for over 50 years but has a contested reputation nationwide. The pesticide was banned in the European Union in 2012 after it was deemed to have a “potential and unacceptable risk” to human health and the environment. Conversely, naled has been approved by the U.S. Environmental Protection Agency (EPA) since 1959 and is sprayed over 16 million acres of U.S. land each year.

The scene painted by beekeeper Juanita Stanely was bleak. “On Saturday, it was total energy, millions of bees foraging, pollinating, making honey for winter,” she said in an interview with CNN on Monday, “Today, it stinks of death. Maggots and other insects are feeding on the honey and the baby bees who are still in the hives. It’s heartbreaking.”

Stanley, co-owner of Flowertown Bee Farm and Supply, said that she lost 46 hives and nearly 3 million bees on Sunday with no warning. She explained, “…when they sprayed by trucks; they told me in advance, and we talked about it so I could protect my bees. But nobody called me about the aerial spraying; nobody told me at all.” The pesticide application was the first aerial spray in the area in over 14 years. Dorchester County Administrator Jason Ward said that attempts were made to notify the public about the aerial spraying through an alert on its website posted two days before spraying. He added that county officials also reached out to beekeepers that were on the local mosquito control registry, but that one country employee failed to follow notification procedure.”He made a mistake in terms of going down his list, and failed to call,” Ward said.

Had she been warned, Stanley said that she would have told officials to do their spraying at night.” ‘Do it at night when bees are done foraging,’ I would have told them,” she said, tears filling her eyes, “But they sprayed at 8 a.m. Sunday, and all of my bees were out, doing their work by then.” Though county officials have publicly apologized, they maintain that the pesticide was used as directed. “We followed that recommendation,” said Ward, “which is also the policy laid out by the state, using a pesticide the state has approved for use.”

Dr. Dennis vanEngelsdorp, a bee researcher at the University of Maryland, said that there are ways to eradicate infected mosquitoes without killing invaluable pollinators. He said the issue reaches beyond honey bees, “If you’re killing honeybees, you’re killing a lot of other non-honeybee pollinators, too, and those populations could take a long time to recover.”