Mosquito Research and Control Unit readies Zika fight

First case of sexual transmission suspected in Texas

The Aedes aegypty mosquito
The Aedes aegypty mosquito

Cayman’s Mosquito Research and Control Unit is gearing up to fight the Aedes aegypti mosquito, responsible for carrying the Zika virus that has recently been called a global public health emergency by the World Health Organization.

The Aedes is a familiar foe for the MRCU – it’s the same mosquito responsible for spreading chikungunya and dengue in Cayman and around the Americas.

At a press conference Tuesday, Cayman’s public health officials said the Zika virus, linked to severe birth defects in babies born to infected mothers, will likely be in Cayman in the coming months.

The virus has been found throughout South and Central America and in many Caribbean states. Jamaica reported its first confirmed case Monday, and the WHO held an emergency meeting on how to deal with the rapid spread of the mosquito-borne virus. Public health officials in the United States said Tuesday they had confirmed a case of sexually transmitted Zika in Texas.

Dr. Samuel Williams-Rodriguez, head of public health for Cayman, said that thanks to the country’s experience fighting dengue and chikungunya, “We are prepared for this threat.”

Public health officials have linked the virus to microcephaly, a rare birth defect that causes babies to be born with underdeveloped brains and abnormally small heads. The condition is frequently fatal.

According to the WHO, only about 20 percent of the people infected with Zika show symptoms of the virus.

Bill Petrie, head of the Mosquito Research and Control Unit, said Tuesday that it’s not a case of if the Zika virus will reach Grand Cayman but when. The mosquitoes responsible for spreading the virus do not live on the Brac or Little Cayman.

“We have the necessary equipment and key staff,” Mr. Petrie said, to combat the Aedes aegypti before and after the Zika virus shows up in Cayman.

On Tuesday, Mr. Petrie announced a new tool for combating Zika – a new lab at the MRCU will be set up to test mosquitoes for the virus instead of relying on testing people who get sick.

The Aedes aegypti pose unique challenges for the MRCU, Mr. Petrie said. “Our Aedes aegypti here are resistant to all commercial pesticides,” he said. To kill the mosquitoes, identifiable by the white stripes on their legs, the unit has two different pesticides it plans to rotate each week so the insects do not build up a tolerance.

“We don’t want to lose the effectiveness,” he said.

The pesticides will be sent up in the ubiquitous red and white MRCU plane, deployed in the unit’s fogger trucks and sent out with workers to be sprayed by hand. But the Aedes aegypti, Mr. Petrie said, is a unique challenge for the MRCU.

“Aedes aegypti is probably the most difficult mosquito to control in the world,” he said.

Instead of growing in swamps or culverts, the Zika mosquitoes lay their eggs around homes and gardens in buckets, containers and rain gutters with standing water. The best thing people can do to prevent the Aedes aegypti, Mr. Petrie said, is to empty out any containers with standing water. “Inspect your own yard, have a look around,” he said.

“They don’t fly far,” he said, and people can do a lot on their own to keep the Zika-carrying mosquitoes away from their homes. Some of the Aedes’s favorite spots include water standing in old tires or in the saucers under potted plants.

The Aedes aegypti, unlike Cayman’s other mosquitoes, is active during the day, not twilight or at night.