In late July, we reported that the U.S-based Centers for Disease Control and Prevention (CDC) announced that the Cayman Islands had been removed from it Zika-related advisory list.
And now Travel Agent tells you exactly how the Cayman Islands was able to pull it off.
We recently chatted with Dr. Alan Wheeler, assistant director for the Cayman Islands Mosquito Research and Control Unit (MRCU), and learned that the destination was able to dramatically reduce the presence of Zika by using genetically modified mosquitoes, or “GM mosquitoes.”
“We are currently releasing a genetically modified mosquito in an area of the island known as West Bay,” Wheeler tells Travel Agent. “The work is ongoing and mosquitoes are only being released in a very small area so that we can assess its potential as a method of reducing the presence of Aedes aegypti on the island. Only male mosquitoes are released and the principle for the technique is that these males will mate with the local female Aedes aegypti mosquitoes resulting in offspring that die before reaching adulthood.”
Wheeler, however, noted that the Aedes aegypti mosquito, which is the primary vector of Zika, is still present on Grand Cayman, as it is on the other Caribbean islands. In an exclusive statement issued to Travel Agent, Moses Kirkconnell, the Cayman Islands’ minister of tourism, however, added that while Grand Cayman had a minimal amount of locally transmitted cases, Cayman Brac and Little Cayman were unaffected by the Aedes aegypti mosquito.
“MRCUs main control efforts, unrelated to GM mosquitoes, primarily focus on targeting the immature stages of this mosquito by searching and destroying any larval breeding sites we can find,” says Wheeler. “Typical larval breeding sites for this mosquito are human-made containers such as buckets, drums and other containers capable of holding rainwater for eight or more days. The work is labour-intensive and work-crews are continually surveying and treating properties for this mosquito.”
Although using GM mosquitoes is often considered controversial by some environmentalists, MRCU first conducted risk assessments and concluded the procedure was safe before executing it, says Wheeler.
“The males being released in Grand Cayman do not bite and are incapable of reproduction. Risk assessments carried out in Grand Cayman and the U.S. have not identified any specific risks associated with these mosquitoes. There will always be opposition by some people to all forms of genetic modification.”
According to the MCRU, evaluation of the “Friendly Aedes aegypti” technique is recommended by the World Health Organization and has been approved for use by the authorities in the Cayman Islands, including the National Conservation Council.
Wheeler says MRCU has been employing a vast array of methods to suppress mosquitoes in the Cayman Islands since the 1960’s. The release of the GM mosquito in West Bay, Grand Cayman was started in July 2016 and is ongoing with results being monitored using a number of different trapping techniques and other survey methods, says Wheeler.
“The Cayman Islands government believe in the rigorous methodology employed by the Mosquito Research and Control Unit (MRCU) and their operational deployment of the ‘Friendly Aedes aegypti Project’ at the end of July 2016 is the main reason the islands are Zika free today,” said Kirkconnell. “The MRCU recognized the Aedes aegypti mosquito as transmitting Zika and conducted a vigorous campaign to remove potential breeding sites of the mosquito, including house-to-house inspections and treatments.”
Caribbean Islands that remain on the travel advisory list, according to the CDC's website, are Anguilla; Antigua and Barbuda; Aruba; the Bahamas; Barbados; Bonaire; the British Virgin Islands; Cuba; Curacao; Dominica; the Dominican Republic; Grenada; Jamaica; Montserrat; Puerto Rico; Saba; St. Kitts and Nevis; St. Lucia; St. Martin; St. Vincent and the Grenadines; St. Eustatius; St. Maarten; Trinidad and Tobago; Turks and Caicos and the U.S. Virgin Islands. Under its “Other Areas with Zika Risk” section, the CDC also lists Haiti.
“The U.S-based Centers for Disease Control and Prevention (CDC) produced the list,” said Kirkconnell, “and after showing that there have been no locally transmitted cases of Zika this year and just one imported case in early February, the Cayman Islands were summarily taken off the list.”
Fast Facts From the MRCU
The Friendly Aedes aegypti is a genetically modified male mosquito which is effectively sterile. When it mates with a female Aedes aegypti mosquito, the offspring die before they can reproduce. Hence, with successive releases, the Aedes aegypti population is reduced.
The Friendly Aedes aegypti Programme is a public health initiative to combat the Aedes aegypti mosquito. The program is being carried out by the MRCU in collaboration with U.K.-based biotech company, Oxitec.
The Aedes aegypti mosquito, which is an invasive species in the Cayman Islands, is the primary vector of viruses including Zika, dengue, chikungunya and yellow fever.