The Mosquito Research and Control Unit has revealed strategies for combatting dengue fever in the Cayman Islands in response to the recent announcement of 34 confirmed cases of the infectious tropical disease in the territory – 23 of which, officials said, were contracted locally.
Alan Wheeler, assistant director of the control unit, said, “During the outbreak, MRCU carried out early evening aerial and ground control operations within the known areas of dengue transmission. Work crews were allowed to the survey and treat all yards within the area and in other areas where suspected cases had occurred. Given that the last confirmed case of locally-transmitted dengue occurred before 10 December, aerial operations have now ceased.”
Mr. Wheeler added that the reason for not spraying at this time was not due to budgetary constraints, but that the control unit does not wish to apply chemicals without a demonstrated need so as to help alleviate the possibility of the mosquito becoming resistant to the chemicals used.
“Mosquito control operations could always benefit from having more staff out in the field; however MRCU feels that it does have the staff and equipment to be able to respond rapidly and effectively to any future outbreak of dengue or other mosquito borne disease,” he said.
“As a responsible government department, MRCU does work within an agreed budget; however this budget does not take precedence over and unduly limit control operations.”
The control unit has sufficient chemical equipment and is able to respond to any mosquito related issues when they arise, the department contends. The control unit added that at the moment, the mosquito population is at a low level and therefore the intensity of both aerial and ground-based control operations has decreased.
With regard to the likelihood of the control unit using genetically-modified mosquitoes as it did in 2010, Mr. Wheeler said, “MRCU is still investigating the potential use of genetically-modified mosquitoes, but has no immediate plans to mount a control campaign using this technique.” He added that, “the recent dengue outbreak was dealt with using proven chemical and environmental clean-up techniques.
William Petrie, director of the control unit, said, “In 2010, MRCU along with Oxitec of Oxford University ran the trial for six months. We chose a small isolated area in East End. This was done in three blocks; one block was where the method was introduced, while nothing was done in another block and the third block was used to monitor the natural population of the Aedes Aegypti mosquito.
“Once the team perfected the technique, monitoring was done by traps. The final statistical analysis has shown a significant reduction in the population of this potential dengue carrier,” he added.
Mr. Petrie said the male Aedes Aegypti mosquito cannot bite and lives a short life-span and since their eggs will not survive using this new method of control, the population of the species has decreased, as did the probability of dengue fever transmission.
Since the Cayman Islands’ success using the genetic modification technique, several other jurisdictions are following suit.