The public health programme to combat the Aedes aegypti mosquitoes which transmit Zika, dengue and chikungunya is firmly on track in West Bay.

Recent results from the programme known as the “Friendly Aedes aegypti Project” show the number of wild Aedes aegypti mosquitoes in the treatment area is greatly reduced compared to the nearby non-treatment area, which is also being monitored.

The Mosquito Research and Control Unit (MRCU) is collaborating with biotechnology company Oxitec on the pioneering technique using genetically modified (GM) male mosquitoes to fight Aedes aegypti.

The GM Aedes aegypti males, which cannot bite, are released to mate with female Aedes aegypti in the wild, producing offspring that die before reaching maturity. The released males also die within a few days without leaving an environmental footprint, making the technique “self-limiting”. Over time, this reduces the population of Aedes aegypti.

Operational deployment of the “Friendly Aedes aegypti Project” began in West Bay at the end of July 2016 as the first phase of an anticipated island-wide treatment, with the interim data report now confirming positive results.

Last week the number of Aedes aegypti eggs collected in traps in the treatment area was 88 per cent less than the nearby non-treatment area, a positive indication of the programme’s success.

Oxitec’s technique also has a built-in biological fluorescent marker to enable monitoring for quality control and safety assurance processes. Fluorescent larvae began to appear shortly after the programme began, and have increased to an average of 94 per cent during the last two months.

“Both these statistics show that the programme is working as we anticipated and, indeed, working very, very well,” said MRCU Director Dr. Bill Petrie. “We expect to see this pattern continue and the population of Aedes aegypti fall even further in the treatment area as time goes on.”

Premier and Minister for Heath Hon. Alden McLaughlin, who has been keeping a close watch on the programme, welcomed the interim results.

“I am very pleased to hear that the public health programme to fight the Aedes aegypti mosquito is on track,” he said. “We must protect our people from viruses such as Zika, so I am proud of the work being done by MRCU in conjunction with Oxitec.”

Grand Cayman experienced an outbreak of Zika last year as the virus swept the region, with 21 clinically diagnosed cases as well as 31 cases confirmed by laboratory tests.

“Zika and other mosquito-borne viruses pose a very real threat to our health so it is important we have new preventative measures to protect people from these illnesses,” said Acting Medical Officer of Health Dr. Samuel Williams-Rodriguez. “I am very glad to note that the new public health programme in West Bay is working as we expected.”

The World Health Organization (WHO) has confirmed that Zika can cause the birth defect microcephaly, in which the baby is born with a deformed head, and the virus is also linked to other serious medical conditions such as Guillain-Barré Syndrome.

A case of a microcephaly baby was last week reported in Grenada, born to a mother who had Zika during pregnancy, and health officials in Jamaica are currently waiting on test results for a Zika-linked case of a suspected microcephaly baby born in December.

The safety and efficiency of Oxitec’s technique was previously demonstrated through field releases in East End, Grand Cayman, in 2009 and 2010, as well as in Brazil and Panama. The Aedes aegypti population was reduced by more than 90 per cent in the areas where these releases took place. Today, Oxitec is currently deploying the GM technique operationally in an area of 65,000 people in Brazil.

Last year, in response to Zika, WHO recommended pilot deployment of the Oxitec technique, under operational conditions. The programme presently under way in West Bay is being integrated with existing MRCU control methods, which include the use of chemical and bacterial insecticides to kill Aedes aegypti.

Photo captions: (Photos by Catherine MacGillivray, GIS)

21: A funnel on the MRCU-Oxitec van allows the “Friendly” mosquitoes to be released in the treatment area of West Bay.

33: Kenroy Millwood and Giselle Johnson, production and field assistants with Oxitec, conduct “Friendly” mosquito releases in West Bay.

100: Giselle Johnson, production and field assistant with Oxitec, releases “Friendly” mosquitoes in West Bay through the funnel in the specially outfitted van. A fan helps blow the mosquitoes through the funnel.