For the benefit of the public’s understanding of the collaboration between MRCU and Oxitec to help suppress Aedes aegypti mosquitoes, the following material has been developed to provide factual responses to a recent article in the Cayman Compass publication relating to a recently released GeneWatch report. That report, and the article that covered it, included significant factual errors, mischaracterizations, and did not represent the formal findings or opinions of the MRCU staff. In addition, the reporter who wrote the story did not consult with Oxitec.
MRCU due diligence
MRCU follows a formal due diligence process for all new technology it adopts and is fully supportive of Oxitec’s technology, after having conducted a review of its capabilities previously. The MRCU staff have designed a protocol and project that satisfies the Grand Cayman’s oversight requirements and is looking forward to a successful outcome for this year’s project, potentially leading to further larger scale deployment of Friendly Mosquitoes in the future.
In a recent GeneWatch report, internal communications by an individual expressing questions regarding due diligence have been taken out of context. The individual was later satisfied with Oxitec’s answers to various questions, most of which were clarified clearly in the same report from which GeneWatch chose to selectively quote. Neither the quotations nor the individual who wrote them represents the Cayman government’s formal position, and the MRCU continues to evaluate Oxitec as a potential long-term, efficient, and cost-effective tool against Aedes aegypti.
Review and impact of Oxitec’s technology
The GeneWatch report included a range of incorrect, misleading, or mischaracterized statements about the effectiveness of Oxitec’s OX513A. Friendly Mosquitoes technology has undergone years of research and has been published in more than 100 peer-reviewed papers, with almost a decade of successful suppression programs in various countries. Friendly Mosquitoes programs in the Cayman Islands, Panama and Brazil have shown that deployment of Oxitec’s solution can result in greater than 80 perecnt reduction in populations of wild Aedes aegypti mosquitoes, compared to control areas. During this time, regulatory authorities and scientists from around the world, including the U.S. and Cayman Islands, have concluded that environmental release of Oxitec’s Friendly Mosquitoes will have no negative effects on human health, animal health, or the environment. Country-specific references to peer reviewed articles are available below:
Cayman: Nature Biotechnology. Field performance of engineered male mosquitoes, June 2011
Panama: Pest Management Science, Short-term suppression of Aedes aegypti using genetic control does not facilitate Aedes albopictus, October 2015
Brazil: PLOS Neglected Tropical Disease, Suppression of a Field Population of Aedes aegypti in Brazil by Sustained Release of Transgenic Male Mosquitoes, July 2015
Releases of female adults
Contrary to claims made in the GeneWatch report and opinions referenced therein, Oxitec was not responsible for a spike in adult female mosquitoes. A spike in adult female numbers, measured with BG-traps, is not associated with Oxitec release as it would be evident 1-2 weeks after initiation of releases, which is not the case. Furthermore, and in the rare case a female mosquito is released, Oxitec female mosquitoes carry two copies of the self-limiting gene, known as homozygous females, and are short lived by design. The FDA has reviewed the risk of inadvertent release of females and concluded OX513A homozygous females have dramatically shorter lifespans than wild mosquitoes (2 days relative to a wild-type median lifespan of 68-days) and thus reduced vectorial capacity. Importantly, the overall trend shows reduced adult female numbers as Oxitec treatment takes effect, corroborating results from Ovitraps.
Population suppression and health
Epidemiological studies for Aedes aegypti have been conducted and showcase a reduction in both mosquito numbers and disease prevalence that are statistically robust. Although Oxitec does not make any claims about the potential health impacts resulting from the use of its technology, many health agencies including CDC, PAHO and WHO recommend vector control as a key tool for preventing the transmission of dengue, yellow fever, chikungunya and Zika. Oxitec technology has also repeatedly demonstrated to be effective at reducing populations of the principle vector, Aedes aegypti. Furthermore, WHO’s Vector Control Advisory has reviewed Oxitec’s technology and issued a positive recommendation for countries to evaluate Oxitec’s OX513A mosquitoes.
MRCU and Oxitec partnership
Deployment of Oxitec’s solution was initiated in West Bay in the wet-/high-season of 2016, in combination with spraying insecticides, as part of an integrated control program. Consequentially, substantial suppression was achieved moving into the 2016-2017 dry-/low-season and maintained into following wet-/high-season in 2017, as stated in the MRCU Annual Review. This is fully anticipated as Oxitec’s technique, unlike insecticides, achieves control over several months. This is also in line with experience from field trials in Cayman (2010) and multiple studies in Panama and Brazil, which demonstrates excellent control in both dry- and wet-/high season.
However, the project was not continued due to the expiration of the contract. Since then, MRCU has worked closely with Oxitec to develop a new project, which is now being implemented. This integrated vector management project will explore the use of various Friendly Mosquitoes release rates in conjunction with traditional control methods. The long-term objective is to provide an efficient and cost effective tool in MRCU’s arsenal against Aedes aegypti.
MRCU has rightfully carried out their due diligence with regards to the Friendly Mosquitoes solution and has always been supportive of the technology. Together, both parties have designed a project that meets MRCU’s requirement and are looking forward to a successful outcome for this year’s project.
Dr. Renaud Lacroix,
Oxitec Cayman Limited
Editor’s note: The Cayman Compass is pleased to publish this Oxitec statement, which was submitted on deadline Tuesday.