PRESS RELEASE: Oxitec and MRCU report 80% suppression of a dengue mosquito population in Grand Cayman by release of engineered sterile male mosquitoes – Nature Biotechnology

September 11, 2012


Embargoed until 2pm EST, Monday 10th September 2012

Oxitec and MRCU report 80% suppression of a dengue mosquito population in Grand Cayman by release of engineered sterile male mosquitoes – Nature Biotechnology

Releases of Oxitec’s genetically modified mosquitoes achieved an 80% reduction of a local mosquito population in the Cayman Islands, as described today in the prestigious international scientific journal Nature Biotechnology.

A paper1  by the Cayman Islands Mosquito Research and Control Unit (MRCU) and Oxitec reports a  successful demonstration of Oxitec’s innovative approach to controlling the Aedes aegypti mosquito – the insect responsible for spreading dengue fever. These data demonstrating the effectiveness of  Oxitec’s  solution, previously made available to the scientific community through conference  presentations, are now published in a major peer-reviewed scientific journal.

Commenting on the publication, Dr William Petrie, Director of the MRCU said:

“Dengue is a dangerous and debilitating disease which affects up to 100 million people each year. The incidence of dengue has grown very rapidly in recent years: it is now a serious  threat  to  global  health,  and  the  only means  of  prevention  is  to target  the mosquitoes which carry it. We need new tools in the fight against these dangerous pests, and today’s publication shows that Oxitec’s approach can provide that”

The dengue mosquito has spread globally during the last 50 years, and is an extremely difficult pest to control as it lives in and around the home. Conventional methods rely on  chemical  pesticides which  can  harm  other insects  and  which are becoming  less effective as mosquitoes develop resistance. Dengue is endemic in at least 100 countries. The World Health Organization (WHO) estimates that 50 to 100 million infections occur yearly, mostly among children.

Oxitec’s approach offers a practical, cost effective alternative to combat this growing problem. It involves the release of non-biting genetically modified ‘sterile’ male Aedes aegypti  mosquitoes  to mate  with  wild  females  and  suppress  the  target  mosquito population.

Oxitec’s Chief Scientific Officer, Luke Alphey, added:

“Today’s  publication  reports  an  important  result  for  us.  We  have  developed  our approach over a  number of years and have conducted rigorous testing to ensure it is both sustainable and safe.   These  data indicate that it is also extremely effective, as previous laboratory and modelling work had led  us  to hope. 80% suppression is an excellent result, especially as wild mosquitoes could migrate into  the trial area – we should see even stronger reduction in larger or more isolated areas. We believe this approach can be used in many countries to offer a more effective, greener solution to controlling the Aedes aegypti mosquito and reducing Dengue Fever.

The trial reported in today’s publication was conducted in 2010 in Grand Cayman by the MRCU, with eggs of Oxitec’s genetically modified Aedes aegypti mosquito provided by Oxitec.

Oxitec CEO Hadyn Parry commented:

“Oxitec’s  innovative  approach  achieved  an  excellent  result  in  Cayman,  dramatically reducing an  urban population of the Dengue mosquito. Following this trial we have since done out-door demonstrations of our solution in Malaysia2  and Brazil. As with all public  health  initiatives,  community  engagement  and  regulatory  oversight  are  very important  and  we  have  been  very  pleased  by  the  interaction  with  regulators  and positive feedback from the local community. We believe our approach can be integrated into many existing vector control programmes and we look forward to working with communities around the world to help combat mosquitoes that spread disease.


Nature Biotechnology publication (Harris et al Nature Biotech. 30:828-830)

Fact box – what’s in this paper

  • 3.3 million Oxitec ‘sterile’ male mosquitoes were released in a site in Grand Cayman over a 23 week period
  • In the final phase of the trial, Oxitec males were released in a 6 hectare area
  • Released Oxitec males successfully mated wild females.
  • By the end of the trial, there was an 80% reduction in the number of mosquitoes found in the trial area, relative to untreated areas.


About dengue fever

Until the 1960’s dengue fever remained a relatively minor, geographically restricted disease. Since then globalisation and urbanisation have assisted the spread of the Aedes mosquito species that transmit  dengue. The disease is caused by any of four closely related viruses or serotypes: dengue 1-4. Infection with one serotype and a consequent immune  response  does  not  protect  against  the  other   serotypes  and  subsequent infections put people at a greater risk of dengue haemorrhagic fever (DHF) and dengue shock syndrome (DSS). Dengue is now endemic in at least 100 countries in Asia, the Pacific,  the  Americas,  Africa,  and  the  Caribbean.  It  was  not  until  1981  that  large numbers of DHF cases began to appear in the Caribbean and Latin America. The World Health Organization (WHO) estimates that 50 to 100 million infections occur yearly, including 500,000 DHF cases and 22,000 deaths, mostly among children.

1 Harris et al (2012) Nature Biotech. 30:828-830

2 A recent publication reporting on the field performance of Oxitec’s mosquitoes in Malaysia is available at


About Oxitec


Twitter and Facebook: Oxitec


Oxitec is a UK company pioneering a new approach to combating insects that spread disease and damage crops. The Oxitec solution harnesses advanced genetics to create

‘sterile’ male insects to mate with females of the same species resulting in a population

decline. Conventional insect pest control in both public health and agriculture focuses on the use of chemical pesticides.  Insect transmitted diseases include Malaria, Dengue and West Nile Virus.  It is also estimated that despite the use of pesticides some 20-40% of food production is lost to insects.


About MRCU

The Mosquito Research & Control Unit (MRCU) was established in 1965 and provides mosquito control on Grand Cayman and its sister islands. MRCU also performs leading research into mosquito behaviour,  insecticide resistance and control methods and is internationally renowned for its public health contribution.

For further information contact or


Hadyn Parry (CEO)

+44 1235 83239


Luke Alphey (CSO)

+44 1235 832393