Oxitec: A New Approach to Controlling Vector Borne Diseases
Posted by Science Oxford on December 8, 2009 | comments
This is article shows you the applications of scientific research, how the science of today can become the products of tomorrow.
Oxitec conduct a lot of work in the area of controlling vector borne disease. They have developed numerous products and have been and continue to be very successful.
Read on to find out more:
Mosquitoes cause more human suffering than any other animal (Source: AMCA). Over a million people die every year from diseases spread by mosquitoes. While two closely related species (Aedes aegypti and Aedes albopictus) are responsible for spreading Dengue, Chikungunya and Yellow Fever, several Anopheline species transmit Malaria. Each year, there are 350-500 million malaria cases and 50-100 million dengue cases. 41% of the world’s population live in areas where malaria is transmitted while dengue threatens 55% of the world’s population in 124 countries (Source: IVI).
Dengue Fever is the most rapidly spreading mosquito borne disease in the tropics and sub tropics. The global burden of disease has increased at least four-fold over the last three decades and is still increasing.
Image: Urbanisation and human global mobility has assisted the main vector Aedes aegypti to spread itself around the world, each year bringing Dengue Fever to new countries.The severe form, Dengue Haemorrhagic Fever is a now leading cause of serious illness and death among children in some Asian countries (Source: WHO). Unfortunately there is neither medicine nor vaccine for Dengue although there are some candidate vaccines in development. Dengue represents a particular challenge as there are four main virus serotypes and any vaccine must provide significant protection to all forms of the virus. At present, the only way to control the disease is to control the vector. This is a challenge as Aedes aegypti is well adapted to the urban environment, biting during the day (making bed nets useless as a preventative measure) and laying its eggs around any still clean water. Anything that can hold water, from a flower pot to a puddle, tree trunk or any concave surface on a building roof is a potential breeding site. Insecticides are the prime method of control. These take the form of indoor residual sprays, fogging or as larvicides placed in water. Trying to treat all potential water containers in a tropical country is an impossible task and this explains why Dengue is the fastest growing vector-borne disease in the world.
Image: Dengue Haemorrhagic Fever patients require constant monitoring
Image: ‘Fogging’ with insecticides is a temporary and unpleasant control measure.To combat Dengue, Oxitec, a UK company, has developed a new approach that draws upon the success of the Sterile Insect Technique (SIT) in agriculture. Conventional SIT uses radiation to sterilise insects that have been reared in a factory environment. Once released, the sterile males compete with native males for the females but no viable progeny result from the matings. The target insect population rapidly declines over a few generations to low or zero levels. However, the dose of radiation required to sterilise insects is damaging to their fitness and this has prevented SIT from being applied to many otherwise suitable target species, including mosquitoes.
Oxitec has introduced genetic sterility (RIDL®) that does not carry the fitness penalty associated with irradiation, allowing the technique to be applied to many more species. The result is both effective and cost efficient. Mosquitoes are a perfect target for an SIT approach as the male mosquito does not bite or spread disease. Only the females do. Hence the release of sterile males provides no danger to humans. Moreover, mosquitoes do not travel far as adults allowing an SIT approach to be focussed in urban areas where it is most needed. Human safety and minimal environmental impact have been critical drivers in developing the Oxitec solution. In most dengue endemic countries the Aedes aegypti mosquito is a non-indigenous species and no other species relies on it exclusively in the food chain, therefore reducing the numbers of this mosquito in an area is unlikely to have a significant impact. The approach is also species specific as these Aedes aegypti mosquitoes only mate with their own species. This is in sharp contrast to the use of general insecticides that will affect most insects coming into contact with the chemical, Cost is another key consideration as many of the countries needing a solution to Dengue Fever are emerging economies. Oxitec’s approach using sterile male mosquitoes to do the work of reducing the target mosquito population in a defined area should be more cost effective and targeted than the use of insecticides.
The introduction of any new technology needs careful consideration. Oxitec is working with leading institutes and regulatory authorities in many countries to evaluate its approach. If successful in Dengue, Oxitec’s approach can also be applied to Malaria-carrying anopheles species, several other disease carrying insect species and in agriculture.
The Company
Oxitec is a UK company founded in 2002 as a spin out from the University of Oxford. The company has developed its RIDL® approach across a number of species relevant to public health and agriculture. In particular Oxitec has developed strains of Aedes aegypti, the principal vector for Dengue Fever, that are now being evaluated on a global basis. Oxitec has also developed an Asian Tiger Mosquito (Aedes albopictus) a secondary Dengue vector. The company is developing partnerships with companies across the world to commercialise its insect strains.Oxitec’s approach to insect control was recognized by the Grand Challenges for Global Health Initiative. In 2008 the World Economic Forum awarded Oxitec the accolade of being a ‘Technology Pioneer’. This award is given to companies whose innovations are deemed to have ‘a critical impact on the future of business and society’.
In November 2009, Oxitec was the winner of the Best Green Technology award and the Overall Winner at the Martin & Audrey Wood Enterprise Awards 2009 which showcase the best innovative companies in Oxfordshire and the Thames Valley.
Visit the company website for more information, here.
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