Saturday, 26 May 2012


Genetically Modified Mosquitoes Bred to Manage Dengue Fever

By Russell Wilton 

Dengue fever is viral disease that is becoming a serious problem in tropical and subtropical climates around the globe. The viruses are transmitted to people via mosquitoes of genus Aedes (primarily Aedes aegypti). The disease is mainly non-lethal, causing fever and other flu like symptoms such as headaches, muscle and joint pains. However complications can occur resulting in death if the person does not  receive proper medical attention.

(WHO, 2012) “The Wold Health Organization estimates there are 50 to 100 million cases of Dengue fever each year around the world and that about 2.5 billion people (that is over 40% of the population) is at risk of it”. Each year the number of cases of Dengue fever recorded is increasing and it is spreading to new areas. This disease has become a serious problem in developing countries where there is limited health care. So many people are not receiving adequate medical attention to fight the disease. “500 000 people require hospitalization each year” (WHO, 2012). This number of people is only going to keep growing until a vaccine or a treatment developed. Currently the only way to stop the spread of the disease is to manage the mosquitoes which transmit the disease. This is done through removal of population of mosquito which carry the virus and the removal of their breeding sites.

However a group of scientist at Oxitec have successfully genetically modified male mosquitoes of species  Aedes aegypt. The mosquitoes were genetically engineered to contain gene called tTA (tetracycline-controlled transcriptional activation) which is used to control pest insect populations (Oxitec). (Black, 2011)” The protein created from tTA gene causes an increase in the gene activity. This generates more tTA genes which in turn produced more genes and so on. This forms a cycle leaving the cell with a restricted ability to make other proteins”. This affects the functioning and development of the cell which leads to the death of the insect. The gene is inserted into the genome of a male Aedes aegypti mosquito which are released into wild population containing the Dengue virus. Where they breed passing on the tTA gene to their offspring (Oxitec). The tTa gene then leads to the death of the offspring because they can’t develop properly, either late in the larvae stage or as pupae.

This gene modification technology will help in the battle against Dengue fever because the disease is transmitted by mosquitoes. And without them, the virus would not have no way of spreading to people. So by reducing the number of mosquitoes, the cases of Dengue would also decrease because there would be fewer mosquitoes to spread the virus.

References

1.       Black R. 2011, BBC News, GM mosquitoes show fever promise, (online) available at, http://www.bbc.co.uk/news/science-environment-15491228 (last accessed on the 17/03/12)

2.       Oxitec undated, Oxitec limited, (Online) available at, http://www.oxitec.com/ridl-science/
( last accessed on the 17/03/12)

3.       WHO 2012, World Health Organization, (Online) available at, http://www.who.int/mediacentre/factsheets/fs117/en/index.html (last accessed on the 17/03/12)

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