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Dengue fever affects more than 390 million people around the world each year and its symptoms can be fatal.

There is no vaccine for the disease, buy researchers believe they have come up with an alternative to curbing the spread of the disease - in the form of genetically modified mosquitoes.

And now Brazil has become the latest country to approve the use of these bugs, which have been engineered in such a way that means their offspring die before reaching maturity.

Brazil is the latest country to approve the use of genetically modified mosquitoes, stock image pictured, to curb the spread of dengue fever. Males have been engineered in such a way that means their offspring die before reaching maturity. If the males breed with enough females, the populations will, in theory, be wiped out

The idea is that the male insects are on a suicide mission which involves mating with wild females before they, and their offspring, die.

This, in theory, can reduce the number of wild mosquitoes which carry and spread dengue fever.

The viral infection causes serious symptoms ranging from high temperatures and muscle pain to bleeding.

Earlier this year, Panama announced plans to release the GM insects into its jungles to similarly help tackle the spread.

The bugs were engineered by Oxford-based firm Oxitec.

Oxitec has developed the technology to create the genetically modified insects which, it claims, can also be used instead of chemicals to protect food crops from pests.

The Oxitec insect is used to control the dengue mosquito, Aedes aegypti, because it is a strain of the wild species that contains two additional genes.

The Oxitec males, which don't bite, are released to seek out and mate with the wild females.

Their offspring inherit the additional genes and die before becoming functional adults.

They also inherit a marker that is visible under a special light, making monitoring in the field simple, and helps ensure that dengue mosquito control programmes succeed.

The idea is that the male insects are on a suicide mission which involves mating with wild females before they and their offspring die. The viral infection causes serious symptoms ranging from high temperatures and muscle pain to bleeding. The bugs were engineered by Oxford-based firm Oxitec

In several trials, successive releases of the Oxitec males have been shown to substantially reduce  the wild population of dengue mosquitoes in the treated area.

The firm has held preliminary talks with UK authorities about releasing GM insects into UK fields or greenhouses to reduce pest numbers.

The GM mosquito trials in Panama began in February in Nuevo Chorillo, in the Arraiján district of Panama.

They have been approved by the Ministry of Health but critics claim no information about the possible downsides have been provided to members of the public.

There is currently no vaccine for dengue fever so authorities advise the best way to prevent catching the infection is to take precautions when travelling in high-risk areas, such as wearing protective clothing or using a mosquito repellent, stock image pictured, throughout the day and night

Oxitec conducted its first experiments of GM mosquitoes in the Cayman Islands in 2009 and 2010, followed by a smaller experiment in Malaysia in 2010 and 11. In several trials, successive releases of the Oxitec males have been shown to reduce substantially the wild population of dengue mosquitoes in the treated area

Oxitec conducted its first open release experiments of GM mosquitoes in the Cayman Islands in 2009 and 2010, followed by a smaller experiment in Malaysia in 2010 and 11.

Both countries have halted further releases. Larger-scale experiments began in Brazil in February 2011.

Director of GeneWatch UK, Dr Helen Wallace, said: 'Local people should be aware that releasing large numbers of GM mosquitoes can pose risks to their health and the environment.

'They also need to know who will be liable if anything goes wrong. Will Oxitec take responsibility for any problems, or just walk away?'

GeneWatch said changes could be introduced into the wild population which means the dengue fever they spread becomes more dangerous to humans.

It claims that if the numbers of one type of mosquito - Aedes aegypti – is reduced as result of the release of GM versions, others, such as the Asian Tiger mosquito, which also carry the virus, could come in and thrive.