Dengue fever has been wiped out of Townsville, Australia, after anti-virus mosquitoes were released.

The experiment started in 2014, with scientists infecting mosquitoes with Wolbachia bacteria, which prevents the insects from spreading the virus. Four million of the midge-like pests were released across Townsville over two years.

Four years on, no cases of the infection have been recorded since in the Queensland city, which has around 167,800 residents, compared to 54 in the previous four years.

These mosquitoes then mated with wild species, causing them to pass on Wolbachia so their offspring also carried the bacteria.

This is the first time modified mosquitoes have wiped out such a virus across an entire city.

The dengue virus infects around 390 million people a year worldwide. Most cases cause just severe, flu-like symptoms, however, some sufferers develop life-threatening complications such as bleeding and reduced organ function.

Scheme could wipe out dengue in hard-hit countries

On the back of Townsville's success, 11 countries, including Brazil and Vietnam, are trialing Wolbachiainfected mosquitoes.

Professor Scott O'Neill, director of the programme at Monash University, Melbourne, said: 'At a cost of around $15 per person, the Townsville trial demonstrates the approach can be rolled out quickly, efficiently and cost effectively to help provide communities ongoing protection from mosquito-borne diseases.'

The programme aims to release Wolbachia mosquitoes in larger cities around the world with a target of reducing the cost to just $1 per person.

Professor O'Neill added: 'Not only