How mosquitoes
spread disease
Mosquitoes pick up viruses by biting infected people. When they bite again, they can transmit the virus to the next person. This is how mosquito-borne diseases spread.
Mosquitoes do not naturally carry viruses – they can only get them from infected people.
Since only female mosquitoes bite humans, only female mosquitoes can transmit viruses.
Aedes aegypti mosquitoes originated in Africa, but they have spread through tropical and subtropical regions around the world.
Aedes aegypti mosquitoes first spread outside Africa during the slave trade between the 15th and 19th centuries. They also spread through trade with Asia during the 18th and 19th centuries, and then again following troop movements in World War II.
The number of people affected by mosquito-borne diseases is rapidly growing.
In recent years, population growth, the movement of people from rural areas to cities, more international travel and climate change have all increased the spread of Aedes aegypti mosquitoes.
And subsequently, the number of people affected by mosquito-borne diseases has also increased.
Dengue fever is now considered the most critical mosquito-borne viral disease in the world, according to the World Health Organization. It’s also the most rapidly spreading, with a 30-fold increase in global incidence over the past 50 years.
Factsheet
How our Wolbachia method works
Our Wolbachia method is simple.
We discovered that Wolbachia blocks viruses like dengue, chikungunya and Zika from growing in the bodies of Aedes aegypti mosquitoes.
This means that Wolbachia mosquitoes have a reduced ability to transmit viruses to people.
When Wolbachia is established in a mosquito population it results in a decreasing incidence of dengue, Zika, chikungunya.
So, at the World Mosquito Program, we breed Wolbachia mosquitoes. Then, in partnership with local communities, we release them into areas affected by mosquito-borne diseases.
Which means less risk of disease in communities where Wolbachia is established in the local mosquito population.
Our Wolbachia method can protect communities from mosquito-borne diseases without posing risk to natural ecosystems. Unlike most other initiatives, our method is natural and self-sustaining.
Wolbachia is one of the world’s most common types of bacteria, present in 50% of all insect species, including bees, beetles, butterflies, moths, and fruit flies.
People are constantly exposed to Wolbachia through the foods they eat and the insects that bite them, but it causes no known health risks. It also does not affect the food chains of other species because Wolbachia does not reduce mosquito populations.
Independent risk assessments of WMP’s Wolbachia technology, undertaken in Colombia, Australia, Vietnam, and Indonesia concluded risk associated with release was negligible, low or acceptable.
Our method is unique and effective
Unlike most other techniques that aim to prevent mosquito-borne diseases, our Wolbachia method is natural and self-sustaining.
Our method does not suppress mosquito populations or involve genetic modification (GM), as the genetic material of the mosquito is not altered.
Long-term monitoring shows that our natural Wolbachia method is self-sustaining in almost all international project sites, with the first mosquitoes released in 2011.
How we release Wolbachia mosquitoes
Together with communities around the world, we’ve released Wolbachia mosquitoes into many towns and cities.
We started our first trials in Australia and, once we proved the method could work, started doing small trials around the world.
We always work with the approval of communities that are affected by mosquito-borne diseases.
We work closely with local governments, health authorities and community groups before we release any mosquitoes.
We spread the word about our Wolbachia method through local events, TV, radio, newspapers, social media and word of mouth.
Then we survey the community to make sure there’s support for the project to go ahead.
Once the project is understood and supported by the community, we breed Wolbachia mosquitoes.
Then, when we have enough, we release them.
This is a team effort! Lots of volunteers get involved for mosquito releases, including individuals, schools, universities and local community groups.
Because mosquitoes don’t fly very far, we usually release a handful of mosquitoes every 50 metres across the target area.
The release period usually lasts for 12 to 20 weeks.
How do we know it works?
We monitor both the Wolbachia mosquito population and incidence of diseases before, during and after releasing Wolbachia mosquitoes.
We have strong evidence showing the effectiveness and safety of our Wolbachia method.
We have set up projects in 14 countries and our Wolbachia mosquitoes have protected almost 11 million people (December 2022).
In areas where Wolbachia is self-sustaining at a high level, dengue transmission has been significantly reduced.
