The World Mosquito Program (WMP) is a not-for-profit group of companies owned by Monash University that works to protect the global community from mosquito-borne diseases such as dengue, Zika, yellow fever and chikungunya.

WMP uses naturally occurring bacteria called Wolbachia to reduce the ability of mosquitoes to transmit viruses to humans. Through our collaborative and innovative approach, we are helping to protect local communities from these diseases in Asia, Oceania and the Americas. Following decades of research and successful deployments, the World Mosquito Program is now operating in 14 countries worldwide.

We are committed to strengthening the capacity of local communities around the world to reduce the threat of mosquito-borne diseases. We are expanding our method for low-cost, large-scale application across urban areas in countries affected by mosquito-borne diseases. We are collaborating with local communities, governments and health agencies to implement our self-sustaining Wolbachia method.

Learn more about our work here.

The World Mosquito Program is currently operating in 14 countries around the world – Australia, Brazil, Colombia, El Salvador, Indonesia, Sri Lanka, Honduras, Laos, Vietnam, Kiribati, Fiji, Vanuatu, New Caledonia, and Mexico.

We are expanding our method for low-cost, large-scale application across urban areas in countries affected by mosquito-borne diseases. We are collaborating with local communities, governments and health agencies to implement our self-sustaining, long-term solution.

In areas where Wolbachia is established in the resident mosquito population, data from those communities show major reductions in disease incidence.

Learn more about our projects here.

Our Wolbachia method is an evidence-based, safe, one-time intervention for protecting communities against dengue and other mosquito-borne diseases. It works by introducing the naturally occurring bacteria Wolbachia into Aedes aegypti mosquitoes. It does not involve genetic modification of the mosquitoes or Wolbachia. Wolbachia mosquitoes have a reduced ability to transmit viruses to people, decreasing the risk of dengue, Zika, chikungunya and yellow fever outbreaks. 

Wolbachia boosts the natural immune system of the mosquito to make it harder for the mosquito to support the virus infection. If the mosquito can’t get infected, then it can’t transmit these viruses to people. It also competes against viruses for key molecules like cholesterol. Both the viruses and Wolbachia need cholesterol to survive inside the mosquito. When Wolbachia is present, it consumes these molecules and makes it harder for the viruses to grow. If it’s harder for the viruses to grow, then it’s harder for them to be transmitted.

When Wolbachia mosquitoes are released, they breed with wild mosquitoes until, over several generations, almost all of the local mosquito population has Wolbachia. Results from our project sites show dengue incidence is significantly lower in Wolbachia-treated communities compared with untreated neighbouring populations. Our Wolbachia method works in conjunction with other existing and novel measures to prevent the spread of mosquito-borne disease. 

WMP’s Wolbachia method provides long-term protection from mosquito-borne diseases without posing any risk to natural ecosystems or human health. Several independent risk assessments have concluded that the risk of Wolbachia mosquitoes causing harm to humans or the environment over a 30-year period is ‘negligible’ – the lowest possible rating.  

Having reviewed all evidence, the WHO Vector Control Advisory Group (VCAG) has concluded that our Wolbachia method ‘demonstrates public health value against dengue’. The VCAG endorsement provides the basis for WHO to initiate a guideline development process with a view to providing a recommendation for WMP’s Wolbachia method as a public health intervention – a vital step towards policy development & routine programming of WMP’s method.

Learn more about our Wolbachia method here.

No. Our method does not involve the use of genetically modified organisms (GMO). GMO technology is defined as the use of particular procedures to alter the natural composition of an animal or plant’s DNA. Our method is not genetic modification, as the genetic material of the mosquito has not been altered. Neither the Aedes aegypti mosquitoes nor the Wolbachia have been genetically modified in the lab and the strain of Wolbachia we are using is naturally occurring.
 

Wolbachia is a bacteria that has evolved to live inside the cells of many insect species. It has maintained this lifestyle for tens of thousands of years. Wolbachia cannot survive outside of insect cells because it does not have the necessary machinery to replicate itself without help from the insect host. This means Wolbachia cannot survive in the environment (e.g. the air or soil). 

None of the Governments in the 14 countries where Wolbachia mosquitoes have been released have considered this to be a GMO technology.

Wolbachia is not a virus or a parasite.  It is not a “gene drive” in the conventional sense. Wolbachia has never been genetically modified by scientists.

A gene drive is a term conventionally used to describe small genetic elements that have been engineered into organisms to manipulate a particular biological property. 

Wolbachia is able to favour its own establishment into mosquito populations by manipulating the outcomes of sexual matings. This is a natural property of the Wolbachia bacteria - it’s a property it has possessed for thousands of years and is expressed every day in other mosquito species e.g. Culex pipiens, Aedes albopictus.

Compare our method to others here.

The World Mosquito Program's Wolbachia method has been proven to reduce the ability of the Aedes aegypti mosquito to transmit several viruses, including dengue, Zika, chikungunya, Mayaro and yellow fever. 

The World Mosquito Program (WMP) has been releasing Wolbachia mosquitoes, with the support of governments and communities, in 14 countries for the last 12 years, protecting more than 11 million people. The first releases in 2011 were in the northern Australian state of Queensland, where city-wide Wolbachia coverage has since led to the cessation of dengue outbreaks for almost a decade. When Wolbachia mosquitoes are released, they breed with wild mosquitoes until, over 6-12 months, Wolbachia mosquitoes replace the local mosquito population. Once Wolbachia is established in the population, it stays there for many years. This makes Wolbachia a safe, one-time intervention for protecting communities against dengue and other mosquito-borne diseases like chikungunya and Zika.

For further information, read our latest research studies here.

No. There is no evidence that deployment of Wolbachia changes the risk of new or old infectious diseases emerging in places that are now protected by Wolbachia.  This is because Wolbachia establishment in the Aedes aegypti population does not alter the distribution or abundance of other mosquito species.

Dengue, Zika, chikungunya and yellow fever are human viruses which are transmitted primarily by the mosquito Aedes aegypti, which is commonly found around homes and workplaces. The transmission cycle for the dengue, Zika and chikungunya viruses is human → mosquito → human, while the transmission cycle for yellow fever can also include non-human primates, such as monkeys. When mosquitoes carry Wolbachia, their ability to transmit these viruses is significantly reduced.

Dengue

Dengue fever is ranked by the World Health Organisation as the most critical mosquito-borne viral disease in the world – and the most rapidly expanding – with a 30-fold increase in global incidence over the past 50 years. More than half of the world’s population, in more than 120 countries, are at risk of dengue infection. The most significant dengue epidemics in recent years have occurred in Southeast Asia, the Americas and the Western Pacific. Each year, an estimated 390 million dengue infections occur around the world. Of these, around 100 million people get sick from their infection and 40,000 die each year from severe dengue.

Brazil had a record number of dengue cases in 2022, with more than two million reported. In 2023, the Americas reported more than 3.5 million dengue cases (October 2023) with large outbreaks in Peru, Bolivia and Brazil. In Asia, Bangladesh has seen its worst-ever dengue outbreak in 2023.

Read more about dengue here. 

Zika

On 1 February 2016, the World Health Organisation declared Zika virus disease a Public Health Emergency of International Concern. Zika has continued to spread geographically where Aedes aegypti mosquitoes are present, with 89 countries reporting infections.

Cases of Zika virus disease globally declined from 2017 onwards; however, Zika virus transmission continues at low levels in several countries in the Americas and in other endemic regions. The first local mosquito-transmitted Zika virus disease cases were reported in Europe in 2019 and Zika virus outbreak activity was detected in India in 2021.

There is no vaccine or treatment for Zika virus, other than rest and treating fever with common medicines.

Read more about Zika here. 

Chikungunya

First identified in an outbreak in Tanzania in 1952, chikungunya is a mosquito-borne disease transmitted between humans by the Aedes aegypti mosquito. Chikungunya’s name is derived from a word in the Kimakonde language, meaning ‘to become contorted’, as the virus causes debilitating joint pain that induces a stooped appearance. Chikungunya is most prevalent in Asia, Africa and India.

The disease has been identified in nearly 115 countries, with seasonal or sporadic outbreaks up to now. In 2023, however, increased chikungunya circulation was detected among five countries in the Americas, greatly surpassing numbers for the same period in previous years.

Read more about chikungunya here.

Yellow fever

Yellow fever is an acute viral haemorrhagic disease transmitted by infected mosquitoes. The virus is endemic in 47 countries across Africa and Latin America. According to the World Health Organization and Pan American Health Organization, yellow fever is estimated to infect 200,000 people, with an estimated 30,000 deaths annually. Thirteen countries in the Americas are considered to be at highest risk for yellow fever outbreaks, including Brazil and Colombia, where we work. While the urban transmission of yellow fever by Aedes aegypti has not been reported in Brazil since 1942, the risk of re-urbanisation of the disease remains, as these mosquitoes are found in most tropical and subtropical cities in the world and have been the main mosquito responsible for epidemic transmission of yellow fever in the past.

Read more about yellow fever here.

There are several different approaches to reducing mosquito-borne diseases that are at various stages of development around the world. A number of dengue vaccine candidates are in development and two (Sanofi’s Dengvaxia® and Takeda’s QDenga®) have been licensed in recent years, however neither is yet in programmatic use in any country.  Methods for reducing mosquito populations that are under development include new insecticides and new methods of applying existing insecticides. Other groups are also exploring ways to suppress mosquito populations by genetically modifying or irradiating mosquitoes, or by releasing only male mosquitoes with Wolbachia. 

Our Wolbachia approach is self-sustaining and predicted to have lasting, major reductions in arboviral disease incidence and is expected to be cost-saving for countries to implement. In contrast, suppression approaches that utilise Wolbachia require significant infrastructure to rear large numbers of male mosquitoes and human resources to distribute them in the community – this must be done continuously, otherwise the wild mosquito population rebounds. There is no evidence yet that suppression approaches can reduce mosquito populations at a large scale (ie. the level of a city), or that this approach can reduce disease incidence. Our approach, however, can be scaled to the level of large towns and cities and we have generated evidence directly on the impact on disease in human populations.

Our approach is a natural method to reduce the transmission of mosquito-borne diseases, which we hope will reduce our reliance on insecticides. Our method does not involve genetic modification, as the genetic material of the mosquito has not been altered. Our approach is particularly effective at controlling mosquito-borne diseases in large urban areas where conventional approaches – such as spraying insecticides – are often ineffective and expensive.

The unique advantage of our Wolbachia method is that in addition to helping to protect communities from mosquito-borne diseases like dengue, Zika, chikungunya, Mayaro and yellow fever, we are not posing a risk to natural ecosystems. Long-term monitoring shows that our natural Wolbachia method is self-sustaining and will maintain itself indefinitely. Our first releases were undertaken in 2011 in Australia and, as predicted, the Wolbachia has maintained itself in those sites ever since.

Learn more about how our method compares here.

Unlike most other measures employed to control mosquito-borne disease, our method is self-sustaining as Wolbachia is passed on from one generation of mosquitoes to the next.

Evidence from the communities we have released shows that Wolbachia can sustain itself in mosquito populations without continual reapplication. This makes our method a one-time, long-term, and cost-effective solution that has no adverse impact on natural ecosystems.

Other strategies that aim to reduce the number of mosquitoes need to be reapplied regularly to keep mosquito numbers low. This commonly involves regular and widespread use of pesticides, which carries an environmental cost and promotes the evolution of resistance.  In contrast, our method introduces Wolbachia into the mosquito population to reduce their ability to transmit viruses and does not require ongoing reapplication. Independent cost-benefit analyses have concluded that Wolbachia deployment in high-density urban communities with a high burden of dengue will pay for itself over time, through savings in healthcare costs and a healthier population.

Learn more about our sustainability model here.

The World Mosquito Program is a not-for-profit group of companies owned by Monash University, in Australia. WMP is funded through major grants or contracts from Foundations (e.g. Wellcome Trust) national governments (e.g. Australian Government)  and philanthropic supporters from all over the world.

See our full list of financial supporters here.

The Bill & Melinda Gates Foundation funded our Wolbachia work through the Grand Challenges in Global Health Program. 

The funding came through a grant from the Foundation for the National Institutes of Health through the Vector-Based Transmission of Control: Discovery Research (VCTR) program of the Grand Challenges in Global Health initiative of the Bill & Melinda Gates Foundation.

The Gates Foundation helped fund WMP’s activities, along with many other partners and donors, for almost 20 years.

Yes. The World Mosquito Program was awarded the Microsoft AI for Earth grant in 2020. The AI for Earth Program, which closed in 2022, provided a grant to WMP to develop a machine-learning model to help identify the best places to release mosquitoes. 

The machine-learning model was used to identify geographic areas most amenable to Wolbachia mosquito releases and identify exclusion zones where it was not suitable to release mosquitoes. The output of the model was optimal release areas highlighted on a map. 

Using publicly available data on human population densities, land use, industrial sites, and weather, combined with satellite imagery, the model automated part of the process of identifying release areas. WMP analysts could then review the outputs and confirm the suitability for release. 

Use of the model was discontinued in 2022 when publicly available datasets became available that fulfilled the same purpose. 

We are present in many LMIC and LIC countries and we do this through strong partnerships with Governments, global and local NGOs, and Communities. Our end-to-end program is designed with Government's objectives in mind. For example, we incorporate community awareness and education for public acceptance before the release of our mosquitoes. Our work continues in Africa, South East Asia and Latin America with the support of our global NGO collaborators and funders to make our technology available across communities affected by dengue. 
 

WMP is a non-profit organisation, owned by Monash University. In fact, we receive in-kind donations and support from the University, along with other donations and grants from Governments and Funders, to continue the work we do.

We have growing evidence for the effectiveness and safety of our Wolbachia method and have set up projects in 14 countries. We have shown in published studies from Australia, Indonesia, Brazil and Colombia that dengue incidence is dramatically lower following Wolbachia mosquito releases compared to the years pre-release and compared to communities without releases. 

To estimate the total number of dengue cases and hospitalisations that have been prevented by WMP’s Wolbachia method to date, we use data from independent modelling studies that predict how many dengue cases occur on average each year in cities worldwide in the absence of Wolbachia.

This model-based data is used because dengue case numbers reported to health authorities are known to greatly underestimate the true disease burden in most locations. Based on a conservative assumption that Wolbachia prevents 80% of the dengue cases and hospitalisations that would otherwise have occurred, and the duration of time that has elapsed since the completion of releases in each site, we estimate that 600,000 dengue cases including 40,000 hospitalisations had been prevented by WMP’s Wolbachia method by June 2023.

WMP’s city-wide deployments of Wolbachia mosquitoes between 2015 and 2022 in Bello, Medellín and Itagüi  — protecting more than three million people — have seen dengue incidence rates drop by at least 95 per cent. Dengue cases have dropped to a 20-year low following large-scale releases of Wolbachia mosquitoes in the Aburrá Valley. Dengue incidence has declined by 95-97% in the three cities since Wolbachia establishment.
 

The first releases in 2011 were in the northern Australian state of Queensland, where city-wide Wolbachia coverage has since led to the cessation of dengue outbreaks for almost a decade. After effectively eliminating transmission of these viruses from Australia, WMP has expanded its work to 14 countries across Asia, Oceania and the Americas.
 

While it's true that Sri Lanka has seen a high incidence of dengue in recent years, this is a trend that has been observed countrywide.

WMP collaborated with the Ministry of Health in Sri Lanka for a focused pilot project in the capital, Colombo, which covered an area of 19.4 km² and 236,000 people, approximately 4% of the population of the Colombo metropolitan area.

With such a relatively small deployment so far, we would not expect to see a measurable impact on dengue incidence in Colombo as a whole, let alone in other areas of Sri Lanka. It is of note, however, that in the districts of Colombo and Kalutara where the pilot release areas were located, dengue incidence has been lower in 2023 than in 2022 as shown on this National Dengue Control Program dashboard, not higher.

We are working with the Sri Lanka National Dengue Control Unit to monitor the levels of Wolbachia in mosquitoes in the pilot release areas, and to compare dengue incidence in the pilot release areas with the rest of Colombo. These analyses are ongoing, and will be made publicly available once complete.

WMP works closely with governments and NGO partners to drive impactful, evidence-based implementation. Across global project sites, ongoing findings are rigorously monitored—either independently or in collaboration with WMP—to ensure transparency and scientific integrity. At multiple locations, both entomological and public health outcomes continue to be assessed through independent oversight by trusted partners.

In Queensland, Australia, the Tropical Public Health Services, Cairns (TPHS) maintains independent monitoring of Wolbachia prevalence. In El Salvador, the U.S. Centers for Disease Control, in collaboration with the Puerto Rico Vector Control Unit, is conducting rigorous independent monitoring of Wolbachia and public health outcomes across three municipalities.

Following the success of the initial randomized controlled trial (RCT) in Yogyakarta, the Indonesian Ministry of Health, supported by the University of Gadjah Mada, has thoroughly evaluated the outcomes. As a result, Indonesia has committed to an expanded national-scale deployment of Wolbachia.

Findings and research from WMP’s projects are disseminated through multiple channels to national stakeholders and donors. Where appropriate, projects undergo ethics review to ensure methodological rigor and adherence to ethical standards.

Preliminary results are presented at leading scientific conferences, while project outcomes undergo rigorous peer review and are published in high-impact scientific journals.

To uphold transparency and scientific integrity, we ensure that once published, the underlying data is made publicly available for independent reanalysis. This reinforces confidence in our findings and fosters collaboration within the global research community.

Multiple independent evaluations have rigorously assessed the impact of Wolbachia across project sites in Colombo, Sri Lanka; the Western Pacific; Medellín, Colombia; and Niterói, Brazil. The findings from these comprehensive assessments are publicly available on the World Mosquito Program website. Furthermore, the independently led EVITA trial, a robust randomized controlled trial (RCT), is currently underway in Belo Horizonte, Brazil. This high-standard RCT is systematically measuring the efficacy of wMel-infected mosquito releases in reducing the seroincidence of arboviral infections.

No. Laboratory research shows Wolbachia (wMel) blocks dengue viruses from infecting the  salivary glands in most, but not all mosquitoes. This has been shown repeatedly by WMP scientists and by others and its implications discussed. In some studies the probability of “breakthrough” infections (i.e. the presence of infectious virus in the saliva of a Wolbachia mosquito) is positively correlated with the concentration of dengue virus RNA in the blood that the mosquito fed upon. Importantly however, complete virus blocking by Wolbachia is not necessary to reduce dengue incidence.

For any intervention to reduce or eliminate dengue virus transmission, it needs to lower the reproductive number of dengue virus. The basic reproduction number (R₀) represents the average number of secondary infections from a dengue virus-infected individual in a fully susceptible population. While R_eff (Effective Reproduction Number) refers to the average number of secondary infections caused by an infected individual in a population where some people may already be immune from prior infection (very common in endemic settings), or rarely, from vaccination. Public health strategies aim to reduce the effective R_eff to below 1, ensuring that, on average, each case generates less than one new infection so that eventually DENV transmission stops. 

Wolbachia-infected mosquitoes transmit dengue virus less efficiently, thereby decreasing the overall potential for new infections. Independent mathematical modelling by Ferguson et al, Dorigatti et al  and Brady et al suggest that Wolbachia should result in a reduction in dengue incidence and even local elimination in some settings.  For example, Ferguson et al used empirical data on wMel virus blocking and predicted that wMel would reduce R₀ by 66% for DENV1 and 75% for DENV 2/3/4. Their models suggest that in low-to-moderate transmission settings (i.e. where R₀ is below 3–4), releasing Wolbachia-infected Aedes aegypti mosquitoes could lead to dengue elimination—even if Wolbachia has no fitness cost for the mosquito population.

The outcomes from the AWED trial in Yogyakarta, and the subsequent field studies from Nth Qld, Yogyakarta, Niteroi and the Aburra Valley, are consistent with the modelling predictions, i.e. when wMel is established at high prevalence, there is a demonstrable public health impact (13, 14). However in settings where the R_eff  is high, DENV transmission and even outbreak levels of dengue incidence may still occur despite a high prevalence of Wolbachia. Importantly, the dengue incidence will be lower than it would be without Wolbachia in the mosquito population. 

Aedes albopictus is a secondary vector of dengue, Zika and chikungunya and prevalent in most dengue endemic countries.  In communities where Ae. albopictus is abundant there will be a risk of DENV transmission even if Wolbachia is at a high prevalence in the Ae. aegypti population. In settings where Wolbachia prevalence is intermediate or oscillating up and down in the Ae. aegypti population, the presence of uninfected individuals will increase the risk of DENV transmission, especially during seasonal periods when the population abundance is high, i.e. there will be sufficient uninfected mosquitoes to drive transmission but at a level lower than if there was no Wolbachia in the Ae. aegypti population.

Aedes aegypti is the primary vector of the dengue, Zika, chikungunya and yellow fever viruses. The Aedes aegypti mosquito looks like many other mosquitoes and is difficult to identify without the use of a microscope. As a rule, if they are dark brown to black in colour, found indoors and bite during the day, it is likely that they are Aedes aegypti mosquitoes.

This single mosquito species is responsible for virtually all of the dengue transmission that occurs in the world. It is found in more than 100 countries and loves to live inside our homes and to feed on humans rather than animals. It is very efficient at transmitting dengue, so even small numbers of these mosquitoes can support a dengue outbreak. They are very hard to control because they have adapted to a domestic lifestyle; breeding around the home, feeding on humans and resting indoors.

There are many different types or species of mosquitoes that live naturally in the environment. Some mosquitoes do not live in close association with humans like Aedes aegypti and prefer to live in natural wetland environments.

Mosquitoes have a variety of roles in the ecosystems in which they live. They act as important pollinators for thousands of plant species, as well as an important food source for animals such as fish and birds. In the standing water of lakes and streams, mosquito eggs and larvae make up a significant portion of the biomass. This provides food not only for fish but also for turtles, amphibians, and larvae of other insects, such as dragonflies. For other animals such as lizards, frogs, spiders, and other insects, adult mosquitoes are the primary food source. 

Aedes aegypti mosquitoes are highly adapted to humans and live where humans live. In this way, they are similar to domestic cockroaches. Their ecology overlaps with human ecology and they prefer to live and breed where humans live. They don’t live in forests or wetlands unless humans live there. As a result, they have little contact or importance to natural ecosystems.

The adult lifespan of the Aedes aegypti mosquito can range from two weeks to a month depending on environmental conditions. The average Aedes aegypti mosquito will fly relatively short distances and travel no more than 150 metres in its lifetime. However, its eggs can withstand drying and can become highly mobile, allowing them to be carried around the world attached to human belongings.
 

The number of mosquito eggs released is carefully calculated to establish the Wolbachia bacteria effectively in the local mosquito population. While millions of Wolbachia mosquitoes may sound large, it is spread over time and space and is a fraction of the natural mosquito population. The vast majority of people never notice an increase in mosquito numbers. This is because of the way we release the mosquitoes (they emerge slowly over several days from buckets of water placed in households distributed around the community) and because Ae. aegypti are just one of the species that come into our homes. The important thing is that after the releases stop, the mosquito numbers return to the original numbers in the environment.  This is because the environment has a “holding capacity” that limits the abundance of Ae. aegypti. 

The results in Yogyakarta, Indonesia, for example clearly show that the mosquito population has not increased over the medium or long term.

There is no “vertical gene transfer” associated with the Wolbachia method. The Wolbachia bacteria gets passed from one generation to the next- just like it does in thousands of other different insects.

Wolbachia are safe, naturally occurring bacteria present in up to 50% of species, including some mosquitoes. Wolbachia has evolved to live inside the cells of many insect species. It has maintained this lifestyle for tens of thousands of years. Wolbachia cannot survive outside of insect cells because it does not have the necessary machinery to replicate itself without help from the insect host. This means Wolbachia cannot survive in the environment (e.g. the air or soil).  

Wolbachia is not a virus or a parasite.  It is not a “gene drive”. Wolbachia has never been genetically modified by scientists.

However, Wolbachia is not usually found in the Aedes aegypti mosquito, the primary species responsible for transmitting viruses such as dengue, Zika, chikungunya and epidemic yellow fever.

For many years, scientists have been studying Wolbachia, looking for ways to use it to potentially control the mosquitoes that transmit human diseases. The World Mosquito Program’s research has shown that when introduced into the Aedes aegypti mosquito, Wolbachia can help to reduce transmission of the dengue, Zika, chikungunya, Mayoro and yellow fever viruses to people.

Learn more about Wolbachia here.

Current evidence indicates that Wolbachia works in two ways within a mosquito. The first way is to boost the natural immune system of the mosquito to make it harder for the mosquito to support the dengue, Zika, chikungunya, Mayaro or yellow fever infection. If the mosquito can’t get infected, then it can’t transmit these viruses to people.

The second way Wolbachia works is by competing against viruses for key molecules like cholesterol. Both the viruses and Wolbachia need cholesterol to survive inside the mosquito. When Wolbachia is present, it consumes these molecules and makes it harder for the viruses to grow. If it’s harder for the viruses to grow, then it’s harder for them to be transmitted.

Learn more about Wolbachia here.

The World Mosquito Program 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, and chikungunya. 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.

WMP has been releasing Wolbachia mosquitoes, with the support of governments and communities, in 14 countries for the last 12 years. The first releases in 2011 were in the northern Australian state of Queensland, where city-wide Wolbachia coverage has since led to the cessation of dengue outbreaks for almost a decade. When Wolbachia mosquitoes are released, they breed with wild mosquitoes until, over 6-12 months, Wolbachia mosquitoes replace the local mosquito population.  Once Wolbachia is established in the population, it stays there for many years, making Wolbachia a safe, one-time intervention for protecting communities against mosquito-borne diseases.

Wolbachia has been present in insect populations for tens of thousands of years and there is no evidence it causes harm to humans or vertebrate animals. Wolbachia is found naturally in butterflies, moths and many different mosquito species (but not the Aedes aegypti mosquito that transmits dengue).

Some of the mosquito species that carry Wolbachia also bite humans e.g. the “common house mosquito” (Culex pipiens).  Just about every person on the planet has been exposed to the bites of insects that carry Wolbachia, without evidence of it causing harm.

Our Wolbachia method helps to protect communities from mosquito-borne diseases like dengue, Zika, chikungunya, Mayaro and yellow fever and does so without risk to natural ecosystems or human health.

Several independent risk assessments have concluded an overall risk rating of ‘negligible’ – the lowest possible rating – for the release of Wolbachia mosquitoes.

WMP has released Wolbachia mosquitoes in 14 countries since 2011. There is no evidence of harm to the environment, humans or animal health.
Learn more about Wolbachia here.

No. Wolbachia are naturally occurring bacteria that are safe for humans, animals and the environment.

Our Wolbachia method helps to protect communities from mosquito-borne diseases like dengue, Zika, chikungunya, Mayaro and yellow fever and does so without risk to natural ecosystems or human health.

Several independent risk assessments have concluded an overall risk rating of ‘negligible’ – the lowest possible rating – for the release of Wolbachia mosquitoes.

For more information, download the CSIRO's Risk Assessment Report.

Wolbachia is common among arthropods (including insects, spiders and other small animals with no backbone). Up to 50 per cent of species naturally carry Wolbachia, including butterflies, dragonflies, moths and some mosquito species, but not the primary species of mosquito involved in the transmission of dengue, Zika, chikungunya and yellow fever.

Wolbachia is also found in certain types of roundworms – known as nematodes – but this is very different to the insect inhabiting Wolbachia that we work with. Wolbachia is not found in any larger animals such as mammals, reptiles, birds and fish.

Wolbachia cannot survive outside of insect cells because it does not have the necessary machinery to replicate itself without help from the insect host. This means Wolbachia cannot survive in the environment (e.g. the air or soil).  

Wolbachia refers to a whole genus of bacteria, of which there are many different types and strains. We’ve examined several strains of insect Wolbachia, and the most effective strain we’ve found is the one that we are currently using in the field, called wMel.

Our researchers have also been examining different strains of Wolbachia including wMelCS, wAlbB, wRi and wPip. While we have had great success in establishing our current Wolbachia strain in wild mosquito populations, testing additional strains could lead to better optimisation of the method in different locations as well as provide a strategy to account for the possible evolution of resistance.

We don’t inject any eggs. Injection of eggs to create the original Wolbachia-carrying females Aedes aegypti was carried out more than 15 years ago.  All the mosquitoes deployed in the 14 countries around the world are the offspring of this mosquito.

Wolbachia and mosquitoes can both be affected by high temperatures. At high temperatures, the density of Wolbachia decreases in the mosquito (larvae and adults) and maternal transmission of Wolbachia is reduced. Importantly, however, the evidence of successful Wolbachia establishment in Indonesia, northern Australia, Brazil and Colombia indicates that temperature is not typically a problem for establishing Wolbachia.

Our method uses Wolbachia mosquitoes to naturally prevent the transmission of mosquito-borne diseases, including dengue, Zika, chikungunya and yellow fever. We release both female and male mosquitoes each week for several months, which facilitates the establishment of Wolbachia into the Aedes aegypti mosquito population. Since Wolbachia mosquitoes can’t transmit diseases, the incidence of mosquito-borne diseases reduces in areas where Wolbachia is established at high levels.

Other methods which use Wolbachia are: 

Sterile Insect Technique (SIT)

The Sterile Insect Technique (SIT) uses irradiation to sterilise male mosquitoes which are then released in large numbers to mate with wild females, thus preventing wild female eggs from hatching. Over time and successive releases the wild population is predicted to decline.

This method relies on the continuous production and release of male mosquitoes and is, therefore, more expensive than the World Mosquito Program's method. There is no field evidence that it can reduce the risk of mosquito-borne diseases.

Incompatible Insect Technique (IIT)

This approach uses Wolbachia but in a different way from how we use it. In this approach, mosquitoes are reared in laboratories that contain Wolbachia. They are sexed and then only males are released. When a Wolbachia infected male mosquito mates with a wild female mosquito without Wolbachia her eggs do not hatch. This has a similar effect as SIT and over time and with repeated releases the wild population should decline.

This method relies on the continuous production and release of male mosquitoes and is, therefore, more expensive than the World Mosquito Program's method. There is no field evidence that it can reduce the risk of mosquito-borne diseases.

Combined Sterile Insect Technique & Incompatible Insect Technique

IIT requires completely accurate sexing to be effective, otherwise the target population will not decline. Completely accurate sexing can be hard to achieve and so it is possible to combine IIT with low doses of irradiation to sterilise any fertile females that are accidentally released in an IIT program.

This method relies on the continuous production and release of male mosquitoes and is therefore more expensive than the World Mosquito Program's method. There is no field evidence that it can reduce the risk of mosquito-borne diseases.

Suppression work is currently carried out in Singapore as part of the National Environment Agency (NEA) national dengue programme and Project Wolbachia. Other countries similarly using this method include Mexico and China (for Ae. albopictus). In the US, there is suppression with Wolbachia male mosquitoes by Verily and GMO releases for suppression by Oxitec in Florida.

Yes. The Malaysia Government has been doing replacement in collaboration with Hoffman/Sinkins groups and using the wAlB strain, with several papers published on this.

 

In Singapore, the National Environment Agency runs a programme of suppression, called Project Wolbachia. The programme produces and releases non-biting male Aedes aegypti mosquitoes at selected locations to mate with their female counterparts. Because the male mosquitoes carry the Wolbachia bacteria, the resultant eggs do not hatch and this helps to suppress the mosquito population.

Project Wolbachia now covers about 352,000 households, about 25 per cent of all households in Singapore (October 2023). This programme is different in that it uses the suppression method rather than the replacement one that WMP uses.
 

At WMP, Community Engagement is about establishing participatory partnerships with local communities. Partnership starts with a commitment to understanding the needs and interests of local communities and to design our campaigns with those in mind. Partnership is also about the involvement of local communities and community engagement is a key way for us to drive collaboration and empowerment.

Community Engagement is how we listen to and collaborate with individuals, groups, and organisations in the community to address common concerns, promote shared goals, and enhance the overall well-being of the community. Community Engagement is at the heart of our projects. We call our Community Engagement approach the Public Acceptance Model (PAM) because we only proceed with mosquito releases after securing widespread support from the community.
 

In collaborating with each community, we customise our approach while maintaining common key elements across projects.

• Successful project delivery hinges on understanding communities which we achieve through developing community profiles.
• In communities, we establish Community Reference Groups to listen to input on our communications and engagement approaches.    
• Before we release mosquitoes, we communicate and engage widely to explain our method and answer their questions. 
• We look to empower communities through involvement in our releases and monitoring.
• Ultimately, we assess community acceptance through independent surveys before proceeding with releases.

Across the globe, we see consistently high levels of acceptance reflecting the significant disease burdens of these locations and the recognition that the World Mosquito Program’s Wolbachia method is helping communities to protect themselves from mosquito-borne diseases.

Saying what we do and doing what we say is key to building trust with communities and our PAM principles guide how we act day to day, week to week, and throughout the project:  

• We are responsive - we listen for and respond to requests, queries and concerns people may have. Listening is a source of input into the design of project activities and an important source of learning. 
• We are respectful - we care for the community, its people, and their interests and concerns. We are respectful of the cultural heritage of communities, both tangible and intangible, so this can mean avoiding certain sensitive locations or changing the timing of releases to avoid significant local events, festivals, and feast days.
• We are transparent - we are clear, open, and honest when we listen to and talk with residents. 
• We are inclusive - we work to include everyone and seek diverse inputs because we know our vision of a world free from the fear and suffering caused by mosquito-borne diseases can only be achieved when WMP integrates gender equality, disability, and social inclusion considerations into our engagement approach. 

In addition to obtaining regulatory permissions, we assess the level of community acceptance of our programmes before we begin field releases using a range of indicators. A key aspect of acceptance is ensuring that we have undertaken a thorough stakeholder engagement and communications campaign so we have indicators to assess that. Additionally, we seek the endorsement of the Community Reference Group, an independent group of community representatives who provide us with input and advice to deliver the programme in the community. We also ensure that we have addressed any queries, concerns, or complaints that come from the community before releases happen. Finally, we commission an independent survey of the target community to assess their level of acceptance and support. Across the globe, we see consistently high levels of acceptance from our target communities.

On each project, WMP or Implementing Partners put in place a community feedback mechanism. We are keen to hear from individuals, groups, and organisations who have queries, concerns, and complaints  because by addressing these, we can deliver a project more effectively for the community. 

Anyone wishing to make a complaint can simply call or send a message to our local project WMP office, details of which are shared in local media and on our local social media channels.