Frequently asked questions

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.

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, collaborating with local communities, governments and health agencies to implement our self-sustaining Wolbachia method.

Our Wolbachia method works by introducing Wolbachia into Aedes aegypti mosquitoes, the primary vector of the dengue, Zika, chikungunya and yellow fever viruses. We release Wolbachia-carrying mosquitoes in areas where these viruses are endemic. Once released, they breed with wild mosquitoes. Over time, the percentage of mosquitoes carrying Wolbachia grows until it remains high without the need for further releases.

Learn more about our method

The World Mosquito Program is currently operating in 14 countries – 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, collaborating with local communities, governments and health agencies.

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 use is naturally occurring.

The World Mosquito Program’s Wolbachia method has been proven to reduce transmission of several viruses transmitted by the Aedes aegypti mosquito, including dengue, Zika, chikungunya, Mayaro and yellow fever. It is also predicted to have potential impacts on diseases like Japanese encephalitis and is known to reduce mosquito infection with human parasites like malaria and filarial nematodes; however, these diseases are not currently our primary focus.

Dengue, Zika, chikungunya and yellow fever are human viruses transmitted primarily by the mosquito Aedes aegypti, which is commonly found around homes and workplaces. The transmission cycle for dengue, Zika and chikungunya is human → mosquito → human, while the 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 is ranked by the World Health Organization 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 40 per cent of the world’s population, in more than 140 countries, is at risk of dengue infection. Each year, an estimated 390 million dengue infections occur around the world. Of these, 500,000 cases develop into dengue haemorrhagic fever, a more severe form of the disease, which results in up to 25,000 deaths annually worldwide.

Zika

On 1 February 2016, the World Health Organization declared Zika virus disease a Public Health Emergency of International Concern. Zika has continued to spread geographically where Aedes aegypti mosquitoes are present, with 84 countries reporting infections. Since 2015, more than 500,000 suspected cases have been reported, with 3,521 recorded cases of congenital brain abnormalities associated with Zika. There is no vaccine or treatment for Zika virus, other than rest and treating fever with common medicines.

Chikungunya

First identified in an outbreak in Tanzania in 1952, 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. It is most prevalent in Asia, Africa and India. In 2015, a large outbreak across the Americas recorded over a million suspected cases in the Caribbean, Latin America and the United States, with more than 190 deaths attributed to the disease.

Yellow fever

Yellow fever is an acute viral haemorrhagic disease endemic in 47 countries across Africa and Latin America. According to the World Health Organization and Pan American Health Organization, it is estimated to infect 200,000 people, with an estimated 30,000 deaths annually. Thirteen countries in the Americas are considered at highest risk, including Brazil and Colombia, where we work. While urban transmission of yellow fever by Aedes aegypti has not been reported in Brazil since 1942, the risk of re-urbanisation remains.

There are several approaches to reducing mosquito-borne diseases at various stages of development, including dengue vaccines, new insecticides and new ways of applying existing ones, genetically modifying mosquitoes to control their breeding, and using Wolbachia as a tool for mosquito suppression.

Our Wolbachia approach is self-sustaining and predicted to have lasting, major reductions in arboviral disease incidence, and in most urban settings is expected to be cost-saving for countries to implement. Suppression approaches require significant infrastructure to rear large numbers of male mosquitoes and distribute them continuously, otherwise the wild population rebounds. There is no evidence yet that suppression can reduce mosquito populations at city scale or reduce disease incidence. Our approach can be scaled to large towns and cities, and we have generated evidence directly on its impact on disease in human populations.

Our approach is natural and does not involve genetic modification. It is particularly effective in large urban areas where conventional approaches – such as spraying insecticides – are often ineffective and expensive. Our first releases were undertaken in 2011 in Australia and, as predicted, Wolbachia has maintained itself in those sites ever since.

We aren’t trying to reduce the overall number of mosquitoes. Instead we aim to boost the number of Wolbachia-carrying mosquitoes to reduce their ability to transmit diseases. We release a small number of male and female mosquitoes with Wolbachia over a number of weeks, and they mate with the wild population. The bacteria are passed from generation to generation until the percentage carrying Wolbachia remains high without further releases.

Our work has shown that Wolbachia can sustain itself in mosquito populations without continual reapplication, making this a long-term, cost-effective and self-sustaining approach.

It’s very difficult to predict how long the Wolbachia method will be effective. Most control measures – whether insecticides or biological control – can become less effective over time due to the evolution of resistance. Currently, we have not detected any signs of resistance in any of our release sites. Our current work suggests we can expect effective control for at least decades and potentially much longer.

The possibility of effective but transient control should not be seen as a negative. Many tools have become less effective over time, yet have been incredibly valuable in saving lives from diseases such as dengue and malaria.

The World Mosquito Program is a not-for-profit group of companies owned by Monash University, Australia. We have developed strong relationships with governments, research institutes and philanthropic partners around the world.

Aedes aegypti is the primary vector of these viruses. It looks like many other mosquitoes and is difficult to identify without a microscope. As a rule, if they are dark brown to black, found indoors and bite during the day, they are likely Aedes aegypti.

Unlike other mosquitoes, Aedes aegypti has adapted to live and breed in urban areas close to humans. It breeds in artificial containers that collect water (such as old tyres and pot-plant trays) and bites humans almost exclusively.

Many mosquito species live naturally in wetland environments, where their larvae can be an important food source for animals such as fish. Aedes aegypti, however, is highly adapted to humans and lives where humans live, much like domestic cockroaches. It doesn’t live in forests or wetlands unless humans live there, so it has little contact with or importance to natural ecosystems.

The adult lifespan ranges from two weeks to a month depending on conditions. The average Aedes aegypti travels no more than 150 metres in its lifetime. However, its eggs can withstand drying and can be carried around the world attached to human belongings.

Wolbachia are safe, natural bacteria present in up to 50% of insect species, including some mosquitoes. However, Wolbachia is not usually found in Aedes aegypti, the primary species responsible for transmitting dengue, Zika, chikungunya and epidemic yellow fever. Our research has shown that when introduced into Aedes aegypti, Wolbachia can help reduce transmission of these viruses to people.

Current evidence indicates Wolbachia works in two ways. It boosts the mosquito’s natural immune system, making it harder for the mosquito to become infected – and if it can’t get infected, it can’t transmit the virus. It also competes with viruses for key molecules like cholesterol, which both need to survive. When Wolbachia is present, it’s harder for viruses to grow and therefore harder for them to be transmitted.

We maintain colonies of Wolbachia-carrying Aedes aegypti in our laboratories. We release relatively small numbers into a target location, where they breed and pass Wolbachia into the wild population. It then typically maintains itself in more than 90% of wild mosquitoes indefinitely.

Wolbachia is safe for humans, animals and the environment. Following years of laboratory and field research, our findings have been subjected to rigorous independent assessments, which concluded there is negligible risk associated with the release of Wolbachia-carrying mosquitoes – the lowest possible risk rating.

No. People bitten by an Aedes aegypti mosquito carrying Wolbachia will not notice any difference or be adversely affected in any way.

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

Wolbachia is common among arthropods. Up to 50 per cent of insect species naturally carry it, including butterflies, dragonflies, moths and some mosquito species. It is also found in certain roundworms (nematodes), but this is very different from the insect-inhabiting Wolbachia we work with. It is not found in mammals, reptiles, birds or fish.

Wolbachia is a whole genus of bacteria with many strains. The most effective strain we’ve found, and the one we currently use in the field, is called wMel. We are also examining wMelCS, wAlbB, wRi and wPip, which could help optimise the method in different locations and guard against the possible evolution of resistance.

Wolbachia is transmitted only from parent to offspring inside the female’s egg. When a male carrying Wolbachia mates with a female without it, her eggs don’t hatch. Females carrying Wolbachia produce normal numbers of offspring, all carrying Wolbachia. Over successive generations, the proportion of mosquitoes with Wolbachia increases. This process is called cytoplasmic incompatibility.

At high temperatures, Wolbachia density in mosquitoes decreases and maternal transmission is reduced. However, successful establishment in Indonesia, northern Australia, Brazil and Colombia indicates temperature is not typically a problem.