01.  What is Wolbachia?

Wolbachia is bacteria that lives only inside insect cells, occurring naturally in up to 60 percent of all insect species, including butterflies, dragonflies and moths, as well as many mosquito species that bite people but do not transmit the disease. Despite the broad range of insects carrying Wolbachia, it is not infectious and cannot be transmitted to any warm-blooded animals, including humans.

02.  What effect will Wolbachia have on mosquitoes carrying dengue?

Wolbachia will reduce the ability of insects to become infected with viruses, including Zika, dengue and chikungunya. If mosquitoes cannot become infected with viruses, they cannot transmit them between people.

03.  How will Wolbachia spread through the mosquito population?

Wolbachia can only be transmitted from parent to offspring inside the female’s egg. It multiplies throughout insect populations when the reproductive success of the insect that carries it is altered.

When a male mosquito that carries Wolbachia mates with a female without the bacteria then that female’s eggs don’t hatch. Wolbachia infected female mosquitoes do not suffer from this effect and produce normal numbers of offspring – which carry Wolbachia. Initially, this reproductive effect will be very small as there will be few Wolbachia infected mosquitoes in the population, but over successive generations the numbers of males and female mosquitoes infected with Wolbachia will increase.

04.  How safe is Wolbachia?

The World Mosquito program has demonstrated that Wolbachia is safe by allowing the mosquitoes to feed directly from researchers on a routine basis. Wolbachia cannot be passed to humans as it is too big to travel down the salivary gland ducts of a mosquito. Many mosquito species naturally have Wolbachia, and they commonly bite people without any adverse effects.

05.  Will the bite of a mosquito infected with Wolbachia hurt more than a normal bite?

No, people who are bitten by an Aedes aegypti mosquito containing Wolbachia will not notice any difference or be harmed in any way.

06. Is Wolbachia harmful to the environment?

No, Wolbachia is naturally occurring bacteria found in up to 60 percent of all insect species, including many mosquitoes that bite people.

07. Do other animals carry Wolbachia?

Wolbachia is common among arthropods (including insects, spiders and other small animals with no backbone). Up to 60% of insect 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.

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

08. What type of Wolbachia does the World Mosquito Program work with?

Wolbachia refers to a whole genus of bacteria, of which there are many different types and strains. We work with several strains of insect Wolbachia, including wMel and wMelPop. The type of Wolbachia we work with exists only within insect cells and has no link to illnesses such as river blindness.

09.  Are mosquitoes which carry Wolbachia more likely to transmit other diseases?

Research shows that Wolbachia does not increase the risk of other pathogens being transmitted by Aedes aegypti mosquitoes. In fact, although the World Mosquito Program's main focus is on reducing dengue transmission, the Wolbachia method has also been shown to reduce transmission of other viruses including Zika, chikungunya and yellow fever.

10. Does heat stress impact the effectiveness of Wolbachia to invade mosquito populations?

Since first starting field deployments in Cairns, Northern Australia in 2011, we have seen no problems with Wolbachia establishing in wild mosquito populations. This is despite often prolonged hot conditions. Wolbachia continues to maintain itself at high levels in our release sites after more than six years and there has been no significant local dengue transmission in these areas once Wolbachia has established. 
Although a recent lab-based research study suggested heat may impact effectiveness, this study used incubator temperatures that are regularly experienced in a number of the World Mosquito Program's field sites and we do not see a loss of effectiveness. The reason is that field conditions and the temperatures insects actually experience in the field are more complex than in an incubator and mosquitoes will actively seek cooler areas to rest or breed. While the results suggest a theoretical impact of temperature, the actual impact in the field appears to be minimal from our current studies.