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Reducing the Threat of Mosquitos: Wolbachia

Reducing the Threat of Mosquitoes
According to the World Health Organization (WHO), viruses spread by mosquitos kill an estimated 700,000 people a year. Out of the mosquito-spread viruses, dengue, Zika and chikungunya are considered some of the most dangerous due to the quickness and severity of their infection rates. Although disease prevention has proven to be expensive for developed and developing countries alike, Wolbachia is increasingly being explored as a new tool in the fight against mosquitos.

Wolbachia Bacteria

Wolbachia, a word most of us are not familiar with, is, in fact, a safe and naturally developed bacteria that is present in 60 percent of all insect species. However, Wolbachia is not found in the Aedes aegypti species of mosquito that are the primary transmitters of dengue, Zika and chikungunya to humans.

The bacteria prevent the spread and outbreak of viruses by acting as a natural competitor in the mosquito. First, Wolbachia boosts the immune systems of Aedes aegypti mosquitos and prevents viruses from being able to spread to and survive on the species. Secondly, Wolbachia effectively consumes molecules, such as cholesterol, which viruses need in order to thrive.

In other words, viruses are being prevented from spreading viruses mosquito-to-mosquito and mosquito-to-human. This bacteria has proven to be very efficient in reducing the threat of mosquitos.

The World Mosquito Program

The leader in utilizing Wolbachia against mosquito-spread viruses is the nonprofit World Mosquito Program (WMP). The WMP conducts research, works with communities, governments and other nonprofit organizations and implements the release and studying of Wolbachia bacteria in mosquito populations.

Currently, the WMP operates in 12 at-risk countries with a primary interest in economically disenfranchised countries and populations.  These 12 countries are Vietnam, India, Sri Lanka, Indonesia, Australia, Kiribati, Vanuatu, New Caledonia, Fiji, Mexico, Colombia and Brazil. According to the U.N. Development Programme, viruses such as Zika pose tremendous economic, health care and tourism risks to countries while simultaneously hurting people in poverty who have a reduced access to health and sanitation facilities.

Support in Reducing the Threat of Mosquitos

Throughout the countries mentioned above, the WMP has gained countless support from communities, governments and nonprofits. For instance, the Australian and New Zealand have worked closely together to fund the WMP projects in Fiji and Vanuatu. In Fiji, these additional funds have allowed the WMP to reach an additional 120,000 people.

A well-known U.S. nonprofit organization, the Bill and Melinda Gates Foundation, has become an important funder for the WMP projects and for developing new technology for research and operations. The U.S. Agency for International Development has proven to be a lead contributor to financing projects against Zika in Colombia, where 25 million people are at-risk to an outbreak.

Other important actors that participate in WMP programs include the U.K. and Brazilian governments, the Candeo Fund, the Wellcome Trust, local rotary clubs and many health ministries and local governments.

Results are just as vital as gaining support for reducing mosquito-spread viruses. While the WMP has not moved onto phase two by analyzing the reduction of viruses, they have collected data for the spread and sustainability of Wolbachia in mosquito populations.

Tri Nguyen Island, Vietnam, Queensland and Australia have witnessed the spread of Wolbachia to nearly 100 percent of their mosquito populations since the projects began.

Doubts about Wolbachia

While initial results look promising, there have been reasonable doubts expressed about using Wolbachia bacteria. Some studies suggest that Wolbachia enhances the ability of West Nile Virus to spread in the Culex tarsalis mosquito and that temperatures play a large role in the effectiveness of the bacteria. However, the WMP has discounted the temperature claim by referencing the success rates in Vietnam, Australia, Brazil and Colombia in reducing the threat of mosquitos.

Despite the possible consequences, the WMP has maintained its belief in the ability of Wolbachia and continuing to research and study the results as much as possible. Looking at their sponsors, the WMP has become a popular potential solution to actors affected by and interested in mosquito-spread viruses.

These sponsors are not the only ones, however, as the WHO has labeled Wolbachia as a viable tool going forward. In 2016, the organization recommended that Wolbachia should be tested in pilot programs in order to gain more beneficial evidence. In fact, their laboratory tests confirmed that Zika, Dengue and Chikungunya were reduced in mosquitos introduced to Wolbachia.

The WMP’s program is meant to be a long-term, low-cost and sustainable virus reduction solution, not the one to be used just in emergency circumstances. With that being said, Wolbachia should be part of a greater toolbox in reducing mosquito-spread viruses through prevention, containment and reduction.

To reiterate, the entomology coordinator for the WMP operations in Brazil stated to the U.N. that Wolbachia bacteria is not a silver bullet, but it is really promising.

– Tanner Helem
Photo: Flickr

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Bacteria that Fight Mosquito-Transmitted Diseases

Mosquito
The Eliminate Dengue Program is developing an approach to fighting mosquito-transmitted diseases by using naturally occurring bacteria that reduce the ability of mosquitoes to transmit harmful human viruses such as dengue fever.

The bacterium, called Wolbachia, is a natural bacterium that is present in several different insect species and is safe for humans, animals and the environment. However, when the bacterium is introduced to the Aedes aegypti mosquito, it stops viruses from growing inside the mosquito and from transmitting to people. Mosquitoes cause millions of deaths every year. The Aedes aegypti mosquito is responsible for the spread of several diseases such as dengue fever, chikungunya, yellow fever and Zika.

Since 2011, the Eliminate Dengue Program has been conducting trials in dengue-affected areas such as Australia, Vietnam, Indonesia, Brazil, Columbia and India. The trails include the release of Wolbachia-infected mosquitoes that breed with wild mosquitoes, establishing the bacteria in the wild mosquito population. Wolbachia can sustain itself in mosquito populations, making this method sustainable and cost-effective in the long-term. The program is targeted to cost U.S. $1 per person. This distinguishes the program from other similar initiatives like the Oxitec program.

Oxitec developed genetically modified male mosquitoes that have a gene preventing offspring from surviving to maturity. The aim is to reduce the mosquito population. This is a more expensive approach because a huge number of mosquitoes have to be released continuously.

In 2016, the Eliminate Dengue Program received additional funding to roll out the program in large areas of Brazil and Colombia to stop the spread of the Zika outbreak. The program is funded by the Wellcome Trust, the Bill and Melinda Gates Foundation, and the Brazilian, U.K. and U.S. governments. The World Health Organization also called for large-scale pilot studies of the Wolbachia mosquito-control method to establish its effectiveness in fighting mosquito-transmitted diseases in humans.

The possibility exists that this approach might provide a similar result in the Anopheles mosquitoes that spread malaria.

– Helena Kamper

Photo: Flickr

How to Defeat Malaria with Mosquitos

defeat-malaria-with-mosquito
Researchers from Michigan State University have found a way to defeat malaria by making mosquitoes resistant to the malaria parasite. The investigators determined that when infected with a specific bacterium, mosquitoes have an increased malaria immunity, which could help reduce human infections and deaths related to the disease.

Wolbachia bacterium is what is credited for providing an increased resistance to malaria in mosquito populations. Temporary infection of the bacterium has “made the insects immune to the malaria parasite,” and after 34 generations of mosquitos mating and passing the Wolbachia from infected females to their offspring, the mosquitos demonstrated malaria levels which were four times lower than mosquitoes that were not infected with the bacterium.

While the Wolbachia infected mosquitoes resist malaria and can pass their immunity too their offspring, the new research on the mosquitoes has found some limitations. Scientists say that the “[bacteria] infected females produced fewer eggs than uninfected females, which meant the infection would struggle to spread in the real world.” Additionally, the research only focused on one species of mosquitoes that inhabits the Middle East and South Asia. Research on Wolbachia still needs to be carried out on African mosquitoes.

In the past, researchers looked to genetically modify mosquitoes to help eliminate the spread of malaria. Investigators at Johns Hopkins University developed a genetically engineered mosquito that showed resistant to the disease in 2007. The University’s current research is investigating what factors exist in mosquito immune systems that allow the insects to fight off the malaria infection.

The World Health Organization estimates that “220 million people are infected annually and 660,000 die” from malaria. Scientists hope that their discoveries, paired with the use of mosquito nets and medication, will help reduce the number of malaria infections and deaths in the future.

– Jordan Kline

Sources: BBC, The Daily Mail
Photo: The Katy News