Zika, Dengue, Chikungunya. These are the most recent viruses causing outbreaks in several regions of the world, all spread through the bite of an infected female Aedes aegypti mosquito. There is currently no cure for these viruses, which makes infection prevention a priority.
Zika, Dengue, Chikungunya. These are the most recent vector-borne viruses causing outbreaks in several regions of the world, and they are all spread through the bite of an infected female Aedes aegypti mosquito. Efforts to eradicate this [deadly] insect need innovative creative thinking.
Complications arising from Zika, Dengue, and Chikungunya have proven to be serious. Although not much is known about Zika, it is proving to be more dangerous every day. Recently, the Centers for Disease Control and Prevention (CDC) has confirmed that Zika causes microcephaly. Not only this, but the virus has been linked to a number of deaths, in Brazil, Puerto Rico, and Colombia. Like Zika, Dengue can also prove fatal. The CDC reports that an estimated 500,000 individuals have developed Dengue Hemorrhagic Fever, and 22,000 have died of infection. In addition, last year, the World Health Organization (WHO) reported an estimated 1,379,788 suspected Chikungunya cases in the Caribbean and South America alone, and 191 confirmed deaths.
Scientists around the world have taken initiative, implementing unconventional vector-control measures, in an effort to ultimately eradicate the Ae. aegypti mosquito. For example, the British company Oxitec has proposed the release of a genetically modified male Ae. aegypti mosquito, OX513A. Since the male mosquito does not bite, its release would not add to the population of virus-spreading mosquitos. Instead, OX513A would pass a modified gene to female Ae. aegypti during the mating process that would potentially cause the premature death of mosquito offspring, in hopes of eliminating the vector from the release site altogether. The FDA is currently reviewing public comments before allowing the release of OX513A.
It’s not just one company that is working diligently to control these vector populations. Others are following suit and using innovative means to tackle the vector population.
In Brazil, controlling the Ae. aegypti population is not just about preventing Zika-related deaths, it is about giving the next generation the chance to lead healthy lives: As of January 2016, WHO reported that in Brazil there have been over 3,000 cases of microcephaly, a complication of the Zika virus, as well as 38 deaths.
A marketing agency project implemented in Rio de Janeiro kills hundreds of Ae. Aegypti mosquitos on a daily basis. By emitting carbon dioxide and lactic acid, the fluorescent-lit, Zika-fighting billboards mimic human odor. This apparatus can attract Ae. aegypti from a distance of up to 2.5 kilometers. The mosquitos enter the billboard through a one-way opening where they fly around until they die of dehydration.
The company has made the billboard’s technology and blueprints available online through Creative Commons, enabling the replication of the project in any city around the world.
Much like Zika in Brazil, Dengue is endemic in Malaysia, due to high amounts of rainfall. Since Ae. aegypti mosquito eggs can only hatch when completely covered in water, puddles and other sources of standing water around the country enable the mosquitos to reproduce efficiently, with one mosquito laying around 300 eggs a day. On April 25, 2016, Dengue Info Asia reported that in only three months, Malaysia has registered approximately 25,000 Dengue fever cases, 5000 more cases than it registered around the same time last year.
Commenting on the importance of fighting the Dengue virus in the country, Sazaly Bin Abu Bakar, PhD, MSc, BSc, director of Tropical Infectious Diseases Research at University Malaya, stated, “Something has to be done. Something simple, something easy, something that fits our normal lifestyle without changing too much.”
Grey Group Malaysia, on behalf of Telekom Malaysia, has produced an umbrella attachment that aims to combat the Ae. aegypti population throughout the country. The Webe RainSprout, which has a replaceable patch containing a non-toxic larvicide, can attach to the top of any umbrella. When the chemicals released from the attachment mix with rain water, they roll off the umbrella and into the puddles, hindering new Ae. aegypti eggs from hatching.
With the use of government data, the company was able to discover the areas with the highest vector and Dengue prevalence across the country, and the RainSprouts have been distributed in these areas. According to the company, “now every umbrella across Malaysia could become an active weapon in the fight against Dengue. Everywhere they went, they weren’t just keeping dry, they were helping keep the community safe, using rain, the very thing that helps create mosquitos, to help control them."
Keeping with the concept of the RainSprout, scientists from Copenhagen, Denmark and the United States have published an article that studies the effectiveness of using insecticide paints (IPs) as a means of vector control. These IPs are commercially available in Europe and North America.
IPs function much like Indoor Residual Spraying (IRS). According to the CDC, IRS does not prevent mosquito bites, but rather kills mosquitos if they rest on the walls or surfaces which have been treated with the insecticide. This helps control the spread of a vector-borne infection, however, for it to work, IRS must cover at least 80% of household surfaces.
In their study, the authors note that many are coming to believe that advancements in IPs can prolong the residual effects of the insecticide, through a more uniform distribution of the active ingredients on treated surfaces. Furthermore, they state that IPs can contain more than one active ingredient, to “ensure different modes of action in one product,” affirming that IPs can protect against a “wide range of vector-borne diseases…such as dengue and chikungunya.” The study notes that IPs have been observed to hinder the presence of Triatoma infestans for up to 32 months in a field trial in Bolivia, and varying anophelin, culicine, and Glossina species for up to 12 months. However, there are no large-scale efficacy trials testing IPs against aedine species (including Ae. aegypti).
Regardless of the residual effects, it is important to note that IPs pose a potential health threat to humans, and can negatively impact the environment. Although IPs have been approved on the national level, international organizations, such as WHO, have yet to support them. The research authors note that high quality studies which analyze “(i) human and ecology safety; (ii) vector and disease impact; (iii) appropriate AI combination strategies for areas with pre-existing insecticide resistance; (iv) economic assessment comparing IPs with alternative interventions; and (v) consumer acceptability and product applicability,” are needed.
Ultimately, Aedes aegypti vector control measures are essential to one day eliminating the threat of Zika, Dengue, and Chikungunya. There is currently no cure for these viruses, which makes infection prevention a priority. Clearly, there is no reason to limit vector control measures to traditional means; new, innovative methods of controlling the Ae. aegypti mosquito population are emerging every day, and many of them are proving effective.