Thyme oil used to combat Aedes aegypti

Known as an adjuvant in the treatment of coughs, natural thyme oil also has properties that can help in the war against dengue. This is the bet Adamantina City Hall, which recently acquired 500 kilos of particles encapsulated with thyme oil, capable of eliminating, within 48 hours, 100% of Aedes aegypti larvae. The mosquito responsible for transmitting dengue also transmits other diseases such as zika virus, yellow fever and chikungunya. “The idea is that these particles are distributed from house to house, with the help of our community health agents, so that all backyards in Adamantina are prepared to face the mosquito Aedes aegypti”, says Gustavo Taniguchi Rufino, Health Secretary of the municipality and responsible for licensing the technology.

Developed in Unicamp Faculty of Food Engineering (FEA), the technology is the result of a study conducted by the team led by professor Ana Silvia Prata. The research showed that particles containing encapsulated thyme oil, when in contact with water, gradually release an active ingredient with larvicidal action, capable of combating 95% of mosquito larvae in 24 hours, reaching 100% effectiveness in 48 hours. . The researcher explains that through a systematic study of formulations it was possible to obtain particles that behave in a similar way to the eggs laid by female Aedes aegypti. Just like eggs, the particles only come into action after contact with water. After this contact, the egg begins incubation to form the larva, which takes about three days. “This is precisely the time it takes for the particles to release the amount of active compound necessary to eliminate mosquito larvae, that is, the particles are able to mimic the egg cycle” reports Prata, listing other characteristics of the product. “Thyme oil is a natural and non-toxic product, and also has antimicrobial properties that contribute to increasing the shelf life of the finished product” emphasizes Prata.

The capsules are produced through a thermoplastic extrusion process, based on corn starch, which represents 95% of the particle composition. This combination of factors resulted in an affordable product due to the cheap raw material and scalable process. It is noteworthy that the particles remain functional for up to five rain cycles.

The particles containing the active compound, encapsulated thyme oil, were developed for use in places where small volumes of water accumulate, such as plant pots, tires and bottles. Prata further explains that as the release of the active compound only occurs in contact with water, as soon as the water evaporates, this release is interrupted until there is new contact with water and a new cycle begins again. Furthermore, the amount of oil that leaves the particle is regulated by its concentration in water and is never released all at once.

Adamantine in the fight against dengue

With a population of around 35 thousand inhabitants, Adamantina has been suffering from high numbers of dengue cases in recent years. There were more than 2.700 cases in 2019 alone, when the city council declared an emergency situation due to the risk of an epidemic. In 2020, even with the coronavirus pandemic, the numbers were high. The city's Health Secretary says that it was through a report that he learned about the research with thyme oil and immediately sought to contact the researcher responsible to find out more details about the project. “After learning about the characteristics of the product, in particular the safety it offers, both for those who will handle it and for the environment, we decided on licensing, which was carried out through the Inova Unicamp Innovation Agency”, explains Rufino.

Rufino intends to monitor the implementation of the strategy in the city, in order to collect data on the efficiency of particle use. For Prata, who was initially surprised by the contact from the Adamantina Health Department, the partnership represents an opportunity to obtain more details about the use of thyme oil in the fight against dengue. “Data collection is important because all the tests we have carried out to date have been laboratory tests, while monitoring in the city will provide us with data on the application in practice, which will certainly help to optimize the entire process”, reports Prata. The execution of the process of using the particles containing the active compound of thyme in Adamantine was originally scheduled for 2020, however the pandemic disrupted the plans, and it was only at the beginning of this year that the particles were ready. Rufino says that due to the dry period they are currently experiencing, there are no cases of dengue fever in the city. The forecast is that as soon as the next rainy season begins, in mid-October, the distribution of capsules will begin.

The researcher and the Secretary of Health are unanimous regarding the potential consequences of the use of particles by the population. “We believe that placing the particles in a plant pot, for example, and monitoring the entire process can play an educational role, making people aware of the importance of avoiding possible breeding sites”, explains Prata. Rufino adds that initially, the idea is to demonstrate to the population that it is a functional, effective and safe product, and then distribute it, so that residents can control it in their own homes. “Our aim is to establish a partnership in the fight against dengue, with the population and public authorities, each doing their part”, concludes Rufino.

Read article in full published on the Unicamp Innovation Agency website.