Study records Aedes eggs with zika and chikungunya viruses – 02/23/2024 – Health

A study conducted by researchers from UFG (Federal University of Goiás), in Goiânia, recorded mosquito eggs Aedes aegypti with the presence of the zika and chikungunya viruses. The mosquitoes that hatched from the eggs were also infected, confirming that there was so-called vertical transmission in the animal.

Vertical transmission occurs when viruses pass from adults to larvae without the need for an intermediate host which, in the case of mosquitoes of the genus Aedesare human beings.

The article describing the finding was published this Friday (23) in the journal of the Brazilian Society of Tropical Medicine. Specialists from the Center for Studies and Research on (Re)emerging Agents and the Institute of Tropical Pathology and Public Health, both at UFG, and the Sentinel Unit and Reference Center for International and Travel Medicine in the city of Goiânia participated in the research.

To test vertical transmission, scientists collected eggs from Aedes aegypti from seven regions of Goiânia (Central, North, South, East, West, Southwest and Northwest) and cultivated them in the laboratory until the larvae hatch. A total of 1,570 eggs were collected, subsequently separated into 157 reservoirs (wells) with ten individuals each. They also separated by sex, since the transmission of viruses to humans occurs through female bites during the reproductive period.

After hatching, PCR tests (a molecular test that detects the presence of genetic material from other organisms, similar to the Covid test) were carried out to identify the presence of dengue, zika and chikungunya viruses in the larvae. Two reservoirs (20 individuals) tested positive for chikungunya and one for Zika.

For Diego Michel, biologist and researcher responsible for the study, the finding is important because it reveals a transmission mechanism for arboviruses, as diseases transmitted by mosquitoes are called. Although similar transmission mechanisms were already known, little was known about their existence in urban areas.

“It may happen that infected eggs resist natural cycles, such as periods of drought, and then hatch when the rainy season comes, thus representing an alert for epidemiological surveillance because these individuals do not need to look for human hosts to begin transmission, they are already highly infectious diseases”, he explains, who is also a PhD student in Molecular Biology at UFG.

According to research, vertical transmission could become a public health problem as it facilitates the transmission of the disease to humans. There is, however, no record of how long viruses remain in insect organisms, says Michel.

“Although it is not possible to estimate the exact time [de incubação do vírus nos ovos]we observed that it remains inactive for a long time, and the eggs themselves can last more than a year, which may point to the direction for future studies,” he said.

The researcher states, however, that although it is a natural transmission mechanism, its real impact on the increase in arboviruses in the region is uncertain. At the time of the experiment, in 2021, the municipality of Goiânia recorded 141 reported cases of chikungunya, 106 of which were confirmed and no deaths, and one case of zika.

“We know that there is the possibility of venereal transmission, which is from a female mosquito to another male, as well as from female to larvae, but we don’t know the impact of this. That’s why mosquito prevention methods, such as avoiding breeding sites, water stopping, using repellents and also monitoring these diseases continue to be fundamental”, he recalls.

The research received support from Capes (Coordination for the Improvement of Higher Education Personnel) and CNPq (National Council for Scientific and Technological Development) and had the collaboration of the Goiânia Health Surveillance Secretariat.