Virus World

Discover how Aedes aegypti mosquito eggs harboring ZIKV and CHIKV pose a new public health challenge, urging a revamp in control strategies. A groundbreaking discovery by scientists at the Federal University of Goiás (UFG) has unveiled that Aedes aegypti mosquito eggs can carry the ZIKV and CHIKV viruses, responsible for Zika and chikungunya respectively. This finding, highlighting a vertical transmission route, underscores a significant public health concern and calls for enhanced surveillance and control measures.

Unveiling the Mechanism of Vertical Transmission

The study, published in the source , marks a paradigm shift in understanding how these viruses are spread. Traditionally, transmission was thought to occur horizontally, with mosquitoes becoming vectors after biting an infected host. However, the detection of ZIKV and CHIKV in mosquito eggs before they hatch means mosquitoes can be born already infected, ready to spread the virus without prior contact with an infected host.

Implications for Public Health and Surveillance

Diego Michel Fernandes da Silva, the study's coordinator and a doctoral student at UFG, emphasized the significance of this discovery for public health. With mosquitoes capable of being born as carriers of these viruses, the potential for rapid spread increases, especially in urban environments. This adaptation mechanism allows for easier dispersal and poses a considerable challenge for controlling outbreaks of Zika and chikungunya. The study's findings necessitate a reconsideration of current prevention strategies, urging health authorities to intensify local epidemiological surveillance and explore innovative ways to eliminate the mosquito population.

Research Methodology and Findings

The research team captured Aedes aegypti eggs and adult mosquitoes across three major regions of Goiânia, Goiás, from January to September 2022. After isolating the heads and thoraxes of 1,570 adult females for analysis, the eggs were raised in laboratory conditions until they hatched. Among these, two groups tested positive for CHIKV and one for ZIKV, confirming that vertical transmission had occurred and that these mosquitoes could transmit the viruses upon reaching maturity. This revelation has profound implications for the fight against diseases like Zika and chikungunya. By demonstrating that viruses can be transmitted vertically from mosquitoes to their offspring, the study not only expands our understanding of these diseases' epidemiology but also underscores the urgent need for innovative control measures. As we grapple with the potential for increased transmission, this research serves as a critical call to action for health authorities worldwide to reassess and fortify their disease prevention strategies.

Cites Study Published in Revista da Sociedade Brasileira de Medicina Tropical (2024):

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10890825/ 

A neonate born to a mother infected with SARS-CoV-2 at a hospital in Wuhan, China, had elevated levels of immunoglobuin M, or IgM, and immunoglobulin G, or IgG, antibodies and abnormal cytokine test results 2 hours after birth, suggesting that the newborn was infected in utero, researchers reported in JAMA.

At 2 hours of age, the neonate’s SARS-CoV-2 IgG level was 140.32 AU/mL, and their IgM level was 45.83 AU/mL, the researchers wrote. Cytokines were elevated (interleukin-6, 28.26 pg/mL; interleukin-10, 153.60 pg/mL), and white blood cell count was 18.08 x 109/L. A chest CT was normal. According to the paper, results from five real-time RT-PCR reaction tests on nasopharyngeal swabs taken between 2 hours and 16 days of age were all negative. At 16 days, the infant’s IgM and IgG levels were still elevated. “Although infection at delivery cannot be ruled out, IgM antibodies usually do not appear until 3 to 7 days after infection and the elevated IgM in the neonate was evident in a blood sample drawn 2 hours after birth,” the researchers wrote.

IgG antibodies, unlike IgM antibodies, can be transmitted to the fetus through the placenta and appear later than IgM antibodies. The elevated IgG level may reflect maternal or infant infection. The mother’s vaginal secretions tested negative for SARS-CoV-2, the researchers reported. According to a second letter in JAMA, neonatal throat swabs and blood samples from newborns born from six pregnant women with confirmed COVID-19 at another hospital in Wuhan all tested negative via RT-PCR, but all six infants had antibodies against SARS-CoV-2 in neonatal blood sera samples.

Original Study Published in Jama (March 26, 2020):

https://doi.org//doi:10.1001/jama.2020.4621