Entomovirological Surveillance in Schools: Are They a Source for Arboviral Diseases Transmission?

Abstract

Surveillance and control activities for virus-transmitting mosquitoes have primarily focused on dwellings. There is little information about viral circulation in heavily trafficked places such as schools. We collected and analyzed data to assess the presence and prevalence of dengue, chikungunya, and Zika viruses in mosquitoes, and measured Aedes indices in schools in Medellín (Colombia) between 2016–2018. In 43.27% of 2632 visits we collected Aedes adults, creating 883 pools analyzed by RT-PCR. 14.27% of pools yielded positive for dengue or Zika (infection rates of 1.75–296.29 for Aedes aegypti). Ae. aegypti was more abundant and had a higher infection rate for all studied diseases. Aedes indices varied over time. There was no association between Aedes abundance and mosquito infection rates, but the latter did correlate with cases of arboviral disease and climate. Results suggest schools are important sources of arbovirus and health agencies should include these sites in surveillance programs; it is essential to know the source for arboviral diseases transmission and the identification of the most population groups exposed to these diseases to research and developing new strategies.

Non-household environments make a major contribution to dengue transmission: Implications for vector control

“…The scientific literature supports the presence of significant risk in spaces other than HH in other parts of the globe [17][18][19][20] . Some of these previously identified spaces that were not evaluated in this work include abandoned and open spaces and hotels, because we did not have data available on time spent in these locations.…”

“…This is especially true in Kisumu, where low overall incidence explains the lack of infections in schools, while the high incidence in Ukunda increases the presence of infected individuals in schools and hence the probability of human-to-vector infections and subsequent spread. Considering the population size with which we worked (see Methods section), previous reports of infection risk in schools 17,18 , and the vulnerability of children that congregate in schools, our data suggests that this type of environment still represents some level of infection risk and its inclusion in vector control activities is necessary. This is particularly true as this is the main NH environment where children are at risk for dengue exposure.…”

“…As a result, most vector control guidelines are marginally or not including Non-Household (NH) locations as targets of interventions [13][14][15] . Yet, recent evidence suggests a larger role of nonhousehold environments in infection risk [16][17][18][19][20] , which was supported by a significant reduction of cases reported during pandemic lockdown, when people spent more time in households and less time outside of them 21,22 .…”

Sociodemographic and environmental factors associated with dengue, Zika, and chikungunya among adolescents from two Brazilian capitals

“…The identification of Ae . aegypti that were positive for DENVand ZIKV inside schools strengthens this conception, characterizing as one of the potential places of transmission [ 21 , 22 ].…”

“…A study in Colombia identified a high frequency and infection rate by Ae . aegypti in schools, showing that they need to be included in the activities of health education, surveillance, and control of these infections [ 21 ]. Another study conducted in Northeast Region of Brazil was able to detect DENV-3 in pools of Aedes mosquitoes collected from several non-residential premises, including public schools, where the authors also observed the highest abundance of Aedes mosquitoes [ 22 ].…”