Is Perceived Exposure to Mosquitoes Associated with Actual Exposure? Results from Studies in High-Risk and Low-Risk Geographic Areas

Validity of Self-Reported Mosquito Bites to Assess Household Mosquito Abundance in Six Communities of Esmeraldas Province, Ecuador

Mosquito-borne diseases are a global burden; however, current methods of evaluating human-mosquito contact rates are expensive and time consuming. Validated surveys of self-reported mosquito bites may be an inexpensive way to determine mosquito presence and bite exposure level in an area, but this remains untested. In this study, a survey of self-reported mosquito bites was validated against household mosquito abundance from six communities in Esmeraldas, Ecuador. From February 2021 to July 2022, households were interviewed monthly, and five questions were used to ask participants how often they were bitten by mosquitoes at different times during the day. At the same time, adult mosquitoes were collected using a Prokopack aspirator. Species were identified and counted. Survey responses were compared with the total number of mosquitoes found in the home using negative binomial regression. More frequent self-reported mosquito bites were significantly associated with higher numbers of collected adult mosquitoes. These associations were driven by the prevalence of the dominant genera, Culex. These results suggest that surveys of perceived mosquito bites relate to actual mosquito presence, making them a potentially useful tool for determining the impact of vector-control interventions on community perceptions of risk but less useful for assessing the risk of nondominant species such as Aedes aegypti. Further work is needed to examine the robustness of these results in other contexts.

Human-Mosquito Contact: A Missing Link in Our Understanding of Mosquito-Borne Disease Transmission Dynamics

Despite the critical role that contact between hosts and vectors, through vector bites, plays in driving vector-borne disease (VBD) transmission, transmission risk is primarily studied through the lens of vector density and overlooks host-vector contact dynamics. This review article synthesizes current knowledge of host-vector contact with an emphasis on mosquito bites. It provides a framework including biological and mathematical definitions of host-mosquito contact rate, blood-feeding rate, and per capita biting rates. We describe how contact rates vary and how this variation is influenced by mosquito and vertebrate factors. Our framework challenges a classic assumption that mosquitoes bite at a fixed rate determined by the duration of their gonotrophic cycle. We explore alternative ecological assumptions based on the functional response, blood index, forage ratio, and ideal free distribution within a mechanistic host-vector contact model. We highlight that host-vector contact is a critical parameter that integrates many factors driving disease transmission. A renewed focus on contact dynamics between hosts and vectors will contribute new insights into the mechanisms behind VBD spread and emergence that are sorely lacking. Given the framework for including contact rates as an explicit component of mathematical models of VBD, as well as different methods to study contact rates empirically to move the field forward, researchers should explicitly test contact rate models with empirical studies. Such integrative studies promise to enhance understanding of extrinsic and intrinsic factors affecting host-vector contact rates and thus are critical to understand both the mechanisms driving VBD emergence and guiding their prevention and control.

The Ecology of Protective Behaviors: A Study in New Risk Areas for Mosquito-Borne Diseases

During the last decade, tiger mosquitoes have rapidly colonized a large number of European countries, increasing the risk of infection with mosquito-borne diseases (MBDs), and constituting an emerging health threat in the region. The objectives of the present study were to prospectively investigate changes in Self-protective Behaviors, beliefs and attitudes regarding MBDs in Mediterranean France, and to assess the influence of social and cognitive time-varying covariates on behaviors. Data were collected using the same computer-assisted telephone survey in 2012, 2013 and 2014 among respondents residing in French Mediterranean regions. Weighted estimates in multivariate analysis were computed using the generalized estimating equation technique, with Self-protective Behaviors as a repeated outcome. Perceived exposure to tiger mosquitoes and knowledge about MBDs increased significantly between 2012 and 2014. Most respondents suffered from mosquito bites over the same period, but only 4 in 10 adopted Self-protective Behaviors. These behaviors were mostly related to the frequency of mosquito bites, perceived exposure to tiger mosquitoes, and to higher perceived vulnerability to MBDs. In conclusion, French Mediterranean residents are increasingly knowledgeable about MBDs and the proximity of tiger mosquitoes. However, self-protection was predominantly related to the frequency of mosquito bites and higher perceived vulnerability. These results suggest that Self-protective Behaviors are being shaped more in new risk areas by environmental cues to which people are exposed than by other common personal determinants of health behaviors.

Knowledge, Attitude and Practices towards the Tiger Mosquito Aedes Albopictus. A Questionnaire Based Survey in Lazio Region (Italy) before the 2017 Chikungunya Outbreak

The invasion of Aedes albopictus has played a major role in the resurgence of mosquito-borne diseases in Italy, generating the two largest chikungunya outbreaks in Europe (2007, 2017). Knowledge, attitude and practice (KAP) are important in order to prevent Aedes-borne disease transmission, yet so far they have not been assessed. To this scope we used multivariate logistic regression to investigate KAP of citizen-to-Aedes ecology and transmitted diseases. Data were collated by a structured questionnaire (18 questions) in 2016. Participants were selected in the Lazio region from members of native populations and two resident communities (RC) originating from the Indian subcontinent where Aedes-transmitted diseases are endemic. Results showed that compared to Italians, RC respondents had a higher knowledge and concern of Aedes-transmitted diseases (Odds Ratio = 2.61 (95%CI: 1.03–6.05); OR = 3.13 (2.15–4.65)) as well as their life cycles (OR = 2.49 (1.75–3.56); OR = 9.04 (6.22–13.66)). In contrast, they perceived a lower nuisance due to the presence of Ae. albopictus (OR = 0.2 (0.13–0.32); OR = 0.55 (0.38–0.78). These findings suggest that citizens in the Lazio region are not prepared to face a potential outbreak of arboviruses and further efforts should be made to increase knowledge, awareness and best practices.