How habitat factors affect an Aedes mosquitoes driven outbreak at temperate latitudes: The case of the Chikungunya virus in Italy

PLoS Negl Trop Dis. 2023 Aug 17;17(8):e0010655. doi: 10.1371/journal.pntd.0010655. eCollection 2023 Aug.

Abstract

Background: Outbreaks of Aedes-borne diseases in temperate areas are not frequent, and limited in number of cases. We investigate the associations between habitat factors and temperature on individuals' risk of chikungunya (CHIKV) in a non-endemic area by spatially analyzing the data from the 2017 Italian outbreak.

Methodology/principal findings: We adopted a case-control study design to analyze the association between land-cover variables, temperature, and human population density with CHIKV cases. The observational unit was the area, at different scales, surrounding the residence of each CHIKV notified case. The statistical analysis was conducted considering the whole dataset and separately for the resort town of Anzio and the metropolitan city of Rome, which were the two main foci of the outbreak. In Rome, a higher probability for the occurrence of CHIKV cases is associated with lower temperature (OR = 0.72; 95% CI: 0.61-0.85) and with cells with higher vegetation coverage and human population density (OR = 1.03; 95% CI: 1.00-1.05). In Anzio, CHIKV case occurrence was positively associated with human population density (OR = 1.03; 95% CI: 1.00-1.06) but not with habitat factors or temperature.

Conclusion/significance: Using temperature, human population density and vegetation coverage data as drives for CHIKV transmission, our estimates could be instrumental in assessing spatial heterogeneity in the risk of experiencing arboviral diseases in non-endemic temperate areas.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aedes*
  • Animals
  • Case-Control Studies
  • Chikungunya Fever* / epidemiology
  • Chikungunya virus*
  • Disease Outbreaks
  • Humans
  • Italy / epidemiology

Grants and funding

This research was supported by: i) EU funding within the NextGenerationEU-MUR PNRR Extended Partnership initiative on Emerging Infectious Diseases (Project no. PE00000007, INF-ACT) to MM, PP, GG, ii) University of Sapienza funding within Bando Ricerca 2022 - Progetti di Ricerca Medi n. RM12218148E7F756 to BC; iii) PRIN 2020, MosqIT, Prot. 2020XYBN88 to BC. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.