Spatio-temporal distribution of dengue and lymphatic filariasis vectors along an altitudinal transect in Central Nepal

PLoS Negl Trop Dis. 2014 Jul 31;8(7):e3035. doi: 10.1371/journal.pntd.0003035. eCollection 2014.

Abstract

Background: Rapidly increasing temperatures in the mountain region of Nepal and recent reports of dengue fever and lymphatic filariasis cases from mountainous areas of central Nepal prompted us to study the spatio-temporal distribution of the vectors of these two diseases along an altitudinal transect in central Nepal.

Methodology/principal findings: We conducted a longitudinal study in four distinct physiographical regions of central Nepal from September 2011 to February 2012. We used BG-Sentinel and CDC light traps to capture adult mosquitoes. We found the geographical distribution of the dengue virus vectors Aedes aegypti and Aedes albopictus along our study transect to extend up to 1,310 m altitude in the Middle Mountain region (Kathmandu). The distribution of the lymphatic filariasis vector Culex quinquefasciatus extended up to at least 2,100 m in the High Mountain region (Dhunche). Statistical analysis showed a significant effect of the physiographical region and month of collection on the abundance of A. aegypti and C. quinquefasciatus only. BG-Sentinel traps captured significantly higher numbers of A. aegypti than CDC light traps. The meteorological factors temperature, rainfall and relative humidity had significant effects on the mean number of A. aegypti per BG-Sentinel trap. Temperature and relative humidity were significant predictors of the number of C. quinquefasciatus per CDC light trap. Dengue fever and lymphatic filariasis cases had previously been reported from all vector positive areas except Dhunche which was free of known lymphatic filariasis cases.

Conclusions/significance: We conclude that dengue virus vectors have already established stable populations up to the Middle Mountains of Nepal, supporting previous studies, and report for the first time the distribution of lymphatic filariasis vectors up to the High Mountain region of this country. The findings of our study should contribute to a better planning and scaling-up of mosquito-borne disease control programmes in the mountainous areas of Nepal.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aedes / growth & development*
  • Animals
  • Culex / growth & development*
  • Dengue / epidemiology
  • Dengue / transmission
  • Ecosystem*
  • Elephantiasis, Filarial / transmission
  • Female
  • Humans
  • Insect Vectors*
  • Longitudinal Studies
  • Male
  • Nepal / epidemiology
  • Spatio-Temporal Analysis

Grants and funding

This research was performed as part of the collaborative research project “A longitudinal study on Aedes mosquitoes and climate change along an altitudinal transect in central Nepal” by the Nepal Health Research Council (NHRC) and the Biodiversity and Climate Research Centre (BiK-F). It was financially supported by the Government of Nepal, a DAAD PhD scholarship to MD and the research funding programme “LOEWE – Landes-Offensive zur Entwicklung wissenschaftlich-ökonomischer Exzellenz” of the Ministry of Higher Education, Research and the Arts of the State of Hesse, Germany. The funding bodies had no role in the study design, data collection, data analysis, interpretation of results, decision to publish or preparation of the manuscript.