Environmental risk modelling and potential sand fly vectors of cutaneous leishmaniasis in Chitral district: a leishmanial focal point of mount Tirich Mir, Pakistan

Trop Med Int Health. 2017 Sep;22(9):1130-1140. doi: 10.1111/tmi.12916. Epub 2017 Jul 27.

Abstract

Objective: To provide baseline information about suspected vectors and the incidence, distribution and an active zone of transmission for cutaneous leishmaniasis (CL) in Chitral, Pakistan, using GIS tools; and to investigate the role of environmental factors in the disease dynamics.

Method: Two surveys in 2014 and 2016 as a basis for choropleth and environmental risk mapping.

Results: A total of 769 captured specimens yielded 14 Phlebotomus and six Sergentomyia species including two potential vectors of CL, i.e. Phlebotomus papatasi and Phlebotomus sergenti. P. papatasi (71%) was dominant, followed by P. sergenti (18%). A choropleth map generated in Arcmap 10.1 based on 1560 CL case reports displayed maximum prevalence (0.92-2.5%) in Ayun, Broz, Charun, Chitral 1 and 2 and Darosh 1 and 2 union councils. An environmental risk map constructed by MaxEnt 3.3.3 defined an active zone of transmission based on leishmaniasis occurrence records (n = 315). The analysis of variable contribution in MaxEnt indicates significance of elevation (54.4%), population density (23.3%) and land use/land cover (6.6%) in CL disease dynamics.

Conclusion: The probability of CL increases (0.6-1 on logistic scale) in severely deforested areas, in lowland valleys and in regions with high-population density.

Keywords: Chitral; Leishmaniose; Leishmaniosis; MaxEnt; Pakistan; Paquistán; Phlébotomes; leishmaniasis; moscas de arena; sand-flies.

MeSH terms

  • Altitude
  • Animals
  • Conservation of Natural Resources
  • Environment*
  • Female
  • Housing
  • Humans
  • Insect Vectors*
  • Leishmania*
  • Leishmaniasis, Cutaneous / epidemiology
  • Leishmaniasis, Cutaneous / parasitology
  • Leishmaniasis, Cutaneous / transmission*
  • Male
  • Pakistan / epidemiology
  • Phlebotomus
  • Population Density
  • Psychodidae / parasitology*
  • Risk
  • Surveys and Questionnaires