Geospatial and Climatic Patterns Associated With the Distribution of Sand Fly (Diptera: Psychodidae) Vectors of Leishmaniasis in Pakistan

Abstract

We provide a comprehensive and updated review on the effects of elevation and climatic factors on distribution of sand fly (Diptera: Psychodidae) vectors of cutaneous leishmaniasis (CL) and visceral leishmaniasis (VL) across Pakistan. Our study was undertaken in view of the increasing risk of leishmaniasis, particularly resulting from climatic deviations and political instability in the region. Literature (published and unpublished) on suspected vectors of CL (Phlebotomus sergenti Parrot and Phlebotomus papatasi Scopoli) and VL (Phlebotomus major Yakimoff and Schokhor and Phlebotomus hindustanicus Theodor) was collected, sorted, and utilized in geospatial analysis. P. papatasi and P. sergenti co-occurred in majority of the referenced localities and were generally distributed toward the western and southern parts across a wide range of elevation, whereas P. major and P. hindustanicus were limited to high elevation in cool and humid northern areas of Pakistan. Conversely P. papatasi and P. sergenti exploited diverse ecological settings across the country, being particularly abundant in warm/hot and arid regions.

Characterization of sand fly breeding sites in district Malakand, Khyber Pakhtunkhwa, Pakistan, and evaluation of risk factors for cutaneous leishmaniasis in the region

“…Among the collected sand fly species, P. sergenti was the most abundant species in the study area. This species is a suspected vector of L. tropica, since its distribution coincides with anthroponotic CL (ACL) in the country (usually caused by L. tropica) (Ali et al, 2016;Khan et al, 2018), and possibly in the study area. Among the other species, P. papatasi is a suspected vector of zoonotic CL (ZCL) in Pakistan (usually caused by L. major) and elsewhere (Khan et al, 2018).…”

“…This species is a suspected vector of L. tropica, since its distribution coincides with anthroponotic CL (ACL) in the country (usually caused by L. tropica) (Ali et al, 2016;Khan et al, 2018), and possibly in the study area. Among the other species, P. papatasi is a suspected vector of zoonotic CL (ZCL) in Pakistan (usually caused by L. major) and elsewhere (Khan et al, 2018). Although their specimens were not abundant in the collection, their presence could represent a potential threat in spread of ZCL in the district.…”

“…Previous studies report P. sergenti numbers to positively correlate with high elevation (Boussaa et al, 2016). In Pakistan, this species is usually observed in abundance at high altitudes (Khan et al, 2018). Phlebotomus papatasi was recorded in the same elevation ranges in Malakand, however, studies report that this species can be preferably observed in abundance at low elevation within the country (Khan et al, 2019).…”

“…Although major portion of the country is still unexplored including the present study area (Ali et al, 2016). Among the recorded species, P. sergenti and Phlebotomus papatasi are the suspected vectors of CL in the region (Khan et al, 2018). Sand fly natural breeding sites, particularly for vector species are poorly investigated since these are the sites where the adult flies probably exist too .…”

“…In Pakistan leishmaniasis, particularly cutaneous leishmaniasis (CL) is widely spread, and major outbreaks are reported in areas neighbouring endemic countries, such as Iran and Afghanistan (Bhutto et al, 2009). The disease is now suspected to be spreading from endemic to non-endemic foci and is thus posing serious challenges for medical entomologists and epidemiologists (Khan et al, 2018). Major outbreaks of CL in various Afghan camps started soon after the mass migration of Afghan Refugees (coming from a country endemic for CL) in 1988.…”