Abstract:
Cutaneous leishmaniasis (CL) is an endemic public health problem in Sri Lanka.
Leishmania donovani is the suspected causative agent of the disease and this parasite
is transmitted by a dipteran fly species; Phlebotomus argentipes. Studies on vector
behavioral and ecological aspects, although important for better understanding of
disease transmission, are still limited. The present study is an attempt to uncover the
vector ecological aspects focusing on the successful vector control interventions.
This study is being carried out in Anuradhapura district, Sri Lanka; where there is a
high disease prevalence of CL. Three sampling sites; Thalawa, Wijayapura and
Padawiya were selected. Adult sand flies were collected monthly over a six months
duration using CDC light traps (5) and yellow sticky traps (30). In the meantime,
relative humidity and air temperature were measured using hygrometer and
thermometer in each site. The collected sand flies were identified up to the species
level using standard keys. Percentage composition of each of the species was
calculated. Temporal variations of primary vector, Phlebotomus argentipes along
with the dynamics of temperature and relative humidity was determined using
regression analysis.
Phlebotomus argentipes was the dominant sand fly species found in the study sites.
The percentage composition of the primary vector exhibited a variation during the
study period and maximum percentage composition was recorded during May and
June, 2016. The relationship between percentage composition of Ph.argentipes
versus mean temperature was significant (P = 0.000, R2 = 97.7%) and elevated
percentage composition were recorded under lower temperature. Further, percentage
composition of Ph.argentipes exhibited an increasing trend with higher humidity
levels (P = 0.000, R2= 98.4%). In conclusion, the primary vector populations of
leishmaniasis are increased with lower temperature and higher humidity. As such,
this relationship will helpful to predict the variation of vector population with the
changes of ecological parameters and finally a successful vector management
strategy can be implemented with the thorough knowledge of its life history
parameters and behavioral pattern.
