Pool screen PCR for estimating the prevalence of Leishmania infantum infection in sandflies (Diptera: Nematocera, Phlebotomidae)

Prevalence studies of infection in the sandfly vector can be used as an indicator of a change in the intensity of Leishmania transmission. However, these studies are difficult to carry out as prevalence in the vector is usually low and its estimation requires a large number of sandflies to be dissected. Our objective was to establish whether a L. infantum-specific PCR-ELISA applied to pools of female sandflies and a previously described algorithm could be useful tools to study the prevalence of infection by this parasite in natural vector populations. We collected sandflies from six collection points in two stable foci of leishmaniasis in southern (N = 3) and north-eastern (N = 3) Spain, following standard procedures. A fraction of the collected females was dissected and morphologically identified. Another fraction was used for pool screening. In total, 127 pools of 30 females (3810 specimens) were studied by PCR-ELISA and 1764 specimens were individually dissected. The prevalence of infection determined by dissection does not differ from that determined by pool screen PCR. The results suggest that pool screen PCR can be of practical use in the epidemiological surveillance of leishmaniasis in European countries of the western Mediterranean basin, associated with control interventions or global change.