Persistence of phlebotomine Leishmania vectors in urban sites of Catania (Sicily, Italy)

Abstract

BackgroundPioneering research on “Mediterranean Kala-Azar” carried out by Adler and Theodor early in the past century (~1930s) had identified Catania city (Sicily) as a major focus of the disease nowadays known as zoonotic visceral leishmaniasis (VL). Despite the fact that disease in both humans and dogs has continued to be highly prevalent in the Catania province up to the present times, research on Leishmania vectors in this urban focus dates back to that distant period. This study aimed to evaluate the persistence and current composition of the sand fly fauna in urban environments of Catania in recent years, 2006 and 2013.MethodsIn 2006 fifty-one suitable collecting sites were identified within 44 sub-units of a grid drawn to include the urban Catania area. In 2013 the survey was restricted to four of the most productive and representative sites resulting from the 2006 survey. In both periods 3 collections per month were performed using standard sticky traps set for 3 days in wall holes/cavities along public roads, from the end of April through December.Results43/51 sites (84.3%) were found positive for sand flies. The 2006 collections accounted for a total of 4341 specimens including six species. Among competent Leishmania vector species, P. perniciosus was the most prevalent (36.5%) being identified in all sand fly-positive sites, with significant abundance in those of the old city centre. Other species of interest were P. sergenti (2.5%) and P. neglectus (1.5%). The 2013 survey produced 1130 sand flies, of which 39.5% were P. perniciosus, 1.6% P. sergenti and 0.7% P. neglectus. A search for Leishmania DNA in a small sample of 72 P. perniciosus females revealed 11% infection prevalence.ConclusionsOur findings from an old urban focus of leishmaniasis demonstrate that phlebotomine sand flies have adapted fairly well to the drastic environmental changes that have occurred in cities of the Western world in the past century and still represent a potential risk for Leishmania transmission.

Identification of trypanosomatids and blood feeding preferences of phlebotomine sand fly species common in Sicily, Southern Italy

“…Four out of five sand fly species analysed in this study are proven vectors of human leishmaniosis. Among the genus Phlebotomus, P. perniciosus was the most abundant species, which is in agreement with other entomological surveys conducted in Southern Italy [13,29,[37][38], and the presence of L. donovani complex DNA in P. perniciosus herein reported confirms the role of this species in the maintenance and spread of leishmaniosis in the Mediterranean area. Only a single P. perniciosus (0.2%; n = 594) tested positive for L. donovani complex.…”

“…Only a single P. perniciosus (0.2%; n = 594) tested positive for L. donovani complex. To the best of our knowledge, the sole data on the prevalence infection for L. infantum in P. perniciosus in Sicily came from a study conducted in the city of Catania where a higher infection rate (i.e., 11%; 8/72) has been detected [13]. This difference may be related to the high endemicity of leishmaniosis in the area of Catania [11,13] and suggest that the risk of transmission of Leishmania can be high even in urban areas.…”

“…It is a well-known hyper-endemic region for CanL with a prevalence of infection up to 40% in dogs which are regarded as the main domestic reservoir hosts and source for human infection [10][11]. According to available entomological surveys on L. infantum vectors in Sicily, P. perniciosus has been recognized as the most abundant species, with P. neglectus and P. perfiliewi much less frequently detected [12][13][14]. The presence of P. sergenti has also been sporadically reported along the east side of the Island [12][13][14] implying the risk for L. tropica transmission.…”

“…According to available entomological surveys on L. infantum vectors in Sicily, P. perniciosus has been recognized as the most abundant species, with P. neglectus and P. perfiliewi much less frequently detected [12][13][14]. The presence of P. sergenti has also been sporadically reported along the east side of the Island [12][13][14] implying the risk for L. tropica transmission. Although no autochthonous cutaneous leishmaniosis cases (ACL) caused by L. tropica have been detected in south-western Europe so far, Sicily is an area potentially susceptible to the introduction of this protozoan species due to its proximity to northern Morocco, an emerging ACL area [15], and to the large migratory flow of people between the two territories.…”

Persistence of phlebotomine Leishmania vectors in urban sites of Catania (Sicily, Italy)

“…Preliminary findings from this study have been presented to the 6 th International Symposium on Phlebotomine Sandflies, Lima, Perù [32]. We warmly thank Dr Fabrizio Vitale of the "Istituto Zooprofilattico Sperimentale della Sicilia" for providing data on CanL serodiagnosis in the province of Catania.…”