Sand Flies and Pathogens in the Lowlands of Emilia-Romagna (Northern Italy)

Abstract

Cases of sand fly-borne diseases in the Emilia-Romagna region, such as meningitis caused by Toscana virus and human leishmaniasis, are reported annually through dedicated surveillance systems. Sand flies are abundant in the hilly part of the region, while the lowland is unsuitable habitat for sand flies, which are found in lower numbers in this environment with respect to the hilly areas. In this study, we retrieved sand flies collected during entomological surveillance of the West Nile virus (from 2018 to 2021) to assess their abundance and screen them for the presence of pathogens. Over the four-year period, we collected 3022 sand flies, more than half in 2021. The most abundant sand fly species was Phlebotomus (Ph.) perfiliewi, followed by Ph. perniciosus; while more rarely sampled species were Ph. papatasi, Ph. mascittii and Sergentomyia minuta. Sand flies were collected from the end of May to the end of September. The pattern of distribution of the species is characterized by an abundant number of Ph. perfiliewi in the eastern part of the region, which then falls to almost none in the western part of the region, while Ph. perniciosus seems more uniformly distributed throughout. We tested more than 1500 female sand flies in 54 pools to detect phleboviruses and Leishmania species using different PCR protocols. Toscana virus and Leishmania infantum, both human pathogens, were detected in 5 pools and 7 pools, respectively. We also detected Fermo virus, a phlebovirus uncharacterized in terms of relevance to public health, in 4 pools. We recorded different sand fly abundance in different seasons in Emilia-Romagna. During the season more favorable for sand flies, we also detected pathogens transmitted by these insects. This finding implies a health risk linked to sand fly-borne pathogens in the surveyed area in lowland, despite being considered a less suitable habitat for sand flies with respect to the hilly areas.

A 10-Year Retrospective Study on Pediatric Visceral Leishmaniasis in a European Endemic Area: Diagnostic and Short-Course Therapeutic Strategies

“…Between November 2012 and May 2013, an outbreak of VL was detected in the regional capital, Bologna; between January and May 2013, there were four of the five reported pediatric cases of VL in 2013, and the fifth of that year was in June [ 6 ]. The cause of this outbreak remains uncertain, although a connection to ongoing climate change has been hypothesized, as raised temperature and dryness in northern Italy are likely responsible for the recent increase in sandfly vectors in the same area [ 6 , 24 , 25 ]. Unlike other Italian regions, such as Sicily, where VL cases occur consistently year-round with no seasonal fluctuations [ 26 ], our area experienced a concentration of cases during the winter months, which is expected as the sandfly transmission period in the Mediterranean area peaks in July–September [ 27 ] and VL exhibits a long incubation period (2–6 months) [ 28 ].…”

Tegumentary Leishmaniasis in Northeastern Italy from 2017 to 2020: A Neglected Public Health Issue

“…Most of the TL cases in the selected region were autochthonous (84% of total cases) and distributed in foothills areas, which are characterized by climatic and environmental conditions more suitable for the occurrence of phlebotomine sand flies as compared to the plain areas of the RER [ 29 ]. Indeed, foothill habitats have previously been reported as supporting large populations of Phlebotomus (Ph).…”

Wildlife Hosts of <em>Leishmania Infantum</em> in a Re-Emerging Focus of Human Leishmaniasis, in Emilia-Romagna, Northeast Italy

“…Recently, anthropophilic rodents have been found to be infected at a prevalence of 11% in plain areas of RER [39], which are historically less involved in human leishmaniasis than the foothill areas. However, the increase in seasonal abundance and the distribution of sand flies due to climate change, together with the detection of Leishmania DNA from lowland sand flies [40], indicate that the role of rodents in the epidemiology of leishmaniasis in RER needs to be monitored and further investigated.…”