Marco Di Luca

Experimental studies of susceptibility of Italian Aedes albopictus to Zika virus.

We report a study on vector competence of an Italian population of Aedes albopictus for Zika virus (ZIKV). Ae. albopictus was susceptible to ZIKV infection (infection rate: 10%), and the virus could disseminate and was secreted in the mosquitos saliva (dissemination rate: 29%; transmission rate: 29%) after an extrinsic incubation period of 11 days. The observed vector competence was lower than that of an Ae. aegypti colony tested in parallel.

First report in italy of the exotic mosquito species Aedes (Finlaya) koreicus, a potential vector of arboviruses and filariae

BackgroundIn the Veneto region (north-eastern Italy) an entomological surveillance system has been implemented since the introduction of the Asian tiger mosquito (Aedes albopictus) in 1991. During the routine monitoring activity in a tiger mosquito-free area, an unexpected mosquito was noticed, which clearly did not belong to the recorded Italian fauna.FindingsAt the end of May 2011, twelve larvae and pupae were collected in a small village in Belluno province (Veneto region) from a single manhole. Ten adults reared in the laboratory were morphologically and genetically identified as Aedes (Finlaya) koreicus (Edwards, 1917), a species native to Southeast Asia. The subsequent investigations carried out in the following months in the same village provided evidence that this species had become established locally. Entomological and epidemiological investigations are currently ongoing in the surrounding area, to verify the eventual extension of the species outside the village and to trace back the route of entry into Italy.ConclusionsThis is the first report in Italy of the introduction of the exotic mosquito Ae. koreicus. This species has been shown experimentally to be competent in the transmission of the Japanese encephalitis virus and of the dog heartworm Dirofilaria immitis and is considered a potential vector of other arboviruses. Thus, the establishment of this species may increase the current risk or pose new potential threats, for human and animal health. This finding considerably complicates the entomological monitoring of the Asian tiger mosquito Ae. albopictus in Italy and stresses the importance of implementing the entomological surveillance for the early detection of and the rapid response against invasive mosquito species.

Understanding West Nile virus ecology in Europe: Culex pipiens host feeding preference in a hotspot of virus emergence

BackgroundUnderstanding wildlife disease ecology is becoming an urgent need due to the continuous emergence and spread of several wildlife zoonotic diseases. West Nile Virus (WNV) is the most widespread arthropod-borne virus in the world, and in recent decades there has been an increase both in geographic range, and in the frequency of symptomatic infections in humans and wildlife. The principal vector for WNV in Europe is the common house Culex pipiens mosquito, which feeds on a wide variety of vertebrate host species. Variation in mosquito feeding preference has been described as one of the most influential parameters driving intensity and timing of WNV infection in the United States, but feeding preferences for this species have been little studied in Europe.MethodsHere, we estimated feeding preference for wild Cx. pipiens in northern Italy, using molecular analysis to identify the origin of blood meals, and avian census to control host abundance variations. Additionally, we used host bird odour extracts to test experimentally mosquito preferences in the absence of environmental variations.ResultsFor the first time, we demonstrate a clear feeding preference for the common blackbird (Turdus merula), both for wild collected specimens and in the lab, suggesting a potential important role for this species in the WNV epidemiology in Europe. A seasonal decrease in abundance of blackbirds is associated with increased feeding on Eurasian magpies (Pica pica), and this may be linked to seasonal emergence of WNV in humans. Feeding preferences on blackbirds are more marked in rural areas, while preference for magpies is higher in peridomestic areas. Other species, such as the house sparrow (Passer domesticus) appear to be selected by mosquitoes opportunistically in relation to its abundance.ConclusionsOur findings provide new insights into the ecology of Cx. pipiens in Europe and may give useful indications in terms of implementing targeted WNV surveillance plans. However, a clearer understanding of spatio-temporal variations of Cx. pipiens feeding preferences, and targeted studies on reservoir competence for WNV for these species are therefore now urgently needed as this is essential to describe disease dynamics and quantify virus transmission risk.

Experimental investigation of the susceptibility of Italian Culex pipiens mosquitoes to Zika virus infection.

We investigated the susceptibility of an Italian population of Culex pipiens mosquitoes to Zika virus (ZIKV) infection, tested in parallel with Aedes aegypti, as a positive control. We analysed mosquitoes at 0, 3, 7, 10, 14, 20 and 24 days after an infectious blood meal. Viral RNA was detected in the body of Cx. pipiens up to three days post-infection, but not at later time points. Our results indicate that Cx. pipiens is not susceptible to ZIKV infection.

Intrapopulation Polymorphism in Anopheles messeae (An. maculipennis Complex) Inferred by Molecular Analysis

Abstract We evaluated the internal transcribed spacer two (ITS2) sequence to detect intraspecific polymorphism in the Palearctic Anopheles maculipennis complex, analyzing 52 populations from 12 countries and representing six species. For An. messeae, two fragments of the cytochrome oxidase I (COI) gene were also evaluated. The results were compared with GenBank sequences and data from the literature. ITS2 analysis revealed evident intraspecific polymorphism for An. messeae and a slightly less evident polymorphism for An. melanoon, whereas for each of the other species, 100% identity was found among populations. ITS2 analysis of An. messeae identified five haplotypes that were consistent with the geographical origin of the populations. ITS2 seems to be a reliable marker of intraspecific polymorphism for this complex, whereas the COI gene is apparently uninformative.

Detection of a chikungunya outbreak in Central Italy, August to September 2017

An autochthonous chikungunya outbreak is ongoing near Anzio, a coastal town in the province of Rome. The virus isolated from one patient and mosquitoes lacks the A226V mutation and belongs to an East Central South African strain. As of 20 September, 86 cases are laboratory-confirmed. The outbreak proximity to the capital, its late summer occurrence, and diagnostic delays, are favouring transmission. Vector control, enhanced surveillance and restricted blood donations are being implemented in affected areas.

Genetic and phenotypic variation of the malaria vector Anopheles atroparvus in southern Europe.

BackgroundThere is a growing concern that global climate change will affect the potential for pathogen transmission by insect species that are vectors of human diseases. One of these species is the former European malaria vector, Anopheles atroparvus. Levels of population differentiation of An. atroparvus from southern Europe were characterized as a first attempt to elucidate patterns of population structure of this former malaria vector. Results are discussed in light of a hypothetical situation of re-establishment of malaria transmission.MethodsGenetic and phenotypic variation was analysed in nine mosquito samples collected from five European countries, using eight microsatellite loci and geometric morphometrics on 21 wing landmarks.ResultsLevels of genetic diversity were comparable to those reported for tropical malaria vectors. Low levels of genetic (0.004 <FST<0.086) and phenotypic differentiation were detected among An. atroparvus populations spanning over 3,000 km distance. Genetic differentiation (0.202 <FST<0.299) was higher between the sibling species An. atroparvus and Anopheles maculipennis s.s. Differentiation between sibling species was not so evident at the phenotype level.ConclusionsLevels of population differentiation within An. atroparvus were low and not correlated with geographic distance or with putative physical barriers to gene flow (Alps and Pyrenées). While these results may suggest considerable levels of gene flow, other explanations such as the effect of historical population perturbations can also be hypothesized.

Assessment of the risk of malaria re-introduction in the Maremma plain (Central Italy) using a multi-factorial approach

AbstractKeywords: Mosquito-borne diseases, Residual anophelism, Anopheles labranchiae, Vectorial capacity, Climatechange, Plasmodium falciparum, Experimental infectionBackgroundIn recent years, the increase in globalization [1], the risein the average temperature of the earth together with anincreasing frequency and intensity of extreme weatherevents, as storms, floods and droughts [2,3], and theenvironmental changes induced by human activities [4],have raised the concern about the possible introductionor reintroduction of Vector Borne Diseases in Countrieswhere these were absent or eradicated [5]. These con-siderations, coupled with the recent spread of somemosquito vector borne diseases in Europe [6,7] and theincreasing number of imported malaria cases recordedin the Continent [8] have renewed interest in the possi-ble reintroduction of malaria in Southern Europe [7-9],particularly in the countries facing the Western Medi-terranean Basin, where potential Anopheline vectors arestill present [10-13]. Moreover, in recent years auto-chthonous malaria cases have been sporadically reportedin Italy, France, Spain and Greece [14-20].In 2005, a five-year study was implemented in Italy, aswell as in other South European countries, with the aim toassess the status of the local potential malaria vectors andthe possible re-introduction of malaria transmission[21-25]. In Italy, the selected study area was the Maremmaplain, a region that was hyperendemic for malaria until60 years ago [26-28] and that more recently was recog-nized as the major “at risk” area for the malaria reintro-duction into Italy [14,29,30].In Maremma, after the malaria eradication campaign(1947-1951), Anopheles labranchiae, the main endophilicvector of the Anopheles maculipennis complex was dra-matically reduced in abundance. However, in subsequentyears, the species has progressively re-colonized most ofthe area coming back to substantial densities [31-33].This was mainly due to the introduction of intensive ricecultivation in the early 1970s. Since then, Maremma hasbeen subjected to continuous entomological surveillancethat was intensified after1997, when an autochthonousPlasmodium vivax malaria case, transmitted byAn. lab-ranchiae, occurred in the Province of Grosseto [14]. Thestudies carried out in the area since eradication, providesa database that allowed a follow-up the history of malariaand its vectors in Maremma over the past 60 years. Start-ing from the findings of the most recent entomologicaland environmental studies [23,34], the present study waschosen to evaluate the malariogenic potential of the areausing a multifactorial approach.Methods

Prevalence of tick-borne pathogens in an urban park in Rome, Italy

INTRODUCTION Limited information is available about the presence of tick-borne pathogens in urban parks in Italy. To fill this gap, ticks were collected in a public park in Rome over a 1-year period and screened by molecular methods for tick-borne pathogens. RESULTS AND CONCLUSION The most abundant tick species were Rhipicephalus turanicus and Ixodes ricinus. The predominant pathogens detected were Borrelia. burgdorferi sensu lato (36%), Rickettsia spp. (36%), and Coxiella burnetii (22%). Among less frequently detected pathogens, Babesia microti was detected for the first time in Italy, with a prevalence of 4%. Neither Bartonella spp. nor Francisella tularensis were detected. With regard to co-infections, the most frequent double and triple infections involved Rickettsia spp., B. burgdorferi sl., and C. burnetii.. A positive correlation was detected between pathogens and I. ricinus. Further studies are needed in order to assess risk associated with tick-borne pathogens in urban areas.

A 2-year entomological study of potential malaria vectors in Central Italy.

Europe was officially declared free from malaria in 1975; nevertheless, this disease remains a potential problem related to the presence of former vectors, belonging to the Anopheles maculipennis complex. Autochthonous-introduced malaria cases, recently reported in European countries, together with the predicted climatic and environmental changes, have increased the concern of health authorities over the possible resurgence of this disease in the Mediterranean Basin. In Italy, to study the distribution and bionomics of indigenous anopheline populations and to assess environmental parameters that could influence their dynamics, an entomological study was carried out in 2005-2006 in an at-risk study area. This model area is represented by the geographical region named the Maremma, a Tyrrhenian costal plain in Central Italy, where malaria was hyperendemic up to the 1950s. Fortnightly, entomological surveys (April-October) were carried out in four selected sites with different ecological features. Morphological and molecular characterization, blood meal identification, and parity rate assessment of the anophelines were performed. In total, 8274 mosquitoes were collected, 7691 of which were anophelines. Six Anopheles species were recorded, the most abundant of which were Anopheles labranchiae and An. maculipennis s.s. An. labranchiae is predominant in the coastal plain, where it is present in scattered foci. However, this species exhibits a wider than expected range: in fact it has been recorded, for the first time, inland where An. maculipennis s.s. is the most abundant species. Both species fed on a wide range of animal hosts, also showing a marked aggressiveness on humans, when available. Our findings demonstrated the high receptivity of the Maremma area, where the former malaria vector, An. labranchiae, occurs at different densities related to the kind of environment, climatic parameters, and anthropic activities.