Michele Maroli

Phlebotomine sandflies and the spreading of leishmaniases and other diseases of public health concern.

Phlebotomine sandflies transmit pathogens that affect humans and animals worldwide. We review the roles of phlebotomines in the spreading of leishmaniases, sandfly fever, summer meningitis, vesicular stomatitis, Chandipura virus encephalitis and Carrións disease. Among over 800 species of sandfly recorded, 98 are proven or suspected vectors of human leishmaniases; these include 42 Phlebotomus species in the Old World and 56 Lutzomyia species in the New World (all: Diptera: Psychodidae). Based on incrimination criteria, we provide an updated list of proven or suspected vector species by endemic country where data are available. Increases in sandfly diffusion and density resulting from increases in breeding sites and blood sources, and the interruption of vector control activities contribute to the spreading of leishmaniasis in the settings of human migration, deforestation, urbanization and conflict. In addition, climatic changes can be expected to affect the density and dispersion of sandflies. Phlebovirus infections and diseases are present in large areas of the Old World, especially in the Mediterranean subregion, in which virus diversity has proven to be higher than initially suspected. Vesiculovirus diseases are important to livestock and humans in the southeastern U.S.A. and Latin America, and represent emerging human threats in parts of India. Carrións disease, formerly restricted to regions of elevated altitude in Peru, Ecuador and Colombia, has shown recent expansion to non‐endemic areas of the Amazon basin.

Control of phlebotomine sandflies

Abstract. Phlebotomine sandflies (Diptera: Psychodidae) transmit many zoonotic diseases (arboviruses, bartonelloses and especially leishmaniases) of importance to human health in at least 80 countries. Measures used to control adult sandflies (Lutzomyia and Phlebotomus) include the use of insecticides (mostly pyrethroids) for residual spraying of dwellings and animal shelters, space‐spraying, insecticide‐treated nets, impregnated dog‐collars and personal protection through application of repellents/insecticides to skin or fabrics. Because the breeding‐sites of sandflies are generally unknown, control measures that act specifically against immatures are not feasible, although the effectiveness of a few biological and chemical agents has been demonstrated in laboratory evaluations. Reports of insecticide‐resistance refer to only three sandfly species (P. papatasi, P. argentipes and S. shorttii) against DDT in one country (India), although there are reports of DDT‐tolerance in several countries. Current knowledge of sandfly susceptibility to various insecticides is summarized. Constraints and advantages of different compounds, formulations and delivery methods for sandfly control under different environmental conditions are discussed.

The northward spread of leishmaniasis in Italy: evidence from retrospective and ongoing studies on the canine reservoir and phlebotomine vectors

Visceral leishmaniasis (VL) incidence has been increased in Italy in humans and dogs since the 1990s, with new foci being detected within traditional boundaries of endemic transmission but also in northern regions previously regarded as non‐endemic. To monitor the putative VL spreading, surveillance was implemented in northern continental Italy comprising: analysis of human cases recorded from 1990 through 2005; retrospective literature analysis of canine leishmaniasis (CanL) and phlebotomine sandfly records through 2002; prospective investigations in dogs from 2003 through 2005 and surveys on sandflies in 2003 and 2004. Two‐hundred‐thirty human cases (11% of Italian cases) were recorded. Their stratification by age and HIV status disclosed a sharp decrease of HIV/VL co‐infections paralleled by concomitant increase of paediatric and HIV‐negative adult patients during the study period. Four patients had no travel history. Seven leishmaniasis foci were retrospectively identified since 1990, whereas prospective investigations in dogs disclosed 47 autochthonous clinical cases and 106 autochthonous seropositives among 5442 dogs (2.1%) from 16 foci of six regions. Parasites were typed as Leishmania infantum MON‐1. Four vector species were identified among 1696 Phlebotomus (Larroussius) collected specimens. Comparisons with historical data showed that P. perniciosus and P. neglectus have increased in density and expanded their geographic range in the study area. Northern continental Italy is now focally endemic for VL and a moderate risk for human disease does exist, although the intensity of transmission seems to be lower than in traditional settings of Mediterranean VL.

Evidence for an impact on the incidence of canine leishmaniasis by the mass use of deltamethrin-impregnated dog collars in southern Italy.

Abstract. Dogs are the domestic reservoir of Leishmania infantum Nicolle (Kinetoplastida: Trypanosomatidae), the agent of zoonotic human visceral leishmaniasis. In southern Europe, where canine leishmaniasis (CanL) is widespread due to L. infantum, killing seropositive dogs is considered unacceptable and drug treatment has low efficacy in preventing transmission. We made a field evaluation of the efficacy of deltamethrin dog collars in a CanL focus of southern Italy, Mount Vesuvius area of Campania region, where the vector is Phlebotomus perniciosus Newstead (Diptera: Psychodidae), by assessing their impact on the incidence of CanL in an intervention town, compared to that in dogs of control towns where no collars were fitted. During two consecutive transmission seasons, collars were fitted to 350 (1998) and 354 (1999) dogs from San Sebastiano al Vesuvio (70% of the canine population). Control dogs (371 and 264 in the 2 years, respectively) were from four towns of the same area. Before each transmission season, the CanL seroprevalence in the intervention and control towns was evaluated by cross‐sectional surveys and found to be similar (about 15% in 1998 and 10% in 1999, respectively). After each transmission period, incidence rates of seroconversions were determined in adult dogs that were serologically negative before the season under evaluation, and in puppies. After the 1998 season, 2.7% of the dogs in the intervention town seroconverted compared to 5.4% in the control towns (50% protection, P = 0.15). After the 1999 season, 3.5% of collared dogs seroconverted compared to 25.8% of control dogs (86% protection, P < 0.001). The increase in seroconversion rates recorded in control dogs suggests an increase in the Leishmania force of infection in the canine reservoir during the 1999 sandfly season, as supported by the concomitant increase of human cases in control towns and in the whole Campania region. Our results suggest that the impact of mass use of deltamethrin‐impregnated dog collars on the incidence of CanL may be negligible during low transmission seasons, or probably in low endemic foci, but can be very strong when the force of transmission is high.

ITS 2 sequences heterogeneity in Phlebotomus sergenti and Phlebotomus similis (Diptera, Psychodidae): possible consequences in their ability to transmit Leishmania tropica.

An intraspecific study on Phlebotomus sergenti, the main and only proven vector of Leishmania tropica among the members of the subgenus Paraphlebotomus was performed. The internal transcribed spacer 2 (ITS2) sequences of 12 populations from 10 countries (Cyprus, Egypt, Italy, Lebanon, Morocco, Pakistan, Portugal, Spain, Syria, and Turkey) were compared. Samples also included three species closely related to P. sergenti: Phlebotomus similis (three populations from Greece and Malta), Phlebotomus jacusieli and Phlebotomus kazeruni. Our results confirm the validity of the taxa morphologically characterised, and imply the revision of their distribution areas, which are explained through biogeographical events. At the Miocene time, a migration route, north of the Paratethys sea would have been followed by P. similis to colonise the north of the Caucasus, Crimea, Balkans including Greece and its islands, and western Turkey. Phlebotomus sergenti would have followed an Asiatic dispersion as well as a western migration route south of the Tethys sea to colonise North Africa and western Europe. This hypothesis seems to be well supported by high degree of variation observed in the present study, which is not related to colonisation or to intra-populational variation. Two groups can be individualised, one oriental and one western in connection with ecology, host preferences and distribution of L. tropica. We hypothesise that they could be correlated with differences in vectorial capacities.

Host preferences of phlebotomine sand flies at a hypoendemic focus of canine leishmaniasis in central Italy

A survey was carried out on phlebotomine sand flies and their feeding habits at a hypoendemic focus of Leishmania infantum in Macerata province, central Italy. During two consecutive years (2000-2001), 1465 sand fly specimens (42.5% of which were males) were collected from a variety of diurnal resting sites in the municipality of Camerino. The most prevalent species was Phlebotomus perniciosus (76.6%), followed by P. papatasi (10.4%), Sergentomyia minuta (9.1%), Phlebotomus perfiliewi (3.3%) and P. mascittii (0.5%). Among the 842 females collected, 578 (68.6%) were blood-fed. Based on the results of blood meal analyses, P. perniciosus fed on man, dogs, equines, sheep and birds; P. perfiliewi on dogs, equines, sheep and birds; P. papatasi on dogs, equines and birds. Two specimens of P. mascittii fed on equines. Forage ratios (FRs) and host selectivity indices gave different results for the large domestic animals. More than 95% of the specimens collected inside a stable, dog kennel, sheep pen and chicken house were found to have fed on the animals housed in the respective shelters. In addition, at one collecting site where almost all the hosts mentioned above were present simultaneously, both P. perniciosus and P. perfiliewi were found to have fed on all five species, indicating that host choice was probably related to its availability (i.e. number and size) rather than specific attractiveness. The feeding habits of the two Leishmania vectors may have implications for the epidemiology of leishmaniasis in urban and peri-urban areas, where sand fly females deprived of other vertebrate hosts (particularly the larger species) may begin to bite humans and dogs more frequently.

Guidelines for treatment of leishmaniasis in dogs

rug treatment of leishmaniasis in dogs is a chal-lenge for veterinary practitioners. Because of its complex pathogenesis, leishmaniasis may manifest with various clinical signs, ranging from mild and nonspe-cific to those reflecting severe involvement of several organs. The immune response plays an important role in the development, outcome, and response to treat-ment of

Molecular homogeneity in diverse geographical populations of Phlebotomus papatasi (Diptera, Psychodidae) inferred from ND4 mtDNA and ITS2 rDNA Epidemiological consequences.

An intraspecific study on Phlebotomus papatasi, the main proven vector of Leishmania major among the members of the subgenus Phlebotomus, was performed. The internal transcribed spacer 2 (ITS 2) of rDNA and the ND4 gene of mt DNA were sequenced from 26 populations from 18 countries (Albania, Algeria, Cyprus, Egypt, Greece, India, Iran, Israel, Italy, Lebanon, Morocco, Saudi Arabia, Spain, Syria, Tunisia, Turkey, Yugoslavia and Yemen), and compared. Samples also included three other species belonging to the subgenus Phlebotomus: P. duboscqi, a proven vector of L. major in the south of Sahara (three populations from Burkina Faso, Kenya and Senegal), P. bergeroti, a suspected vector of L. major (three populations from Oman Sultanate, Iran and Egypt), and one population of P. salehi from Iran. A phylogenetic study was carried out on the subgenus Phlebotomus. Our results confirm the validity of the morphologically characterized taxa. The position of P. salehi is doubtful. Variability in P. papatasi contrasts with that observed within other species having a wide distribution like P. (Paraphlebotomus) sergenti in the Old World or Lutzomyia (Lutzomyia) longipalpis in the New World. Consequently, it could be hypothesized that all populations of P. papatasi over its distribution area have similar vectorial capacities. The limits of the distribution area of L. major are correlated with the distribution of common rodents acting as hosts of the parasites.

Canine Leishmaniasis, Italy

We report the results of a survey to determine the prevalence of canine leishmaniasis and the presence of sand flies in northwestern Italy, where autochthonous foci of canine leishmaniasis have not been reported. Active foci of canine leishmaniasis were identified, which suggests that the disease is now also endemic in continental climate areas.

Host-feeding patterns of aedes albopictus (Diptera: Culicidae) in urban and rural contexts within Rome province, Italy

Knowledge of the frequency of contact between a mosquito species and its different hosts is essential to understand the role of each vector species in the transmission of diseases to humans and/or animals. However, no data are so far available on the feeding habits of Aedes albopictus in Italy or in other recently colonized temperate regions of Europe, due to difficulties in collecting blood-fed females of this diurnal and exophilic species. We analyzed Ae. albopictus host-feeding patterns in two urban and two rural sites within the area of Rome (Italy). Ae. albopictus was collected using sticky-traps and the blood-meal origin of 303 females was determined by direct dot-ELISA. The blood-fed sample, although representing only 4% of the total Ae. albopictus collected, demonstrates the useful application of sticky-trap in studying the feeding behavior of the species. The human blood index was significantly different among sites, ranging from 79-96% in urban sites to 23-55% in rural sites, where horses and bovines represented the most bitten hosts. The results obtained confirm the plastic feeding behavior shown by Ae. albopictus in its original range of distribution and highlights the high potential of this species as a vector of human pathogens in urban areas of Italy, where both humans and the mosquito itself may reach very high densities.