Epidemiological aspects of cutaneous leishmaniasis in the Iguazú falls area of Argentina

Over the last three decades the incidence of American cutaneous leishmaniasis (ACL) has increased sharply in Argentina and throughout the world. In the Iguazú Falls area, on the border between Brazil and Paraguay, the incidence of human ACL has risen since 2004. Most of the 36 cases of human ACL reported until 2005 have involved males over 15 years old (75%) infected during deforestation to establish individual farms. Captures carried out in primary forest, periurban areas, and deforested land sites yielded 18,438 sand flies belonging to 13 species; the most prevalent species were Lutzomyia (Nyssomyia) whitmani (87.4%) and Lutzomyia (Mygonemyia.) migonei (7.6%). Cluster analysis was used to group traps according to species and abundance of sand flies. The group of traps located in recently deforested places, in pig and chicken dwellings of houses where ACL cases had been reported in the past, and at one house with an active ACL case, had the highest abundance of Lu. whitmani and Lu. whitmani + Lu. migonei as well as the highest ratio of Lu. whitmani/Lu. migonei. Leishmania sp. infections, both in Lu. whitmani, in Lu. quinquefer, and in smears from human cases were detected by DNA kinetoplast amplification using a generic PCR protocol. The risk of ACL outbreak in the Iguazú Falls area is still associated with economic and leisure activities in primary-secondary forest, including deforestation, rural settlements, fishing, hunting, and ecotourism. In addition, the risk of periurban transmission seems likely, and this is discussed within the framework of surveillance and prevention strategies.     

Phlebotomine sand fly population dynamics in a leishmaniasis endemic peri-urban area in southern Italy

A 2-year survey was carried out from May to November 2008 and 2009 to study the sand fly species composition, its seasonal phenology and density in Apulia region (southern, Italy). The study was conducted in a dog shelter located in a new residential urban district where Leishmania infantum is endemic. Sand flies were collected using sticky traps from May to November, at about 7-day intervals. Temperature and relative humidity were recorded daily. In December 2008, general environmental improvements (e.g., the ground was covered with gravel and the vegetation present inside the cages was removed to facilitate cleaning) were made in the study area. The most diffused species during the whole study period were Phlebotomus perniciosus (2008, n = 248, 49.4%; 2009, n = 254, 50.6%) followed by Phlebotomus neglectus (2008, n = 76, 39.8%; 2009, n = 115, 60.2%) and Phlebotomus papatasi (2008, n = 5, 50.0%; 2009, n = 5, 50.0%). Four specimens of Phlebotomus perfiliewi were collected only in the first year. The number of Sergentomyia minuta specimens collected increased considerably in the second (n = 548, 86.2%) in comparison to the first year (n = 88, 13.8%). The highest number of phlebotomine sand flies was collected in July and August when a mean temperature from 27.09 to 28.02 °C and mean relative humidity from 47.28 to 56.36% were recorded. The variations in phlebotomine sand fly species diversity and abundance recorded in this study were related to climatic and environmental factors. Data here presented confirm that sand flies easily adapt to the urban environments and that the may represent a public health concern for L. infantum and other pathogen transmission also in similar urban environment of southern Europe.     

Distribution of Lutzomyia ayacuchensis, the vector of Andean-type cutaneous leishmaniasis,at different altitudes on the Andean slope of Ecuador

Distribution of the vector species is a major risk factor for the endemicity of leishmaniasis. In the present study, the vertical distribution of Lutzomyia (Lu.) ayacuchensis, the vector of Leishmania (Leishmania) mexicana in the Ecuadorian Andes, was surveyed at different altitudes (300–2500 m above sea level) of the Andean slope. The vector species Lu. ayacuchensis was identified at an altitude of 650 m and a higher areas, and higher distribution ratio of the species was observed at higher altitudes. In addition, high ratios of L. (L.) mexicana infection were detected in higher areas, but none in lower populations of sand flies. Since an association between sand fly populations and vector competence is suggested in Lu. ayacuchensis, haplotype analysis was performed on the species from different altitudes of the study areas; however, no apparent difference was observed among populations. These results suggested that Lu. ayacuchensis in Andean slope areas of Ecuador has the potential to transmit L. (L.) mexicana and spread leishmaniasis in these areas.     

Observations on the feeding habits of Lutzomyia longipalpis (Lutz & Neiva, 1912) (Diptera: Psychodidae: Phlebotominae) in Campo Grande, an endemic area of visceral leishmaniasis in Mato Grosso do Sul, Brazil

Sand flies were captured weekly with CDC light traps from December 2003 to November 2005 in three areas of Campo Grande, in the Brazilian state of Mato Grosso do Sul. These areas incorporated two patches of remnant forest and five houses. The blood meals of engorged female sand flies were identified using the avidin-biotin system of immunoenzymatic ELISA capture. Most (327/355) of the females analysed were Lutzomyia longipalpis, of which 66.4% reacted with human blood, 64.8% with that of birds and 8.9% with that of dogs. Females that had taken human blood predominated in the residential areas and two forest patches. The following combinations of blood were also detected for L. longipalpis in some of the samples analysed: bird + human (43.4%), bird + human + dog (6.1%). The combination bird + human + dog + pig was also found for Nyssomyia whitmani. Dogs and pigs appear to have little attractiveness for L. longipalpis. The results obtained demonstrate the eclecticism and high anthropophily of L. longipalpis and raise new questions with regard to the importance of dogs in VL epidemiology and the possible role of man as a source of infection for sand flies.     

Phlebotomine fauna in the urban area of Timóteo,State of Minas Gerais,Brazil

This work is characterized by an entomological research and an investigation on whether seasonal behaviours can be associated to the phlebotomine fauna found in the urban area of Timóteo-MG – an endemic focus of tegumentary leishmaniasis (TL). The analysis of the seasonal behaviour of sand flies has taken into account the following climatic variables: rainfall, relative humidity and temperature. Automatic light traps were installed in households between 2009 and 2010. The sand fly species with the highest number captured was Lutzomyia whitmani (66.5%), a TL vector species, whose abundance has provided strong evidences that this species is the main vector of TL in the municipality of Timóteo, with its cycle of transmission developing in its urban area. Amongst the results observed in the analyses of seasonal behaviour, only temperature conveyed particular association between seasonal occurrence of sand flies and climate variables. The findings of this study may assist the local epidemiological surveillance agency in defining strategies and directing efforts for controlling these insects.     

Blood meal identification and parasite detection in laboratory-fed and field-captured Lutzomyia longipalpis by PCR using FTA databasing paper

The phlebotomine sand fly Lutzomyia longipalpis takes blood from a variety of wild and domestic animals and transmits Leishmania (Leishmania) infantum chagasi, etiological agent of American visceral leishmaniasis. Blood meal identification in sand flies has depended largely on serological methods but a new protocol described here uses filter-based technology to stabilise and store blood meal DNA, allowing subsequent PCR identification of blood meal sources, as well as parasite detection, in blood-fed sand flies. This technique revealed that 53.6% of field-collected sand flies captured in the back yards of houses in Teresina (Brazil) had fed on chickens. The potential applications of this technique in epidemiological studies and strategic planning for leishmaniasis control programmes are discussed.     

First human cases of Leishmania (Viannia) naiffi infection in Ecuador and identification of its suspected vector species

Epidemiological surveillance of leishmaniasis was conducted in a northern Amazonian region of Ecuador, in which cutaneous leishmaniasis cases were recently reported. Sand flies were captured in the military training camp, and the natural infection of sand flies by Leishmania species was examined. Out of 334 female sand flies dissected, the natural infection by flagellates was microscopically detected in 3.9% of Lutzomyia yuilli yuilli and 3.7% of Lutzomyia tortura, and the parasite species were identified as Endotrypanum and Leishmania (Viannia) naiffi, respectively. After the sand fly surveillance, specimens from cutaneous leishmaniasis (CL) patients considered to have acquired the infection in the training camp area were obtained, and the infected parasite species were identified as L. (V.) naiffi. The present study reported first cases of CL caused by L. (V.) naiffi infection in Ecuador. In addition, a high ratio of infection of Lu. tortura by L. (V.) naiffi in the same area strongly suggested that Lu. tortura is responsible for the transmission of L. (V.) naiffi in this area.     

Lutzomyia migonei as putative vector of visceral leishmaniasis in La Banda, Argentina

Four autochthonous cases of human visceral leishmaniasis (VL) were reported in La Banda, Santiago del Estero from June 2007 to May 2008. In the vicinity of these cases there were 3/47 rK39 sero-positive dogs, and another 4 dogs with VL were reported by passive surveillance. The sero-positive dogs and infected humans lived within a 3.1 km radius. Phebotomine sand fly captures were performed twice during November/December 2007 and April 2008. In 20 of the 59 sampled sites in the areas of the human and canine cases (220 night/traps) 151 phlebotomine sand flies were collected and consisted of: Lutzomyia migonei 93%, Lutzomyia cortelezzii 5.6% and Lutzomyia neivai 1.4%. We propose that there was an enzootic cycle of VL with accidental human transmission due to L. migonei and suggest that there be a surveillance of human isolated cases of VL within the L. migonei dispersion area.     

Man-biting sand fly species and natural infection with the Leishmania promastigote in leishmaniasis-endemic areas of Ecuador

A countrywide surveillance of sand flies was performed to obtain information on their geographical distribution and natural infection by Leishmania protozoa in Ecuador. A total of 18,119 sand flies were collected by human landing collections during 32 years from 1982 to 2014, and 29 species were recognized. The most prevalent 10 species were Lutzomyia gomezi, Lu. robusta, Lu. hartmanni, Lu. shannoni, Lu. trapidoi, Lu. panamensis, Lu. maranonensis, Lu. ayacuchensis, Lu. tortura and Lu. yuilli yuilli, and their topographical and vertical distributions were identified. Among all the sand flies, only 197 (1.09%) flies of four Lutzomyia species, Lu. gomezi, Lu. trapidoi, Lu. tortura and Lu. ayacuchensis, were positive for Leishmania. Endotrypanum, a flagellate parasite not pathogenic to humans, were detected in five Lutzomyia species, Lu. robusta, Lu. hartmanni, Lu. trapidoi, Lu. panamensis and Lu. yuilli yuilli, suggesting wide vector-ranges of Endotrypanum species. These data on the genus Lutzomyia and their natural infections with Leishmania and Endotrypanum will be useful for transmission studies and surveillance of leishmaniasis.     

Study of sand flies (Diptera: Psychodidade) in visceral and cutaneous leishmaniasis areas in central western of Minas Gerais state – Brazil

The transmission of Leishmania involves several species of sand flies that are closely associated with various parasites and reservoirs, with differing transmission cycles in Brazil. A study on the phlebotomine species composition has been conducted in the municipality of Divinópolis, Minas Gerais, Brazil, an endemic area for cutaneous leishmaniasis (CL), which has intense occurrence of visceral leishmaniasis (VL) cases. In order to study the sand flies populations and their seasonality, CDC light traps (HP model) were distributed in 15 houses which presented at least one case of CL or VL and in five urban parks (green areas). Collections were carried out three nights monthly from September 2010 to August 2011. A total of 1064 phlebotomine specimens were collected belonging to two genera and seventeen species: Brumptomyia brumpti, Lutzomyia bacula, Lutzomyia cortelezzii, Lutzomyia lenti, Lutzomyia sallesi, Lutzomyia longipalpis, Lutzomyia migonei, Lutzomyia intermedia, Lutzomyia neivai, Lutzomyia whitmani, Lutzomyia christenseni, Lutzomyia monticola, Lutzomyia pessoai, Lutzomyia aragaoi, Lutzomyia brasiliensis, Lutzomyia lutziana, and Lutzomyia sordellii. L. longipalpis, the main vector of Leishmania infantum in Brazil, was the most frequent species, accounting for 76.9% of the total, followed by L. lenti with 8.3%, this species is not a proven vector. Green and urban areas had different sand flies species composition, whereas the high abundance of L. longipalpis in urban areas and the presence of various vector species in both green and urban areas were also observed. Our data point out to the requirement of control measures against phlebotomine sand flies in the municipality of Divinópolis and adoption of strategies aiming entomological surveillance.     

Transmissibility, by Glossina morsitans morsitans, of Trypanosoma congolense strains during the acute and chronic phases of infection

In order to verify whether chronic trypanosomal infections can affect the transmissibility of Trypanosoma congolense by tsetse flies, batches of Glossina morsitans morsitans were fed on mice infected with the same level of parasitemia (10^8.1 trypanosomes/ml of blood) of two cloned low virulent T. congolense strains during the acute and the chronic phases of infection. Results showed that the proportions of procyclic infections in flies that were fed during the acute phase (32.6% and 45.4% for isolates 1 and 2, respectively) were significantly higher (χ² = 4.7, P < 0.05 and χ² = 23.7, P < 0.0001, respectively) compared to the proportions of procyclic infections of flies fed during the chronic phase of infection (18.8% and 14.9% for isolates 1 and 2, respectively). Similarly the proportions of metacyclic infections in flies fed during the acute phase (32.6% and 45.4% for isolates 1 and 2, respectively) were significantly higher (χ² = 6.3, P < 0.05 and χ² = 23.7, P < 0.0001, respectively) compared to the proportions of metacyclic infections in flies fed during the chronic phase of infection (16.8% and 14.9% for isolates 1 and 2, respectively). No significant difference was found in the maturation rate of both strains during the acute phase compared to the chronic phase of infection (P > 0.05). The results of this study suggest that T. congolense loses part of its transmissiblity by tsetse flies during the chronic phase of infection.     

Diversity of sand flies (Diptera,Psychodidae) in southwest Iran with emphasis on synanthropy of Phlebotomus papatasi and Phlebotomus alexandri

Zoonotic Cutaneous Leishmaniasis (ZCL) is still a serious health problem in Iran. The objective of the study was to determine the differences in sand fly biodiversity in Shush (plain) and Khorramshahr (littoral) Counties, Khuzestan Province, southwest Iran. Sand flies were collected using sticky paper traps from urban, semi urban, agricultural and natural ecotypes. Alpha and beta diversity were calculated using Shannon–Weiner index and Jaccard's and Sorensen's coefficients, respectively. Synanthropic index was determined for the first time for Phlebotomus papatasi and Phlebotomus alexandri in different land use categories in Iran. Totally 11213 specimens, 68.47% in Shush and 31.53% in Khorramshahr, were collected. Eleven species of sand flies including, 2 of genus Phlebotomus and 9 of genus Sergentomyia were identified. Sergentomyia christophersi was found as a new record. Dominant species were P. papatasi and Sergentomyia sintoni. Shannon–Weiner index, richness and evenness in semi urban area of Shush County were more than other habitats. The analysis of α biodiversity showed that agricultural ecosystem of Khorramshahr County had the highest diversity due to maximal richness and diversity and also relatively high evenness. Comparison of similarity of the sand flies population composition between Shush and Khorramshahr indicated the maximum similarity between the urban area of Shush and the semi urban area of Khorramshahr (S_j = 75% and S_s = 86%). Synanthropic index of P. papatasi and P. alexandri were calculated to be −83.34 and −91.18, respectively in Shush County. Estimated synanthropic indices for P. papatasi and P. alexandri in three habitats (natural, semi urban and urban) of Khorramshahr County were −69.84 and −85.89, in the same order. The factors for having high diversity of sand flies in the plain area studied may be due to higher annual precipitation, the related land use and land cover. The changes on the composition of sand flies are perhaps due to human intervention in their natural habitats.     

Experimental and field investigations on the role of birds as hosts of Leishmania infantum, with emphasis on the domestic chicken

In this study, 19 chickens were experimentally infected by Leishmania infantum and tissue samples, collected at different times, were cultured and subjected to conventional PCR and/or real time PCR (qPCR) to assess their susceptibility to infection. In addition, 121 serum samples from rural chickens (n = 73) and backyard birds (n = 48) were tested for anti-L. infantum antibodies by indirect immunofluorescence test. All the 19 animals showed to be molecularly positive at least at one tissue sample. In particular, 26 tissue samples from the experimentally infected chickens were positive on conventional PCR and/or qPCR but no clinical signs or seroconversion were detected and all tissue cultures were negative. Accordingly, all serum samples from rural chickens were negative whereas four (8.4%) from game birds (three Anser anser and one Phasianus colchicus) were positive. These results indicate that chickens are not suitable hosts for L. infantum under experimental condition. The occurrence of anti-L. infantum antibodies in domestic gooses (A. anser) and in a pheasant (P. colchicus) points out their possible role in the epidemiology of visceral leishmaniasis.     

Effect of night time-intervals,height of traps and lunar phases on sand fly collection in a highly endemic area for canine leishmaniasis

The activity of phlebotomine sand flies was monitored in a sub-urban area of Sicily in order to acquire data on seasonality and to elucidate the effect of the night time-intervals, height of traps from ground and lunar phases on the abundance of the capture. The study was conducted in the farm of the University of Messina (Italy). Light traps were placed as in the following: biweekly, from dusk to dawn, and from May to November; for three consecutive nights from 18:00 to 6:00, with the net bag being changed every 2 h; for 30 days, at different heights from 18:00 to 6:00. A total of five species (i.e., Phlebotomus perniciosus, Phlebotomus neglectus, Phlebotomus sergenti, Phlebotomus perfiliewi, and Sergentomyia minuta), three of which are proven vectors of Leishmania infantum, were captured. The most abundant species was P. perniciosus (73.3%) followed by S. minuta (23.3%). The highest number of phlebotomine sand flies was collected in August and September with a peak of collection recorded in the evening (i.e., from 20:01 to 22.00). The number of phlebotomine sand flies collected at 50 cm above the ground was significantly higher (P = 0.041) than that captured at 150 cm. Results of this study shed light on the ecology of main phlebotomine species in the Mediterranean area, and on the influence of some factors, such as time and height of traps, on the light trap capture efficiency.     

Development of a loop-mediated isothermal amplification method for rapid mass-screening of sand flies for Leishmania infection

Entomological monitoring of Leishmania infection in leishmaniasis endemic areas offers epidemiologic advantages for predicting the risk and expansion of the disease, as well as evaluation of the effectiveness of control programs. In this study, we developed a highly sensitive loop-mediated isothermal amplification (LAMP) method for the mass screening of sand flies for Leishmania infection based on the 18S rRNA gene. The LAMP technique could detect 0.01 parasites, which was more sensitive than classical PCR. The method was robust and could amplify the target DNA within 1 h from a crude sand fly template without DNA purification. Amplicon detection could be accomplished by the newly developed colorimetric malachite green (MG)—mediated naked eye visualization. Pre-addition of MG to the LAMP reaction solution did not inhibit amplification efficiency. The field applicability of the colorimetric MG-based LAMP assay was demonstrated with 397 field-caught samples from the endemic areas of Ecuador and eight positive sand flies were detected. The robustness, superior sensitivity, and ability to produce better visual discriminatory reaction products than existing LAMP fluorescence and turbidity assays indicated the field potential usefulness of this new method for surveillance and epidemiological studies of leishmaniasis in developing countries.     

Combinations of ascaridole,carvacrol, and caryophyllene oxide against Leishmania

To date there are no vaccines against Leishmania and chemotherapy remains the mainstay for the control of leishmaniasis. The drugs currently used for leishmaniasis therapy are significantly toxic, expensive, and result in a growing frequency of refractory infections. In this study, we evaluated the effect of combinations of the main components of essential oil from Chenopodium ambrosioides (ascaridole, carvacrol, and caryophyllene oxide) against Leishmaniaamazonensis. Anti-leishmanial effects of combinations of pure compounds were evaluated in vitro and the fractional inhibitory concentration (FIC) indices were calculated. BALB/c mice infected with L. amazonensis were treated with different concentrations of ascaridole–carvacrol combinations by intralesional doses every 4 days. Disease progression and parasite burden in infected tissues were determined. In vitro experiments showed a synergistic effect of the combination of ascaridole–carvacrol against promastigotes of Leishmania with a FIC index of 0.171, while indifferent activities were observed for ascaridole–caryophyllene oxide (FIC index = 3.613) and carvacrol–caryophyllene oxide (FIC index = 2.356) combinations. The fixed ratio method showed that a 1:4 ascaridole–carvacrol ratio produced a better anti-protozoal activity on promastigotes, lower cytotoxicity, and synergistic activity on intracellular amastigotes (FIC index = 0.416). Significant differences (p < 0.05) in lesion size and parasite burden were demonstrated in BALB/c mice experimentally infected and treated with the ascaridole–carvacrol combinations compared with control animals. Carvacrol showed significant higher anti-radical activity in the DPPH assay compared with caryophyllene oxide. Electron spin resonance spectroscopy in combination with spin trapping suggested the presence of carbon-centered radicals after activation of ascaridole by Fe²⁺. The intensity of the signals is preferably decreased upon addition of carvacrol. The ascaridole–carvacrol combination could represent a future alternative to monotherapeutic anti-leishmanial agents.     

Sand Fly Fauna (Diptera,Pcychodidae, Phlebotominae) in Different Leishmaniasis-Endemic Areas of Ecuador,Surveyed Using a Newly Named Mini-Shannon Trap

To study the sand fly fauna, surveys were performed at four different leishmaniasis-endemic sites in Ecuador from February 2013 to April 2014. A modified and simplified version of the conventional Shannon trap was named “mini-Shannon trap” and put to multiple uses at the different study sites in limited, forested and narrow spaces. The mini-Shannon, CDC light trap and protected human landing method were employed for sand fly collection. The species identification of sand flies was performed mainly based on the morphology of spermathecae and cibarium, after dissection of fresh samples. In this study, therefore, only female samples were used for analysis. A total of 1,480 female sand flies belonging to 25 Lutzomyia species were collected. The number of female sand flies collected was 417 (28.2%) using the mini-Shannon trap, 259 (17.5%) using the CDC light trap and 804 (54.3%) by human landing. The total number of sand flies per trap collected by the different methods was markedly affected by the study site, probably because of the various composition of species at each locality. Furthermore, as an additional study, the attraction of sand flies to mini-Shannon traps powered with LED white-light and LED black-light was investigated preliminarily, together with the CDC light trap and human landing. As a result, a total of 426 sand flies of nine Lutzomyia species, including seven man-biting and two non-biting species, were collected during three capture trials in May and June 2014 in an area endemic for leishmaniasis (La Ventura). The black-light proved relatively superior to the white-light with regard to capture numbers, but no significant statistical difference was observed between the two traps.     

Ecology of phlebotomine sand flies and Leishmania infantum infection in a rural area of southern Italy

Phlebotomine sand flies are insects of major medico-veterinary significance in the Mediterranean region, as they may transmit pathogens to animals and humans, including viruses and protozoa. The present study was conducted in southern Italy, in an area where visceral leishmaniasis caused by Leishmania infantum is endemic. Insects were collected monthly during two consecutive years using light traps set in five different ecologic contexts (i.e., a stonewall near a woodhouse, a tree near volcanic rocks in a high-altitude area, a tree trunk in a meadow habitat, a sheep stable, and a chicken coop) and weekly in one site (the garage of a private house). A total of 13,087 specimens were collected and six species identified (i.e., Phlebotomus perfiliewi, Phlebotomus perniciosus, Phlebotomus neglectus, Phlebotomus papatasi, Phlebotomus mascittii, and Sergentomyia minuta), representing 75% of the total number of phlebotomine species found in Italy. P. perfiliewi was the most abundant species, comprising 88.14% of the specimens identified. The greatest species diversity and abundance was recorded in human dwellings and in animal sheds. Sand flies were active from June to October, peaking in July–August in 2010 and July–September in 2011. Part of the females (n = 8865) was grouped into 617 pools (range, 1–10 insects each) according to species, feeding status, day and site of collection. A total of four pools (10 non-engorged specimens each) and one engorged female of P. perfiliewi were positive for L. infantum. This study confirms that phlebotomine vectors in southern Italy are highly adapted to human-modified environments (e.g., animal sheds) and that P. perfiliewi is a major vector of L. infantum in some regions of southern Italy.     

High efficacy of integrated preventive measures against zoonotic cutaneous leishmaniasis in northern Afghanistan, as revealed by Quantified Infection Rates

Following an outbreak of more than 200 cases of zoonotic cutaneous leishmaniasis (ZCL) during 2004 and 2005 among International Security Assistance Force (ISAF) troops stationed in the Mazar-e Sharif (MeS) airport area, epidemiological investigations indicated the presence of a local high-density ZCL focus. Based on ZCL's specific transmission modes, density and seasonality, integrated preventive measures were continuously implemented from February 2006 at a German military camp constructed at MeS. Preventive techniques included such synergistic measures as skin repellents and insecticide-impregnated clothing, bednets and curtains, sand fly and rodent monitoring and control, extended habitat sanitation, and health education, all designed to achieve maximum protection against ZCL. Habitat alteration included: (a) erection of a 3.0 m high stone wall around the entire camp area; (b) removal of ≥30 cm of the upper earth layer throughout the site; (c) soil compaction and stone paving to a depth of ≥30 cm plus compaction of the surrounding area to a distance of 100 m outside the camp wall; and (d) regular eradication of vegetation. Aggressive implementation of these measures led to a 166-fold and 546-fold reduction in sand fly numbers and complete eradication of the local rodent reservoir, Rhombomys opimus, inside the camp during 2006 and 2007, respectively. ZCL attack rates decreased significantly (p < 0.0001), from 17.5% (14 cases/80 persons) for the 2005 German assessment teams to 0.087% (1 case/1150 persons) for the 2006 contingent, and 0% (0 cases) (p < 0.0001) for the 2007 contingent, with Quantified Infection Rates (QIRs) of 0.058, 0.0000055, and 0.0, respectively. Using QIR values, the protective factor of the integrated preventive measures was shown to be ≥10,545 times higher in the 2006 and 2007 contingents, compared with the 2005 assessment teams. Results show that the continuously implemented, integrated preventive techniques used in this study gave excellent and long-lasting protection against zoonotic cutaneous leishmaniasis under field conditions.     

Characterization of breeding sites of Phlebotomus orientalis – The vector of visceral leishmaniasis in northwestern Ethiopia

We studied breeding sites of Phlebotomus orientalis (Diptera: Psychodidae) the vector of visceral leishmaniasis in northern Ethiopia. Although numbers were rather small, 165 sand flies were captured emerging from vertisol cracks. The most productive breeding sites were cracked vertisols, dry river banks and close to trees. No sand flies were caught emerging from sandy clay loam soils in peri-domestic habitats but a few were captured emerging from gaps in a stone wall. Abiotic parameters in vertisols close to trees and in open field from which P. orientalis had emerged, were compared. Soil pH was slightly alkaline and salinity was low. Organic matter contents were similar in both sites. Temperatures and RH remained relatively stable near trees from the end of the rainy season through mid dry season, yet fluctuated markedly at the shallower depth in the open field. During the rainy season, cracks in the soil were sealed resulting in significant lowering of the oxygen concentrations near the tree. Gravimetric water content of soil near trees was lower than open field at shallow depth but similar deeper down. We conclude that ambient conditions suitable for sand fly larvae at shallow depths (45 cm) are restricted to areas close to trees. However, deeper in vertisols (90 cm) suitable conditions are apparently maintained throughout the dry season even in open fallow fields.