Ecology of sand flies in a low-density residential rural area, with mixed forest/agricultural exploitation, in north-eastern Brazil

Cutaneous leishmaniasis caused by Leishmania braziliensis is endemic in Brazil, where Lutzomyia whitmani is the most important vector involved in the transmission to humans, particularly in the peridomestic environment. Herein, we assessed the ecology of sand flies, including Lu. whitmani, in a low-density residential rural area with mixed forest/agricultural exploitation in north-eastern Brazil, where cutaneous leishmaniasis is endemic. Particularly, we hypothesized that sand fly abundance was correlated with climatic variables. Sand fly collections were carried out monthly from August 2013 to August 2014, using seven CDC light traps, for three consecutive nights, in three kinds of environments: indoor, peridomicile and forest. Collected sand flies were identified based on morphology and females of Lu. whitmani (n=169), Lu. amazonensis (n=134) and Lu. complexa (n=21) were selected and tested by PCR for Leishmania (Viannia) spp. In total, 5167 sand flies belonging to 19 species were identified, being that Lu. choti (43.2%) was the most frequent species, followed by Lu. amazonensis (16.6%), Lu. whitmani (15.8%), Lu. sordellii (10.7%) and Lu. quinquefer (5.8%), which together represented over 90% of the collected sand flies. All females tested by PCR were negative. The number of sand flies collected daily was positively correlated with temperature and negatively correlated with rainfall and relative humidity. Furthermore, there was a positive correlation between daily number of sand flies and daily average saturation deficit. This study points out that the number of sand flies captured daily is correlated to climatic variables, including saturation deficit, which may represent a useful parameter for monitoring sand fly populations in leishmaniasis-endemic areas.

American cutaneous leishmaniasis cases in the metropolitan region of Manaus, Brazil: association with climate variables over time

A temporal series of the normalized difference vegetation index (NDVI) and other environmental parameters covering the years 2002- 2009 was used for the study of the potential association between the climate and the number of cases of American cutaneous leishmaniasis (CL) in Manaus Metropolitan Region (MMR), State of Amazonas, Brazil. The results show that CL has a marked seasonality and a strong linkage with local climate conditions. Dry and warm conditions favor the vector, while the maximum number of CL cases occurs during the following wet season. This has a clear relation to the El Niño/La Niña Southern Oscillation (ENSO) and the results presented here show that uncharacteristic dry conditions in the MMR follow El Niño after a lag period of 3 months, while wet conditions follow La Niña, again after a lag period of 3 months. El Niño brings dry conditions with warming of the land surface leading to increased growth of trees and bushes as indicated by rising NDVI values, eventually producing increased numbers of CL cases, with a peak of new cases occurring 4 to 5 months later. La Niña, on the other hand, produces wet and cool weather, which is less favorable for the leishmaniasis vector and therefore results in comparatively lower number of CL cases. Since these seasonal climate changes affect the dynamics of the CL vector, and thus the number of CL cases, a close watch of the ENSO phenomenon and the weather type it brings should be useful for monitoring and control of CL in the MMR.

Distribution of Lutzomyia longipalpis chemotype populations in São Paulo state, Brazil

BACKGROUND

American visceral leishmaniasis (AVL) is an emerging disease in the state of São Paulo, Brazil. Its geographical expansion and the increase in the number of human cases has been linked to dispersion of Lutzomyia longipalpis into urban areas. To produce more accurate risk maps we investigated the geographic distribution and routes of expansion of the disease as well as chemotype populations of the vector.

METHODOLOGY/PRINCIPAL FINDINGS

A database, containing the annual records of municipalities which had notified human and canine AVL cases as well as the presence of the vector, was compiled. The chemotypes of L. longipalpis populations from municipalities in different regions of São Paulo State were determined by Coupled Gas Chromatography - Mass Spectrometry. From 1997 to June 2014, L. longipalpis has been reported in 166 municipalities, 148 of them in the Western region. A total of 106 municipalities were identified with transmission and 99 were located in the Western region, where all 2,204 autochthonous human cases occurred. Both the vector and the occurrence of human cases have expanded in a South-easterly direction, from the Western to central region, and from there, a further expansion to the North and the South. The (S)-9-methylgermacrene-B population of L. longipalpis is widely distributed in the Western region and the cembrene-1 population is restricted to the Eastern region.

CONCLUSION/SIGNIFICANCE

The maps in the present study show that there are two distinct epidemiological patterns of AVL in São Paulo State and that the expansion of human and canine AVL cases through the Western region has followed the same dispersion route of only one of the two species of the L. longipalpis complex, (S)-9-methylgermacrene-B. Entomological vigilance based on the routes of dispersion and identification of the chemotype population could be used to identify at-risk areas and consequently define the priorities for control measures.

Leishmaniases in Maghreb: an endemic neglected disease

Maghreb is known to be one of the most endemic areas of leishmaniases where both visceral and cutaneous forms are reported. Cutaneous leishmaniasis (CL) is older and has a higher prevalence than visceral one (VL). It is caused by four taxa (Leishmania (L.) major, L. infantum, L. tropica and L. killicki) which are responsible for a large clinical spectrum of lesions. Most transmission cycles of these taxa are known and many phlebotomine sandflies vectors and reservoir hosts are identified. The zoonotic transmission is well established for L. major. However, for L. infantum and L. killicki it needs more investigations to be proven. Regarding L. tropica, studies suggest it to be of both zoonotic and anthroponotic types. The isoenzymatic characterization of these four taxa showed a large enzymatic polymorphism varying from two zymodemes for L. major to 10 zymodemes for L. tropica. Cutaneous leishmaniasis is widely distributed and covers all bioclimatic stages with the coexistence of more than one taxon in the same foci. Visceral leishmaniasis is the second form of leishmaniases in Maghreb. Only L. infantum is known to cause this disease. The transmission cycle of this parasite is zoonotic but still not well known. The isoenzymatic identification of L. infantum causing VL showed the presence of six zymodemes. Geographically, VL is distributed in all bioclimatic stages of Maghreb countries. Despite all the previous studies realized on leishmaniases in Maghreb, they are still considered as neglected diseases because of the rarity or the absence of efficient control strategies.

Spatial and temporal distributions of phlebotomine sand flies (Diptera: Psychodidae), vectors of leishmaniasis, in Iran

Leishmaniasis is a major vector-borne disease and health problem in Iran. Studies on sand flies, as the vectors of the disease, began in the Northern and Western parts of the country in 1930 and have been continued up to now. Concerning many published information in the field of sand flies, providing a digital database for the country will help the public health authorities to make more correct and prompt decisions for planning leishmaniasis control programs as well as modeling and forecasting of transmission potential across the country. All published data on phlebotomine sand flies of Iran were collected. A database was then designed in Excel format, including all available information regarding sand flies. The valid data were transferred to ArcGIS9.3 to prepare the first spatial database of sand flies of Iran. The IrSandflybase includes 131 papers, 2 abstracts and 71 PhD/MSc theses, reporting studies conducted during 1930-2012. This database contains different available data covering all aspects of ecology and biology of 50 sand fly species in two genera of Phlebotomus and Sergentomyia in the country. The temporal activity of sand flies is reported 9 months in warm regions of the southern part, while it may reduce to 7-8 months in central plateau or 4-5 months in cold areas of the northwest. Occasional studies reported rare species from the borderlines of Iran. It seems that changing the climate due to global warming may affect the spatial distribution of different species and expand it into the country, the issue that can be followed by an updated database.

Predicted altitudinal shifts and reduced spatial distribution of Leishmania infantum vector species under climate change scenarios in Colombia

Visceral leishmaniasis (VL) is caused by the trypanosomatid parasite Leishmania infantum (=Leishmania chagasi), and is epidemiologically relevant due to its wide geographic distribution, the number of annual cases reported and the increase in its co-infection with HIV. Two vector species have been incriminated in the Americas: Lutzomyia longipalpis and Lutzomyia evansi. In Colombia, L. longipalpis is distributed along the Magdalena River Valley while L. evansi is only found in the northern part of the Country. Regarding the epidemiology of the disease, in Colombia the incidence of VL has decreased over the last few years without any intervention being implemented. Additionally, changes in transmission cycles have been reported with urban transmission occurring in the Caribbean Coast. In Europe and North America climate change seems to be driving a latitudinal shift of leishmaniasis transmission. Here, we explored the spatial distribution of the two known vector species of L. infantum in Colombia and projected its future distribution into climate change scenarios to establish the expansion potential of the disease. An updated database including L. longipalpis and L. evansi collection records from Colombia was compiled. Ecological niche models were performed for each species using the Maxent software and 13 Worldclim bioclimatic coverages. Projections were made for the pessimistic CSIRO A2 scenario, which predicts the higher increase in temperature due to non-emission reduction, and the optimistic Hadley B2 Scenario predicting the minimum increase in temperature. The database contained 23 records for L. evansi and 39 records for L. longipalpis, distributed along the Magdalena River Valley and the Caribbean Coast, where the potential distribution areas of both species were also predicted by Maxent. Climate change projections showed a general overall reduction in the spatial distribution of the two vector species, promoting a shift in altitudinal distribution for L. longipalpis and confining L. evansi to certain regions in the Caribbean Coast. Altitudinal shifts have been reported for cutaneous leishmaniasis vectors in Colombia and Peru. Here, we predict the same outcome for VL vectors in Colombia. Changes in spatial distribution patterns could be affecting local abundances due to climatic pressures on vector populations thus reducing the incidence of human cases.

Studies on the sand fly fauna (Diptera: Psychodidae) in high-transmission areas of cutaneous leishmaniasis in the Republic of Suriname

BACKGROUND

Sand flies (Diptera: Psychodidae) are the vectors of Leishmania parasites, the causative agents of leishmaniasis. Cutaneous leishmaniasis is an increasing public health problem in the Republic of Suriname and is mainly caused by Leishmania (Vianna) guyanensis, but L. (V.) braziliensis, L. (L.) amazonensis, and L. (V.) naiffi also infect humans. Transmission occurs predominantly in the forested hinterland of the country. Information regarding the potential vectors of leishmaniasis in Suriname is limited. This study aims to broaden the knowledge about vectors involved in the transmission of cutaneous leishmaniasis in Suriname. For this purpose, sand flies were characterized in various foci of cutaneous leishmaniasis in the country, the districts of Para, Brokopondo, and Sipaliwini.

METHODS

Sand flies were collected in areas around mining plots and villages using CDC light traps in the period between February 2011 and March 2013. They were categorized by examination of the spermathecea (females) and the external genitalia (males).

RESULTS

A total of 2,743 sand fly specimens belonging to 34 different species were captured, including four species (Lutzomyia aragaoi, Lu. ayrozai, Lu. damascenoi, and Lu. sordellii) that had never before been described for Suriname. Five percent of the catch comprised Lu. squamiventris sensu lato, one female of which was positive with L. (V.) braziliensis and was captured in a gold mining area in Brokopondo. Other sand fly species found positive for Leishmania parasites were Lu. trichopyga, Lu. ininii, and Lu. umbratilis, comprising 32, 8, and 4%, respectively, of the catch. These were captured at gold mining areas in Brokopondo and Sipaliwini, but the Leishmania parasites they had ingested could not be identified due to insufficient amounts of DNA.

CONCLUSIONS

The sand fly fauna in Suriname is highly diverse and comprises Lutzomyia species capable of transmitting Leishmania parasites. Four new Lutzomyia species have been found, and four species - Lu. squamiventris (s.l.), Lu. trichopyga, Lu. ininii, and Lu. umbratilis - have been found to harbor Leishmania parasites. The latter were among the most abundant species captured. These observations may contribute to the understanding of leishmaniasis transmission and the development of control programs in Suriname.

Ecology of leishmaniasis in the South of France. 22. Reliability and representativeness of 12 Phlebotomus ariasi, P. perniciosus and Sergentomyia minuta (Diptera: Psychodidae) sampling stations in Vallespir (eastern French Pyrenees region)

This study was conducted around Céret (Pyrénées-Orientales, mean elevation 200 m) to test the statistical reliability of 12 stations devoted to sampling the Leishmania infantum vectors Phlebotomus ariasi and P. perniciosus in the South of France. Each station included a retaining wall and the surrounding phytoecological environment (total area: 2,000 m(2)). The wall had rectangular drainage cavities (weep holes) in which flight interception traps (sticky paper) were inserted and stretched every 10 days from May to October. For both vector species, the statistical analysis of 10-day and annual frequencies led to the following conclusions: (1) P. ariasi densities were significantly higher than P. perniciosus densities, (2) densities per species were significantly different at the 12 stations : none of them could be considered as representative of local vector densities, which depend on the wall structure (exposure, shade, vertebrate hosts), (3) the 10-day variation trends were not significantly different between stations, indicating that these variations are not determined by the station structure but rather by a common external factor (likely meteorological) and (4) the phytoecological features at the stations were not correlated with the sandfly densities. Most of the observations obtained with P. ariasi and P. perniciosus are also relevant for the non-vectorial species S. minuta. In conclusion, future research on the dynamics of leishmaniasis outbreaks relative to climate change and agricultural-silvicultural modifications should be very cautiously carried out, while focusing especially on the vector sampling quality and the use of phytoecological maps as vector density indicators.

Current and future niche of North and Central American sand flies (Diptera: psychodidae) in climate change scenarios

Ecological niche models are useful tools to infer potential spatial and temporal distributions in vector species and to measure epidemiological risk for infectious diseases such as the Leishmaniases. The ecological niche of 28 North and Central American sand fly species, including those with epidemiological relevance, can be used to analyze the vector's ecology and its association with transmission risk, and plan integrated regional vector surveillance and control programs. In this study, we model the environmental requirements of the principal North and Central American phlebotomine species and analyze three niche characteristics over future climate change scenarios: i) potential change in niche breadth, ii) direction and magnitude of niche centroid shifts, iii) shifts in elevation range. Niche identity between confirmed or incriminated Leishmania vector sand flies in Mexico, and human cases were analyzed. Niche models were constructed using sand fly occurrence datapoints from Canada, USA, Mexico, Guatemala and Belize. Nine non-correlated bioclimatic and four topographic data layers were used as niche components using GARP in OpenModeller. Both B2 and A2 climate change scenarios were used with two general circulation models for each scenario (CSIRO and HadCM3), for 2020, 2050 and 2080. There was an increase in niche breadth to 2080 in both scenarios for all species with the exception of Lutzomyia vexator. The principal direction of niche centroid displacement was to the northwest (64%), while the elevation range decreased greatest for tropical, and least for broad-range species. Lutzomyia cruciata is the only epidemiologically important species with high niche identity with that of Leishmania spp. in Mexico. Continued landscape modification in future climate change will provide an increased opportunity for the geographic expansion of NCA sand flys' ENM and human exposure to vectors of Leishmaniases.

Larval breeding sites of Lutzomyia longipalpis (Diptera: Psychodidae) in visceral leishmaniasis endemic urban areas in Southeastern Brazil

BACKGROUND

The scarcity of information on the immature stages of sand flies and their preferred breeding sites has resulted in the focus of vectorial control on the adult stage using residual insecticide house-spraying. This strategy, along with the treatment of human cases and the euthanasia of infected dogs, has proven inefficient and visceral leishmaniasis continues to expand in Brazil. Identifying the breeding sites of sand flies is essential to the understanding of the vector's population dynamic and could be used to develop novel control strategies.

METHODOLOGY/PRINCIPAL FINDING

In the present study, an intensive search for the breeding sites of Lutzomyia longipalpis was conducted in urban and peri-urban areas of two municipalities, Promissão and Dracena, which are endemic for visceral leishmaniasis in São Paulo State, Brazil. During an exploratory period, a total of 962 soil emergence traps were used to investigate possible peridomiciliary breeding site microhabitats such as: leaf litter under tree, chicken sheds, other animal sheds and uncovered debris. A total of 160 sand flies were collected and 148 (92.5%) were L. longipalpis. In Promissão the proportion of chicken sheds positive was significantly higher than in leaf litter under trees. Chicken shed microhabitats presented the highest density of L. longipalpis in both municipalities: 17.29 and 5.71 individuals per square meter sampled in Promissão and Dracena respectively. A contagious spatial distribution pattern of L. longipalpis was identified in the emergence traps located in the chicken sheds.

CONCLUSION

The results indicate that chicken sheds are the preferential breeding site for L. longipalpis in the present study areas. Thus, control measures targeting the immature stages in chicken sheds could have a great effect on reducing the number of adult flies and consequently the transmission rate of Leishmania (Leishmania) infantum chagasi.

Ecological and control techniques for sand flies (Diptera: Psychodidae) associated with rodent reservoirs of leishmaniasis

Background

Leishmaniasis remains a global health problem because of the substantial holes that remain in our understanding of sand fly ecology and the failure of traditional vector control methods. The specific larval food source is unknown for all but a few sand fly species, and this is particularly true for the vectors of Leishmania parasites. We provide methods and materials that could be used to understand, and ultimately break, the transmission cycle of zoonotic cutaneous leishmaniasis.

Methods and Findings

We demonstrated in laboratory studies that analysis of the stable carbon and nitrogen isotopes found naturally in plant and animal tissues was highly effective for linking adult sand flies with their larval diet, without having to locate or capture the sand fly larvae themselves. In a field trial, we also demonstrated using this technique that half of captured adult sand flies had fed as larvae on rodent feces. Through the identification of rodent feces as a sand fly larval habitat, we now know that rodent baits containing insecticides that have been shown in previous studies to pass into the rodents' feces and kill sand fly larvae also could play a future role in sand fly control. In a second study we showed that rubidium incorporated into rodent baits could be used to demonstrate the level of bloodfeeding by sand flies on baited rodents, and that the elimination of sand flies that feed on rodents can be achieved using baits containing an insecticide that circulates in the blood of baited rodents.

Conclusions

Combined, the techniques described could help to identify larval food sources of other important vectors of the protozoa that cause visceral or dermal leishmaniasis. Unveiling aspects of the life cycles of sand flies that could be targeted with insecticides would guide future sand fly control programs for prevention of leishmaniasis.

The sand fly Phlebotomus papatasi is the vector of Leishmania major, which is a causative agent of zoonotic cutaneous leishmaniasis in the Old World. Despite its impact on public health, leishmaniasis remains a problem because of the substantial holes that remain in our understanding of sand fly ecology and the failure of traditional vector control methods. We conducted laboratory and field trials to demonstrate for the first time that sand flies are feeding on the feces of rodents (the reservoirs of L. major). Based on this new information, we now can identify areas where sand flies feed on rodent feces and therefore could be targeted using rodent baits containing an insecticide that passes into the feces of baited rodents. We also conducted a field trial using rodent bait containing an insecticide that circulates in the blood of baited rodents. We demonstrated that sand flies feeding on baited rodents were killed, and confirmed this finding using a tracer system that marks sand flies that have fed on baited rodents. Combined, these results show that we now have methods and materials that could be used to break the transmission cycle of zoonotic cutaneous leishmaniasis and target sand flies closely associated with rodents.

Study of sand flies (Diptera: Psychodidae) in visceral and cutaneous leishmaniasis areas in the central-western state of Minas Gerais, 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.

Relationship between digestive enzymes and food habit of Lutzomyia longipalpis (Diptera: Psychodidae) larvae: Characterization of carbohydrases and digestion of microorganisms

The sandfly Lutzomyia longipalpis (Lutz and Neiva, 1912) is the main vector of American Visceral Leishmaniasis. In spite of its medical importance and several studies concerning adult digestive physiology, biochemistry and molecular biology, very few studies have been carried out to elucidate the digestion in sandfly larvae. Even the breeding sites and food sources of these animals in the field are largely uncharacterized. In this paper, we describe and characterize several carbohydrases from the gut of L. longipalpis larvae, and show that they are probably not acquired from food. The enzyme profile of this insect is consistent with the digestion of fungal and bacterial cells, which were proved to be ingested by larvae under laboratory conditions. In this respect, sandfly larvae might have a detritivore habit in nature, being able to exploit microorganisms usually encountered in the detritus as a food source.

Temporal dynamics and impact of climate factors on the incidence of zoonotic cutaneous leishmaniasis in central Tunisia

BACKGROUND

Old world Zoonotic Cutaneous Leishmaniasis (ZCL) is a vector-borne human disease caused by Leishmania major, a unicellular eukaryotic parasite transmitted by pool blood-feeding sand flies mainly to wild rodents, such as Psammomys obesus. The human beings who share the rodent and sand fly habitats can be subverted as both sand fly blood resource. ZCL is endemic in the Middle East, Central Asia, Subsaharan and North Africa. Like other vector-borne diseases, the incidence of ZCL displayed by humans varies with environmental and climate factors. However, so far no study has addressed the temporal dynamics or the impact of climate factors on the ZCL risk.

PRINCIPAL FINDINGS

Seasonality during the same epidemiologic year and interval between ZCL epidemics ranging from 4 to 7 years were demonstrated. Models showed that ZCL incidence is raising i) by 1.8% (95% confidence intervals CI:0.0-3.6%) when there is 1 mm increase in the rainfall lagged by 12 to 14 months ii) by 5.0% (95% CI: 0.8-9.4%) when there is a 1% increase in humidity from July to September in the same epidemiologic year.

CONCLUSION/SIGNIFICANCE

Higher rainfall is expected to result in increased density of chenopods, a halophytic plant that constitutes the exclusive food of Psammomys obesus. Consequently, following a high density of Psammomys obesus, the pool of Leishmania major transmissible from the rodents to blood-feeding female sand flies could lead to a higher probability of transmission to humans over the next season. These findings provide the evidence that ZCL is highly influenced by climate factors that could affect both Psammomys obesus and the sand fly population densities.

Phlebotominae fauna in a recent deforested area with American tegumentary leishmaniasis transmission (Puerto Iguazú, Misiones, Argentina): seasonal distribution in domestic and peridomestic environments

Phlebotominae sand flies have been involved as vectors of Leishmania. In Argentina, Nyssomyia neivai and Nyssomyia whitmani are involved as the main vectors of American Tegumentary Leishmaniasis (ATL). In the northeastern border of the country, an outbreak of ATL during 2004-2005 was associated with deforestation and subsequent settlement of farmers close to the edge of the forest. The aim of this work was to study the community composition of sand flies along time in farms located near primary and secondary forest in two environments: houses and pigsties. The association of abundance with temperature and precipitation was also evaluated for the most prevalent species. A total of 23,659 Phlebotominae belonging to the genera Nyssomyia, Migonemyia, Pintomyia, Evandromyia, Micropygomyia, Sciopemyia, Dampfomyia, Psathyromyia and Brumptomyia were captured. Ny. whitmani, which was the most abundant species, and Migonemyia migonei, which was the second most abundant species, were present throughout the year. Both species were positively associated with temperature, mostly up to 31-47 days, and with precipitation at 31 days before the sampling day. The abundance was higher in pigsties than in houses, but the time pattern was positively associated between both environments. These results confirm that Ny. whitmani is the dominant species in the study area and its presence throughout the year indicates a potential long period of ATL transmission. The presence of Mg. migonei as the second species in abundance is relevant, because it has been described as a secondary vector of the parasites of ATL and a putative vector of the agent of American Visceral Leishmaniasis. We discuss the role of the pigsty as the environment that attract more sandflies, taking into account the number of sand flies captured there, the distance from the home, and the association of sand fly abundance with each of the two environments.

Genotyping of sand fly species in Peruvian Andes where leishmaniasis is endemic

Genotyping of sand fly species circulating in Peru was established on the basis of PCR-restriction fragment length polymorphisms (RFLPs) of the 18S ribosomal RNA (rRNA) gene. The sequences of 18S rRNA gene fragments from 12 Lutzomyia and 1 Warileya species were determined and their RFLP-patterns were analyzed. Consequently, RFLP analysis with the restriction enzyme AfaI and then HapII or KpnI, followed by XspI successfully differentiated them. Intraspecific genetic diversity affecting RFLP-patterns was not detected in the specimens collected from 24 areas of 8 departments. The genotyping was applied to the surveillance of sand flies collected from Andean areas where leishmaniasis is endemic, and its usability was verified. The present method promises to be a powerful tool for the classification and surveillance of sand flies circulating in Peru.

Species composition of Phlebotomine sandflies (Diptera: Psychodidae) in Nikshahr county, south -eastern Iran

BACKGROUND & OBJECTIVES

Sandflies are reported as the vectors of different kinds of leishmaniasis to human. There are foci of the disease in Iran. The aim of this study was to determine the fauna and species composition of sandflies to find the probable vectors of leishmaniasis in Nikshahr county, south-east of Iran, where cutaneous leishmaniasis is endemic.

METHODS

Sandflies were collected by sticky paper traps from 20 collection stations located in plain and mountainous area of Nikshahr county. The sex ratio and relative abundance of different species were also determined.

RESULTS

A total of 11,455 sandflies revealed 23 species collected and identified. Phlebotomus alexandri, P. sergenti, P. papatasi, P. salehi, and P. keshishiani were the most important vector species found in this study.

INTERPRETATION & CONCLUSION

During this survey 13 species are identified for the first time from Nikshahr county-P. bergeroti, P. eleanorae, P. keshishiani, P. halepensis, S. hodgsoni, S. christophersi, S. mervynae, S. dentata, S. dreyfussi, S. iranica, S. africana, S. grekovi and S. palestinensis, while P. keshishiani is an important vector of visceral leishmaniasis in south of Iran. These data demonstrate five vectors of leishmaniasis are active in the study area.

Seasonal distribution of phlebotomine sand flies (Diptera: Psychodidae) in Tham Phra Phothisat temple, Saraburi province, Thailand

Phlebotomine sand flies have long been incriminated as vectors of leishmaniasis in various parts of both the Old and New World. Prompted by recent indigenous cases of leishmaniasis in Thailand, a bionomic study of sand flies was undertaken in Tham Phra Phothisat temple, Saraburi province. In this study, sand flies were collected using Centers for Disease Control (CDC) light traps, to clarify the activity patterns and species composition of the sand flies. Traps were laid from August 2005 to July 2006. The insects were collected monthly between 1800-0600 hours. A total of 8,131 sand flies were collected with a female:male ratio of 1.9:1. Sixteen species were identified, of which 5 belonged to the genus Phlebotomus, 9 to Sergentomyia and 1 to Chinius. Species comprised the abundant species (Sergentomyia silvatica 35.6%, Sergentomyia barraudi 18.1%, Sergentomyia anodontis, 17.1%, Sergentomyia iyengari 11.9%, and Sergentomyia gemmea 11.2%); the less common species (<2%) were Sergentomyia dentata 1.8%, Phlebotomus stantoni 1.1%, Sergentomyia indica 1.0%, Phlebotomus argentipes 0.8%, Sergentomyia perturbans 0.4%, Chinius barbazani 0.3%, Phlebotomus asperulus 0.2%, Phlebotomus philippinensis gouldi 0.1%, Phlebotomus major major 0.1%, Sergentomyia quatei 0.1% and Sergentomyia bailyi 0.1%. The results revealed seasonal variation in sand fly prevalence, with the highest peak in July. Soil samples collected were characterized by alkaline (pH 7.6).

[A case of urogenital myiasis caused by Psychoda albipennis (Diptera: Nematocera)]

Myiasis which is a parasitic disease of humans and vertebrates, is caused by dipterous fly larvae feeding on the host's necrotic or living tissue. Although infestation by fly larvae is much more prevalent in animals, it occurs relatively frequently in humans in rural, tropical and subtropical regions of Africa and America. Myiasis is usually associated with poor general health and hygiene, restricted mobility and ulcerating lesions. The pathophysiology of the human infection differs depending on the fly species and where the larvae are located. It could be external or internal, and the invasion by the maggot could be obligatory, facultative and sometimes acci-dental. Myiasis is a self-limiting infestation with minimal morbidity in the vast majority of cases. Urogenital myiasis, associated with urinary obstruction, poor hygiene of the local site and ulcerating lesions has been infrequently reported. In this report, a case of 29 year-old male patient who presented with genitourinary myiasis caused by Psychoda albipennis (Diptera: Nematocera), was presented. The patient was admitted to the hospital with the complaints of urinary incontinence of one week duration and presence of small, thin, motile, grayishwhite objects in his urine. Physical examination, blood and urine examination and stool microscopy revealed no pathology. No growth was detected in his urine culture. The examination of discharged larva in urine sample at Refik Saydam National Public Health Agency, Parasitology Laboratory led to the diagnosis of urogenital myiasis. No risk factor was identified in the patient who had proper hygienic conditions, was living in urban area and was of high socioeconomic status. This case was presented to withdraw attention to myiasis which is frequent in Turkey, however, is usually overlooked.

Pheromone gland development and pheromone production in lutzomyia longipalpis (Diptera: Psychodidae: Phlebotominae)

The sand fly Lutzomyia longipalpis (Lutz & Neiva) (Diptera: Psychodidae: Phlebotominae) is the main vector of American visceral leishmaniasis. Adult males produce a terpenoid sex pheromone that in some cases also acts as male aggregation pheromone. We have analyzed the correlation between male pheromone production levels and pheromone gland cell morphogenesis after adult emergence from pupae. The abdominal tergites of L. longipalpis males were dissected and fixed in glutaraldehyde for transmission electron microscopy, or the pheromone was extracted in analytical grade hexane. Pheromone chemical analysis was carried out at 3- to 6-h intervals during the first 24 h after emergence and continued daily until the seventh day. All extracts were analyzed by gas chromatography. For the morphological analysis, we used insects collected at 0-6, 9-12, 12-14, and 96 h after emergence. Ultrastructural data from 0- to 6-h-old adult males revealed smaller pheromone gland cells with small microvilli at the end apparatus. Lipid droplets and peroxisomes were absent or very rare, but a large number of mitochondria could be seen. Lipid droplets started to appear in the gland cells cytoplasm approximately 9 h after adult emergence, and their number and size increased with age, together with the presence of several peroxisomes, suggesting a role for these organelles in pheromone biosynthesis. At 12-15 h after emergence, the lipid droplets were mainly distributed near the microvilli but were smaller than those in mature older males (4 d old). Pheromone biosynthesis started around 12 h after emergence and increased continuously during the first 3 d, stabilizing thereafter, coinciding with the period when males are more able to attract females.

A sharp increase in the natural abundance of sand flies in Kfar Adummim, Israel

Monitoring sand flies in the cutaneous leishmaniasis foci Kfar Adummim and Ma'ale Adummim from May to October generally yielded several hundred specimens per CO(2) baited trap. In the summer of 2009, a sharp rise in the number of sand flies trapped was recorded in Kfar Adummim, while numbers were similar to previous years in Ma'ale Adummim; approximately 4,000 specimens compared to about 400, with maximal catches of about 16,500 specimens in Kfar Adummim. We postulate that the sharp increase in sand fly numbers is directly related to the intensive construction conducted which enhanced sand fly breeding habitats.

The sand fly fauna (Psychodidae: Phlebotominae) in the region of Saquarema, State of Rio de Janeiro, Brazil, an endemic area of cutaneous leishmaniasis transmission

Cutaneous leishmaniasis, caused by Leishmania (Viannia) braziliensis, is sporadic in many rural and suburban areas of Rio de Janeiro State. An investigation was carried out during 2008/9 in the Municipality of Saquarema, Rio de Janeiro, Southeast Brazil, in order to identify the phlebotomine sand fly fauna. More than 2,100 sand flies were collected in peridomestic areas in two chicken coops using CDC light traps. Nine species of phlebotomine sand flies were identified: Nyssomyia intermedia, Nyssomyia whitmani, Pintomyia (P.) pessoai, Pintomyia (P.) fischeri, Pintomyia (P.) bianchigalatiae, Migonemyia (M.) migonei, Lutzomyia (L.) longipalpis, Brumptomyia cunhai and Brumptomyia guimaraesi. Based on the results of this study together with related studies in other CL foci in Rio de Janeiro, both Nissomyia intermedia and Migonemyia migonei can be considered suspect vectors of the disease in the region. The potential risk of VL due to the presence of its proven vector L. longipalpis is discussed.

Should sand fly taxonomy predict vectorial and ecological traits?

I review species concepts, the taxonomy of phlebotomine sand flies, and some transmission cycles of leishmaniasis in order to illustrate the difficulties of classifying these vectors in a way that will be ideal both for medical parasitologists and sand fly specialists. Choices will have to be made between different classifications, either maintaining a practical one containing few vectorial genera (mostly Phlebotomus for the Old World and Lutzomyia for the Neotropics) or changing the generic names of many vectors so that the classification represents an evolutionary hypothesis. However, sand flies also transmit arboviruses and members of other sand fly genera bite humans, and so vectorial status alone might not provide the criteria for recognizing only a few genera. Vectorial roles are often determined by species-level co-evolution of susceptibility to Leishmania species, with selection being initiated and maintained by ecological contacts. There is only imperfect co-cladogenesis of genus-level groups or subgeneric complexes of sand flies and Leishmania species. Natural hybridization between sand fly species has been recorded in several species complexes, and this highlights the need to focus on gene flow and the distribution of phenotypes of biomedical importance, not on taxa.