Field evaluation of entomological surveillance techniques for leishmaniasis vector sand flies (Diptera: Psychodidae).

The OFF! Clip-On fan vaporizer device releasing metofluthrin was evaluated against phletobomine sand flies in the Judean Desert, Israel, in October, 2009. A total of 76,400 sand flies was collected, with male flies representing 98.3%Phlebotomus sergenti and 1.7%P. papatasi. Females comprised 43.0% of the total catch and included 6.7% blood-fed females. Similar proportions of flies were collected in both suction and sticky traps. In trials with unbaited suction traps, similar numbers of sand flies were collected in traps with a metofluthrin device, blank device, or no device (i.e., suction only). In suction traps baited with CO(2) , higher numbers of P. sergenti males and blood-fed females were collected in traps with a blank device compared to traps with a metofluthrin device. In sticky traps baited with CO(2) , there were no significant differences between catches in traps with a metofluthrin device, blank device, or no device. The results suggest metofluthrin from the device is not repellent against sand flies in a field environment despite showing insecticidal activity against flies collected in suction traps.

An inventory of a year was achieved using two traps techniques (light and sticky trap) in Oulad Aid (center of Morocco), a focus of cutaneous leishmaniasis (CL), to understand better the phototropism of circulating species of the sandflies dominance according to their physiological states (total number of sandflies collected are to be given). The most abundant species were respectively Phlebotomus papatasi (50.52%), Phlebotomus sergenti (24.7%), Phlebotomus pernicuosis (9.69%), Phlebotomus longicuspis (5.54%), Sergentomyia falax (5.22%), Sergentomyia minuta (3.64%), Sergentomyia antenata (0.4%) and Sergentomyia dreyfussi (0.2 %). With sticky traps, P. papatasi constituted 59% of collected samples against 23% for P. sergenti, 12% for P. pernicuosis and 6% for P. longicuspis. However with light traps, phototropism of P. sergenti was high and represented 56% of collected samples against 36% for P. papatasi and only 4% for P. pernicuosis and P. longicuspis. The trap technique influenced the dominance of females collected according to their physiological state. Non engorged females were dominant (77.73%) when sticky traps were used but gorged and gravid females were, respectively dominant (32.62 and 21.98%) when light traps were used. Statistical analysis showed that significantly more number of sand flies were obtained using sticky traps, compared with that of light traps. Sticky traps were found to be effective, as the sand flies entering the dwellings either for blood meal or mating got trapped, while light traps yielded relatively lesser number of sand flies species. Perhaps the sand flies which are influenced by the light were attracted towards the light traps. This information may be necessary for designing intervention measure and evaluation of the impact on sand fly prevalence in a CL focus area. Key words: Sand flies, Psychodidae, phototropism, leishmania, Morocco.

Background: After the decades of Dichlorodiphenyltrichloroethane (DDT) use, Phlebotomus argentipes reportedly developed resistance against it affecting every aspect of vector control at grass-root level. Although DDT based Indoor Residual Spray (IRS) has been replaced with Alphacypermethrine-a Synthetic Pyrethroid (SP) based insecticide, since 2016 but its successful implementation at the Visceral Leishmaniasis (VL) endemic regime of Bihar doesn’t cause much effect upon VL vector density. Furthermore, the outcomes of existing operational research works, it had been observed that VL vectors are continuously changing its behavior under the pressure of insecticides.
 Methods: For validating the hypothesis, present study has been carried out at Vaishali and Patna being highly and semi-endemic sites respectively for quantifying the oriental behavior among VL vectors persuaded by the IRS and enforce them to remain alive and get trapped in light trap even after changed chemical composition of IRS i.e., SP-IRS from routine DDT-IRS.
 Results: Following results, a significant reduction in sand fly density (i.e., 33.09% and 29.16%) was observed for outdoor and indoor caught sand flies, collected with light trap and aspirator respectively. Significant higher no. of sand fly collection in terms of per light traps per night was recorded from the outdoor sites than those from indoor habitat for each village of Vaishali and Saran district of Bihar. Higher no. of male sand flies than to that of female ones were collected from outdoor sites and only unfed female sand flies (i.e., 100%) were caught following SP-IRS from each study villages of Vaishali and Saran districts of Bihar.
 Conclusions: The results of higher no. of sand flies collection from the outdoor sites as compared with the indoor habitat validate the hypothesis of gradual shifting of habitat of VL vectors from endophilic to exophilic which is undoubtedly followed due to the fact of developed resistance among them against chemical constituent of IRS. Results provide very useful information about the sand fly dynamics under the impact of IRS and accordingly, advocates the combined approach of IRS along with insecticidal fogging together at a same time that could be an effective dividend for maximum VL vector control along for negotiating VL cases at par for longer duration during the maintenance phase at the VL foci.

Background: Leishmaniasis is identified as a neglected tropical disease in the world and considered a notifiable disease in Sri Lanka. It has shown an upward trend in Kurunegala district since 2008. Studies on vector bionomics, although important for implementing effective vector control, are still limited in Sri Lanka. Objective: To describe the abundance, composition, peak active-period and vertical flight range of sand flies in the Kurunegala district Methods: A descriptive study was conducted in two selected disease-endemic areas in Rideegama and Ibbagamuwa Medical Officer of Health areas in Kurunegala district during February-March, 2019. sand flies were collected using different standard sampling techniques (CDC Light-traps, Sticky-traps and Cattle-Baited-Net-Traps and by hand collections). The identification of sand flies was done up to Genus level. Sticky traps were set up at different heights on walls of houses to determine the vertical flight range of sand flies. The hourly sand fly collections were used to determine the active peak times. The abundance was calculated as per trap density and hourly collections were monitored to identify peak active-period of sand flies. Results: The total number of sand flies collected during the study period was 773. The light- traps were found to be more productive than other collection methods. The numbers of sand flies belonging to geni Phlebotomus and Sergentomyia were 525 and 248 respectively. The average vertical flight range of flies was less than two feet from the ground level. A higher percentage of sand flies was collected from outdoors (n = 74%) than indoors (n = 26%). The highest active period of sand flies was between 18.00 hr and 22.00 hr of the day, although it was slightly different in Phlebotomus (from 18.00 hr to 20.00 hr) species and Sergentomyia species (from 18.00.00 hr to 22.00 hr). Conclusions and Recommendations: Sand flies belonging to the genus Phlebotomus and Sergentomyia were present in the area. The peak aggregation time was at night starting at 18.00 hrs in the day for both genera. The vertical flight range of sand fly was approximately less than two feet from the ground level.

Background: leishmaniasis causes ninth largest burden among infectious diseases and has been known forseveral hundred years in Iran. Phlebotominae sand flies are proven vectors of leishmaniasis and some otherinfectious diseases such as sand fly fever, summer meningitis, vesicular stomatitis, Carri ?on’s disease andChandipura virus encephalitis to human and animals.Aim: To reveal the species diversity and distribution of leishmaniasis vectors, the present study wasconducted with the aim of investigating the fauna and monthly activity of sand flies of Kuhdasht.Methodology: This cross-sectional descriptive study was done on sand flies distribution and seasonalactivity in Kuhdasht city. Using sticky traps and light traps sand flies were collected during activity seasonfrom the end of March to mid-December, 2016.Results: During 8 months of study, totally 4455 sand flies (4157 with sticky trap and 298 with light trap) werecollected. Sandflies include a collection of 7 species composed of Phlebotomus (Phlebotomus) papatasi, P(Paraphlebotomus) sergenti, P (Paraphlebotomus) alexandri, P (Adlerius) halpensis, P (Paraphlebotomus)caucasicus, P (Phlebotomus) salehi and Sergentomyia (Sergentomia) antenata. Activity of sand flies startedin late May and continued until the end of November. Phlebotomus papatasi, P. sergenti and P. alexandriwere three prevalent species in studied areas and two activity peaks were recorded in the end of June and inearly-September.Conclusions: Regarding the presence of proven vectors of leishmaniasis in studied areas and neighboringwith important foci of cutaneous leishmaniasis, monitoring the status of vectors and epidemiology of thedisease in the city and suburb of the Kuhdasht is very important in the prevention of forming a new focusof leishmaniasis.

The epidemiological trend of cutaneous leishmaniasis in Kegalle district, Sri Lanka: A newly established disease focus and assessment of bioclimatic suitability for disease establishment using ecological niche modelling

The role of sand flies in Leishmania transmission in Cameroon remains understudied, limiting the implementation of a national control program. To address this, a one-year survey, from September 2020 to August 2021, was conducted in Kousseri a visceral leishmaniasis (VL) endemic focus with the aim to evaluate the efficiency of light traps and detect Leishmania sp. infection in sand fly specimens. The checklist and distribution map of sand fly species from Cameroon are also provided. Light traps efficiency was evaluated using incandescent and ultraviolet (UV) Centre for Disease Control and Prevention (CDC) miniature light traps. These traps were deployed across the selected sites in Kousseri, and the captured female specimens were morphologically identified to the species level and tested for Leishmania donovani infection by polymerase chain reaction (PCR) targeting the Internal Transcribed spacer 1 (ITS1) region. Out of 2150 females collected, eleven species across three genera were identified: 81.44% belonged to the genus Sergentomyia, 17.49% to Grassomyia, and 1.07% to Phlebotomus. UV light traps were more efficient in capturing abundant sand fly specimens than incandescent light traps, specifically, Se antennata, Se schwetzi, Se adleri, and Ph. duboscqi were highly captured. None of the tested sand fly species were positive for Leishmania donovani infection. The present study confirms the existence of Ph. duboscqi, a proven vector of cutaneous leishmaniasis (CL) in sub-Saharan Africa foci, including Cameroon. Based on previous reports of Leishmania transmission, this sand fly species could be the likely vector of leishmaniasis in Kousseri. This study underscores the need for further ecological and epidemiological investigations to deepen our understanding of leishmaniasis transmission dynamics and inform the development of effective control strategies in Northern Cameroon.

Polymerase Chain Reaction and Mosquito Dissection as Tools to Monitor Filarial Infection Levels Following Mass Treatment in Gampaha District, Sri Lanka

BackgroundSand flies are responsible for the transmission of several disease pathogens including Leishmania. Sand flies breed in habitats with high levels of humidity and organic matter. They are nocturnal in nature and peak activity ranges from dusk to dawn. The scientific evidence on breeding ecology and diurnal resting sites of sand fly fauna are important aspects of planning and implementing vector control activities. However, such fundamental information is grossly inadequate in Sri Lanka to support the control efforts in the country. Therefore, the present study addresses some of the important aspects of sand fly breeding ecology and diurnal resting sites.MethodsPotential resting sites were thoroughly observed, and sand flies were collected using a battery-operated aspirator and sticky papers when appropriate from three selected Medical Officer of Health (MOH) areas (Polpithigama, Maho and Galgamuwa) in Kurunegala district, Sri Lanka. Soil samples were collected from each potential breeding site. Half of each soil sample was incubated for 45 days. The other half was screened for immature stages. Adult sand flies collected from field and emerged adults at the insectary under confined incubation were identified using morphological characteristics.ResultsPepper bushes and termite mounds were the most notable resting sites while, betel bushes, cattle huts, piles of coconut shells, latrines, manna bushes and tree holes were also positive for sand fly adults. Only two species, Phlebotomus argentipes and Sergentomyia punjabensis, were reported. Soil samples were collected from a total of 432 sites and 7 of them were positive for immature stages. Predominant breeding habitats identified during the present study were mud flats and moist soils of rice paddies, the soil below decaying hay, drying irrigational tank bottom moist soil, and the floors of cattle huts.ConclusionThis study demonstrates that the potential adult resting sites and breeding habitats are abundant in the Polpithigama, Maho and Galgamuwa MOH areas. Therefore, vector control activities targeting both adult and immature stages of sand flies are recommended.

: Vector-borne diseases are a serious health threat to U.S. troops stationed around the world. U.S. forces deployed to Iraq following the 2003 invasion experienced serious risk of infection by several vector-borne pathogens, specifically cutaneous (CL) and visceral leishmaniasis (VL) (Aliaga and Aronson 2007). Camp Ramadi, a U.S. military Forward Operating Base, was established in 2003 at the Al Anbar provincial capital of Ramadi, approximately 110 km west of Baghdad. In Iraq the total number of cases of CL reported per year from 2004 to 2008 was 1,655 and for VL was 1,711 (Alvar et al. 2012). In Al Anbar province in 2008, the estimated incidence of CL and VL was 1 per 10,000 (Alvar et al. 2012). Because of the war, the number of cases of both CL and VL was most likely underreported in Al Anbar and all provinces of Iraq (Alvar et al. 2012). Because of the risk of vector-borne diseases, each large U.S. military facility, such as Camp Ramadi, had a vector control program operating throughout the year. As part of a base-wide vector control program, unbaited Center for Disease Control and Prevention (CDC) light traps were placed at three locations on Camp Ramadi between April and August, 2009 to gather baseline population estimates of adult sand flies and monitor the success of subsequent control measures. This paper reports sand fly collections over the five-month period, whether they were positive for Leishmania, and describes efforts to control sand fly populations using ultra-low volume (ULV) insecticide applications. Three sites on Camp Ramadi were established for trap placement in areas where U.S. troops worked and lived. Site one was in a grove of palm trees near troop living quarters and the base medical clinic. Site two was in a plot of scrub vegetation near the helicopter landing pad, and site three in tall vegetation near buildings occupied by the base Commander. All three sites had active rodent burrows.

The present study was conducted to determine the prevalence of filariasis causing parasites in adult mosquitoes and vector mosquito larval breeding in four Medical Officer of Health (MOH) areas in Gampaha district, Sri Lanka. Adult female mosquitoes at their resting places were collected using a prokopack aspirator operated twice a day from 7.00 am to 8.00 am and 8.00 pm to 9 pm in predetermined dates. Microfilarial worms in dissected mosquitoes were morphologically identified. Nine species of mosquitoes, namely, Culex quinquefasciatus, Cx. pipiens, Cx. fuscocephala, Cx. gelidus, Armigeres subalbatus, Mansonia uniformis, Ma. annulifera, Aedes aegypti, and Ae. Albopictus, were captured. A total of 1194 mosquito larvae were collected that belonged into three genera, namely, Culex (62.73%), Armigeres (25.62%), and Mansonia (11.64%), from blocked drains, polluted drains, blocked canals, large polluted water bodies, stagnant water bodies, marsh lands, rice field mudflats, and concrete pits. Large polluted water bodies (Shannon-Wiener diversity index/H' = 1.5591) were the most diversed habitat type. In breeding water, average pH mainly lied in between 6 and 8 and average dissolved oxygen ranged from 3 to 7 mg/L. Cx. quinquefasciatus and Armigeres subalbatus adult female mosquitoes captured from Kelaniya MOH area were positive for microfilariae and were identified as Wuchereria bancrofti and Dirofilaria repens, respectively. This study concludes possible lymphatic filariasis situation is in extremely very low level persistent (0.06%) where transmission cannot be sustained and is restricted only to isolated pockets in the study area. The zoonotic strains of filariasis causing subcutaneous dirofilariasis in humans by Dirofilaria repens is continuing to survive due to the presence of stray dogs that serve as reservoir hosts.

Simplified and improved monitoring traps for sampling sand flies Gunter C. Muller1, Edita, E. Revay2, and John C. Beier3 1Department of Microbiology and Molecular Genetics , IMRIC, Kuvin Centre for the Study of Infectious and Tropical Diseases, Faculty of Medicine, Hebrew University, Jerusalem 91120, Israel, guntercmuller@hotmail.com 2Department of Anatomy and Cell Biology, Bruce Rappaport Faculty of Medicine, Technion, Haifa, Israel 3Department of Epidemiology and Public Health, University of Miami Miller School of Medicine, Miami, FL 33136, U.S.A.

Leishmaniasis has emerged as an escalating public health problem in Sri Lanka, with reported cases increasing nearly three folds over past decade, from 1,367 in 2014 to 3714 cases in 2023. Phlebotominae sand flies are the vectors of leishmaniasis. Their density is known to be influenced by context-specific climatic and land use patterns. Thus, we aimed to investigate how these factors drive sand fly density across Sri Lanka. We analysed monthly collections of sand flies (n = 38,594) and weather data from ten sentinel sites representing three main geo-climatic zones across Sri Lanka, over 24 months. Site-specific land use data was also recorded. The influence of climate and land use patterns on sand fly density across the sentinel sites were estimated using distributed lag non-linear models and machine learning. We found that climate played a major role on sand fly density compared to land use structure. Increase in rainfall and relative humidity at real time, and ambient temperature and soil temperature with a 2-month lag were associated with a statistically significant increase in sand fly density. The maximum relative risk (RR) observed was 3.76 (95% CI: 1.58-8.96) for rainfall at 120 mm/month, 2.14 (95% CI: 1.04-4.38) for relative humidity at 82% (both at real time). The maximum RR was 2.81 (95% CI: 1.09-7.35) for ambient temperature at 34.5°C, and 11.6 (95% CI, 4.38-30.76) for soil temperature (both at a 2-month lag). The real-time increase in ambient temperature, sunshine hours, and evaporation rate, however, reduced sand fly density homogeneously in all study settings. The high density of chena and coconut plantations, together with low density of dense forests, homesteads, and low human footprint values, positively influenced sand fly density. The findings improve our understanding of the dynamic influence of environment on sand fly densities and spread of leishmaniasis. This knowledge lays a foundation for forecasting of sand fly densities and designing targeted interventions for mitigating the growing burden of leishmaniasis among the most vulnerable populations, particularly in an era of changing climate.

BackgroundThe Leishmaniases are caused by the protozoan parasites of the genus Leishmania and are transmitted to humans by the bite of infected female phlebotomine sand flies. Both visceral and cutaneous leishmaniases are widely distributed in different parts of Ethiopia. The aim of this study was to determine the diversity and altitudinal distribution of phlebotomine sand flies from Kafta Humera to Gondar town in northwest Ethiopia. MethodsSeven localities were selected with distinct altitudinal variations between 550m above sea level (m a.s.l) and 2300m a.s.l. In each locality, sand flies were collected using standard CDC light traps and sticky traps during the active sand fly season from December 2012 to May 2013. Shannon-Weiner species diversity index and Jaccard’s coefficient were used to estimate species diversity and similarity between altitudes and localities, respectively. ResultsA total of 89,044 sand flies (41,798 males and 47, 246 females) were collected from the seven localities/towns throughout the study period. Twenty-two species belonging to 11 species in the genus Phlebotomus and 11 species in the genus Sergentomyia were documented. Of these, Sergentomyia clydei (25.87%), S. schwetzi (25.21%), S. africana (24.65%), S. bedfordi (8.89%), Phlebotomus orientalis (6.43%), and S. antennata (4.8%) were the most prevalent species. The remaining 10 Phlebotomus species and six Sergentomyia were less frequent catches. In CDC light trap and sticky trap, higher species diversity and richness for both male and female sand flies was observed at low altitude ranging from 550 to 699m a.s.l in Adebay village in Kafta Humera district whereas low species richness and high evenness of both sexes were also observed in an altitude 1950–2300m a.s.l. ConclusionThe results revealed that the presence of leishmaniasis vectors such as P. orientalis, P. longipes, P. papatasi, and P. duboscqi in different altitudes in northwest Ethiopia. P. orientalis a vector of L. donovani, occurred between altitude 500–1100m a.s.l, the area could be at high risk of VL. P. longipes a vector of L. aethiopica, was recorded in the highland area in Tikil-Dingay and Gondar town, implicating the possibility of CL transmission. Hence, further investigation into vector competence in relation to leishmaniasis (VL and CL) in the region is very vital.

BackgroundVisceral Leishmaniasis (VL) is a vector-borne infectious disease, caused by the protozoan Leishmania donovani, which is transmitted by phlebotomine sand flies. In an earlier study in Bihar, India, we found an association between incidence of VL and housing conditions. In the current study we investigated the influence of housing structure and conditions in and around the house on the indoor abundance of Phlebotomus argentipes, the vector of VL in this area.MethodsIn each of 50 study villages in Muzaffarpur district, we randomly selected 10 houses. Light traps were installed in each house for one night during three annual peaks of sand fly density over two successive years. Sand flies captured were morphologically identified and segregated by species, sex and feeding status. Data on housing conditions and socio-economic status were also collected. We fitted a linear mixed-effects regression model with log-transformed P. argentipes counts as outcome variable and village as random effect.Results P. argentipes was found in all but four of the 500 households. There was considerable variability between the years and the seasons. On bivariate analysis, housing structure, dampness of the floor, keeping animals inside, presence of animal dung around the house, and socio-economic status were all significantly associated with sand fly density. Highest sand fly densities were observed in thatched houses. In the multivariate model only the housing structure and socio-economic status remained significant.ConclusionsBetter housing conditions are associated with lower sand fly densities, independent of other socio-economic conditions. However, in this area in Bihar even in the better-built houses sand flies are present.