Attractiveness of black and white modified Shannon traps to phlebotomine sandflies (Diptera, Psychodidae) in the Brazilian Amazon Basin, an area of intense transmission of American cutaneous leishmaniasis

Data-driven predictions of potential Leishmania vectors in the Americas

The incidence of vector-borne diseases is rising as deforestation, climate change, and globalization bring humans in contact with arthropods that can transmit pathogens. In particular, incidence of American Cutaneous Leishmaniasis (ACL), a disease caused by parasites transmitted by sandflies, is increasing as previously intact habitats are cleared for agriculture and urban areas, potentially bringing people into contact with vectors and reservoir hosts. Previous evidence has identified dozens of sandfly species that have been infected with and/or transmit Leishmania parasites. However, there is an incomplete understanding of which sandfly species transmit the parasite, complicating efforts to limit disease spread. Here, we apply machine learning models (boosted regression trees) to leverage biological and geographical traits of known sandfly vectors to predict potential vectors. Additionally, we generate trait profiles of confirmed vectors and identify important factors in transmission. Our model performed well with an average out of sample accuracy of 86%. The models predict that synanthropic sandflies living in areas with greater canopy height, less human modification, and within an optimal range of rainfall are more likely to be Leishmania vectors. We also observed that generalist sandflies that are able to inhabit many different ecoregions are more likely to transmit the parasites. Our results suggest that Psychodopygus amazonensis and Nyssomia antunesi are unidentified potential vectors, and should be the focus of sampling and research efforts. Overall, we found that our machine learning approach provides valuable information for Leishmania surveillance and management in an otherwise complex and data sparse system.

Phlebotomine Fauna (Diptera: Psychodidae) and Infection by Leishmania spp. in Forest Fragments of a University Campus, Western Amazon

Forest fragments consist of important ecosystems for the maintenance of sand fly populations and Leishmania hosts. This study sought to identify the phlebotomine fauna and its infection by Leishmania spp. in forest fragments on the campus of the Federal University of Acre (UFAC), Western Amazon. Monthly collections with CDC traps were carried out from March 2020 to June 2021, in four forest fragments of UFAC. Male and female insects were processed and identified at species level. A sample of females was subjected to polymerase chain reaction (PCR) analysis to verify the presence Leishmania DNA. In total, 465 specimens were collected, of which 238 were males and 227 were females. The most frequent species were Nyssomyia antunesi (Coutinho, 1939) (47.3%), Trichophoromyia sp. (Mangabeira, 1942) (18.70%), and Ny. whitmani (Antunes & Coutinho, 1939) (8.81%). Molecular analysis detected the presence of Leishmania (Ross, 1903) DNA in a specimen of Ny. antunesi, and another one of Evandromyia walker (Newstead, 1914). The forest fragments of the university campus harbor a diverse sand fly fauna with the presence of Leishmania DNA in these insects, in addition to the presence of other species considered incriminated vectors of Leishmania parasites.

Remarkable diversity, new records and Leishmania detection in the sand fly fauna of an area of high endemicity for cutaneous leishmaniasis in Acre state, Brazilian Amazonian Forest

The species richness of Amazonian phlebotomines is considered to be one of the highest in the world. In the present study, we investigated the richness and diversity of phlebotomine fauna in Xapuri city, Acre state, Western Brazilian Amazonia, which is an area that is highly endemic for cutaneous leishmaniasis. Sand fly collections were performed monthly from August 2013 to July 2015 (288 h total of sampling effort) in intradomiciliary, peridomiciliary, and forested environments of two localities. Collected females were dissected, microscopically examined for flagellates in their guts, and preserved in ethanol. A total of 21,197 specimens comprising 14 genera and 57 species were collected, and the majority of these were Nyssomyia, Psychodopygus, and Trichophoromyia genera. Three new records of phlebotomine species for Acre are presented here, including Brumptomyia brumpti, Psathyromyia pradobarrientosi, and for the first time in Brazil, Th. omagua. In Xapuri, the phlebotomine fauna of different ecotopes was varied in regard to abundance, diversity, and frequency, and they included proven and permissive vectors of Leishmania spp. The fauna discovered in the forested areas (57 species) was richer and more diverse than was that (33 species) identified in the peri‑ and intra-domiciles. The identification of Leishmania subgenera that were present in sand fly guts according to SSU rRNA sequences revealed ten and three species harboring Leishmania of subgenera Viannia and Leishmania (most likely Leishmania amazonensis), respectively. The presence of Leishmania (Leishmania) in sand flies are reported here for the first time in Acre. The presence of L. (Viannia) spp. in Brumptomyia sp. and Lutzomyia sherlocki. and the occurrence of mixed infections with Leishmania of both subgenera in Ps. lainsoni have been reported for the first time in Brazil. Taken together, data from previous studies and from the present study highlight the remarkable complexity of phlebotomine fauna that is possibly due to the well-preserved Xapuri forested areas sustaining vital economic activities of plant extraction and ecological tourism. Our findings also provide new insights into the ongoing adaptation of Trichophoromyia and Psychodopygus species to human habitats.

Comparison of sand fly trapping approaches for vector surveillance of Leishmania and Bartonella species in ecologically distinct, endemic regions of Peru

BACKGROUND

In Peru, the information regarding sand fly vectors of leishmaniasis and bartonellosis in the Amazon region is limited. In this study, we carried out sand fly collections in Peruvian lowland and highland jungle areas using different trap type configurations and screened them for Leishmania and Bartonella DNA.

METHODOLOGY/PRINCIPAL FINDINGS

Phlebotomine sand flies were collected in Peruvian Amazon jungle and inter Andean regions using CDC light trap, UV and color LED traps, Mosquito Magnet trap, BG Sentinel trap, and a Shannon trap placed outside the houses. Leishmania spp. screening was performed by kDNA PCR and confirmed by a nested cytochrome B gene (cytB) PCR. Bartonella spp. screening was performed by ITS PCR and confirmed by citrate synthase gene (gltA). The PCR amplicons were sequenced to identify Leishmania and Bartonella species. UV and Blue LED traps collected the highest average number of sand flies per hour in low jungle; UV, Mosquito Magnet and Shannon traps in high jungle; and Mosquito Magnet in inter Andean region. Leishmania guyanensis in Lutzomyia carrerai carrerai and L. naiffi in Lu. hirsuta hirsuta were identified based on cytB sequencing. Bartonella spp. related to Bartonella bacilliformis in Lu. whitmani, Lu. nevesi, Lu. hirsuta hirsuta and Lu. sherlocki, and a Bartonella sp. related to Candidatus B. rondoniensis in Lu. nevesi and Lu. maranonensis were identified based on gltA gene sequencing.

CONCLUSIONS/SIGNIFICANCE

UV, Blue LED, Mosquito Magnet and Shannon traps were more efficient than the BG-Sentinel, Green, and Red LED traps. This is the first report of L. naiffi and of two genotypes of Bartonella spp. related to B. bacilliformis and Candidatus B. rondoniensis infecting sand fly species from the Amazon region in Peru.

Diversity, distribution and natural Leishmania infection of sand flies from communities along the Interoceanic Highway in the Southeastern Peruvian Amazon

The Peruvian-Brazilian border is a highly endemic tegumentary leishmaniasis region in South America. The interoceanic highway is a commercial route that connects Peru and Brazil through Madre de Dios and has raised concerns about its impact on previously undisturbed areas. In order to assess leishmaniasis transmission risk along this highway, we conducted a surveillance study of the sand fly populations in this area. Sand flies were collected between 2009 and 2010 along transects at 200 m, 600 m and 1000 m from six study sites located along the highway (Iberia, La Novia, Alto Libertad, El Carmen, Florida Baja, Mazuko and Mavila) and an undisturbed area (Malinowski). Collected specimens were identified based on morphology and non-engorged females of each species were pooled and screened by kinetoplast PCR to detect natural Leishmania infections. A total of 9,023 specimens were collected belonging to 54 different Lutzomyia species including the first report of Lu. gantieri in Peru. Four species accounted for 50% of all specimens (Lutzomyia carrerai carrerai, Lu. davisi, Lu. shawi and Lu. richardwardi). El Carmen, Alto Libertad, Florida Baja and Malinowski presented higher Shannon diversity indexes (H = 2.36, 2.30, 2.17 and 2.13, respectively) than the most human disturbed sites of Mazuko and La Novia (H = 1.53 and 1.06, respectively). PCR detected 10 positive pools belonging to Lu. carrerai carrerai, Lu. yuilli yuilli, Lu. hirsuta hirsuta, Lu. (Trichophoromyia) spp., and Lu. (Lutzomyia) spp. Positive pools from 1,000 m transects had higher infectivity rates than those from 600 m and 200 m transects (9/169 = 5.3% vs 0/79 = 0% and 1/127 = 0.8%, p = 0.018). El Carmen, accounted for eight out of ten positives whereas one positive was collected in Florida Baja and Mazuko each. Our study has shown differences in sand fly diversity, abundance and species composition across and within sites. Multiple clustered Lutzomyia pools with natural Leishmania infection suggest a complex, diverse and spotty role in leishmaniasis transmission in Madre de Dios, with increased risk farther from the highway.

Detection of Leishmania species (Kinetoplastida, Trypanosomatidae) in phlebotomine sand flies (Diptera, Psychodidae) from Porto Velho, Northern Brazil

Cutaneous Leishmaniasis (CL) is a vector-borne disease caused by Leishmania species and transmitted by infected female sand flies. CL is widely distributed in Brazil, but knowledge about vectors and transmission cycles could be complex according to localities. The sand fly fauna in Rondônia State is extensive, diverse, and largely unexplored. Although the state records a mean of 1,000 CL cases per year, the vectors of CL are unknown. The aim of this study was to assess phlebotomine sand fly fauna composition using diversity indexes (Shannon [H'] and Simpson [1/D]) and to detect the prevalence of Leishmania infection to verify potential vectors in three ecotopes: (i) forest fragment (FF), (ii) forest edge (FE), and (iii) peridomicile (PE). Captures were performed in four rural districts in the municipality of Porto Velho. A total of 7,026 specimens were captured comprising 72 species, and individuals classified in subgenus level. Overall, the most abundant species were Lutzomyia davisi (n: 1,105), Lutzomyia melloi (n: 760), Lutzomyia auraensis (n: 738) and Lutzomyia antunesi (n: 479). Fauna was most diverse in the FF ecotope (H' = 20.2, 1/D = 11.2), followed by the FE (H' = 18.0, 1/D = 10.1) and PE (H' = 16.6, 1/D = 10.1) ecotopes. Leishmania DNA was detected in 24 of 232 pools. In every ecotope, Leishmania naiffi DNA was identified in the following sand fly species: Lu. antunesi, Lu. davisi, Lu. hirsuta hirsuta, Lu. shawi, Lu. sordellii and Lu. (Trichophoromyia) spp. This observation may indicate that a Le. naiffi transmission focus is present in the study localities. In addition, Leishmania lainsoni was detected in Lutzomyia (Trichophoromyia) spp. Our findings show that sand fly fauna in the study localities is diverse, that Leishmania parasites are circulating in all three ecotopes, and that some sand fly species may be implicated in the transmission of Leishmania to humans in localities evaluated.

An overview of the sandfly fauna (Diptera: Psychodidae) followed by the detection of Leishmania DNA and blood meal identification in the state of Acre, Amazonian Brazil

BACKGROUND

In Acre state, Brazil, the dissemination of cutaneous leishmaniasis has increased in recent years, with limited knowledge of the potential Leishmania spp. vectors involved.

OBJECTIVES

Here, data concerning the sandfly fauna of Brasiléia municipality, Leishmania DNA-detection rates and the identification of blood meal sources of insects captured in 2013-2015 are presented.

METHODS

Parasite detection in female sandflies was performed individually by multiplex polymerase chain reaction (PCR) (Leishmania kDNA/sandfly cacophony-gene), with the identification of Leishmania spp. by hsp70-PCR and sequencing. The identification of blood gut-content from fed females was performed by cyt b-PCR and sequencing.

FINDINGS

A total of 4,473 sandflies were captured. A subgroup of 864 non-blood-fed females evaluated for the presence of Leishmania DNA showed 2.9% positivity for Leishmania (Viannia) braziliensis and L. (V.) guyanensis. The identification of blood meal sources was performed in 96 blood-fed females, allowing the identification of 13 vertebrate species. In nine/96 fed females, DNA from L. (V.) shawi, L. (V.) guyanensis, L. (V.) braziliensis and Endotrypanum sp. was detected.

MAIN CONCLUSIONS

In Brumptomyia sp. and Evandromyia termitophila, the first report of Leishmania DNA-detection is provided in Acre; Nyssomyia shawi is implicated as potential vector of L. (V.) braziliensis and L. (V.) guyanensis for the first time in Brazil.

First report of an Onchocercidae worm infecting Psychodopygus carrerai carrerai sandfly, a putative vector of Leishmania braziliensis in the Amazon

Sandflies are insects of public health interest due to their role as vectors of parasites of the genus Leishmania, as well as other pathogens. Psychodopygus carrerai carrerai is considered an important sylvatic vector of Leishmania (Viannia) braziliensis in Amazonia. In this study, sandflies were collected in a forested area in the Xapuri municipality, in the State of Acre (Northern Brazil). Two Ps. carrerai carrerai females were found parasitized with a larval form of a filarial worm, one in the labium of the proboscis, the other after the head was squashed, suggesting they were infective larvae. Sandflies were identified through morphological characters as well as amplification and sequencing of the cytochrome oxidase gene (COI). This was the first sequence obtained for Ps. carrerai carrerai for this marker. The obtained nematodes were also characterized through direct sequencing of a fragment of COI and 12S genes, both mitochondrial, and ITS1, a nuclear marker. Phylogenetic analyses revealed that the filarial nematodes belong to a species without sequences for these markers in the database, part of family Onchocercidade and closely related to genus Onchocerca (12S tree). Although sandfly infection with nematodes including members of the Onchocercidae has been reported in the Old World, this is the first report of sandfly infection by a member of the Onchocercidae family in the New World, to the best of our knowledge. Considering that the phylogenetic relationships and location in the insect, it can be expected that this is a parasite of mammals and the transmission cycle should be clarified.

Disney Trap Attractiveness for the Cortelezzii Series (Diptera: Psychodidae, Phlebotominae) in a Fishing Tourism Area, Bonito Municipality, Mato Grosso do Sul State, Brazil

Sand fly fauna is frequently sampled using automatic light or Shannon traps, yet few studies have been devoted to investigating the effectiveness of Disney traps baited with live animals as an attractant. This study sought to identify the phlebotomine fauna attracted to Disney traps having hamsters (Mesocricetus auratus) as bait. A hamster-baited Disney trap was installed in a gallery forest located in Águas do Miranda District, Bonito Municipality, Mato Grosso do Sul state, Brazil, from November 2011 to October 2012. A total of 717 phlebotomines were collected, in which male (251) and female (463) specimens of the Cortelezzii series (Diptera: Psychodidae) predominated (99%). Males were attracted from January to July, whereas the females were predominantly attracted from January to May. No significant correlation was observed between the monthly climatic averages of temperature, rains and humidity, and the numbers of insects collected. Although these findings showed the attractiveness of both sexes of the species of the Cortelezzii series to golden hamsters, further studies are needed to investigate the blood meal preferences of these females to other rodents. As rodents have been reported as reservoirs of Leishmania spp. (Kinetoplastida: Trypanosomatidae), research using live-baited traps can reveal feeding preferences of sand flies and the importance of various rodent species in the zoonotic cycle.

Ecological aspects of Phlebotomines (Diptera: Psychodidae) and the transmission of American cutaneous leishmaniasis agents in an Amazonian/ Guianan bordering area

BACKGROUND

An entomological study was conducted in the municipality of Oiapoque (lower Oyapock River Basin) in the Brazilian side bordering French Guiana to gain information on the transmission pattern of American cutaneous leishmaniasis (ACL) in that region, presumed to reflect the classical Amazonian/Guianan enzootic scenario.

METHODS

Three ecologically isolated forested areas near urban environments were surveyed during the rainy and dry seasons of 2015 and 2016, using a multi-trapping approach comprising ground-level and canopy light traps, black and white colored cloth Shannon traps and manual aspiration on tree bases. Female phlebotomines were dissected to find infections and isolate flagellates from Leishmania spp. The strains were characterized by restriction fragment length polymorphism analysis and compared with those of local ACL cases and World Health Organization reference strains.

RESULTS

Nyssomyia umbratilis, Trichopygomyia trichopyga and Evandromyia infraspinosa were the most frequently found species. Findings on relative abundance, spatiotemporal vector/ACL congruence, natural infections and anthropophilic insights strengthened the Guianan classical transmission of Leishmania (Viannia) guyanensis by Ny. umbratilis and suggested further investigations for Ev. infraspinosa. Nyssomyia umbratilis showed an eclectic feeding habit, including bird blood. Ecological data and literature reports also included Psychodopygus squamiventris maripaensis and Bichromomyia flaviscutellata on the list of suspected vectors.

CONCLUSIONS

These findings contributed to understanding ACL ecoepidemiology in the Amazonian/Guianan scenario. Local studies are required to better comprehend the Leishmania spp. enzootic mosaic in specific ecotopes.