Preferência alimentar sanguínea de Lutzomyia whitmani (Diptera, Psychodidae) em área de transmissão de leishmaniose cutânea americana, no Estado do Maranhão, Brasil

Survey of phlebotomine sand fly fauna in a public Zoo in Brazil: Species diversity, seasonality, and host variety

Leishmaniasis is a dynamic disease in which transmission conditions change due to environmental and human behavioral factors. Epidemiological analyses have shown modifications in the spread profile and growing urbanization of the disease, justifying the expansion of endemic areas and increasing number of cases in dogs and humans. In the city of Belo Horizonte, located in the southeastern state of Minas Gerais (Brazil), visceral leishmaniasis (VL) is endemic, with a typical urban transmission pattern, but with different regional prevalence. This study was conducted at the Zoo of the Foundation of Municipal Parks and Zoobotany of Belo Horizonte (FPMZB-BH), located in the Pampulha region, which is among the areas most severely affected by VL. This study aimed to determine the taxonomic diversity of native phlebotomine sand flies (Diptera: Psychodidae), identify climatic variables that potentially affect the phenology of these insects, and determine the blood meal sources for female phlebotomine sand flies. To achieve this, 10 mammal enclosures in the zoo were selected using the presence of possible leishmaniasis reservoirs as a selection criterion, and sampled using light traps between August 2019 and August 2021. A total of 6034 phlebotomine sand flies were collected, indicating nine species, with Lutzomyia longipalpis being the very abundant species (65.35% of the total). Of the 108 engorged phlebotomine collected females, seven samples (6.5%) were positive for blood meals from humans, marsupials, canids, and birds. Relative humidity and rainfall increased the phenology of phlebotomine sand flies, with population increases in the hottest and wettest months. The data obtained will provide guidelines for competent health agencies to implement vector control measures to reduce the risk of leishmaniasis transmission in the FPMZB-BH.

Influence of Moonlight on Male Mating Aggregations of Nyssomyia whitmani, a Vector of American Cutaneous Leishmaniasis in Brazil

Nyssomyia whitmani (Antunes & Coutinho) is the sandfly vector of causative agents of American cutaneous leishmaniasis in South and Central America. It is widely spread throughout Brazil, in a close association with domestic animals. Almost nothing is known about male mating aggregations in N. whitmani, let alone the influence of moonlight on this behavior. Thus, the influence of moonlight on male N. whitmani aggregations was investigated by using non-attractant suction traps deployed in chicken cages under full moon and new moon nights. In this 18-night study, 2,160 specimens and seven species were collected. The most frequent species was N. whitmani accounting for 91.48% of the total sample. The abundance of males of N. whitmani was significantly higher in the presence than in the absence of moon. The sex ratio on new moon nights was 1:1 (M:F) and on full moon nights was male-biased (1.7:1). Based on this study, an influence of moonlight on male mating aggregations of N. whitmani was verified. The extent of this influence on increasing sandfly aggregation at hosts, the moonlight influence on the early flight activity of male sandflies and the use of chickens as aggregation sites for males of N. whitmani, are all discussed.

Effects of forest degradation on the sand fly communities of northeast Brazil

The richness and abundance of sand fly species were studied in northeastern Brazil in areas of leishmaniasis transmission. The study was carried out in two forest areas with different deforestation times for agricultural and livestock activities: one modified by long-term settlement (more than 50 years of occupation) and another less impacted by short-term settlement (10 years). The sand flies were captured with CDC light traps from 18:00 to 06:00 for three consecutive nights, once a month, from May, 2012 to April, 2014. The study captured 21,708 specimens and also 33 species of Lutzomyia and two of Brumptomyia. Species richness and abundance were higher in the more conserved area of short-term occupation (31 species; 61.7%) than in the more degraded area with long-term occupation (17 species; 38.3%). In the most conserved area, the species richness was higher in the forest fragment than in the rural settlement, whereas in the degraded area the richness was higher in the peri-domicile than in the forest. The diversity was higher in the degraded area forest. There were significant statistical differences when comparing the means of total abundance with the intra-domicile, peri-domicile, and forest environments. The average abundance was statistically higher in the peri-domicile compared to the forest (p = 0.009), but there were no statistically significant differences between intra-domicile-peri-domicile (p = 0.11) and forest-intra-domicile (p = 0.87). In conclusion, a change in vegetation cover negatively affects the richness and abundance of sand flies in the natural environment.

Fast multiplex real-time PCR assay for simultaneous detection of dog and human blood and Leishmania parasites in sand flies

Background

The blood-feeding behaviour of female sand flies may increase their likelihood of acquiring and transmitting Leishmania parasites. Studies on the host usage by these insects may thus improve our understanding of the Leishmania transmission risk in leishmaniasis-endemic areas. Here, we developed a fast multiplex real-time PCR assay for simultaneous detection of dog, human and Leishmania DNA in sand flies.

Methods

Primers and TaqMan probes targeting the mitochondrial cytochrome c oxidase subunit 1 and cytochrome b genes of dog and human, respectively, were combined in a multiplex assay, which also includes primers and a TaqMan probe targeting the Leishmania minicircle kinetoplast DNA.

Results

The multiplex assay was 100% specific, with analytical sensitivities of 10³ fg/reaction for dog and human and 1 fg for Leishmania. By testing field-collected engorged female sand flies (95 Migonemyia migonei and two Nyssomyia intermedia), 50 M. migonei were positive for one or two targets (positivity rates: 45.4% for human, 4.1% for dog and 12.4% for Leishmania DNA).

Conclusions

This multiplex real-time PCR assay represents a novel fast assay for detecting dog, human and Leishmania DNA in female sand flies and therefore a tool for assessing the risk of Leishmania transmission to these hosts in areas of active transmission.

Spatial analysis of leishmaniasis in Brazil: a systematized review

The aim of this study was to perform a systematic review of scientific papers that used spatial analysis tools in cases of leishmaniasis, in Brazil. The search for articles was carried out in PubMed, SciELO, Scopus and Web of Science databases. The keywords used in the identification of the articles were Thematic map AND Leishmaniasis, Spatial analysis AND Leishmaniasis, and Geoprocessing AND Leishmaniasis, in English language. A total of 360 articles were found, and 11 of them were analyzed after screening by title and abstract as well as reading of the full articles. The States studied were Sao Paulo, Acre, Maranhao, Piaui, Minas Gerais, Parana and Tocantins. Cutaneous leishmaniasis occurred predominantly in rural areas, with clusters in forest reserve regions or modified forest areas. Conversely, visceral leishmaniasis mainly occurred in peripheral and central urban areas associated with poorer environments and urban infrastructure, including worse sanitation. We conclude that the spatial distribution of leishmaniasis is closely related to the living environment of the risk population. The analyzed articles associated geospatial data with some risk factors for the disease, pointing out the locations where most cases occur, creating a relevant source to define control strategies.

Occurrence of Phlebotominae (Diptera: Psychodidae) in Urban Leishmaniasis Transmission Foci in North-Eastern Brazil

In this study, we analyzed species composition, richness, and monthly and seasonal abundance of sand flies in an urban area, municipality Caxias, state Maranhão, endemic for American visceral and tegumentary leishmaniasis. Sand flies were caught using Center for Disease Control (CDC) light traps in peridomicile (animal shelter) and extradomicile (forest) environments twice a month for 1 yr. A total of 16,332 specimens belonging to 20 species were captured. The predominant species identified in this study were Lutzomyia longipalpis (Diptera: Psychodidae) (Lutz and Neiva 1912) (43.08%) and Lutzomyia whitmani (Diptera: Psychodidae) (Antunes and Coutinho 1939) (43.02%), which occurred throughout the year (every month). The highest abundance of phlebotomine was recorded during the dry season (53.75%) and in the urban peridomicile environment (59.1%), wherein 17 species were found. In the study area, L. longipalpis and L. whitmani are reported to be effective visceral or tegumentary leishmaniasis vectors, respectively, due to their abundance throughout the year.

Molecular Identification of Leishmania spp. in Sand Flies (Diptera: Psychodidae: Phlebotominae) in the Lençóis Maranhenses National Park, Brazil

Sand flies are very common in the region of Lençóis Maranhenses National Park, an important tourist attraction in Brazil. However, the role of some species and their relative importance locally in Leishmania Ross 1903 transmission is unclear. The objective of this study was to identify Leishmania infection in phlebotomine sand flies collected around the Lençóis Maranhenses National Park, an important conservation area and popular international/national tourist destination with a high incidence of leishmaniasis. Sand flies were collected in peridomiciliary areas on the tourist route from September 2012 to August 2013. The captured females were subjected to molecular analyses for the detection of Leishmania DNA. Sand flies were infected with four Leishmania species: Leishmania (Viannia) braziliensis (Vianna, 1911) was found in Lutzomyia whitmani (Antunes and Coutinho, 1939) (2.1%) and Lutzomyia longipalpis (Lutz and Neiva, 1912) (1.7%); Leishmania (Leishmania) infantum (Nicole, 1908) infected Lutzomyia wellcomei (Fraiha, Shaw, and Lainson, 1971) (20%), Lutzomyia sordellii (Shannon and Del Ponte, 1927) (4.3%), Lu. longipalpis (3.7%), and Lu. whitmani (0.8%); Leishmania (Leishmania) amazonensis (Lainson & Shaw, 1972) was found in Lu. whitmani (0.58%), while Leishmania (Viannia) lainsoni infected Lutzomyia evandroi (Costa Lima and Antunes, 1936) (3.4%), Lu. longipalpis (1.06%), and Lu. whitmani (0.29%). The occurrence of these parasites requires control measures to reduce the incidence of cutaneous leishmaniasis and to contain a possible epidemic of visceral leishmaniasis, the most severe form of the disease.

Risk factors for cutaneous leishmaniasis in the rainforest of Bolivia: a cross-sectional study

Background

Cutaneous leishmaniasis (CL) is an endemic disease in Bolivia, particularly in the rainforest of Cochabamba, in the municipality of Villa Tunari. The precarious, dispersed, and poorly accessible settlements in these farming communities make it difficult to study them, and there are no epidemiological studies in the area. The aim of the present study was to identify the risk factors associated with cutaneous leishmaniasis.

Methods

A cross-sectional study was conducted in August 2015 and August 2016 in two communities of Villa Tunari, Cochabamba. The cases were diagnosed through clinical examinations, identification of the parasite by microscopic examination, and the Montenegro skin test. Risk factors were identified through logistic regression.

Results

A total of 274 participants (40.9% female and 59.1% male) were surveyed, of which 43% were CL positive. Sex was the only factor associated with CL with three times more risk for men than for women; this finding suggests a sylvatic mechanism of transmission in the area.

Conclusions

It is advisable to focus on education and prevention policies at an early age for activities related to either leisure or work. Further research is needed to assess the influence of gender-associated behavior for the risk of cutaneous leishmaniasis.

Assessment of the role of small mammals in the transmission cycle of tegumentary leishmaniasis and first report of natural infection with Leishmania braziliensis in two sigmodontines in northeastern Argentina

To contribute to the knowledge of the role of small mammals in the transmission cycle of tegumentary leishmaniasis caused by Leishmania braziliensis, we studied the small mammal community and its temporal and spatial association with phlebotominae, as well as small mammal infection by Leishmania spp. by PCR-RFLP analyses in an endemic area of northeastern Argentina. Ten small mammal samplings were conducted (2007-2009, 7506 Sherman trap nights and 422 cage trap nights). In two of these samplings, 16 capture stations each one consisting of a CDC light trap to capture phlebotominae, two to four Sherman traps and two cage traps were placed. We found co-occurrence of phlebotominae and small mammal captures in four stations, which were all the stations with small mammal captures and yielded 97% (2295 specimens, including 21 gravid females) of the total phlebotominae captures, suggesting that small mammals may provide a potential source of blood for phlebotominae females. One Didelphis albiventris and two Rattus rattus were associated with high captures of Nyssomyia whitmani, vector of L. braziliensis in the study area. The PCR-RFLP analyses confirm the presence of L. braziliensis in two sigmodontine small mammals (Akodon sp. and Euryoryzomys russatus) for the first time in Argentina, to our knowledge.

Feeding Patterns and Xenomonitoring of Trypanosomes among Tsetse Flies around the Gashaka-Gumti National Park in Nigeria

In order to understand the epidemiology of trypanosomoses in Gashaka-Gumti National Park, Nigeria, we determined the density, infection rates, and feeding patterns of tsetse flies using biconical traps, ITS, and mitochondrial cytochrome b PCRs. A total of 631 tsetse flies were captured, of which 531 (84.2%) and 100 (15.8%) were analyzed for trypanosomes and blood meals, respectively. Tsetse distribution varied significantly (p < 0.05) across study sites with average trap and daily catches of 4.39 and 26.34, respectively. Overall tsetse infection rate was 5.08% and ranged between 3.03% and 6.84% across study sites. We identified 10 T. brucei, 3 T. congolense savannah, 2 T. congolense forest, and 2 mixed infections among the 13 pools made from the 27 flies positive for trypanosomes with light microscopy. The distribution of vertebrate blood meals in tsetse flies varied significantly (p < 0.05) and ranged between 6.0% and 45% across hosts. We also observed dual feeding patterns involving at least 2 hosts in 24% and multiple feeding involving at least 3 hosts in 17% of the flies. We observed predominance of G. palpalis which also recorded higher infection rate. T. brucei was more prevalent among tsetse flies. Tsetse flies fed predominantly on cattle and less frequently on humans and also showed mixed feeding habits.

Experimental Infection of Lutzomyia (Nyssomyia) whitmani (Diptera: Psychodidae: Phlebotominae) With Leishmania (Viannia) braziliensis and Leishmania (L.) amazonensis, Etiological Agents of American Tugumentary Leishmaniasis

Leishmania (L.) amazonensis (Lainson & Shaw, 1972) and Leishmania (Viannia) braziliensis (Vianna, 1911) are the principal causative agents of American tegumentary leishmaniasis (ATL) in Brazil. L. amazonensis also causes diffuse cutaneous leishmaniasis (DCL) vectored principally by Lutzomyia flaviscutellata and secondarily by Lutzomyia whitmani (Antunes & Coutinho, 1939). The latter is the most common phlebotomine in the state of Maranhão, and it is the focal species for potential ATL transmission. For this reason, we tested the ability of L. whitmani to become infected with Lutzomyia parasites. Phlebotomines were derived from a colony maintained in the laboratorial conditions. The first generation, uninfected females were offered a bloodmeal with mice infected with the strains of both parasites. We found that L. whitmani can become infected with both parasite species, with infection rates of 65.2% (L. braziliensis) and 47.4% (L. amazonensis). We conclude that in Maranhão, L. whitmani is likely an important vector in the transmission of ATL and may function as a vector of DCL. This possibility should be further investigated.

Identification of phlebotomine sand fly blood meals by real-time PCR

Background

Phlebotomine sand flies are blood-feeding insects of great medical and veterinary significance acting as vectors of Leishmania parasites. Studying the blood-feeding pattern of these insects may help in the understanding of their interactions with potential reservoir hosts of Leishmania parasites. In this study, we developed real time PCR assays for the identification of sand fly blood meal.

Methods

Six pairs of primers were designed based on cytochrome b gene sequences available in GenBank of the following potential hosts: dog, cat, horse, chicken, black rat, and human. Firstly, SYBR Green-based real time PCR assays were conducted using a standard curve with eight different concentrations (i.e., 10 ng, 1 ng, 100 pg, 10 pg, 1 pg, 100 fg, 10 fg and 1 fg per 2 μl) of DNA samples extracted from EDTA blood samples from each target animal. Then, DNA samples extracted from field-collected engorged female sand flies belonging to three species (i.e., Lutzomyia longipalpis, L. migonei and L. lenti) were tested by the protocols standardized herein. Additionally, female sand flies were experimentally fed on a black rat (Rattus rattus) and used for evaluating the time course of the detection of the protocol targeting this species.

Results

The protocols performed well with detection limits of 10 pg to 100 fg. Field-collected female sand flies were fed on blood from humans (73%), chickens (23%), dogs (22%), horses (15%), black rats (11%) and cats (2%). Interestingly, 76.1% of the L. longipalpis females were positive for human blood. In total, 48% of the tested females were fed on single sources, 31% on two and 12% on three. The analysis of the time course showed that the real time PCR protocol targeting the black rat DNA was able to detect small amounts of the host DNA up to 5 days after the blood meal.

Conclusions

The real time PCR assays standardized herein successfully detected small amounts of host DNA in female sand flies fed on different vertebrate species and, specifically for the black rats, up to 5 days after the blood meal. These assays represent promising tools for the identification of blood meal in field-collected female sand flies.

Molecular detection of the blood meal source of sand flies (Diptera: Psychodidae) in a transmission area of American cutaneous leishmaniasis, Paraná State, Brazil

The feeding behavior of sand flies provides valuable information about the vector/host interactions and elucidates the epidemiological patterns of American cutaneous leishmaniasis (ACL) transmission. The aim of this study was to identify the blood meal sources of sand flies in endemic areas of leishmaniasis in Paraná State through polymerase chain reaction (PCR) amplification of a prepronociceptin (PNOC) gene fragment and its subsequent DNA sequencing. Moreover, molecular assays were conducted to evaluate the sensitivity and reproducibility of the PNOC gene amplification. Besides that, a time-course digestion test of the blood using sand flies that fed artificially on BALB/c mice was performed. Of 1263 female sand flies collected in the field, 93 (3.6%) specimens were engorged and 27 allowed efficient amplification of the PNOC gene. These flies had fed on equine (Equus caballus), porcine (Sus scrofa) and canine (Canis lupus familiaris) species. The results also showed that the identification of the blood meal sources of the sand flies using the molecular method was directly linked to the level of digestion of the blood (time-course) and not to the amount of blood that had been ingested or to the presence of inhibitors in the blood.

Ecology of phlebotomines (Diptera, Psychodidae) in rural foci of leishmaniasis in tropical Brazil

INTRODUCTION

This work aimed to study the community structure of sandflies, with regard to the richness, constancy, abundance, and monthly frequency of the species with a focus on the transmission of leishmaniasis.

METHODS

The study was conducted in the rural villages of Bom Jardim and Santa Maria, situated on the edge of a tropical rain forest in the municipality of São Jose de Ribamar, Maranhão, Brazil. The phlebotomines were captured in the intradomiciles and peridomiciles of each village, with Centers for Disease Control (CDC) light traps set in 10 homes in each village, for 1 year, once a month, from 18h to 6h.

RESULTS

We collected 1,378 individuals of 16 sandfly species. The capture success rate was higher in Bom Jardim (0.61 specimens/hour/trap) than that of Santa Maria (0.35/specimens/hour/trap). The sandflies were more abundant in the peridomiciles (86.1%) and in the rainy season (77%). Five species were considered constants (occurring in more than 50% of samples), 5 accessory (25%-50%), and 6 accidental (<25%). The most abundant species were Lutzomyia longipalpis (59.7%) and L whitmani (28%). The permutation analysis showed differences between the species composition of the villages and no separation between the intradomicile and peridomicile of each village. The species that most contributed to the dissimilarity between the light traps of the 2 villages were L. longipalpis, L. whitmani, and L. evandroi, contributing to 80.8% of the variation among groups.

CONCLUSIONS

The high level of richness and abundance of species and the presence of competent vectors throughout the year and around houses justify the occurrence of leishmaniasis cases reported in the area.

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.

Distribution and abundance of phlebotominae, vectors of leishmaniasis, in Argentina: spatial and temporal analysis at different scales

The spatial-temporal analysis of the abundance of insects, vectors of tegumentary leishmaniasis (TL) and visceral leishmaniasis (VL), was performed in Argentina using spatial-temporal increasing scales. In the microscale (microfocal), the effect of the primary vegetation-crop interface in vector abundance was observed, and also how the shelters, food sources, and other environmental characteristics contribute to habitat microheterogeneity and so to a microheterogeneous vector distribution. In the mesoscale (locality or epidemic focus), the results from different foci of TL (rural and periurban) and VL (urban) suggested a metapopulation structure determined partially by quantifiable habitat variables that could explain the increase of risk associated to an increase of vector-human contact due to climatic or anthropogenic changes. In the macroscale (regional), captures of vectors and records of human cases allowed the construction of risk maps and predictive models of vector distribution. In conclusion, in order to obtain valid results transferrable to control programs from spatial studies, special attention should be paid in order to assure the consistency between the spatial scales of the hypotheses, data, and analytical tools of each experimental or descriptive design.

Forty years of visceral leishmaniasis in the State of Piaui: a review

Visceral leishmaniasis (VL) has been known to occur in the state of Piauí since 1934. The typically rural disease began to appear in urban areas over time, being concentrated mainly in Teresina, the capital of Piauí. Teresina was also affected by the first urban epidemic of VL in Brazil. Over 1,000 cases of the disease were reported during urbanization (1981-1986). Human population growth and migration led to land occupation on the outskirts of Teresina. These factors have contributed to vector proliferation, increasing the incidence of VL. At present, the incidence of human and canine disease is quite high and uncontrolled in Piauí. It seems that some measures, such as the elimination of seropositive dogs, failed to significantly reduce the number of new VL cases in Teresina. Despite previously conducted studies, little is known about VL epidemiology in urban areas. The aim of this review is to reveal the situation of VL in Teresina during the last 40 years, focusing on the major factors that may contribute to the high incidence and persistence of VL infection.