Biogeographical aspects of the occurrence of Nyssomyia neivai and Nyssomyia intermedia (Diptera: Psychodidae) in a sympatric area of the Brazilian savannah

Sand fly population dynamics in areas of American cutaneous leishmaniasis, Municipality of Paraty, Rio de Janeiro, Brazil

The present study is the second and last part of the study that investigated the fauna and behavior of sand flies in areas prone to cutaneous leishmaniasis outbreaks, in the State of Rio de Janeiro, in the municipality of Paraty. To collect the sand flies, CDC and Shannon light traps were used, installed in the peridomiciliary and forest areas, and manual suction tubes on the walls of the home and in the animal shelters. A total of 102,937 sand flies, belonging to nine genera and 23 species were captured from October 2009 to September 2012. Regarding the monthly frequency of sand flies, the period of highest density was from November to March, with a maximum peak in January. The lowest density was observed in June and July. In the studied area, the species of epidemiological importance, Nyssomyia intermedia, Pintomyia fischeri, Migonemyia migonei and Nyssomyia whitmani, were found in all months of the year, a period in which residents may be in contact with these vectors of the etiological agent of cutaneous leishmaniasis.

The transmission of visceral leishmaniasis in the municipality of Guarujá, on the Coast of São Paulo state, Brazil

OBJECTIVE

To perform an entomological survey, evaluating the circulation of Leishmania spp. in sand flies captured from the new foci of visceral leishmaniasis (VL) in the coastal region of São Paulo state.

METHODS

Sand flies were captured from November 2016 to September 2018 using light traps of the Centers for Disease Control (CDC), in the neighborhood where VL cases were reported. Leishmania spp. circulation was evaluated by gut dissection and molecular analysis of the females captured.

RESULTS

Nyssomyia intermedia was the more frequent species (90,7%) within the 1,203 sand flies captured. We found no flagellates in dissected females, but two pools containing females of Ny. intermedia presented DNA of L. infantum.

CONCLUSION

Our results suggest that Ny. intermedia might be involved in the establishment of this new VL focus in Sao Paulo. However, before incriminating this species as a L. infantum vector, further studies should investigate other vectorial capacity parameters, including competence, survival, and feeding habits.

Sand fly behavior: much more than weak-flying

BACKGROUND

Leishmaniases are diseases transmitted by some species of sand flies and are widely distributed throughout the tropical regions of the planet. Despite the low mobility of these vectors, the geographical distributions of some species are quite extensive, which hinders control and surveillance measures in endemic areas.

OBJECTIVES

The present study investigated the flying capacity of sand flies.

METHODS

Four Hoover Penido (HP)-type light traps were positioned in the centre of the Velhas' River, about 80 metres equidistant from each other. We also realised capture/release/recapture attempts to assess possible capacity of phlebotomine fly uninterrupted up to 150 metres. Captured sand flies from one side of the river were marked using fluorescent powder (Luminous Paint kit, Bioquip®) and released on the other side, approximately 150 m distant. Recapture attempts were made on river's bank up to 30 days post-release.

FINDINGS

Six sand flies of the species Nyssomyia neivai (n = 4), Ny. intermedia (n = 1) and Evandromyia lenti (n = 1) were captured in the centre of the river. There were no recaptures of the 1,450 marked-and-released sand flies.

MAIN CONCLUSIONS

The results obtained disagree with data found in the literature regarding the flight capacity of sand fly vectors of leishmaniasis.

The sand fly (Diptera: Psychodidae) fauna of the urban area of Lassance, Northeast Minas Gerais, Brazil

The present study aimed to check the sand flies' fauna on the municipality of Lassance, Minas Gerais, Brazil and detect the presence of Leishmania DNA on the female captured and determine the risk areas of the municipality. Sand flies were collected monthly from May 2018 to April 2019 using automatic light traps for 3 consecutive nights. Eight houses were selected as sample points due its previous reports of tegumentary leishmaniasis and/or canine leishmaniasis. The sand fly's fauna found on the present study it's represented by several medical importance species and the most abundant species found were Lutzomyia longipalpis (77.09%) and Nyssomyia intermedia (10.06%). Leishmania infantum DNA was detected in a pool of Lu. longipalpis resulting on a 2.81% of infection rate. By the frequency of the two most abundant species on this study, we developed a risk area map and it draws attention to sample point 6 due to disparate abundance of sand flies at this site (81.81%). Statistical overview shows Lu. longipalpis as dominant species and, still, Non-Metric Multidimensional Scaling analysis reveal high similarity on fauna's diversity on the study area. Our findings suggest that the diversity of sand flies from the municipality of Lassance may promote the circulation of Leishmania infantum parasites putting in risk the habitants and other mammal's species. Still, our study reinforces the necessity of specific studies focused on breed sites of phlebotomine and its' ecology to expand the knowledge about the behaviour of this group of insects applying directly to leishmaniases' epidemiology.

GENETIC DIVERSITY OF Lutzomyia (Nyssomyia) intermedia IN AN ENDEMIC AREA OF AMERICAN CUTANEOUS LEISHMANIASIS, STATE OF PARANÁ, BRAZIL

Lutzomyia intermedia (Diptera: Psychodidae) features as one of the main vectors that are involved in the transmission of American cutaneous leishmaniasis (ACL) in the Neotropical region. However, genetic studies involving this taxon are still incipient and important for understanding the level of variability of different populations, their role, and implications as vectors. The aim of this study was to determine the level of genetic diversity of L. intermedia present in the Ribeira River Valley, an area of ACL transmission in the state of Paraná, Brazil, through the Random amplified polymorphic DNA (RAPD). Two municipalities were chosen to collect sand flies: Cerro Azul (new transmission area of the ACL) and Adrianópolis (endemic area of the ACL). The insects were captured in the house, in the peridomicile and in the wild (forest). Two of the used markers made it possible to estimate the polymorphism of the studied populations, resulting in 40 genotypes, most of them from peridomicile. The dendrogram generated by the analysis with the primer A10 showed different degrees of similarity, suggesting that there may be gene flow in the studied populations. The Principal Coordinate Analysis (PCO) with the A2 primer, was useful in grouping L. intermedia according to its ecological and geographical origin. There was no distinction between the lineages composing the L. intermedia complex. The results of this study, with the record of great genotypic diversity in L. intermedia, may contribute to explain the maintenance of the life cycle of Leishmania braziliensis (Kinetoplastida: Trypanosomatidae) in the region.

Environmental Niche Modelling of Phlebotomine Sand Flies and Cutaneous Leishmaniasis Identifies Lutzomyia intermedia as the Main Vector Species in Southeastern Brazil

Cutaneous leishmaniasis (CL) is caused by a protozoan of the genus Leishmania and is transmitted by sand flies. The state of Espírito Santo (ES), an endemic area in southeast Brazil, has shown a considerably high prevalence in recent decades. Environmental niche modelling (ENM) is a useful tool for predicting potential disease risk. In this study, ENM was applied to sand fly species and CL cases in ES to identify the principal vector and risk areas of the disease. Sand flies were collected in 466 rural localities between 1997 and 2013 using active and passive capture. Insects were identified to the species level, and the localities were georeferenced. Twenty-one bioclimatic variables were selected from WorldClim. Maxent was used to construct models projecting the potential distribution for five Lutzomyia species and CL cases. ENMTools was used to overlap the species and the CL case models. The Kruskal-Wallis test was performed, adopting a 5% significance level. Approximately 250,000 specimens were captured, belonging to 43 species. The area under the curve (AUC) was considered acceptable for all models. The slope was considered relevant to the construction of the models for all the species identified. The overlay test identified Lutzomyia intermedia as the main vector of CL in southeast Brazil. ENM tools enable an analysis of the association among environmental variables, vector distributions and CL cases, which can be used to support epidemiologic and entomological vigilance actions to control the expansion of CL in vulnerable areas.

Incipient colonisation of Lutzomyia longipalpis in the city of Resistencia, province of Chaco, Argentina (2010-2012)

Lutzomyia longipalpis was recorded for the first time in Argentina in 2004, in the province of Formosa. In the following years, the vector spread to the south and west in the country and was recorded in the province of Chaco in 2010. From November 2010-May 2012, captures of Phlebotominae were made in the city of Resistencia and its surroundings, to monitor the spread and possible colonisation of Lu. longipalpis in the province of Chaco. In this monitoring, Lu. longipalpis was absent in urban sampling sites and its presence was restricted to Barrio de los Pescadores. This suggests that the incipient colonisation observed in 2010 was not followed by continuous installation of vector populations and expansion of their spatial distribution as in other urban centres of Argentina.

Effect of environmental disturbance on the population of sandflies and leishmania transmission in an endemic area of Venezuela

The exploitation of new wilderness areas with crops is increasing and traditional crop substitution has been modified by new more productive crops. The results show the anthropogenic disturbance effect on the sandflies population and Leishmania transmission in endemic areas of Venezuela. Three agroecosystems with variable degrees of ecological disturbance, forest (conserved), cacao (fragmented), and orangery (disturbed), were selected. Four methods to sandfly capture were used; the specimens were identified and infected with Leishmania. Diversity, population structure, ANOVA, Tukey test, and simple correlation analysis were carried out. Shannon traps were able to capture 94.7% of the total sandflies, while CDC light traps, Sticky traps, and direct suction just captured 2.2%, 1.2%, and 0.9%, respectively. The results showed the effect of ecological disturbance degree on the composition of sandflies and population structure, revealing a dominance level increased but decreased on the diversity and richness of sandflies species in the greatest ecological disturbance area in relation to areas with less organic disturbance. Environments more disturbed cause adaptability of certain species such as Lutzomyia gomezi and Lutzomyia walkeri. These changes on the composition of sandflies population and structure emerging species could cause increasing of leishmaniasis transmission.