Integrated Tools for American Cutaneous Leishmaniasis Surveillance and Control: Intervention in an Endemic Area in Rio de Janeiro, RJ, Brazil

Global Dilemma and Needs Assessment Toward Achieving Sustainable Development Goals in Controlling Leishmaniasis

Leishmaniasis is a disease of poverty that imposes a devastating medical, social, and economic burden on over 1 billion people nationwide. To date, no in-depth study to analyze the major global challenges and needs assessment has been carried out. This investigation aimed to explore a comprehensive narrative review of leishmaniasis's main challenges and initially highlight obstacles that might impede the implementation of control measures. Also, we propose a specific list of priorities for needs assessment. The presence of socioeconomic factors, multiple clinical and epidemiological forms, various Leishmania species, the complexity of the life cycle, the absence of effective drugs and vaccines, and the lack of efficient vector and reservoir control make this organism unique and sophisticated in playing a tangled role to react tricky with its surrounding environments, despite extensive efforts and implementation of all-inclusive former control measures. These facts indicate that the previous strategic plans, financial support, and basic infrastructures connected to leishmaniasis surveillance are still insufficient. Strengthening the leishmaniasis framework in a context of accelerated programmatic action and intensification of cross-cutting activities along with other neglected tropical diseases (NTDs) is confidently expected to result in greater effectiveness, cost-benefit, and fruitful management. Sensitive diagnostics, effective therapeutics, and efficacious vaccines are vital to accelerating advancement toward elimination, and reducing morbidity/mortality and program costs. Collective actions devoted by all sectors and policy-makers can hopefully overcome technical and operational barriers to guarantee that effective and coordinated implementation plans are sustained to meet the road map for NTDs 2021- 2030 goals.

Population dynamics of Nyssomyia whitmani (Diptera: Psychodidae) in domestic and peridomestic environments in Northeast Argentina, a tegumentary leishmaniasis outbreak area

In the present study, the temporal dynamics of the main vector of Leishmania braziliensis, Nyssomyia whitmani, was measured by monthly captures of phlebotominae sandflies during 5 consecutive years (from 2011 to 2016) in the Paranaense region of South America. The captures were performed in environments where the human-vector contact risk is high: domiciliary and peridomiciliary environments in a rural area endemic of tegumentary leishmaniasis. Nyssomyia whitmani was recorded as the dominant species of the phlebotominae ensemble in all domiciliary and peridomiciliary environments (House, Chicken Shed, Pigsty, and Forest Edge). Using generalized additive models, intra- and interannual fluctuations were observed, modulated by meteorological variables such as the minimum temperature and the accumulated precipitation 1 wk prior to capture. The installation of a pigsty by the farmer during the study period allowed us to observe and describe the so-called "pigsty effect" where the Ny. whitmani population was spatially redistributed, turning the pigsty as the environment that obtained the highest phlebotominae record counts, thus maintaining the farm overall abundance, supporting the idea that the environmental management of the peridomicile could have an impact on the reduction of epidemiological risk by altering the spatial distribution of the phlebotominae ensemble in the environments.

Ecological characterization of a cutaneous leishmaniasis outbreak through remotely sensed land cover changes

In this work we assessed the environmental factors associated with the spatial distribution of a cutaneous leishmaniasis (CL) outbreak during 2015-2016 in north-eastern Argentina to understand its typical or atypical eco-epidemiological pattern. We combined locations of human CL cases with relevant predictors derived from analysis of remote sensing imagery in the framework of ecological niche modelling and trained MaxEnt models with cross-validation for predictors estimated at different buffer areas relevant to CL vectors (50 and 250 m radii). To account for the timing of biological phenomena, we considered environmental changes occurring in two periods, 2014-2015 and 2015-2016. The remote sensing analysis identified land cover changes in the surroundings of CL cases, mostly related to new urbanization and flooding. The distance to such changes was the most important variable in most models. The weighted average map denoted higher suitability for CL in the outskirts of the city of Corrientes and in areas close to environmental changes. Our results point to a scenario consistent with a typical CL outbreak, i.e. changes in land use or land cover are the main triggering factor and most affected people live or work in border habitats.

Spatial-temporal pattern of cutaneous leishmaniasis in Brazil

Background

Cutaneous leishmaniasis (CL) is a vector-borne disease classified by the World Health Organization as one of the most neglected tropical diseases. Brazil has the highest incidence of CL in America and is one of the ten countries in the world with the highest number of cases. Understanding the spatiotemporal dynamics of CL is essential to provide guidelines for public health policies in Brazil. In the present study we used a spatial and temporal statistical approach to evaluate the dynamics of CL in Brazil.

Methods

We used data of cutaneous leishmaniasis cases provided by the Ministry of Health of Brazil from 2001 to 2017. We calculated incidence rates and used the Mann–Kendall trend test to evaluate the temporal trend of CL in each municipality. In addition, we used Kuldorff scan method to identify spatiotemporal clusters and emerging hotspots test to evaluate hotspot areas and their temporal trends.

Results

We found a general decrease in the number of CL cases in Brazil (from 15.3 to 8.4 cases per 100 000 habitants), although 3.2% of municipalities still have an increasing tendency of CL incidence and 72.5% showed no tendency at all. The scan analysis identified a primary cluster in northern and central regions and 21 secondary clusters located mainly in south and southeast regions. The emerging hotspots analysis detected a high spatial and temporal variability of hotspots inside the main cluster area, diminishing hotspots in eastern Amazon and permanent, emerging, and new hotspots in the states of Amapá and parts of Pará, Roraima, Acre and Mato Grosso. The central coast the state of Bahia is one of the most critical areas due to the detection of a cluster of the highest rank in a secondary cluster, and because it is the only area identified as an intensifying hotspot.

Conclusions

Using a combination of statistical methods we were able to detect areas of higher incidence of CL and understand how it changed over time. We suggest that these areas, especially those identified as permanent, new, emerging and intensifying hotspots, should be targeted for future research, surveillance, and implementation of vector control measures.

Graphic abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s40249-021-00872-x.

Lutzomyia evandroi in a New Area of Occurrence of Leishmaniasis

PURPOSE

Sand flies are vectors of medical and veterinary concern, responsible for the transmission of Leishmania parasites. These invertebrates are widely distributed throughout the world and their abundance and diversity is dependent on several biotic and physical factors. Based on the epidemiological importance of these insects, the aim of this study was to assess the sand fly fauna of a new area of occurrence of leishmaniasis.

METHODS

From October 2018 to September 2019, samplings were performed using CDC light traps at six different collection points located in a high altitude area in the municipality of Garanhuns, Northeastern Brazil. Geographic coordinates were recorded using the satellite remote sensing Global Positioning System (GPS) Garmin Etrex20. The spatial distribution of sand flies was evaluated using kernel density estimation (KDE). Engorged females (n = 12) were molecularly processed to search for Leishmania DNA.

RESULTS

A total of 138 sand fly specimens were collected during the study period, with 100% (138/138) identified as Lutzomyia evandroi. Climatic conditions did not influence the number of sand flies (males and females) collected monthly, but a statistically significant difference was observed between the number of specimens and different collections points. The kernel map showed a heterogeneous spatial distribution of sand flies in the municipality of Garanhuns with a hotspot in the south of the region.

CONCLUSION

Data presented herein are pivotal in filling the gap on the epidemiology of leishmaniasis in this high altitude area, serving as an alert to local health authorities. It also indicated that the putative role of L. evandroi in the transmission of Leishmania parasites should be clarified.

Major environmental and socioeconomic determinants of cutaneous leishmaniasis in Brazil - a systematic literature review

Cutaneous leishmaniasis (CL) is a zoonotic disease with complex transmission cycle. Some environmental and socioeconomic factors are known to be the major determinants of the transmission process, which are involved in configuring the spatiotemporal patterns and thus can be delimiting. However, the relevance of these socioeconomic and environmental determinants is still not well understood. In this study, we aimed to identify the major environmental and socioeconomic determinants of CL in Brazil by articulating a systematic literature review of studies that are based on this subject. The methodology included a search for studies according to a structured protocol using the scientific platforms, such as Scielo and PubMed. The references of each identified article were who referred to CL determinants were further screened, and so on. We extracted information from 41 articles and the determinants were grouped accordingly. Two measures were evaluated as follows: a) the frequency of citations of the determinants; and b) the proportion of determinants identified as having "significant association in analytical studies" with respect to the total number of determinants analyzed in other analytical studies using the same concept. The analyzed articles covered most of the regions of Brazil and 7 other countries bordering Brazil. We found 43 concepts of determinants. However, the final selection resulted in the identification of 14 major determinants. These results therefore contribute in the identification of major CL determinants and this information can be used to establish strategies for identifying risk prone areas for disease surveillance.

Distribution of the assemblage of phlebotomine sandflies (Diptera: Psychodidae) along an environmental gradient

Abstract The geographical distribution of leishmaniasis has undoubtedly expanded, and is now being reported to be in areas that were previously non-endemic. This study therefore aimed to investigate whether there is any variation in the structure and in the composition of phlebotomine communities along an environmental gradient - from a mesic to a xeric environment, across different climatic periods (rainy and dry seasons). Furthermore, we test whether there were differences in sex ratio of sand flies between wet and dry environments. A total of 535 specimens of sand flies belonging to 18 species were recorded. Richness, abundance, and composition of species were significatively higher in the xeric environment (semidecidual Forest) compared to the mesic environment (Riparina Forest). We unveiled site specific differences in sand fly collections since the community composition changes with the geographic distance among the sampling points. These results led to the conclusion that for sand flies species, the environmental conditions available for each species could be different within the habitat taking into account the degree of humidity in the forest as well as the climatic season (dry or wet). The present study gives a valuable contribution to the knowledge of sand flies, as a group of insects, from the Atlantic Forest biome.

Social and Economic Burden of Human Leishmaniasis

Leishmaniasis continues to pose a major public health problem worldwide. With new epidemics occurring in endemic areas and the spread of the disease to previously free areas because of migration, tourism, and military activities, there is a great need for the development of an effective vaccine. Leishmaniasis is a disease of the poor, occurring mostly in remote rural villages with poor housing and little or no access to modern health-care facilities. In endemic areas, diagnosis of any form of leishmaniasis puts a huge financial strain on an already meagre financial resource at both the individual and community levels. Most often families need to sell their assets (land and livestock) or take loans from informal financial outfits with heavy interest rates to pay for the diagnosis and treatment of leishmaniasis. Here, we discuss the disease with special emphasis on its socioeconomic impact on the affected individual and community. In addition, we highlight the reasons why continued research aimed at developing an effective Leishmania vaccine is necessary.

Leishmaniasis transmission in an ecotourism area: potential vectors in Ilha Grande, Rio de Janeiro State, Brazil

BACKGROUND

The south coast of Rio de Janeiro State, in Brazil, is endemic for cutaneous and visceral leishmaniases and is frequently visited by tourists from different parts of the world. Since the complex epidemiology of leishmaniases demands local studies, the goal of this study was to investigate the phlebotomine sand fly fauna and leishmaniases transmission in Ilha Grande, an ecotourism area of Angra dos Reis municipality.

METHODS

Sand fly fauna was sampled in three monitoring stations using HP light traps in domiciles, peridomiciles and forests. Species abundance was evaluated by the Index of Species Abundance. A Leishmania natural infection survey was done using multiplex PCR and dot blot hybridization.

RESULTS

During 15 consecutive months of sand fly monitoring, 1093 specimens from 16 species were captured. The potential leishmaniases vectors found were Lutzomyia (Nyssomyia) intermedia, L. migonei, L. (N.) flaviscutellata, L. (Psychodopygus) ayrozai and L. (Lutzomyia) longipalpis. Five species were new records in Ilha Grande: L. (Sciopemyia) microps, L. termitophila, L. firmatoi, L. rupicola and L. (P.) ayrozai. Higher species richness was found inside forest areas, although potential leishmaniases vectors were present in deforested areas, peridomiciles and inside houses. Lutzomyia (N.) intermedia and L. migonei were the most abundant species. Females of L. migonei showed a high rate (10.3%) of natural infection by Leishmania (Viannia) sp., probably Leishmania (V.) braziliensis.

CONCLUSIONS

The detection of leishmaniases transmission and potential vectors in Ilha Grande is of public health concern, especially because tourists are frequently visiting the island. Besides reinforcing the epidemiological importance of L. (N.) intermedia in Rio de Janeiro State, the role of L. migonei in cutaneous leishmaniasis transmission is highlighted with its high rate of Leishmania natural infection. The finding of L. (L.) longipalpis confirmed the human autochthonous case of visceral leishmaniasis from the island. The presence of L. (N.) flaviscutellata in peridomestic areas is also an important finding, since the species is involved in the transmission of diffuse cutaneous leishmaniasis. Health education practices directed to the local community and tourists are important control actions that can be taken in Ilha Grande to reduce the burden of leishmaniases.