Human and canine visceral leishmaniasis in an emerging focus in Araçuaí, Minas Gerais: spatial distribution and socio-environmental factors

Factors associated with the expansion of leishmaniasis in urban areas: a systematic and bibliometric review (1959-2021)

This work describes a systematic and bibliometric review of the factors that contribute to the expansion of leishmaniasis in urban areas. Three scientific databases were used: Scientific Electronic Library (SciELO), Scopus and Web of Science, encompassing all original and review articles between 1959 and 2021. Three descriptors were used: "leishmaniasis" AND "urban" AND "rural." Planning, execution, summarization, and selection processes were performed using StArt (State of the Art through Systematic Review) software. We obtained a total of 304 articles, 60 of which concerned canine leishmaniasis. The factors associated with the expansion of leishmaniasis in urban areas are interrelated, including socioenvironmental and economic complexity, the type of leishmaniasis, the reservoirs, vectors, deforestation, disorderly occupation of space, poor sanitary conditions, and human migration trends. A lack of diagnosis and underreporting of cases in some regions may reflect the increase of cases seen in urban areas. A majority (n = 121) of studies were conducted in Brazil, followed by Iran (n = 43). In relation to publications; in general, output has increased over the years, particularly in 2021. The majority of published studies were in the area of epidemiology (n = 158).

Spatial and spatiotemporal patterns of human visceral leishmaniasis in an endemic southeastern area in countryside Brazil

Visceral leishmaniasis (VL) has shown endemic pattern and epidemic episodes in urban and rural areas, however, there are still gaps in knowledge with regards to disease transmission. This study aimed to analyze the spatiotemporal dispersion of VL cases in the municipality of Araçuaí, Minas Gerais. A study of confirmed VL cases was conducted considering the endemic and epidemic periods between 2012 and 2017. The incidence rate was calculated, and for spatial analysis, the kernel map, directional distribution ellipse, and space-time scanning techniques were used. The correlations between VL cases and exposure variables (precipitation, humidity, and temperature) were calculated. The mean incidence of VL in the endemic period was 18.5 (95% confidence interval (CI) 5.9-32.5) and 44.4 in the epidemic period (95%CI, 12.0-28.6) by 100,000 inhabitants. The relative risk for the epidemic period was 2.4 (95% CI 1.4-4.1) when compared to the endemic period. A higher incidence of the disease was observed in rural areas of the municipality. Kernel mapping analysis revealed hotspots in the urban area of the municipality. The directional distribution ellipse encompasses the urban perimeter and part of the rural area of the municipality, expanding eastward during the epidemic period. Spatial analysis revealed a high-risk cluster for VL in rural areas. A positive correlation was observed between VL cases and temperature during the endemic period. Spatial analysis allowed us to outline the epidemiological scenario of human VL cases. These findings may be useful in case surveillance and in the work of health professionals and managers in Brazil.

Passive case detection for canine visceral leishmaniasis control in urban Brazil: Determinants of population uptake

BACKGROUND

In Brazil, the transmission of Leishmania infantum in urban settings is closely related to infection among dogs, with occasional transmission to humans. Serological screening of dogs for Leishmania spp. infection on requests of their owners (passive case detection) represents a frequent, but little studied, practice within the scope of Brazilian public health. This study identified factors associated with canine visceral leishmaniasis (CVL) diagnosis-seeking behavior of dog owners in Rondonópolis (236,000 inhabitants), a municipality in Central-Western Brazil where VL is endemic. Also, we evaluated the profile of dog owners and their animals screened on free demand.

METHODOLOGY/PRINCIPAL FINDINGS

Using mixed effects negative binomial regression, we modelled the number of dogs screened for Leishmania infection on free demand per neighborhood from 2011 to 2016 as a function of time-dependent predictors (current or recent canine seropositivity and human VL incidence), distance to the screening site, and demographic variables. We assessed potential delays in the effect of time-dependent predictors on the outcome. Among 12,536 dogs screened for Leishmania infection, 64.2% were tested during serosurveys and 35.8% were tested on free demand. Of these, 63.9% were positive. Uptake of screening under free demand was strongly associated with higher levels of canine seropositivity in the neighborhood (current or recent) and decreasing distance to the screening site. A subsample of dog owners (n = 93) who sought CVL screening between 2016 and 2017 were interviewed in more detail. Owners with better socioeconomic status and dogs with apparent CVL clinical manifestations prevailed among them.

CONCLUSIONS/SIGNIFICANCE

To support timely CVL management, passive case detection along with awareness activities aimed at dog owners should be encouraged in endemic areas. Screening sites should be prioritized in accessible zones, as well as in socio-economically disadvantage areas. In parallel, CVL active case detection should be continued as a surveillance tool to guide control actions.

Human visceral leishmaniasis in Central-Western Brazil: Spatial patterns and its correlation with socioeconomic aspects, environmental indices and canine infection

In this ecological study, we investigated spatial patterns of human visceral leishmaniasis (VL) incidence, its correlation with socioeconomic aspects, environmental indices (obtained through remote sensing) and canine VL during 2011-2016 in the municipality of Rondonópolis, a relevant endemic area for VL in Central-Western Brazil. Human VL cases were georeferenced and point patterns were analyzed by univariate Ripley's K function and Kernel density estimation (KDE). Poisson-based scan statistics were used to investigate spatial and spatiotemporal clusters of human VL incidence at the neighborhood level. Socioeconomic and environmental characteristics were compared between neighborhoods within and outside spatial human VL clusters. Also, we assessed the correlation between smoothed human VL incidence and canine VL seropositivity rates within and between neighborhoods. Human VL cases were clustered up to 2000 m; four hotspots were identified by KDE in peripheral areas. Spatial and spatiotemporal low-risk clusters for human VL were identified in central and southern areas. Neighborhoods within spatial low-risk cluster presented higher mean income, literacy rate, sanitary sewage service coverage and lower altitude, compared to the rest of the municipality. A positive correlation was found between the occurrence of human and canine VL. On the northern outskirts, high human VL incidence was spatially correlated with high canine VL seropositivity in surrounding neighborhoods. In conclusion, human VL demonstrated a heterogeneous, aggregated and peripheral spatial pattern. This distribution was correlated with intra-urban socioeconomic differences and canine VL seropositivity at the neighborhood level.

Leishmania infantum in US-Born Dog

Leishmaniasis is a vectorborne disease that can infect humans, dogs, and other mammals. We identified one of its causative agents, Leishmania infantum, in a dog born in California, USA, demonstrating potential for autochthonous infections in this country. Our finding bolsters the need for improved leishmaniasis screening practices in the United States.

The effects of natural disasters on leishmaniases frequency: A global systematic review and meta-analysis

OBJECTIVES

Natural disasters (NDs) may increase the outbreaks and transmissions of vector-borne diseases such as cutaneous leishmaniasis (CL) and visceral leishmaniasis (VL). However, the relationship between leishmaniases and NDs has not yet been clearly established. Here, we systematically reviewed all reported articles in this field to answer whether NDs increase the frequency of leishmaniases.

METHODS

All the related articles published during January 2000 till January 2020 were reviewed. Moreover, all NDs and the associated leishmaniases frequencies reports in 17 leishmaniases endemic countries were searched to find any ND-leishmaniases relationship.

RESULTS

After the initial screening, 39 articles on ND-leishmaniases were selected and systematically reviewed. These articles showed different frequencies of CL in the endemic areas before and after NDs in some regions of Pakistan and Iran and in case of VL in Brazil, Ethiopia, and Sudan. After thorough deliberation, four studies for CL-ND and five studies for VL-ND relationships were selected for meta-analysis. The results showed increases in the leishmaniases incidences after NDs, although not robustly.

CONCLUSION

The lack of a strong leishmaniases-ND relationship could be attributed to the local compilations of such data in scattered regions of the endemic countries. Therefore, currently a substantial knowledge gap on leishmaniases-ND relationship is apparent.

An investigation of the effects of environmental and ecologic factors on cutaneous leishmaniasis in the old world: a systematic review study

OBJECTIVES

Leishmaniasis is a neglected and widespread parasitic disease that can lead to serious health problems. The current review study aimed to synthesize the relationship between ecologic and environmental factors (e.g., weather conditions, climatology, temperature and topology) and the incidence of cutaneous leishmaniasis (CL) in the Old World.

CONTENT

A systematic review was conducted based on English, and Persian articles published from 2015 to 2020 in PubMed/Medline, Science Direct, Web of Science and Google Scholar. Keywords used to search articles were leishmaniasis, environmental factors, weather condition, soil, temperature, land cover, ecologic* and topogr*. All articles were selected and assessed for eligibility according to the titles or abstracts. The quality screening process of articles was carried out by two independent authors. The selected articles were checked according to the inclusion and exclusion criteria.

SUMMARY AND OUTLOOK

A total of 827 relevant records in 2015-2020 were searched and after evaluating the articles, 23 articles met the eligibility criteria; finally, 14 full-text articles were included in the systematic review. Two different categories of ecologic/environmental factors (weather conditions, temperature, rainfall/precipitation and humidity) and land characteristics (land cover, slope, elevation and altitude, earthquake and cattle sheds) were the most important factors associated with CL incidence.

CONCLUSIONS

Temperature and rainfall play an important role in the seasonal cycle of CL as many CL cases occurred in arid and semiarid areas in the Old World. Moreover, given the findings of this study regarding the effect of weather conditions on CL, it can be concluded that designing an early warning system is necessary to predict the incidence of CL based on different weather conditions.

Demographic and spatial study of visceral leishmaniasis in the state of Alagoas, Brazil, during 2007-2018

INTRODUCTION

Visceral leishmaniasis has a broad worldwide distribution and constitutes a public health problem in the Northeast of Brazil. Located in this region is the state of Alagoas, where the disease is endemic in humans and where there has been a significant increase in the number of positive dogs. The objective of this study was to describe the temporal and spatial distribution of the cases of human VL in the state of Alagoas with the aim of identifying transmission risk areas in the period from 2007 to 2018.

METHODS

The data available in the National Disease Notification System (SINAN-NET) were used. The Bayesian incidence rate and the Moran's global index were calculated using the Terra View 4.2.2 program, and the maps were created using QGIS2.18.0.

RESULTS

From the 102 municipalities, 68.6% (n= 70) had at least one notified case of VL in the years of study. A total of 489 cases were registered, with an average of 40.7 cases per year and an incidence rate of 1.25/100,000 inhabitants. The highest number of confirmed cases (105) occurred in 2018. Male individuals and children between 1-4 years old were the most affected, and 64% of the cases were in rural areas. Spatial dependence was detected in all the intervals except for the first triennium, and clusters were formed in the west of the state.

CONCLUSIONS

Alagoas presented an accentuated geographical expansion of VL, and it is necessary to prioritize areas and increase surveillance actions and epidemiological control.

Spatial analysis of canine leishmaniasis in an area of transmission of the semi-arid region of the State of Paraíba, Brazil

Visceral leishmaniasis is a widely distributed zoonosis and canine infection is an important indicator of risk for the occurrence of the disease in humans. The goal of this analysis was to study the spatial clustering of canine leishmaniasis (CL) in the municipality of Santa Luzia, state of Paraíba. For this, 749 samples of canine plasma were tested using three serological tests. The dog was considered positive if it reacted in two serological tests. The location of the residences was performed with a Global Positioning System receiver (GPS Garmin® eTrex 30), and used to perform georeferencing and spatial analysis. The prevalence of CL was 15.49% and it was observed that most cases of the urban area were concentrated in the Frei Damião neighborhood, on the outskirts of the city, where a high-risk cluster for the occurrence of the disease was formed (p = 0.02; RR = 2.48). No statistically significant cluster was observed in rural areas. CL is widely distributed in the municipality of Santa Luzia in a heterogeneous manner and with a tendency to urbanization. The areas identified with high prevalence and highest risk should be prioritized to maximize the efficiency of the Visceral Leishmaniasis Surveillance and Control Program and minimize the chance of new canine and human cases.

Differentials in the epidemiological profile of canine visceral leishmaniasis in the semi-arid region of Paraíba, Brazil

ABSTRACT: The objective of this study was to estimate the prevalence of canine visceral leishmaniasis (CVL) and to identify the differences in associated factors to its occurrence in urban area and countrysides in the municipality of Santa Luzia located in the semi-arid region of Paraíba. In the years 2015 and 2016, 779 blood samples from dogs were collected. The prevalence was determined by three serological techniques, ELISA-S7® Kit, DPP® Rapid Test and EIE-LVC® Kit, considering positive the samples that reacted in at least two assays. Associated factors were determined by univariate and multivariate analyzes of the guardians’ responses to the epidemiological questionnaire. The prevalence of anti-Leishmania infantum antibodies in the studied municipality was 15.00% (117/779), being higher in the urban area (15.20%) than in the countryside (13.60%). The neighborhood with the highest prevalence was Frei Damião with 26.40% (33/125), being considered a hotspot (OR 1.245, p=0.007). Other associated factors were the semi-domiciliary breeding (OR 1.798, p=0.025), in the urban area, and hunting dog (OR 18.505, p=0.016), contact with cattle (OR 17.298, p=0.022) and environment where the dog is raised (OR 4.802, p=0.024) in the countryside. In the municipality of Santa Luzia, the prevalence of canine visceral leishmaniasis is high and the disease is widely distributed. Epidemiological differences between urban area and the countryside could be observed demonstrating the need for more adequate control measures for each locality and proving the urbanization process.

Spatio-temporal modeling of visceral leishmaniasis in Midwest Brazil: An ecological study of 18-years data (2001-2018)

Visceral leishmaniasis (VL) is a neglected vector-borne disease associated with socioeconomic and environmental issues. In Brazil, epidemics of VL have occurred in major cities since 1980. Applied models for medical and epidemiological research have been used to assess the distribution and characteristics of disease endpoints and identify and characterize potential risk factors. This study described the demographic features of VL and modeled the spatio-temporal distribution of human VL cases and their relationship with underlying predicitve factors using generalized additive models. We conducted an ecological study covering an 18-year period from the first report of an autochthonous case of VL in Campo Grande, state of Mato Grosso do Sul, in 2001 to 2018. The urban area of the city has 74 neighborhoods, and they were the units of analysis of our work. Socioeconomic and demographic data available from Brazilian public databases were considered as covariables. A total of 1,855 VL cases were reported during the study period, with an annual mean incidence rate of 13.23 cases per 100,000 population and a cumulative crude incidence of 235.77 per 100,000 population. The results showed the rapid transition from epidemic to endemic and the centrifugal dispersal pattern of the disease. Moreover, the model highlighted that the urban quality of life index, which is calculated based on income, education, housing conditions, and environmental sanitation data, plays a role in VL occurrence. Our findings highlighted the potential for improving spatio-temporal segmentation of control measures and the cost-effectiveness of integrated disease management programs as soon as VL is difficult to control and prevent and has rapid geographical dispersion and increased incidence rates.

Epidemiological aspects and spatial patterns of human visceral leishmaniasis in Brazil

Human visceral leishmaniasis (HVL) cases are important public health problems due to their zoonotic aspect, with high rates of morbidity and mortality in Brazil. The aim of this this study was to identify spatial patterns in both rates of HVL cases in Brazilian states during the period from 2006 to 2015. This is an ecological study, using geoprocessing tools to create choropleth maps, based on secondary data from open access platforms, to identify priority areas for control actions of the disease. Data were collected in 2017 and analysed according to the global and local Moran's I, using TerraView 4.2.2 software. Similar clusters were observed in neighbouring municipalities in thematic maps of HVL, suggesting spatial similarity in the distribution of the disease in humans mainly in the North and Northeast Regions, which concentrate the states with the highest rates of HVL. Heterogeneous spatial patterns were observed in the distribution of HVL, which show municipalities that need higher priority in the intensification of disease surveillance and control strategies.

Canine visceral leishmaniasis: perception, prevalence, and spatial distribution in municipality of Nossa Senhora do Livramento, Mato Grosso, Brazil

The midwest region of Brazil has witnessed an increase in the number of cases of human (HVL) and canine visceral leishmaniasis (CVL). The aim of the present study was to evaluate the population's perception of these diseases, factors associated with CVL, its spatial distribution, and the prevalence of anti-Leishmania spp. in 385 dogs, determined using a commercially available immunochromatographic rapid test and confirmed using enzyme-linked immunosorbent assay (ELISA). Of the 385 samples, 54 were positive for CVL and confirmed by ELISA, corresponding to a prevalence of 14%. Knowledge of signs of CVL by tutors (p = 0.038); previous occurrence of CVL in the vicinity (p = 0.022); symptomatic dog(s) (p = 0.014), splenomegaly (p = 0.055), and ear ulcer(s) (p = 0.059) were significantly associated with CVL. The results revealed a significant prevalence of CVL spatially distributed in rural and urban contexts. The association between environmentally related variables and perception and the occurrence of CVL underscores the importance of implementing control and prevention strategies primarily focused on environmental management and health education activities.

A cross-sectional approach including dog owner characteristics as predictors of visceral leishmaniasis infection in dogs

BACKGROUND

Visceral leishmaniasis (VL) is relevant for human and animal public health. Several factors have been associated with the risk of Leishmania infantum infection in dogs. However, dog owner characteristics have been rarely explored.

OBJECTIVES

To estimate the prevalence and to identify the associated factors for VL infection including dog owners characteristics.

METHODS

A cross-sectional study was conducted including dogs from an endemic canine visceral leishmaniasis (CVL) region in the Federal District, Brazil. The infection was detected using parasitological, serological, and molecular methods. The associated factors were identified through Poisson regression modelling.

FINDINGS

The prevalence of infection was 26.25% [95% confidence interval (CI): 20.05 to 33.57]. The associated factors were: short coat prevalence ratio (PR) = 2.33 (95% CI: 1.02 to 5.22); presence of backyard with predominance of soil and/or vegetation PR = 4.15 (95% CI: 1.35 to 12.77); and highest gross family income score PR = 2.03 (95% CI: 1.16 to 3.54).

MAIN CONCLUSION

This is the first study that relates higher socioeconomic status of dog owners as an independent factor associated with higher prevalence of VL infection, along with other strongly associated factors related to receptive environment for phlebotomines. Our findings strengthen the need for exploration of the biological and behavioural bases linking dog owner characteristics to the risk of canine infection in prospective cohort studies.

Eco-epidemiological study on sandflies and environmental aspects related to the transmission of leishmaniasis in a municipality of Minas Gerais, Brazil, 2015-2016

ABSTRACT The aim of this study was to evaluate Leishmania vectors and investigate the environmental and climatic characteristics related to their transmission. This was a prospective eco-epidemiological study involving the systematic collection of sandflies and a canine serological survey in areas of municipality in Brazil. Blood samples from 1,752 dogs were examined to test for canine visceral leishmaniasis (VL). An entomological evaluation was carried out using 24 light traps in the peridomicile and intradomicile areas of 12 households for 12 months. Climate variables were analyzed using a simple Spearman correlation and a spatial analysis via the fuzzy logic method and K function. The prevalence rate of canine VL was 4.1% and 7.1% in the two areas that were studied, respectively. The entomological study resulted in the capture of 431 sandflies. Most (74%) of the specimens were captured in the peridomiciliary area, and 5.6% of the samples that were analyzed using molecular biology were positive for Leishmania spp. In particular, Leishmania infantum was found in 100% of the positive samples. The spatial analysis showed that one particular area presented a higher concentration of high-density overlapping points of Lutzomyia longipalpis and seropositive dog populations, indicating a higher risk of the concomitant occurrence of both events. The results show that a parasite-reservoir-vector interface is active in the studied areas.

Twice upon a time: The progression of canine visceral leishmaniasis in an Argentinean city

Canine Visceral Leishmaniasis (CVL) prevalence, spatial distribution and associated factors were assessed in four locations in Iguazú department in 2014 and in Puerto Iguazú city again in 2018. The city areas were divided into a grid of 400x400m cells. All cells were sampled in 2014 and a random subsampling was developed in 2018. In each cell, five dogs clustered in a 'critical scenario' (prone to have vectors) were sampled. A rapid immunochromatographic dipstick was used to detect antibodies against Leishmania infantum, confirming by lymph node smears observation and PCR. For Puerto Iguazú, Generalized Linear Models (GLMs) were constructed considering environmental, dog and clinical variables. Pearson's Chi square and Fisher's exact tests were employed to evaluate the association between CVL, dog clinical signs and infestation with other parasites. Cartographic outputs were made and Moran's I indices were calculated as spatial autocorrelation indicators. CVL prevalence rates were 26.18% in 2014 and 17.50% in 2018. No associations were established in environmental models, but dog age and repellent use were significant when running 2014 dog models. Clinical models showed significant associations between seropositive dogs and ophthalmological, dermal signs and onychogryphosis in 2014. In 2018, only adenomegaly was associated. The results of global Moran´s I were not significant but regarding local analysis, six sites in 2014 and one in 2018 presented autocorrelation with neighboring sites. The decrease in CVL prevalence may be associated to transmission stabilization, which could explain the lack of associations with dog-related variables. Further, spatial distribution of CVL is a poor evidence for design of transmission control measures but could be important in case of intensive parasite circulation or when the first autochthonous cases appear. For control success, sensitivity of diagnostic methods, political will and adequate material resources remain critical. Modeling of multiple variables will be required to identify factors that drive disease stabilization/destabilization.

Factors associated with Leishmania spp. infection in domestic dogs from an emerging area of high endemicity for visceral leishmaniasis in Central-Western Brazil

The factors associated with Leishmania spp. infection in dogs are still poorly understood. This study aimed to identify such factors among domestic dogs from the Brazilian municipality of Rondonópolis, which recently emerged as an endemic area with intense transmission of human visceral leishmaniasis (VL). It was a household-based cross-sectional study conducted between 2016 and 2017. Interviews were conducted with 405 dog owners considering their socioeconomic characteristics, and environmental aspects of the household and its adjacent areas. In addition, 600 dogs were evaluated regarding physical characteristics, behavior, and care provided by the owner. Seropositive animals were those that showed reactivity in a rapid immunochromatographic test and enzyme-linked immunosorbent assay, which are currently recommended for canine visceral leishmaniasis (CVL) diagnosis in Brazil. A multivariable logistic regression analysis was employed to determine the associated factors. Low social class [OR = 2.0; _95%CI = (1.2-3.2)], presence of acerola tree (Malpighia emarginata) in the yard [OR = 2.2; _95%CI = (1.2-4.1)], presence of more than one dog in the household [OR = 2.0; _95%CI = (1.3-3.3)], horse and/or cattle breeding [OR = 12.0; _95%CI = (1.9-73.6)], existence of houses with yard adjacent to the home [OR = 4.0; _95%CI = (1.3-12.2)], presence of apparent signs consistent with CVL [OR = 10.6; _95%CI = (5.8-19.4)], dog staying mostly in the yard during the day [(OR = 4.8; _95%CI = (1.1-21.4)], and lack of cleaning of the dog's shelter [(OR = 1.9; _95%CI = (1.1-3.2)] were identified as the factors associated with Leishmania spp. infection. These results support the importance of socioeconomic and environmental aspects in the occurrence of Leishmania spp. infection. In addition, they may be useful in guiding control strategies in areas where zoonotic VL is endemic.

Sex-Related Differences in Immune Response and Symptomatic Manifestations to Infection with Leishmania Species

Worldwide, an estimated 12 million people are infected with Leishmania spp. and an additional 350 million are at risk of infection. Leishmania are intracellular parasites that cause disease by suppressing macrophage microbicidal responses. Infection can remain asymptomatic or lead to a spectrum of diseases including cutaneous, mucocutaneous, and visceral leishmaniasis. Ultimately, the combination of both pathogen and host factors determines the outcome of infection. Leishmaniasis, as well as numerous other infectious diseases, exhibits sex-related differences that cannot be explained solely in terms of environmental exposure or healthcare access. Furthermore, transcriptomic evidence is revealing that biological sex is a variable impacting physiology, immune response, drug metabolism, and consequently, the progression of disease. Herein, we review the distribution, morbidity, and mortality among male and female leishmaniasis patients. Additionally, we discuss experimental findings and new avenues of research concerning sex-specific responses in cutaneous and visceral leishmaniasis. The limitations of current therapies and the emergence of drug-resistant parasites underscore the need for new treatments that could harness the host immune response. As such, understanding the mechanisms driving the differential immune response and disease outcome of males versus females is a necessary step in the development of safer and more effective treatments against leishmaniasis.

Human visceral leishmaniasis and relationship with vector and canine control measures

OBJECTIVE

Estimate the coverage of control measures of visceral leishmaniasis and relate them with the occurrence of human visceral leishmaniasis in endemic urban area.

METHODS

Cases of human and canine visceral leishmaniasis were considered as study population and evaluated by a serological survey conducted in Araçatuba, state São Paulo, from 2007 to 2015. The cases of human visceral leishmaniasis were geocoded by the address of the patients and the canine disease by the address of the dogs’ owners. The coverage of serological survey, euthanasia, and insecticide spraying was calculated, as well as the canine seroprevalence and the incidence rates of human visceral leishmaniasis. The relationship between human visceral leishmaniasis and control measures was evaluated, as well as the seroprevalence by comparing maps and by linear regression. The relationship between the canine and the human disease was also evaluated by the Ripley’s K function.

RESULTS

The incidence rates of human visceral leishmaniasis showed a period of decline (2007 to 2009) and a period of stability (2010 to 2015), a behavior similar to that of canine seroprevalence. In general, the coverage of control measures was low, and the non-association with the incidence of human visceral leishmaniasis can be a result of the period analyzed and of the small number of analyzed units (sectors of the Superintendence for the Control of Endemic Diseases). The distribution of human cases showed spatial dependence with the distribution of seropositive dogs from 2007 to 2009.

CONCLUSIONS

This study reaffirmed the relationship between the occurrence of the disease in humans and dogs, it verified a decrease in the rates of visceral leishmaniasis in Araçatuba over time, even at low coverage of control activities. However, further studies are needed to determine if factors beyond monitoring and control measures are involved in the reduction of incidences.

Visceral leishmaniasis and vulnerability conditions in an endemic urban area of Northeastern Brazil

BACKGROUND

Visceral leishmaniasis (VL) is considered an urban endemic that may be related to sociodemographic factors and urban infrastructure. The objective of this study was to analyze the conditions of vulnerability and the incidence of VL, and to identify the spatiotemporal pattern of the disease.

METHODS

Data on reported cases of VL were collected from 2007 to 2016. Thematic maps on the spatiotemporal distribution were produced using values normalized by the area of the neighborhoods. The primary indicators of vulnerability were normalized for later construction of the synthetic indicators of vulnerability of social structure, household structure, and urban infrastructure, and from these, a vulnerability index was developed. The bivariate global Moran index was used to verify the existence of spatial autocorrelation between the incidence of VL and the conditions of vulnerability, while the bivariate local Moran index was used to identify the existence of spatial clusters.

RESULTS

The 695 cases reported presented a diffuse distribution when the spatial pattern was evaluated. The incidence of the disease was correlated with worsened living conditions. Statistically significant clusters were revealed between the incidence of the disease and the vulnerability indicators of social structure, household structure, urban infrastructure and composite vulnerability index.

CONCLUSION

Addressing the local vulnerability conditions is important to the understanding of the distribution of visceral leishmaniasis, identifying the most susceptible areas, and planning control strategies.

Visceral leishmaniasis in a Brazilian endemic area: an overview of occurrence, HIV coinfection and lethality

The Brazilian municipality of Rondonópolis, Mato Grosso State, represents an important visceral leishmaniasis (VL) endemic area. This study described epidemiological and clinical aspects of the occurrence, VL/HIV coinfection and lethality related to VL in Rondonópolis. Data from autochthonous cases reported between 2011 and 2016 were obtained from official information systems. During this period, 81 autochthonous cases were reported, with decreasing incidence through 2016. Contrastingly, the lethality rate was 8.6% overall, but varied widely, reaching a peak (20%) in 2016. Almost 10% of patients had VL/HIVcoinfection. The occurrence of VL prevailed among men (56.8%), brown-skinned (49.4%), urban residents (92.6%), aged 0-4 years (33.3%). Housewives or retired (29.6%) were the most affected occupational groups. Lower age was the main difference among the total VL cases and those who were coinfected or died. Clinically, fever, weakness and splenomegaly were more frequent among all VL cases and VL/HIV coinfected individuals. Bacterial infections (p=0.001) and bleeding (p<0.001) were associated with death due to VL. Pentavalent antimonial and liposomal amphotericin B were the first choices for treatment among all VL cases (71.6%) and those who died (71.4%), respectively. VL/HIV patients were equally treated with both drugs. These findings may support control measures and demonstrate the need for further investigations.

Spatial and simultaneous seroepidemiology of anti-Leishmania spp. antibodies in dog owners and their dogs from randomly selected households in a major city of southern Brazil

Although leishmaniasis has been described as a classic example of a zoonosis requiring a comprehensive approach for control, to date, no study has been conducted on the spatial distribution of simultaneous Leishmania spp. seroprevalence in dog owners and dogs from randomly selected households in urban settings. Accordingly, the present study aimed to simultaneously identify the seroprevalence, spatial distribution and associated factors of infection with Leishmania spp. in dog owners and their dogs in the city of Londrina, a county seat in southern Brazil with a population of half a million people and ranked 18th in population and 145th in the human development index (HDI) out of 5570 Brazilian cities. Overall, 564 households were surveyed and included 597 homeowners and their 729 dogs. Anti-Leishmania spp. antibodies were detected by ELISA in 9/597 (1.50%) dog owners and in 32/729 (4.38%) dogs, with significantly higher prevalence (p = 0.0042) in dogs. Spatial analysis revealed associations between seropositive dogs and households located up to 500 m from the local railway. No clusters were found for either owner or dog case distributions. In summary, the seroepidemiological and spatial results collectively show a lack of association of the factors for infection, and the results demonstrated higher exposure for dogs than their owners. However, railway areas may provide favorable conditions for the maintenance of infected phlebotomines, thereby causing infection in nearby domiciled dogs. In such an urban scenario, local sanitary barriers should be focused on the terrestrial routes of people and surrounding areas, particularly railways, via continuous vector surveillance and identification of phlebotomines infected by Leishmania spp.

High seroprevalence and peripheral spatial distribution of visceral leishmaniasis among domestic dogs in an emerging urban focus in Central Brazil: a cross-sectional study

The Brazilian municipality of Rondonópolis is an emerging urban focus of intense transmission of visceral leishmaniasis (VL), where few investigations have addressed canine reservoirs. This study assessed the seroprevalence and spatial distribution of canine visceral leishmaniasis (CVL) in the urban area of Rondonópolis. A CVL serosurvey was conducted between October 2016 and February 2017 using an immunochromatographic rapid test and enzyme-linked immunosorbent assay. Domestic dogs were sampled from 25 heterogeneous regions previously defined by the Spatial 'K'luster Analysis by Tree Edge Removal algorithm, which considered the socioeconomic and environmental features from the last demographic census. The CVL spatial distribution was analyzed by kernel density estimation (KDE) and spatial scan statistic. All the  autochthonous human VL cases reported between 2014 and 2016 were georeferenced. Of the 600 dogs tested, 115 were seropositive in both tests. The overall CVL prevalence was 19.2% (95%CI: 16.1-22.3%), which varied widely among the evaluated regions (0.0-35.1%). Almost 25% of the sampled households (n = 405) had at least one infected dog. KDE demonstrated that positive CVL households were concentrated in the peripheral areas of the city. Spatial scan statistics detected a spatial cluster with significantly low CVL prevalence in the central region (relative risk = 0.37; p = 0.04), where only one human VL case was reported. Thus, we demonstrated a high prevalence of CVL in domestic dogs from diverse socioeconomic and environmental urban contexts in Rondonópolis. The CVL cases were peripherally distributed and occurred more frequently in areas that had reported human VL.

Spatial and temporal trends of visceral leishmaniasis by mesoregion in a southeastern state of Brazil, 2002-2013

BACKGROUND

Visceral leishmaniasis (VL) is expanding in Brazil and in other South American countries, a process that has been associated with the urbanization of the disease. This study analyzes the spatial and temporal distribution of VL in the Brazilian state of Minas Gerais and identifies the areas with higher risks of transmission.

METHODOLOGY

An ecological study with spatial and time series analyzes of new confirmed cases of VL notified to the Brazilian Notifiable Disease Information System between 2002 and 2013, considering the 12 mesoregions of Minas Gerais. Two complementary methodologies were used: thematic maps of incidence and Poisson (log-linear) generalized linear model. Thematic maps using crude and smoothed cumulative incidences were generated for four trienniums. Poisson Regression measured the variation of the average number of cases from one year to the following, for each mesoregion.

PRINCIPAL FINDINGS

The 5,778 cases analyzed revealed a heterogeneous spatial and temporal distribution of VL in Minas Gerais. Six mesoregions (Central Mineira, Jequitinhonha, Metropolitan area of Belo Horizonte, Northwest of Minas, North of Minas, and Vale do Rio Doce) were responsible for the expansion and maintenance of VL, with incidence rates as high as 26/100,000 inhabitants. The Vale do Rio Doce and Jequitinhonha mesoregions showed a considerable increase in the incidence rates in the last period studied. The other six mesoregions reported only sporadic cases and presented low and unsteady incidence rates, reaching a maximum of 1.2/100,000 inhabitants.

CONCLUSIONS/SIGNIFICANCE

The results contribute to further the current understanding about the expansion of VL in Minas Gerais and may help guide actions for disease control.