Epidemiological aspects of human and canine visceral leishmaniasis in State of Alagoas, Northeast, Brazil

Prediction of visceral leishmaniasis incidence using the Seasonal Autoregressive Integrated Moving Average model (SARIMA) in the state of Maranhão, Brazil

Abstract Visceral leishmaniasis (VL) is an infectious disease predominant in countries located in the tropics. The prediction of occurrence of infectious diseases through epidemiologic modeling has revealed to be an important tool in the understanding of its occurrence dynamic. The objective of this study was to develop a forecasting model for the incidence of VL in Maranhão using the Seasonal Autoregressive Integrated Moving Average model (SARIMA). We collected monthly data regarding VL cases from the National Disease Notification System (SINAN) corresponding to the period between 2001 and 2018. The Box-Jenkins method was applied in order to adjust a SARIMA prediction model for VL general incidence and by sex (male or female) for the period between January 2019 and December 2013. For 216 months of this time series, 10,431 cases of VL were notified in Maranhão, with an average of 579 cases per year. With regard to age range, there was a higher incidence among the pediatric public (0 to 14 years of age). There was a predominance in male cases, 6437 (61.71%). The Box-Pierce test figures for overall, male and female genders supported by the results of the Ljung-Box test suggest that the autocorrelations of residual values act as white noise. Regarding monthly occurrences in general and by gender, the SARIMA models (2,0,0) (2,0,0), (0,1,1) (0,1,1) and (0,1,1) (2, 0, 0) were the ones that mostly adjusted to the data respectively. The model SARIMA has proven to be an adequate tool for predicting and analyzing the trends in VL incidence in Maranhão. The time variation determination and its prediction are decisive in providing guidance in health measure intervention.

Temporal trend in the incidence of human visceral leishmaniasis in Brazil

It is an ecological study that analyzed the time trend of visceral leishmaniasis incidence rates in Brazil using segmented time regression by joinpoints. There was a decreasing incidence rate of this disease in the country with an average annual percent change (AAPC) of -5 (CI95%: -9.1; -0.6) and a reduction of 1.69 cases/100 thousand inhabitants in 2007, and 0.91/100 thousand inhabitants in 2020. The Central-West region showed the highest reduction percent (AAPC: -9.1; CI95%: -13.8; -4.3), followed by the Southeast region (AAPC: -8.7; -14.6; -2.5). The North and South regions showed the largest number of joinpoints in the time series. The highest incidences were recorded in the male population, however, stable (AAPC: 2.14; CI95%: -8.3; 0). In the age group analysis, the trend was decreasing for the groups from 0 to 4 years old (AAPC: -7.7; CI95%: -12.6; -2.4), 5 to 9 years old (AAPC: -7.3; CI95%: -13.6; -0,4) and 10 to 14 years old (AAPC: -5.5; CI95%: -10.3; -0.3). It was found that although Visceral Leishmaniasis is an endemic disease in Brazil, there was a decrease in its incidence rate from 2007 to 2020.

Space-time patterns and associated factors of leishmaniasis in Colombia, 2008-2016

Objective

To analyze the space-time aspects and epidemiological characteristics of leishmaniasis in Colombia from 2008 to 2016.

Methodology

This was an cross-sectional and ecological study of the morbidity and mortality from leishmaniasis and its spatial, temporal, and socio-demographic associated factors based on reported cases of ACL and VL obtained from the National Public Health Surveillance System (Sivigila) of the Ministry of Health of Colombia.

Results

In all, 99,503 cases of leishmaniasis were reported in Colombia in the 9-year period (2008-2016), where ACL accounted for 99.78% of the cases, with 14 deaths, and VL accounted for 0.21% of the cases, with four deaths. People living in the rural areas were the most affected by both forms of leishmaniasis. In the spatial analysis, ACL was widely distributed in Colombian territory, but the patterns of occurrence were not consistent throughout the study period. Further, the majority of the population affec-ted by VL resided in the Caribbean and Central regions, during the second three-year study period, indicating dispersion of the disease.

Conclusions

The recent epidemiological patterns of leishmaniasis show variations in morbidity and mortality, with a higher incidence of ACL than of VL and high concentration of cases in certain regions of Colombia. This study contributes to a better unders-tanding of this important public health problem so that measures to control the spread of this disease in Colombia can be intensified.

First molecular description of autochthonous urban cases of canine visceral leishmaniasis in the city of Belém, Pará, Brazil

Leishmaniasis is an anthropozoonosis transmitted by vectors, with dogs being the main domestic reservoirs. Brazil is one of the countries most affected by this disease, and it has been described in humans and dogs in every region in the country. In the northern region leishmaniasis cases in humans have been described in more than 100 municipalities in the State, including the capital, Belém. This study involves two cases of canine visceral leishmaniasis in which the animals developed clinical signs compatible with the disease in urban areas in Belém, the Pará state capital. The diagnosis was confirmed via polymerase chain reaction (PCR) to detect SSUr-rDNA and kDNA of Leishmania sp. and Leishmania infantum, respectively. In one of the cases the animal died and in the other the animal underwent treatment with medicines prescribed for dogs. Through this treatment, parasitemia in the second animal has been kept under control and is being monitored through molecular tests. Previously, no canine cases had been notified from urban neighborhoods in the city of Belém, but only on the island of Cotijuba, at a distance of 29 kilometers from the city. Cases of canine and human leishmaniasis have been recorded close to the capital, Belém, which has areas of conserved vegetation and where the presence of disease vectors has been described. Thus, as has been done in several other Brazilian cities, this study uses clinical and laboratory findings to confirm the presence of autochthonous cases of canine visceral leishmaniasis in the city of Belém.

Visceral Leishmaniasis Associated with HIV Coinfection in Pará, Brazil

Introduction

Human visceral leishmaniasis (VL) is a zoonosis of great importance to public health due to its epidemiological diversity, with emphasis on the possibility of aggravation by coinfection with the human immunodeficiency virus (HIV).

Objective

The aim was to study the epidemiological characteristics of VL cases associated with HIV coinfection in Pará. Methods. Reported cases of VL from January 2006 to December 2016 were investigated. A descriptive epidemiological method related to age, gender, area of residence and coinfection with HIV was used. To calculate variance and test equity, the F-test (Fisher) was performed. To observe the influence of one aspect on another, the chi-square was used to verify if there was dependence or independence between the variables.

Results

A total of 1171 cases of VL were reported during the study period. There was an annual mean of LV of 94.9, with a statistical difference (p<0.05) between age groups, with the highest number of cases being observed in children aged 1 to 4 years (27.16%). Males and the urban area had a higher number of cases. There were 57 cases of VL/HIV coinfection, with emphasis on the year 2013 and the municipality of Santarém, which had the highest number of cases. During the ten years studied, there was a correlation between coinfection VL/ HIV, with significant differences between patients with and without HIV who contracted VL (p<0.001).

Conclusion

The data reveal the endemic nature of VL in the region, with a high percentage of infection in children living in urban areas. Although the studied region is not identified as a predominant area of HIV cases, this study showed a high annual average (10.3) of cases of VL/HIV coinfection being the first time that cases of VL/HIV coinfection were reported in the Mesoregion of the Lower Amazon and Southwest Pará.

Epidemiological and clinical factors associated with lethality from Human Visceral Leishmaniasis in Northeastern Brazil, 2007 to 2018

Human Visceral Leishmaniasis (HVL) presents a subacute clinical evolution with systemic involvement, which can result in high case fatality, especially among untreated individuals or those with low socioeconomic status. This study aimed to identify epidemiological and clinical factors associated with HVL case fatality in the Ceara State, from 2007 to 2018. This is an analytical cross-sectional study. The bivariate analysis was performed by Stata 15.1 using Pearson’s Chi-square or Fisher’s exact test; and Poisson regression for age-controlled multivariate analysis. From 2007 to 2018, there were 4,863 new confirmed cases and 343 deaths from HVL (case fatality rate=7.05%). The risk factors associated with case fatalities were: age group (RR=8.69; 95%CI:3.56-21.20); black population (RR=2.21; 95%CI:1.45-3.35); jaundice symptoms (RR=1.72; 95%CI:1.38-2.14); edema (RR=2.62; 95%CI:2.10-3.26) and hemorrhagic phenomena (RR=1.63; 95%CI:1.26-2.10); and no prescription drug intake (RR=4.03; 95%CI:2.98-5.46). Treatment with pentavalent antimonial was a protective factor (RR=0.35; 95%CI:0.27-0.45). The number of deaths increased among the elderly, illiterate, urban residents, and black skin color individuals. The drugs pentavalent antimonial and amphotericin B showed an association with death, but were not considered causal factors. Treatment failure led to a high risk of death. In multivariate analysis, the risk factors for fatal cases were age group, black skin, symptoms of jaundice, edema and hemorrhagic phenomena; and failure to take the prescription drugs. Treatment with pentavalent antimonial was shown to be a protective factor. Knowing the factors associated with the fatality of VL-HIV cases may help to improve public policies, in order to refine the epidemiological surveillance program and, consequently, prevent deaths related to the disease in Ceara.

Epidemiological Aspects and High Magnitude of Human Visceral Leishmaniasis in Ceará, Northeast of Brazil, 2007-2021

BACKGROUND

Human visceral leishmaniasis HVL is endemic to 75 countries. The state of Ceará, the Northeast region of Brazil, is of great sanitary importance for the transmission of HVL, and it stands out as an area of interest for epidemiological aspects and control strategies. This study aimed to characterize HVL in relation to epidemiological aspects, composite incidence, and mortality rates in the state of Ceará, Brazil, from 2007 to 2021.

METHODS

This ecological study used temporal and spatial cuts of HVL data from the notifiable diseases information system. Epidemiological indicators such as incidence, mortality, and composite indices of incidence and mortality were calculated according to the Ministry of Health standardization.

RESULTS

There were 6,775 confirmed cases, with high incidence coefficients in 2009 6.96 cases/100,000 inhabitants and 2011 9.83 cases/100,000 inhabitants, and the highest mortality rate in 2011 6.96 deaths/100,000 inhabitants. The composite index of incidence and mortality identified municipalities in the Northern, Northwestern, and Southern regions of Ceará as having the highest risk of HVL.

CONCLUSIONS

HVL remained endemic throughout the study period, with epidemiological indicators and risk of transmission expressing high magnitude, mainly in the Northeast, Northwest, and South regions of Ceará.

Bayesian latent class models for identifying canine visceral leishmaniosis using diagnostic tests in the absence of a gold standard

Background

Like many infectious diseases, there is no practical gold standard for diagnosing clinical visceral leishmaniasis (VL). Latent class modeling has been proposed to estimate a latent gold standard for identifying disease. These proposed models for VL have leveraged information from diagnostic tests with dichotomous serological and PCR assays, but have not employed continuous diagnostic test information.

Methods/Principal findings

In this paper, we employ Bayesian latent class models to improve the identification of canine visceral leishmaniasis using the dichotomous PCR assay and the Dual Path Platform (DPP) serology test. The DPP test has historically been used as a dichotomous assay, but can also yield numerical information via the DPP reader. Using data collected from a cohort of hunting dogs across the United States, which were identified as having either negative or symptomatic disease, we evaluate the impact of including numerical DPP reader information as a proxy for immune response. We find that inclusion of DPP reader information allows us to illustrate changes in immune response as a function of age.

Conclusions/Significance

Utilization of continuous DPP reader information can improve the correct discrimination between individuals that are negative for disease and those with clinical VL. These models provide a promising avenue for diagnostic testing in contexts with multiple, imperfect diagnostic tests. Specifically, they can easily be applied to human visceral leishmaniasis when diagnostic test results are available. Also, appropriate diagnosis of canine visceral leishmaniasis has important consequences for curtailing spread of disease to humans.

[Epidemiological profile and time trend in visceral leishmaniasis: Piauí, Brazil, 2008-2018]

Visceral leishmaniasis (VL) or kala azar is one of the main neglected tropical diseases, of major importance due to the lethal nature of this zoonosis caused by protozoa of genus Leishmania. The study aimed to analyze the time trend in VL cases in the state of Piauí, Brazil, from 2008 to 2018, within the total period from 1971 to 2018. Data were obtained from the Brazilian Information System for Notificable Diseases (SINAN) and the Brazilian Mortality Information System (SIM). For burden of disease analysis, data were collected from the Institute for Health Metrics and Evaluation through the Global Burden of Diseases, Injuries, and Risk Factors (GBD Compare). Prais-Winsten regression analysis was used. A total of 2,374 cases were recorded with probable infection in the state of Piauí and 2,492 cases in residents of the state. The historical series analyzed, from 1971 to 2018, reaffirms the cyclical nature of the disease, based on the identification of epidemic peaks in 1983-1984, 1993-1994, 2003-2004, and 2013-2014. No significant alterations were identified in the trends in incidence, mortality, and case-fatality coefficients in the state. However, there was a significant increase in the incidence coefficient in the Chapada das Mangabeiras Development Territory, with an annual percent change of 17.5%, and a decrease in the Vale do Sambito Development Territory (-18.3%) and Vale do Rio Guaribas Development Territory (-8,1%). VL has a high burden of disease, measured by disability-adjusted life years, and is among the leading neglected tropical diseases in the state of Piauí. The study concludes by recommending the improvement of surveillance and control measures for this disease.

Analysis of spatial clustering, time trend, social vulnerability and risk of human visceral leishmaniasis in an endemic area in Brazil: an ecological study

BACKGROUND

More than 95% of visceral leishmaniasis (VL) cases in Latin America occur in Brazil, most of them in the northeast. The objective of this study was to identify spatial clusters with the highest risks of VL and to analyse the temporal behaviour of the incidence and the effects of social vulnerability on the disease transmission dynamic in northeastern Brazil.

METHODS

All confirmed cases registered as residents in the state of Pernambuco during the period from 2007 to 2017 were analysed. The local empirical Bayesian method was applied and the association -between the VL incidence rate and municipal social vulnerability was tested via classic multivariate regression.

RESULTS

A total of 1186 new cases were registered during the study period. Spatial analysis showed heterogeneous distribution, with the highest rates observed in the São Francisco and Sertão mesoregions. Moreover, the main factors associated with VL were urban infrastructure, income and work.

CONCLUSIONS

It was observed that spatial and temporal techniques are important tools for defining risk areas for VL, in conjunction with the evaluation of indexes of social vulnerability, which was shown to be an important factor for comprehending associations with VL in the state of Pernambuco.

Risk areas for Human Visceral Leishmaniosis 2007-2018: A temporal and spatial analysis in Ceará, Brazil

Visceral leishmaniasis (VL) is considered as an important tropical disease because it rapidly spreads across a wide geographical area. This study aimed to analyse the temporal and spatial patterns of incidence, mortality and case fatality rates due to human VL in Ceará, Brazil, from 2007 to 2018. This is an ecological study involving time series and spatial analyses, and data were obtained from human VL notifications. Temporal trend analysis was carried out using the Joinpoint Regression Program. SaTScan 9.6 was used for conducting spatial analyses, and ArcMap 9.2 was used for building maps. There were 6,066 incident cases and 516 deaths due to human VL. There was an increasing trend in the incidence rate from 2007 to 2014 (annual per cent change [APC] = 3.8; 95% confidence interval [CI]:0.5 to 7.3; p = .031). Mortality (APC = -0.3; 95%CI: -2.5 to 1.9; p = .765) and VL case fatality rates (APC = -3.0; 95%CI: -4.3 to -1,7; p = .188) showed non-significant decline. The incidence rates were higher in the northwest and south regions of the state, with 11 high incidence rate clusters from 2007 to 2010, seven clusters in 44 municipalities from 2011 to 2014, and six clusters in 49 municipalities from 2015 to 2018. During 2007-2010, only one significant mortality rate cluster was identified in the southern region (relative risk [RR] = 7.6); during 2011-2014, two clusters in the northwest region were identified (RR=3.9 and RR=4.6). In the last period, a cluster of 11 municipalities in the southern region was identified (RR = 4.2). Mortality rate clusters were identified in the centre-south (2007-2010), northwest and south (both from 2011 to 2018). VL has a heterogeneous distribution, with maintenance of clusters with high incidence and mortality rates, as well as case fatality rates in municipalities in the northwest and south regions. These clusters present areas with the greatest risk of transmission of human VL.

First case of canine visceral leishmaniasis in the midwestern of Santa Catarina State, Brazil

Canine visceral leishmaniasis (CVL) caused by Leishmania (Leishmania) infantum is transmitted by phlebotomine sandflies and a major zoonotic disease in Brazil. Due to the southward expansion of the disease within the country and the central role of dogs as urban reservoirs of the parasite, we have investigated the occurrence of CVL in two municipalities Erval Velho and Herval d'Oeste in the Midwest region of Santa Catarina state. Peripheral blood samples from 126 dogs were collected in both cities and tested for anti-L. infantum antibodies by indirect enzyme-linked immunosorbent assay (ELISA) and indirect immunofluorescence reaction (IIF) and for the presence of parasite DNA by polymerase chain reaction (PCR) in peripheral blood. From examined dogs, 35.71% (45/126) were positive for at least one of the three tests and two (1.6%) were positive in all performed tests. Twelve dogs (9.5%) were positive for both ELISA and IIF, while 21 dogs were exclusively positive for ELISA (16.7%), and 15 (11.9%) for IIF. L. infantum k-DNA was detected by PCR in 9 out of 126 dogs (7.1%) and clinical symptoms compatible with CVL were observed for 6 dogs. Taken together, these results indicate the transmission of CVL in this region, highlighting the needs for epidemiological surveillance and implementation of control measures for CVL transmission in this region.

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.

Leishmaniose visceral: distribuição temporal e espacial em Fortaleza, Ceará, 2007-2017

Resumo Objetivo: Analisar a tendência temporal e descrever a distribuição espacial da leishmaniose visceral (LV) em Fortaleza, 2007-2017. Métodos: Estudo ecológico, mediante regressão temporal segmentada e mapeamento temático. Resultados: No período 2007-2017, foram confirmados 1.660 casos novos e 97 óbitos. No período 2007-2010, a incidência foi ascendente (variação percentual anual [Annual Percent Change], APC=8,7% - IC95% -3,3;34,1), enquanto a mortalidade (APC=-25,9 - IC95% -48,5; -10,6) e a letalidade (APC=-33,0 - IC95% -53,7;-17,6), descendentes. No período 2010-2015, a incidência reduziu (APC=-15,8 - IC95% -25,1;-4,0), mas a mortalidade (APC=18,7 - IC95% 9,4;50,6) e a letalidade (APC=40,1 - IC95% 22,5;72,0) apresentaram tendência de crescimento. Em 2015-2017, decresceram a incidência (APC=-24,6 - IC95% -36,2;-10,3) e a mortalidade (APC= -44,6 - IC95% -58,8;-17,6); a letalidade se manteve estável (APC=-13,5 - IC95% -38,7;3,8). Houve concentração de bairros com incidência elevada na região oeste da cidade; porém, a mortalidade e a letalidade não apresentaram padrões espaciais definidos. Conclusão: A LV é endêmica em Fortaleza, embora tenha havido declínio no último triênio estudado.

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.

Improving the reference standard for the diagnosis of canine visceral leishmaniasis: a challenge for current and future tests

BACKGROUND

Studies aimed at validating canine visceral leishmaniasis diagnostic tests present heterogeneous results regarding test accuracy, partly due to divergences in reference standards used and different infection evolution periods in animals.

OBJECTIVE

This study aimed to evaluate the accuracy of the rapid test-dual path platform (TR-DPP) (Biomanguinhos®), EIE-Leishmaniose-Visceral-Canina-Biomanguinhos (EIE-LVC) (Biomanguinhos®), enzyme-linked immunosorbent assay (ELISA) rK39 (in-house), and the direct agglutination test (DAT-Canis) against a reference standard comprising parasitological and molecular techniques.

METHODS

A phase II/III validation study was carried out in sample sera from 123 predominantly asymptomatic dogs living in an area endemic for visceral leishmaniasis.

FINDINGS

Sixty-nine (56.1%) animals were considered infected according to the reference standard. For each test, the sensitivity and specificity, respectively, were as follows: TR-DPP, 21.74% [confidence interval (CI)95% 13.64% to 32.82%] and 92.59% (CI95% 82.45% to 97.08%); EIE-LVC, 11.59% (CI95% 5.9% to 21.25%) and 90.74% (CI95% 80.09% to 95.98%); ELISA rK39, 37.68% (CI95% 27.18% to 49.48%) and 83.33% (CI95% 71.26% to 90.98%); and DAT-Canis, 18.84% (CI95% 11.35% to 29.61%) and 96.30% (CI95% 87.46% to 98.98%).

CONCLUSION

We concluded that improving the sensitivity of serum testing for diagnosing asymptomatic dogs must constitute a priority in the process of developing new diagnostic tests to be used in the visceral leishmaniasis control program in Brazil.