Factors associated with human visceral leishmaniasis cases during urban epidemics in Brazil: a systematic review

Clinical validation of circulating immune complexes for use as a diagnostic marker of canine leishmaniosis

Introduction

Canine leishmaniosis (CanL) is a systemic disease that affects dogs. When multiplication of the parasite cannot be controlled, dogs consistently show high levels of antigen and IgG antibodies, which lead to the formation of circulating immune complexes (CIC). Timely intervention to reduce the parasite load and CIC levels is crucial for preventing irreversible organ damage. However, a diagnostic test to quantify CIC levels is currently lacking.

Methods

In this real-world study, we aimed to examine the performance of a new ELISA to measure CIC levels in dogs naturally infected with Leishmania infantum. Thirty-four dogs were treated according to their clinical condition and followed for 360 days. Before (day 0) and after treatment (days 30, 90, 180, 270, and 360), all dogs underwent a physical examination, and blood samples were obtained for CBC, biochemical profile, serum protein electrophoresis and IFAT. Serum PEG-precipitated CIC were determined by ELISA.

Results

Our results indicate higher CIC levels in dogs in advanced disease stages showing higher antibody titres (p < 0.0001, r = 0.735), anemia (p < 0.0001), dysproteinemia (p < 0.0001), and proteinuria (p = 0.004). Importantly, dogs responding well to treatment exhibited declining CIC levels (p < 0.0001), while in poor responders and those experiencing relapses, CIC were consistently elevated. CIC emerged as a robust discriminator of relapse, with an area under the curve (AUC) of 0.808. The optimal cut-off to accurately identify relapse was an optical density of 1.539.

Discussion

Our findings suggest that declining CIC levels should be expected in dogs showing a favorable treatment response. Conversely, in dogs displaying a poor response and recurrent clinical relapses, CIC levels will be high, emphasizing the need for vigilant monitoring. These findings suggest that CIC could serve as a valuable biomarker for disease progression, treatment efficacy, and relapse detection in CanL. Our study contributes to enhancing diagnostic approaches for CanL and underscores the potential of CIC as a complementary tool in veterinary practice. As we move forward, larger studies will be essential to confirm these findings and establish definitive cut-offs for clinical application.

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.

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.

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.

Recurrence and Driving Factors of Visceral Leishmaniasis in Central China

Visceral leishmaniasis (VL) is an important vector-borne zoonosis caused by Leishmania spp. that has been spreading in China. It has been posing a significant risk to public health in central China due to its recurrence in recent decades. Yet, the spatiotemporal patterns and the driving factors of VL in central China remain unclear at present. The purpose of this study was to analyse spatiotemporal distribution, explore driving factors, and provide novel insight into prevention and control countermeasures of the VL spreading in central China. Based on data of human VL cases from 2006 to 2019 obtained from the Chinese Centres for Disease Control and Prevention (CDC), we depicted the map showing the spatiotemporal distribution of VL in central China. We further explored the driving factors contributing to the spread of VL through the general additive model (GAM) by combining maps of environmental, meteorological, and socioeconomic correlates. Most VL cases were reported in Shaanxi and Shanxi provinces, the number of which has been increasing every year in the last 14 years, from 3 new cases in 2006 to 101 new cases in 2019. The results of GAM revealed that environmental (i.e., changes in grasslands/forests), meteorological (i.e., temperature and relative humidity), and socioeconomic (i.e., population density) factors are significantly associated with the prevalence of VL in central China. Our results provide a better understanding regarding the current situation and the driving factors of VL in central China, assisting in developing the disease prevention and control strategies implemented by public health authorities.