Visceral leishmaniasis lethality in Brazil: an exploratory analysis of associated demographic and socioeconomic factors

The Parasitemia has Contributed to the Severity of Cases of Visceral Leishmaniasis

Visceral leishmaniasis (VL) occurs due to the evolution, virulence, and adaptation of Leishmania, vector biology, host immune system evasion, and reservoir hosts. Parasitemia can be involved as a warning regarding the clinical severity of VL The present study aims to evaluate the relationship between parasitemia and the prognosis of individuals with VL. Blood and bone marrow samples from individuals with VL were analyzed to identify parasite and quantify or measure parasite burden. Individuals were classified in the clinical score model of risk of death by disease proposed by Coura-Vital et al. (PLoS Negl Trop Dis 8(12): e33742014, 2014). 39/74 individuals presented a better prognosis, and 35/74 individuals presented a worse prognosis. HIV + VL co-infection was present in 32 individuals, of which 12 were considered severe. The group aged 51 to 64 was classified as severe, with a decrease in leukocytes (p-value 0.0295) and neutrophils (p-value 0.0476). L. infantum DNA was identified in blood and bone marrow, in 69 individuals, and not detected in 5 individuals. The quantification of the parasite showed greater parasitemia in bone marrow (P = 0.0003) with an average of 4.70 × 104 Leishmanias/mL about blood, with 0.29 × 104 Leishmanias/mL. Individuals in the age group aged 51 to 64 co-infected with HIV + VL had higher parasitemia (p-value 0.0150) with 2.44 × 104 Leishmanias/mL in blood and bone marrow than in the group aged 20 to 50. Parasitemia, measured by molecular biology in blood and bone marrow, was related to the worst clinical prognosis of VL in the age group aged 51 to 64.

Factors associated with survival in patients with visceral leishmaniasis treated at a reference hospital in northern Minas Gerais - Brazil

BACKGROUND

Visceral leishmaniasis (VL) is a public health problem and is a relevant cause of death in developing countries. This study aimed to evaluate the 20-year survival and predictors of worse prognosis in patients with VL admitted to a reference hospital for the treatment of infectious diseases between 1995 and 2016 in northern Minas Gerais, an area of high endemicity for VL.

METHODS

This retrospective cohort study was conducted at a hospital in northern Minas Gerais, Brazil. All patients with VL were evaluated over a 20-year period. The medical records were thoroughly analyzed. Cox regression analysis was performed to estimate factors associated with the probability of survival.

RESULTS

The cohort included 972 individuals, mostly male children <10 years old, from urban areas who presented at admission with the classic triad of fever, hepatosplenomegaly, and skin pallor. The mean hemoglobin level was 7.53 mg/dl. The mean interval between symptom onset and hospital admission was 40 days. The instituted therapies ranged from pentavalent antimonates to amphotericin, or both. The probability of survival was reduced to 78% one year after symptom onset. Hemoglobin levels and age were strongly associated with the probability of survival.

CONCLUSIONS

Regardless of the mechanism underlying the reduction in hemoglobin and the non-modifiable factors of age, early initiation of drug treatment is the most appropriate strategy for increasing survival in patients with VL, which challenges health systems to reduce the interval between the onset of symptoms and hospital admission.

Epidemiology of visceral leishmaniasis in municipalities of Mato Grosso and the performance of surveillance activities: an updated investigation

Visceral leishmaniasis (VL) is considered a globally neglected disease. To address the problem of VL endemic to Brazil, the Visceral Leishmaniasis Control Program (VLCP) was created, which recommends the development of health surveillance actions such as the identification of human and canine cases, vector control and prevention of disease. We aimed to investigate the epidemiological situation of VL in municipalities of the State of Mato Grosso (MT) and assess the execution of VLCP activities. Data on human cases were obtained from the Information System for Notifiable Diseases (SINAN), and data from entomological and canine inquiry were provided by the State's Health Department. Analyzes from the period 2019 - 2021 recorded 30 cases of human VL, distributed among 16 municipalities. Vectors were identified in 50% of the municipalities where entomological investigations were carried out, and the predominant specie was Lutzomyia longipalpis. A total of 15,585 dogs were subjected to serological examination, of which 18.91% tested seropositive for Leishmania infantum. However, it must be emphasized that only three municipalities conducted consecutive inquiries involving canine VL. Although VL is distributed widely throughout the State, only a few municipalities have undertaken the actions of the VLCP, thus highlighting the neglected status of the disease.

Visceral leishmaniasis and HIV coinfection in Brazil: epidemiological profile and spatial patterns

BACKGROUND

Geographical overlap of human visceral leishmaniasis (HVL) and HIV infection favors occurrences of HVL/HIV coinfection. The increasing numbers of cases of HVL/HIV coinfection are a worldwide concern and knowledge of the factors involved can help in developing preventive measures.

METHODS

We aimed to identify spatial patterns and describe the epidemiological profile of HVL/HIV coinfection in Brazil from 2007 to 2015. This was an ecological study, in which thematic maps were created through geoprocessing tools, based on secondary data obtained from open-access platforms, to identify priority areas for interventions for controlling HLV/HIV coinfection, using the TerraView 4.2.2 software.

RESULTS

We found spatial autocorrelations between the HVL/HIV rates of neighboring municipalities according to the global Moran index (0.10; p<0.01). The highest HVL/HIV rate was in the central-western region. Among the epidemiological characteristics according to the regions, an increasing trend in the annual variation rate was observed, with positive values over the years and statistical significance (p<0.05) in the North with 1.62 (95% CI 0.57 to 2.69; p=0.02) and Northeast with 6.41 (95% CI 2.60 to 10.37; p=0.006). Similarly, increasing trends were observed in the states of Maranhão with 21.34 (95% CI 13.99 to 9.16; p<0.001) and Sergipe with 5.44 (95% CI 0.61 to 10.50; p=0.04).

CONCLUSIONS

Our results showed spatial overlap between occurrences of HVL and HIV with spatial patterns of HVL/HIV coinfection, thus revealing that the numbers of cases reported are increasing. Identifying areas with higher coinfection indices contributes to applying interventions and control measures among targeted populations, to prevent new cases.

Spatio-temporal relative risks and priority areas for visceral leishmaniasis control in Brazil, between 2001 and 2020

Visceral leishmaniasis (VL) is a pressing public health problem in Brazil. The proper implementation of disease control programs in priority areas is a challenge for healthcare managers. The present study aimed to analyze the spatio-temporal distribution and identify high risk areas of VL occurrence in the Brazilian territory. We analyzed data regarding new cases with confirmed diagnosis of VL in Brazilian municipalities, from 2001 to 2020, extracted from the Brazilian Information System for Notifiable Diseases. The Local Index of Spatial Autocorrelation (LISA) was used to identify contiguous areas with high incidence rates in different periods of the temporal series. Clusters of high spatio-temporal risk were identified using the scan statistics. The accumulated incidence rate in the analyzed period was 33.53 cases per 100,000 inhabitants. The number of municipalities that reported cases showed an upward trend from 2001 onward, although there was a decrease in 2019 and 2020. According to LISA, the number of municipalities considered a priority increased in Brazil and in most states. Priority municipalities were predominantly concentrated in the states of Tocantins, Maranhão, Piauí, and Mato Grosso do Sul, in addition to more specific areas of Pará, Ceará, Piauí, Alagoas, Pernambuco, Bahia, São Paulo, Minas Gerais, and Roraima. The spatio-temporal clusters of high-risk areas varied throughout the time series and were relatively higher in the North and Northeast regions. Recent high-risk areas were found in Roraima and municipalities in northeastern states. VL expanded territorially in Brazil in the 21st century. However, there is still a considerable spatial concentration of cases. The areas identified in the present study should be prioritized for disease control actions.

Epidemiological patterns related to deaths caused by visceral leishmaniasis in the southern Amazon region of Brazil

Background

We analysed the spatial and spatiotemporal patterns of visceral leishmaniasis (VL) mortality at the municipality level in an endemic state in the southern Amazon region of Brazil. Individual-level factors associated with death due to VL were also investigated.

Methods

All VL cases and deaths reported between 2007 and 2018 were included. The global and local bivariate Moran's index assessed the space–time autocorrelation of smoothed triennial VL mortality. Kulldorff's scan statistics investigated spatial and spatiotemporal clusters. A multivariable logistic regression explored sociodemographic, diagnostic and clinical variables associated with death due to VL.

Results

We observed an overall VL mortality and lethality of 0.14 cases/100 000 inhabitants and 11.2%, respectively. A total of 14% of the municipalities registered at least one VL-related death. In the southeastern mesoregion of the state, we detected high-risk spatial (relative risk [RR] 14.14; p&lt;0.001) and spatiotemporal (RR 15.91; p&lt;0.001) clusters for VL mortality. Bivariate Moran's analysis suggested a high space–time autocorrelation of VL mortality. Death by VL was associated with age ≥48 y (odds ratio [OR] 7.2 [95% confidence interval {CI} 3.4 to 15.3]), displacement for notification (OR 3.3 [95% CI 1.5 to 7.2]) and occurrence of oedema (OR 2.8 [95% CI 1.3 to 6.1]) and bleeding (OR 5.8 [95% CI 2.6 to 12.8]).

Conclusions

VL mortality has a heterogeneous spatiotemporal distribution. The death-related factors suggest late diagnosis as an underlying cause of mortality.

Magnitude of visceral leishmaniasis and HIV coinfection and association with social determinants of health in the Northeast region of Brazil: a retrospective, spatiotemporal model (2010-2018)

The Northeast region of Brazil (NRB) includes the states with the highest prevalence of visceral leishmaniasis (VL), as well as those with significant increases in HIV cases. This study aims to analyze the spatiotemporal patterns of VL-HIV coinfection and its association with the social determinants of health (SDH) in the NRB. Time trend analysis and Bayesian spatial statistical inferences, Moran's autocorrelation, and retrospective space-time scanning were performed. Spatial regression modelling was used to build an explanatory model for the occurrence of VL-HIV coinfection within NRB. A total of 1550 cases of VL-HIV coinfection were confirmed. We observed a higher prevalence among males (1232; 83%), individuals aged from 20 to 59 years (850; 54.8%), non-white skin color (1,422; 91.7%), and with low education (550; 35.48%). NRB showed an increasing and significant trend in the detection rate of coinfection (APC, 5.3; 95% CI, 1.4 to 9.4). The states of Maranhão and Piauí comprised the high-risk cluster. The SDH that most correlated with the occurrence of coinfection were poor housing, low income, and low education. VL-HIV is dispersed in the NRB but chiefly affects states with greater social vulnerability. Taken together, these findings reinforce the necessity to implement surveillance strategies that will contribute to the reduction of cases in these populations.

Extracellular Vesicles during TriTryps infection: Complexity and future challenges

The trypanosomatid pathogens Leishmania spp., Trypanosoma cruzi, and Trypanosoma brucei, currently grouped as TriTryps, have evolved through the time to overcome the upfront innate immune response and establish the infection in humans adapting many aspects of the parasite-cell host interaction. Extracellular vesicles (EVs) emerge as critical structures carrying different key molecules from parasites and target cells that interact continuously during infection. Current information regarding the structure and composition of these vesicles provide new insights into the primary role of TriTryps-EVs reviewed in this work. Expanding knowledge about these critical vesicular structures will promote advances in basic sciences and in translational applications controlling pathogenesis in the neglected tropical diseases caused by TriTryps.

Insecticide-impregnated netting: A surface treatment for killing Lutzomyia longipalpis (Diptera: Psychodidae), the vector of Leishmania infantum

The sand fly Lutzomyia longipalpis is the main vector of Leishmania infantum in Brazil. Synthetic male-produced sex/aggregation pheromone co-located with micro-encapsulated λ-cyhalothrin in chicken sheds can significantly reduce canine infection and sand fly densities in a lure-and-kill strategy. In this study, we determined if insecticide-impregnated netting (IN) could replace insecticide residual spraying (IRS). We compared numbers of Lu. longipalpis attracted and killed in experimental and real chicken sheds baited with pheromone and treated with a 1 m² area of either insecticide spray or netting. First, we compared both treatments in experimental sheds to control mortality established from light trap captures. We then compared the long-term killing effect of insecticide spray and netting, without renewal, in experimental sheds over a period of 16 weeks. Finally, a longitudinal intervention study in real chicken sheds compared the numbers and proportions of Lu. longipalpis collected and killed before and after application of both treatments. In Experiment 1, a higher proportion of males and females captured in IRS- and IN-treated sheds were dead at 24 h compared to controls (P < 0.05). No difference was found in the proportion of females killed in sheds treated with IN or IRS (P = 0.15). A slightly higher proportion of males were killed by IRS (100%) compared to IN (98.6%; P < 0.05). In Experiment 2, IN- and IRS-treated traps were equally effective at killing females (P = 0.21) and males (P = 0.08). However, IRS killed a significantly higher proportion of females and males after 8 (P < 0.05) and 16 (P < 0.05) weeks. In Experiment 3, there was no significant difference between treatments in the proportion of females killed before (P = 0.88) or after (P = 0.29) or males killed before (P = 0.76) or after (P = 0.73) intervention. Overall, initially the IN was as effective as IRS at killing female and male Lu. longipalpis in both experimental and real chicken sheds. However, the relative lethal effect of the IN deteriorated over time when stored under prevailing environmental conditions.

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Chicken sheds treated with netting or spray insecticide killed Lutzomyia longipalpis.

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Same effect was seen in experimental and real chicken sheds.

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Netting was as effective as spraying insecticide initially.

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Sprayed insecticide killed a higher proportion of both sexes after 8 and 16 weeks.

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The relative lethal effect of the netting deteriorated over time.