Spatial epidemiological approaches to inform leptospirosis surveillance and control: a systematic review and critical appraisal of methods

Leptospirosis is a global zoonotic disease that the transmission is driven by complex geographical and temporal variation in demographics, animal hosts and socioecological factors. This results in complex challenges for the identification of high‐risk areas. Spatial and temporal epidemiological tools could be used to support leptospirosis control programs, but the adequacy of its application has not been evaluated. We searched literature in six databases including PubMed, Web of Science, EMBASE, Scopus, SciELO and Zoological Record to systematically review and critically assess the use of spatial and temporal analytical tools for leptospirosis and to provide general framework for its application in future studies. We reviewed 115 articles published between 1930 and October 2018 from 41 different countries. Of these, 65 (56.52%) articles were on human leptospirosis, 39 (33.91%) on animal leptospirosis and 11 (9.5%) used data from both human and animal leptospirosis. Spatial analytical (n = 106) tools were used to describe the distribution of incidence/prevalence at various geographical scales (96.5%) and to explored spatial patterns to detect clustering and hot spots (33%). A total of 51 studies modelled the relationships of various variables on the risk of human (n = 31), animal (n = 17) and both human and animal infection (n = 3). Among those modelling studies, few studies had generated spatially structured models and predictive maps of human (n = 2/31) and animal leptospirosis (n = 1/17). In addition, nine studies applied time‐series analytical tools to predict leptospirosis incidence. Spatial and temporal analytical tools have been greatly utilized to improve our understanding on leptospirosis epidemiology. Yet the quality of the epidemiological data, the selection of covariates and spatial analytical techniques should be carefully considered in future studies to improve usefulness of evidence as tools to support leptospirosis control. A general framework for the application of spatial analytical tools for leptospirosis was proposed

Prediction mapping of human leptospirosis using ANN, GWR, SVM and GLM approaches

© 2019 The Author(s). Background: Recent reports of the National Ministry of Health and Treatment of Iran (NMHT) show that Gilan has a higher annual incidence rate of leptospirosis than other provinces across the country. Despite several efforts of the government and NMHT to eradicate leptospirosis, it remains a public health problem in this province. Modelling and Prediction of this disease may play an important role in reduction of the prevalence. Methods: This study aims to model and predict the spatial distribution of leptospirosis utilizing Geographically Weighted Regression (GWR), Generalized Linear Model (GLM), Support Vector Machine (SVM) and Artificial Neural Network (ANN) as capable approaches. Five environmental parameters of precipitation, temperature, humidity, elevation and vegetation are used for modelling and predicting of the disease. Data of 2009 and 2010 are used for training, and 2011 for testing and evaluating the models. Results: Results indicate that utilized approaches in this study can model and predict leptospirosis with high significance level. To evaluate the efficiency of the approaches, MSE (GWR = 0.050, SVM = 0.137, GLM = 0.118 and ANN = 0.137), MAE (0.012, 0.063, 0.052 and 0.063), MRE (0.011, 0.018, 0.017 and 0.018) and R2 (0.85, 0.80, 0.78 and 0.75) are used. Conclusion: Results indicate the practical usefulness of approaches for spatial modelling and predicting leptospirosis. The efficiency of models is as follow: GWR > SVM > GLM > ANN. In addition, temperature and humidity are investigated as the most influential parameters. Moreover, the suitable habitat of leptospirosis is mostly within the central rural districts of the province

Predicting environmental risk of transmission of leptospirosis

Leptospirosis is a zoonotic disease distributed worldwide, caused by contact with the spirochete bacteria Leptospira. The bacteria are transmitted when animal and human reservoirs come into contact with an environment contaminated with the urine of an infected animal. The ecology of leptospirosis includes complex interactions between the environmental reservoir, the animal reservoir, human infection and the bacteria. Most of the knowledge built up about leptospirosis and human infection is related to medical epidemiology and the animal reservoir. In this thesis, some of the main issues related to the dynamics of Leptospira in the environment were explored and tools were developed to improve understanding of the dynamics of the bacteria in the environment. In order to improve parameter estimation related to the dynamics of the bacteria in the environment, some major gaps were identified and techniques to fill those gaps improved. The first technique developed was to improve animal abundance estimation using removal methods. The improvement of the technique showed that animal abundance could be estimated more accurately and precisely while also being robust to intrinsic variation. This method will provide a more accurate estimation of the level of environmental contamination by rats. Although models that estimate bacterial survival in the environment exist, no models specifically looked at the survivability of leptospires within the environment. Therefore, a survival model was developed that could estimate survival rates of leptospires in microcosms designed to replicate natural environments. The results provided very insightful results that can help planning the duration and frequency of an environmental intervention. Water has been shown to be very relevant for the transmission of human leptospirosis, where rainfall has been associated with infections in endemic regions. The last two studies developed here explored different hydrological techniques in order to produce fine scale environmental risk maps which can be used in disease management. The results obtained here demonstrated in particular the role of multidisciplinary research. Here, the research produced an improvement of the knowledge in different areas such as population ecology, microbiology, hydrology and public health

The Latin American and Caribbean Climate Landscape for ZIKV Transmission

This document presents a short review of the basic climate of Latin America and the Caribbean (LAC), focusing on the rainfall and temperature regional differences at multiple timescales, and where present climate forecasts tend to be more skillful for these two variables. The paper aims to provide information to understand how the regional climate plays an important role in vector borne diseases in general and Zika virus (ZIKV) in particular. As an emerging disease a great deal of basic information on ZIKV transmission dynamics is lacking. Knowledge on other Flaviviruses such as chikungunya virus (CHIKV) and dengue virus (DENV), also transmitted by the same mosquito vectors may therefore be used to impute likely climate-related impacts

Incidencia y subregistro de casos de leptospirosis diagnosticados con tres métodos diferentes en Urabá, Colombia

Introduction: Leptospirosis represents a public health problem and is a significant cause of morbidity and mortality in the region of Urabá. However, its notification reveals diagnostic limitations.Objective: To establish the incidence of leptospirosis in the municipalities of the so-called eje bananero in the Urabá region, to describe the magnitude of underreporting, and to propose guidelines for laboratory diagnosis by the public health network. Materials and methods: Two leptospirosis information sources were used: The national official surveillance system and a cross-sectional study of 479 acute-phase patients from April, 2010, to May, 2012. The diagnosis was made using three different tests: Indirect immunofluorescence, microagglutination test, and blood cultures. The exhaustiveness percentage of each information source was calculatedusing thecapture and recapture test. Results: From the total number of cases, 58% (278/479) were positive for leptospirosis at least by a test and 10.43% (29/278) of cases were positive by all three methods. The inclusion of a native strain in the microagglutination test panel increased the percentage of positivity by 15%. The cumulative incidence rate was 66.5/100,000 inhabitants and the case fatality ratio was 2.15%. The underreporting rates of leptospirosis in the Urabá region were 27.8% in morbidity and 66.6% in mortality.Conclusion: Under-registration of leptospirosis in the region highlights the necessity to use more than one diagnostic test to identify Leptospira in patients from endemic areas. Underregistration could be a common situation throughout the country.Introducción. La leptospirosis representa un problema de salud pública y es una causa importante de morbimortalidad en la región de Urabá, cuya notificación se ve afectada por las deficiencias en el diagnóstico.Objetivo. Establecer la incidencia de la leptospirosis en los municipios del llamado ‘eje bananero’ de la región de Urabá, documentar la magnitud del subregistro y proponer orientaciones para el diagnóstico por laboratorio por parte de la red de salud pública. Materiales y métodos. Se compararon dos fuentes de información sobre la leptospirosis: el sistema oficial nacional de vigilancia y un estudio transversal de 479 pacientes febriles, llevado a cabo entre abril de 2010 y mayo de 2012. El diagnóstico se hizo con base en tres pruebas: inmunofluorescencia indirecta, microaglutinación y hemocultivo. La exhaustividad de cada fuente de información se estimó mediante el método de captura y recaptura. Resultados. El 58 % (278/479) de los pacientes fueron positivos para leptospirosis, por lo menos, en una de las pruebas y, el 10,43 % (29/278), en las tres. La inclusión de una cepa nativa en el panel de la prueba de microaglutinación aumentó el porcentaje de positividad en 15 %. La tasa acumulada de incidencia fue de 66,5 por 100.000 habitantes y la proporción de letalidad fue de 2,15 %. El subregistro de la morbilidad por leptospirosis en la región de Urabá, fue de 27,8 % y, el de la mortalidad, de 66,6 %.Conclusión. El subregistro de leptospirosis en la región reitera la necesidad de usar más de una prueba diagnóstica para identificar Leptospira spp. en pacientes de zonas endémicas. Este subregistro podría ser una situación común en todo el país

Identifying gaps on health impacts, exposures, and vulnerabilities to climate change on human health and wellbeing in South America: a scoping review

There is an important gap in regional information on climate change and health, limiting the development of science-based climate policies in South American countries. This study aims to identify the main gaps in the existing scientific literature on the impacts, exposure, and vulnerabilities of climate change on population health. A scoping review was performed guided by four sub-questions focused on the impacts of climate change on physical and mental health, exposure and vulnerability factors of population to climate hazards. The main findings showed that physical impacts mainly included infectious diseases, while mental health impacts included trauma, depression, and anxiety. Evidence on population exposure to climate hazards is limited, and social determinants of health and individual factors were identified as vulnerability factors. Overall, evidence on the intersection between climate change and health is limited in South America and has been generated in silos, with limited transdisciplinary research. More formal and systematic information should be generated to inform public policy

Abstract Book of the II Congress of the Latin American Society for Vector Ecology

Recopilación de los resúmenes de las conferencias, simposios, paneles de discusión y "turbo talks" ofrecidos en el II Congreso de la Sociedad Latinoamericana de Ecología de Vectores (LA SOVE), realizado entre el 29 de octubre y el 3 de noviembre de 2022 en la ciudad de La Plata (Buenos Aires, Argentina).Sociedad Latinoamericana de Ecología de Vectores (LA SOVE

Spatial dependence of body mass index and exposure to night-time noise in the Geneva urban area

In this study, we calculated the night-noise mean (SonBase 2014, compatible with the EU Environmental Noise Directive) for the 5 classes obtained after computation of Local Indicators of Spatial Association (LISA; Anselin et al 1995) on the BMI of the participants in the Bus Santé study, a cohort managed by the Geneva University Hospitals (N=15’544; Guessous et al 2014). We expected the mean of dBs to be significantly higher in the group showing spatial dependence of high BMI values (high-high class). We ran an ANOVA and multiple T-tests to compare the dB means between LISA clusters. The approach was applied to the participants of the whole State Geneva cohort, and to a reduced set of individuals living in the urban environment of the municipality of Geneva only

Climate variability and human anthropometric outcomes: Evidence from India

The World Meteorological Organisation defines Climate Variability as “variations in the mean state and other statistics of the climate on all temporal and spatial scales, beyond individual weather events”1. These variations can cause natural disasters, such as floods or prolonged droughts, which in turn may have numerous consequences for public health. While previous work has considered the health effects of extreme climate events, this thesis focuses on the full range of variability in precipitation and temperature as the exposure, and human health indicators, including attained or completed growth and nutritional status, as primary outcomes among both children and adults (Height-for-Age z-score (HAZ), Weight-for-Age z-score (WAZ) and Weight-for-Height z-score (WHZ) for children and height, weight and Body Mass Index (BMI) for adult women). Using this framework and utilising a large Demographic and Health Survey dataset, this thesis tested whether climate variability in India and more specifically in Uttar Pradesh, a large state that faces extreme fluctuations in weather patterns, is associated with short- and long-term effects on human health indicators, using a sample size of 32,498 children and 21,793 adult women. The investigation involved exploring the effect of climate exposure at the time of birth in children, the propagation of this effect to adulthood and its inter-generational persistence, using multiple linear regression models. Finally, the association of climate exposure at various times around birth with health outcomes was also explored. The outcomes of the analysis supported the hypotheses, indicating that the precipitation and temperature patterns in early life explain some of the variability in child HAZ, WAZ and WHZ, as well as in women’s adult height, weight and BMI. This can be assumed to reflect differential exposure to ecological factors associated with precipitation and temperature that affect early growth rate. Broadly the effects were negative, but at a more subtle level they had more complex components and also interacting associations, which are described later in detail. The associations were stronger mostly in the rural areas compared to urban areas and also the younger children were found to be more sensitive to climate variability than the older children. At the inter-generational level, the signal detected was positive but small and did not seem to denote biological significance. The investigation of the effect of climate exposure at various early life timings indicated that the effect varies between the different timings and the time of birth is not always the most sensitive one. Overall, the results suggest that there is no single association of climate with these human health indicators