Incidence and distribution of human leptospirosis in the Western Cape Province, South Africa, (2010-2019): A retrospective study.

Background Leptospirosis is an emerging zoonosis of global importance. In South Africa, the infection is an underreported public health concern, with limited information on its incidence and distribution. This study aimed to determine the incidence of human leptospirosis from 2010 to 2019 in Western Cape Province (WPC), and to compare the incidence based on seasonal and demographic factors. Methods A retrospective study was conducted with data on leptospirosis diagnoses by sex, age, season, and year in WCP obtained from the National Health Laboratory Services. With the provincial population sizes as the denominator, the incidence of leptospirosis was estimated and expressed as cases per 100,000 population. Negative binomial regression was used to estimate the effect of sex, season, and year on the incidence of leptospirosis. Results A total of 254 cases of leptospirosis were reported between 2010 and 2019, with the highest number of cases being in 2015. The annual incidence ranged between 0.15 and 0.66/100,000 population with a 10-year average incidence of 0.40/100,000 population. The incidence was higher among males than in females (0.55 vs. 0.25/ 100,000 population; incidence rate ratio (IRR) 2.2, 95% CI: 1.66,3.03). The 18-44 age cohort and had the highest average incidence (0.56/100,000 population), while the less or equal to 17 age cohort had the lowest incidence (0.07/100,000 population). The 18-44 (IRR 8.0, 95% CI: 4.65,15.15) and the greater or equal to 45 (IRR 7.4, 95% CI: 4.17,14.17) age cohorts were more at risk of infection compared to the less or equal to 17 age cohort. The average incidence of the infection was similar among seasons and there was no significant association between season and incidence of leptospirosis. Conclusions The results highlight that leptospirosis is an important zoonosis within the province disproportionately affecting males and the productive age demographic groups. These findings should enhance targeted prevention and provoke further investigation on the importance of environmental and socioeconomic factors on leptospirosis burden.

Climatic Variability and Human Leptospirosis Cases in Cartagena, Colombia: A 10-Year Ecological Study

Leptospirosis is an acute febrile disease that mainly affects developing countries with tropical climates. The complexity and magnitude of this disease is attributed to socioeconomic, climatic, and environmental conditions. In this study, in a 10-year period from 2008 to 2017, the relationship between human leptospirosis cases and climatic factors in Cartagena de Indias, Colombia were evaluated. Monthly leptospirosis cases, climatic variables, and macroclimatic phenomena (El Niño and La Niña) were obtained from public datasets. Local climatic factors included temperature (maximum, average, and minimum), relative humidity, precipitation, and the number of precipitation days. Time series graphs were drawn and correlations between cases of leptospirosis and climatic variables considering lags from 0 to 10 months were examined. A total of 360 cases of leptospirosis were reported in Cartagena during the study period, of which 192 (53.3%) were systematically notified between October and December. Several correlations were detected between the number of cases, local climatic variables, and macroclimatic phenomena. Mainly, the increase of cases correlated with increased precipitation and humidity during the La Niña periods. Herein, seasonal patterns and correlations suggest that the climate in Cartagena could favor the incidence of leptospirosis. Our findings suggest that prevention and control of human leptospirosis in Cartagena should be promoted and strengthened, especially in the last quarter of the year.

Epidemiological situation of human leptospirosis in Brazil and challenges in its diagnosis with a focus on molecular approaches

Leptospira interrogans is one of the causative agents of human leptospirosis, a zoonotic disease with worldwide distribution. Nowadays, this zoonosis is considered one of the biggest in terms of morbidity and mortality (even considering Dengue, the major arbovirosis affecting humans), having in Brazil 3,800 human cases per year. Currently, difficulties imposed by the absence of a rapid, sensitive diagnostic test that can be used as a routine test for the detection of leptospirosis lead to misdiagnosis and underreported cases. The gold standard diagnostic test for leptospirosis is the microscopic agglutination test (MAT), which presents difficulties in execution and interpretation. Therefore, this review proposes a general view of the epidemiologic situation of the disease in Brazil, in addition to the current contributions in the literature for the development of new diagnostic methods. Amongst them, the gene sequences polymorphism analysis, which presents potential for phylogenetic and populational analysis and genotyping of Leptospira spp.

Tracking Animal Reservoirs of Pathogenic Leptospira: The Right Test for the Right Claim

Leptospirosis is the most prevalent bacterial zoonosis worldwide and, in this context, has been extensively investigated through the One Health framework. Diagnosis of human leptospirosis includes molecular and serological tools, with the serological Microscopic Agglutination Test (MAT) still being considered as the gold standard. Mammals acting as reservoirs of the pathogen include species or populations that are able to maintain chronic infection and shed the bacteria via their urine into the environment. Animals infected by Leptospira are often identified using the same diagnosis tool as in humans, i.e., serological MAT. However, this tool may lead to misinterpretations as it can signal previous infection but does not provide accurate information regarding the capacity of animals to maintain chronic infection and, hence, participate in the transmission cycle. We employ in this paper previously published data and present original results on introduced and endemic small mammals from Indian Ocean islands to show that MAT should not be used for the identification of Leptospira reservoirs. By contrast, serological data are informative on the level of exposure of animals living in a specific environment. We present a sequential methodology to investigate human leptospirosis in the One Health framework that associates molecular detection in humans and animals, together with MAT of human samples using Leptospira isolates obtained from reservoir animals occurring in the same environment.

Human Leptospirosis Outbreak: A Year After the ‘Cempaka’ Tropical Cyclone

Introduction: The ‘Cempaka’ Tropical Cyclone hit south Java in November 2017, causing heavy rainfall and severe flooding. Changes in climate variability and extreme weather events may shift the geographic and seasonal patterns of neglected tropical diseases such as leptospirosis. This study analyses the Spatiotemporal pattern between flooding, weather, and human leptospirosis cases after a tropical cyclone. Methods: This was an ecological study that collected monthly flooding data, weather data, and human leptospirosis data cases per village from November 2017 to October 2018, a year after the ‘Cempaka’ Tropical Cyclone in Bantul. Spatio-temporal analyses were calculated to 0-3 months lag by Pearson's correlation, spatial mapping, and time-series graphs. Results and Discussion: As many as 99 people infected with leptospirosis were found in all 75 villages in Bantul. The villages affected by flooding were 44% and leptospirosis cases spread in 68% of villages. A 1-month lag (r = 0.6849; p < 0.05) and 3-months lag (r = 0.6666; p < 0.05) of relative humidity along with a 1-month lag (r = 0.7451; p < 0.05) and 3-months lag (r = 0.8561; p < 0.05) of rainfall were found to be correlated to human leptospirosis cases. Heavy rain due to the Cempaka Tropical Cyclone caused flooding and transmission of Leptospira bacteria into the water and heightened contact between humans, animals, and the environment. Conclusion: It is found that flooding, relative humidity, and rainfall after the Cempaka Tropical Cyclone would be followed by human leptospirosis outbreaks 1 and 3 months later. Cross-sectoral cooperation of public health authorities should integrate climatic information as an early warning for disaster-prone areas and community groups at risk.

Tracking animal reservoirs of pathogenic Leptospira: the right test for the right claim.

Leptospirosis, caused by a pathogenic Leptospira bacteria, is the most prevalent zoonosis worldwide and in this context has been extensively investigated through a One Health framework. Diagnosis of human leptospirosis includes molecular and serological tools, with serological Microscopic Agglutination Test (MAT) still being considered as a gold standard. Mammals considered as biological reservoirs include species or populations that are able to maintain chronic infection and shed the bacteria via their urine in the environment. Leptospira bacteria are often investigated using the same diagnosis tool, serological MAT. However, MAT testing of putative animal reservoirs can lead to mis-interpretations as it can signal previous infection and not necessarily bring in robust information regarding the capacity of such sero-positive animals to maintain chronic infection. We use previously published data and present new results on introduced and endemic small mammals to show that MAT should not be used for the identification of reservoirs. By contrast, serological data are informative on the level of exposure of animals occupying a specific environment. Finally, we present a sequential methodology to investigate human leptospirosis in a One Health framework that associates molecular detection in humans and animals, together with MAT of human samples using Leptospira isolates obtained from reservoir animals occurring in the same environment.

EPIDEMIOLOGICAL CHARACTERISTICS OF LEPTOSPIROSIS IN VOJVODINA, SERBIA, 2009-2018, FROM THE ASPECT OF ONE HEALTH

This study attempts to summarize epidemiological characteristics of human leptospirosis and to determine the seroprevalence of this disease among domestic animals in the Autonomous Province of Vojvodina, for the period 2009-2018. Chronological, demographic and topographic characteristics of human cases were analyzed. Pearson's correlation was used to explore correlations between different meteorological factors and trends in time-series of human cases. Overall 87 human cases of leptospirosis and five subsequent deaths (CFR: 5.75%) were recorded in the ten-year period. The average annual incidence rate was 0.45/100,000 (range: 0.16-1.50/100,000). The disease was more prevalent in males (M/F=16.40:1), with the majority of cases reported in August (N=23; 26.44%), September (N=20; 23.00%) and October (N=15; 17,24%). A statistically significant weak positive correlation was observed between the mean monthly air temperature and the number of human cases of leptospirosis of the same month (r=0.30, p<0.01) and a statistically significant weak positive correlation was found between the number of human cases and the sum of precipitation in the previous month (r=0.27, p<0.01). The average annual seroprevalence among domestic animals in total was 1.13% (range: 0.23% -3.65%). Seropositivity of tested samples of cats, dogs, cattle, donkeys, horses, sheep, pigs and goats was 25%, 9.50%, 8.55%, 6.25%, 1.59%, 0.25%, 0.18%, 0.00, respectively. Human and animal leptospirosis continuously occurs in Vojvodina, which implies the need for continuous and quality monitoring of the epidemiological and epizootiological situation of this disease. Further, more comprehensive parallel studies in humans and animals are needed, as well as additional studies of living conditions of animals on farms with leptospirosis and the studies that will determine the strength of association between climatic/ environmental factors and leptospirosis in Vojvodina. Key words: Human leptospirosis, animal leptospirosis, zoonosis, epidemiology, seroprevalence, one health.

Pathogenesis of Pulmonary Hemorrhagic Syndrome in Human Leptospirosis

Based on a previous study and by incorporating new knowledge, the goal of our study was to understand more fully the pathogenesis of hemorrhagic pneumonia of severe human leptospirosis, highlighting the onset of capillary lesions by Leptospira itself and/or its antigenic/toxic products acting on the endothelium and binding to cadherins. Both events lead to loss of endothelial integrity, alter permeability, cause rupture, and open intercellular junctions, contributing to the hemorrhagic phenomena associated with severe leptospirosis.