Spatio-temporal analysis of leptospirosis in Brazil and its relationship with flooding

Abstract

Leptospirosis is a serious public health problem in Brazil, which can be observed after flooding events. Using an exploratory mixed clustering method, this ecological study analyzes whether spatial-temporal clustering patterns of leptospirosis occur in Brazil. Data from the Brazilian Unified Health System (SUS) were used to calculate the prevalence of leptospirosis between 2007 and 2017 in all counties of the country. Clustering techniques, including spatial association indicators, were used for analysis and evaluation of disease yearly spatial distribution. Based on Local Indicators of Spatial Association (LISA) with Empirical Bayesian rates detected spatial patterns of leptospirosis ranging from 0.137 (p = 0.001 in 2009) to 0.293 (p = 0.001 in 2008). Over the whole period, the rate was 0.388 (p = 0.001). The main pattern showed permanence of leptospirosis clusters in the South and emergence and permanence of such clusters in northern Brazil. The municipalities with leptospirosis cases and at least one flood occurrence registered in the Brazilian Integrated Disaster Information System were incorporated into the LISA cluster map with Empirical Bayesian rates. These counties were expected to exhibit clustering, not all did. The results of the cluster analysis suggest allocation of health resources in areas with leptospirosis clustering.

Effect of Demographics and Time to Sample Processing on the qPCR Detection of Pathogenic Leptospira spp. from Human Samples in the National Reference Laboratory for Leptospirosis, Brazil

“…In the period analyzed in the paper, we found a positivity rate of 44.5% among tested samples for suspected cases. The high prevalence among these samples can be related to two main reasons: first, the samples were collected in a period of seasonal increase in tropical floods and storms, which increases the number of related febrile illnesses over its duration [ 21 ]. Second, testing only suspected cases, we had a trend toward increasing the rate, in comparison with larger observational studies based on serological surveys [ 22 , 23 , 24 ].…”

Catastrophic Floods in Rio Grande do Sul, Brazil: The Need for Public Health Responses to Potential Infectious Disease Outbreaks

“…Floodwaters, often contaminated by fecal matter and rodent urine, pose severe health risks by facilitating the spread of diseases such as hepatitis A, typhoid fever, and leptospirosis 5 - 7 . The compromise of sanitary infrastructure during these disasters also leads to contamination of water and food sources, increasing the likelihood of disease and diarrhea outbreaks, particularly affecting older individuals, those with severe dehydration, and people of lower socioeconomic status 8 - 10 .…”