Seasonality of Human Leptospirosis in Reunion Island (Indian Ocean) and Its Association with Meteorological Data

Abstract

BackgroundLeptospirosis is a disease which occurs worldwide but particularly affects tropical areas. Transmission of the disease is dependent on its excretion by reservoir animals and the presence of moist environment which allows the survival of the bacteria.Methods and FindingsA retrospective study was undertaken to describe seasonal patterns of human leptospirosis cases reported by the Centre National de Références des Leptospiroses (CNRL, Pasteur Institute, Paris) between 1998 and 2008, to determine if there was an association between the occurrence of diagnosed cases and rainfall, temperature and global solar radiation (GSR). Meteorological data were recorded in the town of Saint-Benoît (Météo France “Beaufonds-Miria” station), located on the windward (East) coast. Time-series analysis was used to identify the variables that best described and predicted the occurrence of cases of leptospirosis on the island. Six hundred and thirteen cases were reported during the 11-year study period, and 359 cases (58.56%) were diagnosed between February and May. A significant correlation was identified between the number of cases in a given month and the associated cumulated rainfall as well as the mean monthly temperature recorded 2 months prior to diagnosis (r = 0.28 and r = 0.23 respectively). The predictive model includes the number of cases of leptospirosis recorded 1 month prior to diagnosis (b = 0.193), the cumulated monthly rainfall recorded 2 months prior to diagnosis (b = 0.145), the average monthly temperature recorded 0 month prior to diagnosis (b = 3.836), and the average monthly GSR recorded 0 month prior to diagnosis (b = −1.293).ConclusionsLeptospirosis has a seasonal distribution in Reunion Island. Meteorological data can be used to predict the occurrence of the disease and our statistical model can help to implement seasonal prevention measures.

Leptospirosis in the Republic of Korea: Historical Perspectives, Current Status and Future Challenges

“…A study in southern Brazil reported that maximum daily and total monthly rainfalls for the present and previous months were statistically significant predictors of the number of cases of leptospirosis in Poisson regression models [51]. Another study using time series analysis identified a significant correlation between the number of cases in a given month and the associated cumulative rainfall as well as the mean monthly temperature recorded 2 months prior to diagnosis [52]. The study by Robertson et al indicated a 2-month lag in rainfall-case association during the baseline period, but the role of rainfall in the outbreak revealed a more complex relationship [53].…”

Revisão sistemática dos fatores associados à leptospirose no Brasil, 2000-2009

“…28 Na África (Ilha da Reunião), os casos de leptospirose tiveram distribuição sazonal e os autores concluíram que dados meteorológicos podem ser utilizados como preditores para a ocorrência da doença, auxiliando na implementação de medidas preventivas. 29 31 Estudos de revisão sistemática, em geral, contribuem para consolidar os achados de diferentes estudos e concluir sobre os fatores associados ao objeto de análise. A diversidade da metodologia, entretanto, pode significar um limitador para a comparação dos resultados encontrados.…”

The influence of climatic factors on the development of hemorrhagic fever with renal syndrome and leptospirosis during the peak season in Korea: an ecologic study

“…The relationship between meteorological variables and HFRS and leptospirosis has been assessed in many regions [7–11]. Most studies have focused on the effects of temperature, rainfall, and humidity on the incidences of HFRS and leptospirosis [8–10, 12, 13].…”