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Seasonality of human leptospirosis in Reunion Island (Indian Ocean) and its association with meteorological data.

Desvars A, Jégo S, Chiroleu F, Bourhy P, Cardinale E, Michault A - PLoS ONE (2011)

Bottom Line: 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).Meteorological data can be used to predict the occurrence of the disease and our statistical model can help to implement seasonal prevention measures.

View Article: PubMed Central - PubMed

Affiliation: Unité Mixte de Recherche Contrôle des Maladies Animales Exotiques et Emergentes, Centre de Coopération Internationale en Recherche Agronomique pour le Développement, Sainte-Clotilde, La Réunion, France. amelie.desvars@cirad.fr

ABSTRACT

Background: Leptospirosis 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 findings: A 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).

Conclusions: Leptospirosis 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.

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Observation and prediction of the monthly number of cases of leptospirosis in Reunion Island.Monthly number of cases reported by the CNRL from 1 January 1998 to 31 December 2008 (continuous line), number of cases predicted by the model from 1 January 1998 to 31 December 2009 (dotted line), and 95% confidence interval of the prediction for 2009 (dot-dashed line).
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pone-0020377-g004: Observation and prediction of the monthly number of cases of leptospirosis in Reunion Island.Monthly number of cases reported by the CNRL from 1 January 1998 to 31 December 2008 (continuous line), number of cases predicted by the model from 1 January 1998 to 31 December 2009 (dotted line), and 95% confidence interval of the prediction for 2009 (dot-dashed line).

Mentions: The best fitting ARIMAX model of cases of leptospirosis (p = 1, d = 0, q = 0; AIC = 208.29, estimated variance = 0.26, d.f. = 129) included the cases diagnosed in the previous month. Both the cumulated monthly rainfall and average monthly temperature recorded 0, 1, 2, and 3 months prior to diagnosis, as well as the average monthly GSR recorded 0 month prior to diagnosis were associated the model. Only the cumulated rainfall at a 2 months lag and the average temperature and GSR both at a 0 month lag were used in the model (Table 5). ACF and PACF of the residuals of the model appeared stationary (not shown) and the augmented Dickey-Fuller test confirmed the stationarity (p = 0.02). Between1998 and 2008, the correlation coefficient of our predictive model with the observed data is 0.677 (p<10−4) (Figure 4). With meteorological data from 2009, the ARIMAX model could make a prevision of the monthly number of leptospirosis cases with 95% confidence interval (Figure 4, Table 6).


Seasonality of human leptospirosis in Reunion Island (Indian Ocean) and its association with meteorological data.

Desvars A, Jégo S, Chiroleu F, Bourhy P, Cardinale E, Michault A - PLoS ONE (2011)

Observation and prediction of the monthly number of cases of leptospirosis in Reunion Island.Monthly number of cases reported by the CNRL from 1 January 1998 to 31 December 2008 (continuous line), number of cases predicted by the model from 1 January 1998 to 31 December 2009 (dotted line), and 95% confidence interval of the prediction for 2009 (dot-dashed line).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3105052&req=5

pone-0020377-g004: Observation and prediction of the monthly number of cases of leptospirosis in Reunion Island.Monthly number of cases reported by the CNRL from 1 January 1998 to 31 December 2008 (continuous line), number of cases predicted by the model from 1 January 1998 to 31 December 2009 (dotted line), and 95% confidence interval of the prediction for 2009 (dot-dashed line).
Mentions: The best fitting ARIMAX model of cases of leptospirosis (p = 1, d = 0, q = 0; AIC = 208.29, estimated variance = 0.26, d.f. = 129) included the cases diagnosed in the previous month. Both the cumulated monthly rainfall and average monthly temperature recorded 0, 1, 2, and 3 months prior to diagnosis, as well as the average monthly GSR recorded 0 month prior to diagnosis were associated the model. Only the cumulated rainfall at a 2 months lag and the average temperature and GSR both at a 0 month lag were used in the model (Table 5). ACF and PACF of the residuals of the model appeared stationary (not shown) and the augmented Dickey-Fuller test confirmed the stationarity (p = 0.02). Between1998 and 2008, the correlation coefficient of our predictive model with the observed data is 0.677 (p<10−4) (Figure 4). With meteorological data from 2009, the ARIMAX model could make a prevision of the monthly number of leptospirosis cases with 95% confidence interval (Figure 4, Table 6).

Bottom Line: 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).Meteorological data can be used to predict the occurrence of the disease and our statistical model can help to implement seasonal prevention measures.

View Article: PubMed Central - PubMed

Affiliation: Unité Mixte de Recherche Contrôle des Maladies Animales Exotiques et Emergentes, Centre de Coopération Internationale en Recherche Agronomique pour le Développement, Sainte-Clotilde, La Réunion, France. amelie.desvars@cirad.fr

ABSTRACT

Background: Leptospirosis 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 findings: A 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).

Conclusions: Leptospirosis 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.

Show MeSH
Related in: MedlinePlus