The non-linear and lagged short-term relationship between rainfall and leptospirosis and the intermediate role of floods in the Philippines

Matsushita, Naohiko; Ng, Chris Fook Sheng; Kim, Yoonhee; Suzuki, Motoi; Saito, Nobuo; Ariyoshi, Koya; Salva, Eumelia P.; Dimaano, Efren M.; Villarama, Jose Benito; Go, Winston S.; Hashizume, Masahiro

doi:10.1371/journal.pntd.0006331

Cited by 32 publications

(47 citation statements)

References 28 publications

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“…This relationship have also been found out from the study conducted by Matsushita et al in Philippines who found out that the risk of post-rainfall, leptospirosis peaked at a lag of 2 weeks (using 0 cm/week rainfall as the reference) with RRs of 1.30, 1.53, 2.45, 4.61, and 13.77 for light, moderate, heavy, intense and torrential rainfall (at 2, 5, 16, 32 and 63 cm/week), respectively. 13 In the study conducted by Pawar et al in Maharashtra rainfall was associated with increasing cases of leptospirosis at a lag of 1-2 months similar to our study. 10 Flooding after rainfall can force humans and rodents into closer contact, which can result in further contamination of surrounding water.…”

Section: Resultssupporting

confidence: 90%

Trend of leptospirosis and its association with meteorological factors in Thrissur district, Kerala

Premdas

Areekal

Sukumaran

et al. 2019

Int J Community Med Public Health

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Background: Leptospirosis is a common zoonosis caused by bacteria, Leptospira. The core determinants of the disease are the presence of carrier animals, environmental factors and the interaction between man, carrier and the environment. Understanding the type of relation between these factors and leptospirosis will help in controlling the disease. The current study intends to find the trend of leptospirosis cases, to forecast the disease and to correlate number of cases of leptospirosis with meteorological factors. Methods: The data of leptospirosis cases and the meteorological factors in Thrissur district were collected and entered in MS-Excel and statistical analysis was done using SPSS-16.0. For analysing the trend and to forecast the same, time series analysis method was used. The correctness of the model was tested using Ljung-Box statistics. Results: Time series chart, autocorrelation and partial autocorrelation show leptospirosis follows a seasonal trend. Forecasting of leptospirosis cases from July 2018 to May 2019 made by the model matched with original number reported in Thrissur district. Cross correlation of total rainfall and total rainy days showed that leptospirosis peak approximately 1 month after the onset or together with the rain (lag-1 and 0, r0.471 and 0.380 for total rainfall, lag-1 and 0, r0.501 and 0.469 for total rainy days). Humidity positively affects number of leptospirosis cases (lag-1 and 0, r0.464 and 0.435). June to October, seasonally adjusted factor (SAF) was >100% with highest SAF in August (202.2%). Conclusions: Leptospirosis shows a seasonal trend with more cases in June to October and correlates with change in meteorological factors of the region.

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Section: Resultssupporting

confidence: 90%

Trend of leptospirosis and its association with meteorological factors in Thrissur district, Kerala

Premdas

Areekal

Sukumaran

et al. 2019

Int J Community Med Public Health

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“…Floods can potentially increase the spread of vector-borne diseases, such as leptospirosis, Japanese encephalitis, malaria, dengue, rabies, etc. (Afzal and Sultan, 2013;Ding et al, 2014;Matsushita et al, 2018;Mohd Radi et al, 2018;Saeed and Piracha, 2016;Smith et al, 2013;Zhang et al, 2016). Similar findings have been reported in our study.…”

Section: Discussionsupporting

confidence: 92%

A time-trend ecological study for identifying flood-sensitive infectious diseases in Guangxi, China from 2005 to 2012

Ding

et al. 2019

Environmental Research

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Background: Flood-related damage can be very severe and include health effects. Among those health impacts, infectious diseases still represent a significant public health problem in China. However, there have been few studies on the identification of the spectrum of infectious diseases associated with floods in one area. This study aimed to quantitatively identify sensitive infectious diseases associated with floods in Guangxi, China. Methods: A time-trend ecological design was conducted. A descriptive analysis was first performed to exclude infectious diseases with low incidence from 2005 to 2012 in ten study sites of Guangxi. The Wilcoxon rank-sum test was applied to examine the difference in the ten-day attack rate of infectious diseases between the exposure and control periods with different lagged effects. Negative binomial, zero-inflated Poisson and zero-inflated negative binomial models were used to examine the relationship and odd ratios (ORs) of the risk of floods on infectious diseases of preliminary screening. Results: A total of 417,271 infectious diseases were notified. There were 11 infectious diseases associated with floods in the preliminary screening process for flood-sensitive infectious diseases. The strongest effect was shown with a 0-9 ten-day lag in different infectious diseases. Multivariate analysis showed that floods were significantly associated with an increased the risk of bacillary dysentery (odds ratio (OR) = 1.268, 95% confidence interval (CI): 1.072-1.500), acute haemorrhagic conjunctivitis (AHC, OR = 3.230, 95% CI: 1.976-5.280), influenza A (H 1 N 1 ) (OR = 1.808, 95% CI: 1.721-1.901), tuberculosis (OR = 1.200, 95% CI: 1.036-1.391), influenza (OR = 2.614, 95% CI: 1.476-4.629), Japanese encephalitis (OR = 2.334, 95% CI: 1.119-4.865), and leptospirosis (OR = 1.138, 95% CI: 1.075-1.205), respectively. Conclusion: The spectrum of infectious diseases which are associated with floods are bacillary dysentery, AHC, influenza A (H 1 N 1 ), tuberculosis, influenza, Japanese encephalitis and leptospirosis in Guangxi. Floods can result in differently increased risk of these diseases, and public health action should be taken to control a potential risk of these diseases after floods.

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“…Our study identified positive short-term associations of rainfall with leptospirosis at lags of 1 and 2 weeks. Previous work in Manila identified that rainfall was associated with higher number of clinically suspected leptospirosis cases at a lag time of 2 weeks [27]. Reasons for the shorter time lags found in our work may be explained by differences in methodology.…”

Section: Discussionmentioning

confidence: 37%

“…Our study performed active case finding across the study period for ascertainment of clinical leptospirosis, and our findings were confirmed with the gold standard laboratory testing. The study in Manila included only suspected leptospirosis cases [27] with an expected rate of laboratory confirmation of 54% [44]. Correct estimates of this time lag between rainfall and disease incidence are important for accurate prediction of short-term leptospirosis risk and accurately direct public health interventions.…”

Section: Discussionmentioning

confidence: 99%

“…Previous studies have suggested that, in addition to rainfall, other climatic factors, such as temperature and humidity may also independently contribute to leptospirosis transmission [18,20,26]. A recent study by Matsushita et al [27] describes correlations between moderate-to-low rainfall events and clinically suspected cases of leptospirosis, but without considering other climactic factors related to leptospirosis in the urban setting of Manilla. No study to date has disentangled the complex interaction and short time lag of rain, temperature and humidity on the epidemiology of urban leptospirosis.…”

Section: Introductionmentioning

confidence: 99%

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Rainfall and other meteorological factors as drivers of urban transmission of leptospirosis

Cunha

Costa

et al. 2019

Preprint

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word count: 220 2 Manuscript word count: 3,574 ABSTRACT Background. Leptospirosis is an important public health problem affecting vulnerable urban slum populations in developing country settings. However, the complex interaction of meteorological factors driving the temporal trends of leptospirosis remain incompletely understood.Methods and findings. From 1996 to 2010, we investigated the association between the weekly incidence of leptospirosis and climatic variables in the city of Salvador, Brazil by using a dynamic generalized linear model that accounted for time lags, overall trend and seasonal variation. Our model showed an increase of leptospirosis cases associated with rainfall, lower temperature and higher humidity. There was a lag of one-to-two weeks between weekly values for significant meteorological variables and leptospirosis incidence. Independent of the season, a weekly cumulative rainfall of 20 mm increased the risk of the leptospirosis by 10% compared to a week without rain. Finally, over the 14 year study period the incidence of leptospirosis decreased significantly by four fold (12.8 versus 3.6 per 100,000 people), independently of variations in climate. Conclusions.Strategies to control leptospirosis should focus on avoiding contact with contaminated sources of Leptospira as well as on increasing awareness in the population and health professionals within the short time window after both low-level and extreme rainfall events. Increased leptospirosis incidence was restricted to one-to-two weeks after those events suggesting that infectious Leptospira survival may be limited to short time intervals.Author Summary: To determine the role of meteorological variables, seasonal variation and temporal trends in the incidence of leptospirosis, we investigated the time series of leptospirosis incidence amongst residents of Salvador, Brazil, from 1996 Exploratory and confirmatory statistical methods detected associations between meteorological factors and disease incidence. Results showed the importance of extreme meteorological conditions, particularly rainfall, as short-term predictors of leptospirosis incidence. In addition, we found a long-term decreasing trend of in disease incidence over the observation period.

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The non-linear and lagged short-term relationship between rainfall and leptospirosis and the intermediate role of floods in the Philippines

Cited by 32 publications

References 28 publications

Trend of leptospirosis and its association with meteorological factors in Thrissur district, Kerala

Trend of leptospirosis and its association with meteorological factors in Thrissur district, Kerala

A time-trend ecological study for identifying flood-sensitive infectious diseases in Guangxi, China from 2005 to 2012

Rainfall and other meteorological factors as drivers of urban transmission of leptospirosis

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