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

Abstract

BackgroundHemorrhagic fever with renal syndrome (HFRS) and leptospirosis are seasonal rodent-borne infections in the Republic of Korea (Korea). The occurrences of HFRS and leptospirosis are influenced by climatic variability. However, few studies have examined the effects of local climatic variables on the development of these infections. The purpose of this study was to estimate the effect of climatic factors on the occurrence of HFRS and leptospirosis in Korea.MethodsDaily records on human cases of HFRS and leptospirosis between January 2001 to December 2009 were analyzed. The associations of climatic factors with these cases in high incidence provinces were estimated using the time-series method and multivariate generalized linear Poisson models with a maximal lag of 12 weeks.ResultsFrom 2001 to 2009, a total of 2912 HFRS and 889 leptospirosis cases were reported, with overall incidences of 0.67 and 0.21 cases per 100,000, respectively, in the study areas. The increase in minimum temperature (1 °C) at a lag of 11 weeks was associated with 17.8% [95% confidence interval (CI): 15.1, 20.6%] and 22.7% (95% CI: 16.5, 29.3%) increases in HFRS and leptospirosis cases, respectively. A 1-h increase in the daily sunshine was related to a 27.5% (95% CI: 18.2, 37.6%) increase in HFRS at a lag of 0 week. A 1% increase in daily minimum relative humidity and a 1 mm increase in daily rainfall were associated with 4.0% (95% CI:1.8, 6.1) and 2.0% (95% CI: 1.2, 2.8%) increases in weekly leptospirosis cases at 11 and 6 weeks later, respectively. A 1 mJ/m2 increase in daily solar radiation was associated with a 13.7% (95% CI: 4.9, 23.2%) increase in leptospirosis cases, maximized at a 2-week lag.ConclusionsDuring the peak season in Korea, climatic factors play a significant role in the development of HFRS and leptospirosis. The findings of this study may be applicable to the forecasting and prediction of disease outbreaks.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-017-2506-6) contains supplementary material, which is available to authorized users.

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

“…Our identification of one-to-two-week time lags is consistent with the expected incubation period plus the time until onset of illness, between 5 and 14 days [45]. The 1 to 2 weeks lag between rainfall, temperature, or humidity and leptospirosis identified here, as well as the 2 weeks lag between rainfall and flooding reported in Manila, contrast with results from previous studies that used monthly data and suggested longer temporal association between onset of symptoms of leptospirosis and meteorological data (2 to 10month lags respectively) [18][19][20]46]. Therefore, though leptospires survive for up to one year and remain virulent in culture conditions that mimic the external environment in vitro [45,47,48], L. interrogans survival in spring water decreases to 3 weeks [49].…”

Leptospirosis in Wardha District, Central India—Analysis of hospital based surveillance data

“…Hence, they are more exposed to animal urine and thus have more leptospirosis in the district. Majority of the studies have reported this disease to be common among males, while a study from Korea found females to be more affected 25 . In Wardha district, relative humidity in the month and rainfall in the previous month were the significant determinants of leptospirosis cases in a given month.…”

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

“…The most important environmental factors associated with leptospirosis are temperature, humidity and rainfall prevalent in the region. 5 An understanding of the type of relation between these factors and leptospirosis will go a long way in controlling the leptospirosis menace in a community. If we are able to predict the occurrence of cases early enough, it would be a great help to the health administrators to take appropriate actions to control and prevent future outbreaks.…”