Childhood leptospirosis in an industrialized country: Population-based study in Okinawa, Japan

Abstract

Leptospirosis is considered underdiagnosed because of its nonspecific presentation and lack of proper understanding of its epidemiology. Early diagnosis and treatment are crucial. However, few data are available on confirmed leptospirosis cases in children in industrialized countries. We therefore aimed to describe epidemiologic and clinical characteristics of laboratory-confirmed childhood leptospirosis in Okinawa, Japan. We reviewed the national surveillance data of pediatric leptospirosis in Okinawa, Japan from January 2003 through December 2015. The database included all of laboratory-confirmed leptospirosis diagnosed at the only central laboratory for leptospirosis in the region. There were 44 children (0–20 years of age) with laboratory-confirmed leptospirosis. Of these, 90% were male, 91% were 10–20 years of age, and 96% of cases occurred in August and September. The number of laboratory-confirmed patients ranged from 0 to 11 per year (mean: 3.3 per year), and the estimated annual rate was 1.0 per 100,000 pediatric populations. In all cases, the presumed infection route was recreational exposure to river water. Commonly observed manifestations include fever (95%), myalgia (52%), and conjunctival suffusion (52%). Childhood leptospirosis in Okinawa, Japan occurred predominantly in teenage boys after freshwater exposure in summer, and most patients had characteristic conjunctival suffusion. Cohort studies would be helpful to better understand more detailed clinical manifestations in association with prognosis.

Age-specific epidemiology of human leptospirosis in New Caledonia, 2006-2016

“…Secondly, school-age children were infected earlier in the calendar year, suggesting that returning to school classes in February strongly decreased the infection risk in this specific population subgroup. Interestingly, a very similar pattern was observed in Japan, where young boys were infected through recreational freshwater activities during summer holidays [36]. As speculated by the authors of the study in Japan, the demographic features and exposure history reported in both studies are very similar and probably widely shared in the subtropical populations [36].…”

“…Interestingly, a very similar pattern was observed in Japan, where young boys were infected through recreational freshwater activities during summer holidays [36]. As speculated by the authors of the study in Japan, the demographic features and exposure history reported in both studies are very similar and probably widely shared in the subtropical populations [36]. In this study conducted in the most tropical part of Japan, a high proportion of mild clinical forms was described, also in agreement with our observation of only non-fatal cases in New Caledonia.…”

A systematic literature review of leptospirosis outbreaks worldwide, 1970–2012

“…Similar to our findings, studies have reported more frequent acute renal injury ( 40 ) and higher fatality rate in adults than in children ( 38 , 40 ). Pediatric leptospirosis is relatively less described in the literature and mild illness is common ( 41 , 42 ). More research is needed to fully understand distinct clinical patterns that can help with early detection of outbreaks in children and diagnosis and treatment.…”

Environmental DNA metabarcoding to detect pathogenic Leptospira and associated organisms in leptospirosis-endemic areas of Japan

“…Leptospirosis is endemic in Okinawa, the southernmost prefecture of Japan, where infection occurs predominantly after freshwater exposure 3,4 . Sporadic cases and outbreaks of leptospirosis after recreational activities in rivers have been reported mainly in the northern part of Okinawa Island and the Yaeyama region 5–7 . Outbreaks among US military personnel have also been reported several times in Northern Okinawa, where the Jungle Warfare Training Center operates 8 .…”