A Comparative Study of the Epidemiological Aspects of Legionnaires’ Disease: Outbreaks in Korea and Japan, 2010 - 2014

Abstract

BackgroundIn the present study, we compared the epidemiological aspects of Legionnaire’ disease (LD) outbreaks in Korea and Japan by analyzing the current state from 2010 to 2014.MethodsThe following factors were analyzed: nationwide cumulative incidence rate (CIR) per 100,000 populations and case-fatality rate in percentage, epidemiological aspects (i.e., case related to gender), male to female morbidity ratio (MFMR), age, seasonality and habitat distribution of LD cases.ResultsIn total, there were 134 cases of LD with the CIR of 0.05 per 100,000 populations in Korea from 2010 to 2014. During the same period in Japan, there were 4,840 cases of LD with a CIR of 0.76 per 100,000 populations. The CIR in Japan was significantly higher than that in Korea. However, the case-fatality rates were at similar levels (3.0% vs. 5.9%). Moreover, LD affects both sexes differently, accounting for 2.05 and 4.41 of MFMR in Korea and Japan, respectively. In both countries, the incidence mainly occurred among people aged 40 years or older, and peaked in summer (37.3% vs. 33.7% of total cases). Significant differences were observed in the incidence of LD cases between the capital city and county areas in both two countries. These differences in LD risk factors reflect the different influences of reservoir/host with natural or artificial aquatic environments.ConclusionThis study provides a quantitative analysis of the epidemiological aspects and risk factors of LD outbreaks in Korea and Japan. We hope this study would be helpful for providing insight on effective future strategies to reduce LD outbreaks.

Sexual dimorphism in bacterial infections

“…Legionellosis is mainly characterized by pneumonia with a high incidence of mortality rates, and although it is frequently observed as sporadic cases, it has been also reported in community and hospital outbreaks mainly due to contamination in the air conditioning systems [ 128 – 130 ]. It has been reported a strong association of legionellosis with male gender in many European, American, and Asian countries, as well as in Australia, and in fact, male gender is considered as a poor prognostic factor [ 131 – 141 ].…”

“… Gastroenteritis and wound infections [ 57 , 200 , 245 , 246 ] Women Enterohemorrhagic Escherichia coli Hemolytic–uremic syndrome and irritable bowel syndrome [ 59 , 60 ] Respiratory tract infections Men Streptococcus pneumoniae Community-acquired pneumonia [ 79 ] Mycobacterium tuberculosis Tuberculosis [ 93 – 100 ] Legionella spp. Legionnaires’ disease [ 131 , 132 , 141 , 133 – 140 ] Bloodstream infections Men Many bacterial species Septic shock, organ dysfunction, severe sepsis [ 18 , 162 , 177 , 163 , 165 – 167 , 173 – 176 ] Urinary tract infections Women Escherichia coli Acute cystitis, inflammation, and sepsis [ 229 , 231 ] Lyme borreliosis Women Borrelia burgdorferi Erythema migrans and facial nerve palsy [ 232 , 233 ] Sexually transmitted infections Women Chlamydia trachomatis Infertility, ectopic pregnancy, and pelvic inflammatory disease [ 235 , 237 ] Neisseria gonorrhea …”

Incidence and risk factors associated with progression to severe pneumonia among adults with non-severe Legionella pneumonia

“…The number of cases reported to the Korea Centers for Disease Control and Prevention was 6 in 2006 in contrast to 501 in 2019 [ 10 ]. The reasons for such a sharp increase include widespread nucleic acid amplification, urinary antigen testing, and the introduction of mandatory reporting systems for the disease in several countries [ 11 - 13 ]. Furthermore, an aging population, infrastructure, and changes in the global climate have been suggested as factors contributing to this increase [ 14 ].…”