Seroepidemiology of Hepatitis A Infection in Northeastern China, Korea, and Japan.

0.33 MB·English

by  Yun, Haesun

OsongPublicHealthResPerspect20123(1),31e35
doi:10.1016/j.phrp.2012.01.005
pISSN2210-9099 eISSN2233-6052
- -
ORIGINAL ARTICLE
Seroepidemiology of Hepatitis A Infection in
Northeastern China, Korea, and Japan
Haesun Yun a,*, Hyeok-Jin Leea, Youngsil Yoon a, Kisang Kim a,
Sungsoo Kim b, Myung-Hee Shin c, Miyuki Taniguchid, Soo Ryang Kim d,
Mi Kyung Kim e
aDivision of Enteric and Hepatitis Viruses, Korea National Institute of Health, Osong, Korea.
bDivision of Epidemiology and Health Index, Korea Centers for Disease Control and Prevention,
Osong, Korea.
cDepartment of Social & Preventive Medicine, Sungkyunkwan University School of Medicine,
Suwon, Korea.
dDepartment of Gastroenterology, Kobe Asahi Hospital, Kobe, Japan.
eDepartment of Preventive Medicine, College of Medicine, Hanyang University, Seoul, Korea.
Received:October18, Abstract
2011 Objectives:TheepidemiologicalpatternsofendemichepatitisAvirus(HAV)are
Revised:December 15, unclear in northeastern Asia dependingon the ethnicity of the country in ques-
2011 tion. The purpose of this study was to investigate the seroprevalence of HAV in
Accepted: January5, northeastern China,SouthKorea,andJapan.
2012 Methods: A total of 1,500 serum samples were collected from five groups of
inhabitants (300 each) who were over 40 years of age (Korean Chinese, indige-
KEYWORDS: nous Chinese, South Korean, Korean living in Japan, and indigenous Japanese).
The samples were screened for antibodies to HAV using an enzyme-linked
hepatitisAvirus,
immunosorbent assay.
NortheasternAsia,
Results: Positivity for HAV antibodies was 93.7% (95% confidence interval [CI]:
seroepidemiology 90.9e96.4)inKoreanslivinginnortheasternChina,99.7%(95%CI:99.0e100.3)in
indigenousChinese,98.0%(95%CI:96.4e99.6)inindigenousKoreans,33.3%(95%
CI: 28.0e38.7) in Koreans living in Japan, and 20.4% (95% CI: 15.8e25.0) in
indigenous Japanese persons. The overall anti-HAV prevalence was not signifi-
cantly different between northeastern China and South Korea, but it was
differentinJapan.
Conclusions: These results indicate that differences in seroprevalence can be
attributed to geological, environmental, and socioeconomic conditions rather
than ethnicity.
Abbreviations:HAV,hepatitisAvirus;CI,confidenceinterval.
*Correspondingauthor.
E-mail:[email protected]
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License
(http://creativecommons.org/licenses/by-nc/3.0)whichpermitsunrestrictednon-commercialuse,distribution,andreproductionin
anymedium,providedtheoriginalworkisproperlycited.
Copyrightª2012KoreaCentersforDiseaseControlandPrevention.PublishedbyElsevierKoreaLLC.Allrightsreserved.
32 H. Yun, et al
1. Introduction 2.2. Serologic tests and statistical analysis
To determine the seroprevalence in our study pop-
Hepatitis A virus (HAV) is transmitted via the oral- ulations, the presence of anti-HAV immunoglobulin
fecalroute,mainlybytheconsumptionofcontaminated (IgG) in human sera was determined using Axsym
water, and is found worldwide. The epidemiologic Abbott assays according to the manufacturer’s
patterns (e.g., low, intermediate, and high) of ende- instructions (Abbott Diagnostics Division, Wiesbaden,
micity are dependent on age and the level of hygiene Germany). We calculated the proportion of the HAV
[1e3]. Even within a designated country, each pattern antibody-positive persons and achieved a 95% confi-
isreflectiveofthevariableinfectionrate,prevailingage dence interval (CI) using a modification of the Wald
of the population, and mode of transmission [4,5]. method. We used the c2 test to compare proportions
Although the seroprevalence of HAV is low in children between two groups. A p value <0.05 was considered
in industrialized countries with low levels of ende- significant.
micity,theagegroupofthemostsusceptiblepopulation
willchangefromchildrentoolderchildrenandadultsin
these countries [6e8]. Recently, severe cases of HAV 3. Results
infection in nonimmune and nonimmunized adultshave
been on the rise [2,8,9]. The overall prevalence of HAV was 96.7% among
In developing countries, low economic status, high the inhabitants of northeastern China, 99.7% (95% CI:
population density, and inadequate water treatment 99.0e100.3) among the population of indigenous
might contribute to higher levels of endemicity; more Chinese, and 93.7% (95% CI: 90.9e96.4) among
than 90% of the population acquires natural immunity KoreanslivinginChina.Intheformer,theprevalenceof
before 10 years of age [5,10]. Due to improved stan- HAV was 99.2% (124/125) in men and 100.0% (175/
dards of hygiene, sanitation, and socioeconomic condi- 175) in women with no significant difference between
tions, the epidemiological pattern of HAV infection the two. In terms of age, the ratios were 99.4% (among
and other infectious diseases are currently undergoing individuals in their 40s), 100.0% (50s), and 100.0%
changesinmanydevelopingcountries[4,10,11].Studies (over 60 years of age) with no significant differences
conducted in emerging countries have reported epide- between age groups. Among Koreans living in China,
miological changes over the last several decades, indi- the prevalence was 94.6% (123/130) in men and 92.9%
cating that HAV affects the population at a later age (158/170) in women with no significant difference
withanincreasedriskofmanifestinginitssymptomatic, betweenthetwo;intermsofage,theratioswere93.1%
potentially more severe form [8,9,12]. (amongindividualsintheir40s),91.3%(50s),and100%
This study was conducted in order to improve our (over 60 years of age) with no significant differences
understandingofthecomparativeepidemiologyofHAV between age groups.
in northeastern China, South Korea, and Japan. TheoverallprevalenceofHAVwas98.0%(95%CI:
96.4e99.6) among the inhabitants of South Korea:
98.2% (111/113) in men and 97.9% (183/187) in
2. Materials and Methods women. The age ratios were 95.8% (among individuals
in their 40s), 99.1% (50s), and 100.0% (over 60 years
2.1. Study design and population of age).
This study is part of the Korean Emigrant Study The overall prevalence of HAV was 26.9% among
supportedbytheKoreaCentersforDiseaseControland inhabitants of Japan: 20.4% (95% CI: 15.8e25.0)
Prevention (KCDC). This study was initiated to eluci- among indigenous Japanese and 33.3% (95% CI:
date the effects of environmental change, genetic 28.0e38.7) among Koreans living in Japan. Among
susceptibility, and their interaction of hypertension, indigenous Japanese, the prevalence was 13.4% (17/
diabetes,andmetabolicsyndromebycomparingKorean 127) in men and 25.6% (44/172) in women with
emigrants, their host country residents, and Koreans a significant difference (p Z 0.010) between the two;
livinginKorea.Theratiobetweenthetwoethnicgroups the age ratios were 4.7% (among individuals in their
was 1:1. From May 2005 to February 2008, a total of 40s), 20.0% (50s), and 55.0% (over 60 years of age)
3,142 men and women aged 40 years or over partici- with a significant and gradual increase noted with
pated in the Korean Emigrant Study. increasingage(p<0.00004).AmongKoreanslivingin
For this study, we randomly selected 300 Korean Japan, the prevalence was 34.4% (44/128) in men and
emigrants, 300 Chinese in Yanbian, 300 Korean 32.6%(56/172)inwomenwithnosignificantdifference
emigrants, and 300 Japanese from the Kinki area between the two; the age ratios were 6.8% (among
(western Japan). We also randomly selected 300 individuals in their 40s), 40.7% (50s), and 78.3% (over
Koreans living in Korea who were matched in terms of 60 years of age) with a significant and gradual increase
age and sex to the Chinese and Japanese sample notedwithincreasingage(p<0.00004)(Figure.1AeC)
populations. (Table 1).
Epidemiology of HAV in Northeastern Asia 33
Figure1. PrevalenceofHAV.PrevalenceamongKoreanslivinginnortheasternChina,indigenousChinese,indigenousKoreans,
KoreanslivinginJapan,andindigenousJapanese(A).Prevalencebysex(B)andage(C)amongthefivepopulationgroups.Men:
openbar;women:hatchedbar.*pZ0.010;**p<0.00004.Agesareindicatedasfollow:0e49yearsofage,hatchedbar;50e59
years, openbar; > 60years,closed bar.
4. Discussion older patients [18,19]. Patients with HAV are mostly in
their 20s (57.5%) and 30s (31.5%). The number of
Since 2001, Korea has experienced a nationwide patients in the age groups ((cid:1)20 or >40 years) is rela-
outbreak of HAV, as reported in the nationwide tively lower (5.2 and 5.7 %, respectively) [19].
surveillance report on acute HAV published by KCDC- In 2007, Lu et al reported the serological prevalence
Korea. Thenumberofannualreportedcases ofHAVin of viral HAV, B, C, and E in 8762 randomly selected
2005 was 798, which increased to 2081 in 2006 and Chinese subjects in six areas of China in a cross-
2233 in 2007. The number of cases exhibited an abrupt sectionalstudy.Theoverallprevalenceoftheanti-HAV
increasefrom2008(nZ7,895)to2009(nZ15,231), antibody was as high as 72.87% [21]. Anti-HAV prev-
butappearedtobedecliningin2010(nZ6,794through alence in the (cid:1)5, (cid:1)10, (cid:1)20, (cid:1)30, (cid:1)40, (cid:1)50, (cid:1)60, and
Oct2010).Asaresultofimprovedstandardsofhygiene > 60 years age groups was 44.7%, 51.9%, 57.6%,
andsanitation,HAVepidemiologyhasrapidlyshiftedin 73.5%, 88.3%, 91.1%, 93.5%, and 97.3%, respectively
Korea. At present, adolescents and young adult are the [21]. In Heilongjiang, which is located in northeastern
most susceptible to HAV infection because they were China,theprevalenceofanti-HAVwasover95%inthe
not naturally infected with HAV during childhood, nor population>40yearsofage.Yanbianisalsolocatedin
have they been immunized against HAV [13e18]. NortheasternChina,andtheseroprevalenceinourstudy
In the past, HAV was endemic in South Korea isconsistentwithpreviouslypublishedstudiesonChina
(especially in the 1980s), and most adults acquired [21e25]. In this region there are significant differences
natural immunity through asymptomatic infection between the two ethnic groups (i.e., Koreans living in
[13,14]. Due to improved socioeconomic and sanitation China and indigenous Chinese). The rate of HAV
conditions, the epidemiological pattern of HAV has seroprevalence was also found to be over 95% in
rapidly improved in Korea; the seroprevalence has Koreans > 40 years of age. These results suggest that
decreased in children, teenagers, and young adults in thenortheastregionofChinaandSouthKoreamightbe
their 20s, though there has been an abrupt increase in highly endemic to HAV.
patients aged 20e30 years [16,19,20]. The seropreva- According to the current age-specific rates of
lenceisnowverylowinteenagersorthoseintheir20s, immunity to HAV in various regions around the world
higher among people in their 30s, and >90% among that were obtained by conducting a systematic review
34 H. Yun, et al
Table 1. Prevalence of HAV among indigenous Japanese, Koreans living in Japan, indigenous Chinese, Koreans living in
northeastern China,and indigenous Koreans
Japan (nZ599)
IndigenousJapanese Koreans livinginJapan
Age (y) 0e49 50e59 >60 Total 0e49 50e59 >60 Total
Men 2/55 6/48 9/24 17/127 5/55 20/48 19/25 44/128
% positive 3.6 12.5 37.5 13.4 9.1 41.7 76.0 34.4
Women 4/74 16/62 24/36 44/172 4/77 24/60 28/35 56/172
% positive 5.4 25.8 66.7 25.6 5.2 40.0 80.0 32.6
Total 6/126 22/110 33/60 61/299 9/132 44/108 47/60 100/300
% positive 4.7 20.0 55.0 20.4(15.8e25.0) 6.8 40.7 78.3 33.3(28.0e38.7)
(95%CI)
China (nZ600)
IndigenousChinese Koreans livinginnortheastern China
Age (y) 0e49 50e59 >60 Total 0e49 50e59 >60 Total
Men 68/69 33/33 23/23 124/125 40/41 51/57 32/32 123/130
% positive 98.6 100.0 100.0 99.2 97.6 89.5 100.0 94.6
Women 90/90 57/57 28/28 175/175 55/61 65/70 38/38 158/170
% positive 100.0 100.0 100.0 100.0 90.2 92.9 100.0 92.9
Total 158/159 90/90 51/51 299/300 95/102 116/127 70/70 281/300
% positive 99.4 100.0 100.0 99.7(99.0e100.0) 93.1 91.3 100.0 93.7(90.9e96.4)
(95%CI)
South Korea (nZ300)
IndigenousKoreans
Age (y) 0e49 50e59 >60 Total
Men 43/45 37/37 31/31 111/113
% positive 95.6 100.0 100.0 98.2
Women 71/74 69/70 43/43 183/187
% positive 95.9 98.6 100.0 97.9
Total 114/119 106/107 74/74 294/300
% positive 95.8 99.1 100.0 98.0(96.4e99.6)
(95%CI)
and meta-analysis of published data, in Japan, South transmission mode, this study does provide certain
Korea, and Singapore the estimated level of endemicity important information concerning the prevalence of
“very low,” which means <50% of the populations has HAV in northeastern China, South Korea, and Japan
immunity by age 30 [3]. A study of the shifting seroe- based on socioeconomic status, environmental condi-
pidemiological patterns of HAV found an association tions, and ethnicity. Our data show that among people
with improvedsanitary conditionsinJapan.Theoverall > 40 years of age, the prevalence of anti-HAV is not
seroprevalence was 12.2% in 2,430 serum specimens significantly different between northeastern China and
obtained during 2003. Anti-HAV antibodies are rarely South Korea; however, this prevalence is different in
detected in individuals between 0e44 years of age, Japan. These results suggest that differences in sero-
although the prevalence in individuals >50 years was prevalence could be attributed to geological, environ-
50.3% in 2003 [26]. These results were significantly mental, and socioeconomic changes rather than
lower than those of corresponding studies conducted in ethnicity.
1994 (74.3%),1984 (96.9%)and 1973 (96.9%)[26,27].
Inourstudy,thesamplesobtainedfromatotalof1,500
men and women aged >40 years were collected from Acknowledgements
May2005throughFebruary2008.Theoverallprevalence
of HAV was 26.9% among the inhabitants of Japan: This work was supported by an intramural fund of
20.4%(95% CI: 15.8e25.0)of indigenous Japanese and KoreaNationalInstituteofHealth(No.4800-4863-300).
33.3% (95% CI: 28.0e38.7) of Koreans living in Japan.
The decline in the prevalence of anti-HAV is consistent
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