Volume 1(1); December

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Osong Public Health Res Perspect > Volume 1(1); 2010
Kim, Cheun, Cheun, Lee, Kim, Lee, Lee, and Cho: Prevalence of Clonorchis sinensis Infections Along the Five Major Rivers in Republic of Korea, 2007

Abstract

Objectives

The prevalence of Clonorchis sinensis infection was investigated among residents of the five major river basins, that is, Hangang, Nakdonggang, Seomjingang, Yeongsangang, and Geumgang River basins in Korea.

Methods

From January to December 2007, a total of 31,268 stool samples were collected from 29 localities and examined by the formalin-ether sedimentation technique.

Results

Intestinal parasite eggs and/or protozoan cysts were detected from 2957 (9.5%) inhabitants. Number of residents harbouring helminth eggs in the faeces was 2542 (8.1%) for C. sinensis, 255 (0.8%) for Heterophyes spp., 36 (0.1%) for Echinostoma spp., 30 (0.1%) for Trichuris trichiura, 8 (0.03%) for Ascaris lumbricoides, 7 (0.02%) for Gymnophalloide seoi, and 50 (0.02%) for Trichostrongylus orientalis. Number of residents harbouring protozoan cysts in the faeces was 133 (1.3%) for Entamoeba spp. and 50 (0.2%) for Giardia lamblia. The positive rates of C. sinensis in Nakdonggang, Seomjingang, Yeongsangang, Geumgang, and Hangang River basins were 12.2%, 9.5%, 3.3%, 3.0%, and 1.0%, respectively. The egg positive rate of C. sinensis was higher in male (10.6%) than in female (6.1%), and the age group of 50s had the highest positive rate (10.4%).

Conclusion

The result of this study revealed little decrease in positive rate of C. sinensis compared with the result of southern endemic areas of Korea in 2006.

Key words

Clonorchis sinensis; five major rivers; intestinal parasites; prevalence

Introduction

Intestinal parasitic infections were highly prevalent until 1970s in Korea, especially among residents of major river basins of the country. During the past decade, a rapid decrease in the overall prevalence of intestinal parasites has been observed and is attributed mainly by nationwide control programs and health education undertaken by the Korean government along with increases in living conditions and quality of life among people living in Korea. Despite the remarkable decrease in soil-transmitted nematode infections,1 however, the prevalence of fish-borne trematode infections such as with Clonorchis sinensis and Metagonimus yokogawai has been maintained at relatively high level.
The liver fluke, C. sinensis, is currently the most important parasite infecting humans in Korea. Egg positive rates of C. sinensis in general population were 4.6% in 1971, 1.8% in 1976, 2.6% in 1981, 2.7% in 1986, 2.2% in 1992, 1.4% in 1997, and 2.4% in 2004.2 In 1981, the egg positive rates of people living in those river basins differed considerably; 40.2% in Nakdonggang, 30.8% in Yeongsangang, 17.3% in Seomjingang, 15.7% in Hangang, 15.9% in Tamjingang, 12.0% in Geumgang, and 8.0% in Mangyeonggang Rivers.3
The infection of C. sinensis is contracted by eating undercooked fishes that harbour the metacercariae. Contaminated fishes are mainly found from streams and rivers where the freshwater snail Parafossarulus manchouricus thrive. The liver fluke in the biliary passage provokes severe pathologic changes therein, such as bile duct dilatation, ductal wall thickening, ductal inflammation, biliary mucosal hyperplasia, and biliary cirrhosis. The infection with C. sinensis was also found to induce cholangiocarcinoma in experimental hamsters acting as a promoter.4 Clonorchiasis has been recognized as one of several factors of cholangiocarcinoma in humans.5,6
Although some local data are previously available on this issue, no nationwide surveys have been conducted. The present survey on the prevalence and distribution of human clonorchiasis is one of the prerequisites for the government to implement its national control measures.

Materials and Methods

2.1 Surveyed area

Twenty-nine counties (Figure 1 and Table 1) were selected in five major river basins, which were located near or alongside the major rivers of Korea with reference to the nationwide survey in 2004.2 The study was undertaken for 1 year from January to December 2007.

2.2 Stool collection and examination

Stool specimens were collected in plastic containers and transferred to the laboratory of National Institute of Health. A total of 31,268 subjects were recruited from villages for stool collection by a random household sampling method to assess the prevalence of parasitic infection. The formalin-ether sedimentation technique was used to examine helminth eggs, larvae, and protozoan cysts. One gram of each faecal sample was fixed with 10% neutral formalin in a 10-mL test tube. The formalin-fixed stool specimen was further processed by the formalin-ether concentration technique and examined for parasites in the laboratory. Parasite-positive individuals were treated with praziquantel and other appropriate anti-parasitic drugs at the end of the study.

Results

3.1 Number of positive cases of total intestinal parasites

Of 31,268 stool samples examined, 2957 (9.5%) were found to contain various intestinal parasite eggs, cysts, or larvae. Eggs of C. sinensis, Heterophyes spp., Echinostoma spp., Trichuris trichiura, Ascaris lumbricoides, Gymnophalloide seoi, and Trichostrongylus orientalis were detected from 2542 (8.1%), 255 (0.8%), 36 (0.1%), 30 (0.1%), 8 (0.03%), 7 (0.02%), and 5 (0.02%) individuals, respectively. Protozoan cysts were detected from 133 (1.3%) individuals for Entamoeba spp. and 50 (0.2%) for Giardia lamblia (Table 2).

3.2 Egg positive cases of C. sinensis by river basin and gender

Infection rates of C. sinensis by river basin, locality, and gender are summarized in Table 3. The overall egg positive rate of C. sinensis was 8.1%. The highest rate was observed in the Nakdonggang River basin, which showed an average infection rate of 12.2%, ranging from 2.8% to 23.1% by counties. Yecheon-gun showed the highest rate at 23.1%, followed by Sangju-si (20.8%). The next highest rate was observed in the Seomjingang River basin with an average infection rate of 9.5%, ranging from 6.8% to 14.4%. The lowest infection rate was observed in the Hangang River basin, which showed an average of 1.0%.
The egg positive rate of C. sinensis was higher in male (10.6%) than in female (6.1%). The highest rate of male residents infected with C. sinensis was observed in the Nakdonggang River basin, which showed an average infection rate of 15.3%, ranging from 3.6% to 28.5%. Male residents living in Yecheon-gun showed the highest infection rate at 28.5%, followed by Sangju-si (22.9%). The next highest rate was observed in the Seomjingang River basin (12.7%), followed by the Yeongsangang (5.1%) and the Geumgang (4.6%) River basins. The overall egg positive rate of female residents was 6.1%. The highest female egg positive rate was also observed in the Nakdonggang River basin with an average of 9.7%, ranging from 1.8% to 19.2%. The next highest rate was in the Seomjingang River basin (6.8%), followed by Yeongsangang (2.1%), Geumgang (1.8%), and Hangang (0.6%) River basins.

3.3 Egg positive cases of C. sinensis by age group

Among the 31,268 cases examined by age group, the positive rate of C. sinensis was highest in the age group between 50 and 59 years (10.4%), followed by the order of 40–49 (8.7%), 60–69 (8.3%), and 70–79 (7.7%) years (Table 4).

Discussion

The present study indicated that the overall prevalence of intestinal parasites was 9.5% and 2957 individuals were infected with 13 species of intestinal parasites. This result, however, is considerably lower than that of 2006, which was observed a 14.3% positive rate in southern endemic areas.7
The positive rate of C. sinensis was the highest, covering 85.6% of all positive cases. The egg positive rate of C. sinensis (8.1%) decreased slightly compared with the result of 2006 investigation. In the nationwide surveys in 1997 and 2004, C. sinensis positive rates were 1.4% and 2.4%, respectively, and these results suggested that C. sinensis are prevalent along major river basins. The present study was mainly focused on residents of villages where clonorchiasis has been endemic or suspected. Thus, it is the main reason for the higher egg positive rate of C. sinensis of the present study (8.1%) than that (2.4%) of 2004.
Clonorchiasis has been regarded as a persisting helminthiasis and has largely disappeared throughout the country.1 In 2006, the total egg positive rate of C. sinensis was 11.1% among residents living in the river basins of South Korea. The egg positive rates observed in the river basins of Nakdonggang, Seomjingang, Yeongsangang, and Geumgang were 17.1%, 11.2%, 5.5%, and 4.6%, respectively. In 2007, the total egg positive rate of C. sinensis was 8.1% (Table 3). The positive rates observed in the river basins of Nakdonggang, Seomjingang, Yeongsangang, Geumgang, and Hangang were 12.2%, 9.5%, 3.3%, 3.1% and 1.0%, respectively (Table 3). Especially, the river basins of Nakdonggang and Seomjingang Rivers still appear to be endemic.
The average egg positive rate of C. sinensis among male was 10.6%, which ranged from 0.2% to 28.5% by river basin areas, whereas the average positive rate among female was 6.1% with a range from 0.2% to 19.2% (Table 3). Infection rates of male and female residents showed between 3.0% and 2.8% decrease compared with results of 2006.
The egg positive rate increased as age increased, reaching a maximum of 10.4% in the age group of 50–59- years (Table 3), followed by 40–49 (8.4%), 60–69 (8.3%), 70–79 (7.7%), and older than 80 (6.5%) years. The infection status of C. sinensis among Koreans by age in this study showed the same peak at the 50- to 59-year-old group as compared with the result in 2006.3 This result appears to be the typical pattern of C. sinensis infection, showing a peak at the age group of 40–49 or 50–59 years,7 which is then rapidly decreased afterwards. Because the life span of C. sinensis is known to be up to 30 years, the infection peak in the age group of 50s is comprehended as an accumulation effect of reinfection or superinfection with age because epidemiologic studies indicate that humans do not develop any resistance to reinfection or superinfection by the parasites.4 However, the egg positive rate decreased after the peak, in spite of the cumulative effect in the age group of 60s or more. This decreasing phenomenon in senior groups has been commonly observed in previous investigations4,7–9 and may suggest the possibility of shorter lifespan of residents with clonorchiasis than those of uninfected ones at the endemic areas.10 This decrease of 27% compared with the previous year appears to be an outcome of low endemicity by praziquantel medication. The clonorchiasis in the endemic area of South Korea is under continuous anthelminthic intervention, and the intervention makes the decrease in positive rate.11 Our data have been updated the status of clonorchiasis in endemic area of Korea as reduced egg positive rate and lower intensity of infection compared with previous reports.3,8,9,11,12
In conclusion, the result of this study revealed little decrease in positive rate of C. sinensis compared with the result of southern endemic areas of Korea in 2006. Therefore, continuous and repeated praziquantel medication is necessary in the endemic in Korea.

Notes

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) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

References

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2. Prevalence of Intestinal Parasitic Infections in Korea. The 7th Report

3. Seo B.S., Lee S.H., Cho S.Y.. An epidemiologic study on clonorchiasis and metagonimiasis in riverside areas in Korea. Korean J Parasitol 19:1981;137−150.
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4. Lee J.H., Yang H.M., Bak U.B., Rim H.J.. Promoting role of Clonorchis sinensis infection on induction of cholangiocarcinoma during two-step carcinogenesis. Korean J Parasitol 32:1994;13−18.
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5. Shim H.S., Lim B.J., Kim M.J.. Mucinous cholangiocarcinoma associated with Clonorchis sinensis infestation: a case report. Korean J Hepatol 10:2004;223−227.

6. Choi D., Lim J.H., Lee K.T.. Cholangiocarcinoma and Clonorchis sinensis infection: a case-control study in Korea. J Hepatol 44:2006;1066−1073.
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7. Cho S.H., Lee K.Y., Lee B.C.. Prevalence of clonorchiasis in southern endemic areas of Korea in 2006. Korean J Parasitol 46:2008;133−137.
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8. Kim B.J., Ock M.S., Kim I.S., Yeo U.B.. Infection status of Clonorchis sinensis in residents of Hamyang-gun, Gyeongsangnam-do, Korea. Korean J Parasitol 40:2002;191−193.
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9. Lee G.S., Cho I.S., Lee Y.H.. Epidemiological study of clonorchiasis and metagonimiasis along the Geum-gang (river) in Okcheon-gun (county), Korea. Korean J Parasitol 40:2002;9−16.
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10. Hong S.T.. Clonorchis sinensis. (Chapter 35). Edited by Miliotis M.D., Bier J.W.. International Handbook of Foodborne Pathogens. 2003. Marcel Dekker, Inc.; USA: pp 581−592.

11. Hong S.T., Rim H.J., Min D.Y.. Control of clonorchiasis by repeated treatments with praziquantel. Korean J Parasitol 39:2001;285−292.
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12. Rim H.J.. Clonorchiasis: an update. J Helminthol 79:2007;269−281.
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Figure 1
The surveyed areas and five major rivers located in Korea.
gr1
Table 1
The subject of investigation according to localities and sex.
Locality (river basin) No. of residents examined
Total* Male Female
Hangang 1 1,029 477 550
2 988 453 535
Subtotal 2,017 930 1,085
Guemgang 3 1,038 480 558
4 868 390 478
5 1,120 532 588
6 1,056 528 528
7 1,076 467 609
Subtotal 5,158 2,397 2,761
Seomjingang 8 1,213 547 666
9 2,424 1,120 1,304
10 1,193 545 648
11 1,072 508 563
12 922 411 511
Subtotal 6,824 3,131 3,692
Youngsangang 13 1,256 468 788
14 1,098 426 672
15 1,009 397 612
16 1,049 503 546
Subtotal 4,412 1,794 2,618
Nakdonggang 17 836 349 486
18 919 430 489
19 1,001 359 642
20 1,002 334 668
21 936 414 522
22 1,175 515 660
23 1,165 589 575
24 880 371 509
25 1,172 670 502
26 695 302 393
27 953 397 556
28 1,163 526 637
29 960 421 539
Subtotal 12,857 5,677 7,178



Total 31,268 13,929 17,334

Sex unidentified: five.

Table 2
Positive cases of intestinal helminths and protozoa according to locality and parasites species
Locality (river basin) No. of Examined No. of Positive (%) Helminth
Protozoa
Others*
Cs (%) Het Ech Gs Al Tt To Am Gl
Hangang 1 1,029 21 (2.0) 19 (1.8) 1 0 0 0 0 0 0 2 0
2 988 12 (1.2) 2 (0.2) 1 0 0 1 0 0 4 1 3
Subtotal 2,017 33 (1.6) 21 (1.0) 2 0 0 1 0 0 4 3 3
Geumgang 3 1,038 9 (0.9) 3 (0.3) 0 0 0 0 1 0 3 1 1
4 868 45 (5.2) 41 (4.7) 0 0 0 0 2 0 1 1 1
5 1,120 37 (3.3) 30 (2.7) 0 0 0 0 3 0 4 1 0
6 1,056 58 (5.5) 48 (4.5) 0 0 0 0 4 0 3 3 0
7 1,076 45 (4.2) 37 (3.4) 5 0 0 1 1 0 0 0 1
Subtotal 5,158 194 (3.8) 159 (3.1) 5 0 0 1 11 0 11 6 3
Seomjingang 8 1,213 96 (7.9) 83 (6.8) 5 0 0 0 0 0 7 2 3
9 2,424 284 (11.7) 247 (10.2) 43 1 0 0 0 0 11 3 2
10 1,193 124 (10.4) 111 (9.3) 4 0 0 0 1 2 7 2 0
11 1,072 109 (10.2) 77 (7.2) 16 0 1 2 0 0 14 5 0
12 922 182 (19.7) 133 (14.4) 50 0 0 0 0 0 11 2 0
Subtotal 6,824 795 (11.7) 651 (9.5) 118 1 1 2 1 2 50 14 5
Youngsangang 13 1,256 101 (8.0) 40 (3.2) 37 33 0 0 1 0 7 1 0
14 1,098 58 (5.3) 44 (4.0) 3 1 2 0 1 0 8 2 0
15 1,009 41 (4.1) 30 (3.0) 10 0 1 0 0 0 5 1 0
16 1,049 56 (5.3) 31 (3.0) 7 0 1 0 3 1 12 3 0
Subtotal 4,412 256 (5.8) 145 (3.3) 57 34 4 0 5 1 32 7 0
Nakdonggang 17 836 109 (13.0) 99 (11.8) 10 0 0 0 0 0 0 0 0
18 919 141 (15.3) 141 (15.3) 5 0 0 0 0 0 0 0 0
19 1,001 63 (6.3) 59 (5.9) 4 0 0 0 0 0 0 0 0
20 1,002 80 (8.0) 73 (7.3) 5 0 0 0 2 0 0 0 0
21 936 149 (15.9) 142 (15.2) 1 0 1 0 2 0 2 1 0
22 1,175 150 (12.8) 138 (11.7) 4 0 0 0 1 1 4 4 0
23 1,165 154 (13.2) 145 (12.4) 6 0 0 0 1 0 2 6 0
24 880 101 (11.5) 98 (11.1) 3 0 0 0 0 0 0 0 0
25 1,172 57 (4.9) 33 (2.8) 0 0 1 2 1 0 19 0 1
26 695 103 (14.8) 94 (13.5) 14 0 0 0 2 0 0 0 0
27 953 211 (22.1) 198 (20.8) 3 1 0 0 3 1 2 7 1
28 1,163 131 (11.3) 124 (10.7) 10 0 0 0 1 0 3 0 0
29 960 230 (24.0) 222 (23.1) 8 0 0 2 0 0 4 2 2
Subtotal 12,857 1,679 (13.1) 1,566 (12.2) 73 1 2 4 13 2 36 20 4
Total 31,268 2,957 (9.5) 2,542 (8.1) 255 36 7 8 30 5 133 50 15

Cs, Clonorchis sinensis; Het, Heterophyes spp.; Ech, Echinostoma spp.; Gs, Gymnophalloides seoi; Al, Ascaris lumbricoides; Tt, Trichuris trichiura; To, Trichostrongylus orientalis; Am, Entamoeba spp.; Gl, Giardia lamblia.

Hook worm, Diphyllobothrium latum, Enterobius vermicularis, Paragonimus westermani

Table 3
Positive rates of C. sinensis according to localities and gender.
Locality (river basin) Total
Male
Female
No. of Examined No. of Positive (%) No. of Examined No. of Positive (%) No. of Examined No. of Positive (%)
Hangang 1 1,029 19 (1.8) 477 13 (2.7) 550 6 (1.1)
2 988 2 (0.2) 453 1 (0.2) 535 1 (0.2)
Subtotal 2,017 21 (1.0) 930 14 (1.5) 1,085 7 (0.6)
Guemgang 3 1,038 3 (0.3) 480 2 (0.4) 558 1 (0.2)
4 868 41 (4.7) 390 23 (5.9) 478 18 (3.8)
5 1,120 30 (2.7) 532 24 (4.5) 588 6 (1)
6 1,056 48 (4.5) 528 33 (6.3) 528 15 (2.8)
7 1,076 37 (3.4) 467 28 (6) 609 9 (1.5)
Subtotal 5,158 159 (3.1) 2,397 110 (4.6) 2,761 49 (1.8)
Seomjingang 8 1,213 83 (6.8) 547 61 (11.2) 666 22 (3.3)
9 2,424 247 (10.2) 1,120 149 (13.3) 1,304 98 (7.5)
10 1,193 111 (9.3) 545 71 (13) 648 40 (6.2)
11 1,072 77 (7.2) 508 40 (7.9) 563 36 (6.4)
12 922 133 (14.4) 411 77 (18.7) 511 56 (11)
Subtotal 6,824 651 (9.5) 3,131 398 (12.7) 3,692 252 (6.8)
Youngsangang 13 1,256 40 (3.2) 468 24 (5.1) 788 16 (2)
14 1,098 44 (4.0) 426 28 (6.6) 672 16 (2.4)
15 1,009 30 (3.0) 397 16 (4) 612 14 (2.3)
16 1,049 31 (3.0) 503 23 (4.6) 546 8 (1.5)
Subtotal 4,412 145 (3.3) 1,794 91 (5.1) 2,618 54 (2.1)
Nakdonggang 17 836 99 (11.8) 349 49 (14) 486 50 (10.3)
18 919 141 (15.3) 430 73 (17) 489 68 (13.9)
19 1,001 59 (5.9) 359 31 (8.6) 642 28 (4.4)
20 1,002 73 (7.3) 334 36 (10.8) 668 37 (5.5)
21 936 142 (15.2) 414 74 (17.9) 522 68 (13)
22 1,175 138 (11.7) 515 81 (15.7) 660 57 (8.6)
23 1,165 145 (12.4) 589 97 (16.5) 575 48 (8.3)
24 880 98 (11.1) 371 56 (15.1) 509 42 (8.3)
25 1,172 33 (2.8) 670 24 (3.6) 502 9 (1.8)
26 695 94 (13.5) 302 58 (19.2) 393 36 (9.2)
27 953 198 (20.8) 397 91 (22.9) 556 107 (19.2)
28 1,163 124 (10.7) 526 78 (14.8) 637 46 (7.2)
29 960 222 (23.1) 421 120 (28.5) 539 102 (18.9)
Subtotal 12,857 1,566 (12.2) 5,677 868 (15.3) 7,178 698 (9.7)
Total 31,268 2,542 (8.1) 13,929 1,481 (10.6) 17,334 1,060 (6.1)

Sex unidentified: five

Table 4
Positive rates of C. sinensis according to localities and age groups
Age group (yr)
Locality (river basin) Total
1–19
20–29
30–39
40–49
50–59
60–69
70–79
Over 80
Unknown
No. of Examined No. of Positive (%) No. of Examined No. of Positive (%) No. of Examined No. of Positive (%) No. of Examined No. of Positive (%) No. of Examined No. of Positive (%) No. of Examined No. of Positive (%) No. of Examined No. of Positive (%) No. of Examined No. of Positive (%) No. of Examined No. of Positive (%) No. of Examined No. of Positive (%)
Hangang 1 1,029 19 (1.8) 65 0 (0.0) 18 0 (0.0) 44 0 (0.0) 167 5 (3.0) 249 6 (2.4) 244 3 (1.2) 153 1 (0.7) 28 2 (7.1) 61 2 (3.3)
2 988 2 (0.2) 39 0 (0.0) 19 0 (0.0) 46 122 122 0 (0.0) 192 1 (0.5) 324 0 (0.0) 198 1 (0.5) 42 0 (0.0) 6 0 (0.0)
Subtotal 2,017 21 (1.0) 104 0 (0.0) 37 0 (0.0) 90 0 (0.0) 289 5 (1.7) 441 7 (1.6) 568 3 (0.5) 351 2 (0.6) 70 2 (2.9) 67 2 (3.0)
Guemgang 3 1,038 3 (0.3) 10 0 (0.0) 15 0 (0.0) 42 0 (0.0) 122 1 (0.8) 194 0 (0.0) 275 1 (0.4) 295 1 (0.3) 69 0 (0.0) 16 0 (0.0)
4 868 41 (4.7) 91 0 (0.0) 39 1 (2.6) 46 2 (4.3) 116 8 (6.9) 137 12 (8.8) 205 11 (5.4) 188 7 (3.7) 35 0 (0.0) 11 0 (0.0)
5 1,120 30 (2.7) 0 0 (0.0) 33 1 (3.0) 62 2 (3.2) 114 5 (4.4) 250 9 (3.6) 320 5 (1.6) 287 8 (2.8) 46 0 (0.0) 8 0 (0.0)
6 1,056 48 (4.5) 78 0 (0.0) 24 0 (0.0) 55 0 (0.0) 161 5 (3.1) 257 13 (5.1) 233 22 (9.4) 165 6 (3.6) 34 2 (5.9) 49 0 (0.0)
7 1,076 37 (3.4) 94 0 (0.0) 14 0 (0.0) 38 3 (7.9) 124 7 (5.6) 179 12 (6.7) 311 10 (3.2) 244 4 (1.6) 72 1 (1.4) 0 0 (0.0)
Subtotal 5,158 159 (3.1) 273 0 (0.0) 125 2 (1.6) 243 7 (2.9) 637 26 (4.1) 1,017 46 (4.5) 1,344 49 (3.6) 1,179 26 (2.2) 256 3 (1.2) 84 0 (0.0)
Seomjingang 8 1,213 83 (6.8) 48 1 (2.1) 13 1 (7.7) 50 1 (2.0) 136 10 (7.4) 194 17 (8.8) 349 25 (7.2) 340 23 (6.8) 81 5 (6.2) 2 0 (0.0)
9 2,424 247 (10.2) 37 1 (2.7) 31 1 (3.2) 81 6 (7.4) 304 25 (8.2) 421 47 (11.2) 750 79 (10.5) 617 67 (10.9) 135 13 (9.6) 48 8 (16.7)
10 1,193 111 (9.3) 2 0 (0.0) 9 1 (11.1) 31 2 (6.5) 95 13 (13.7) 213 26 (12.2) 365 31 (8.5) 383 33 (8.6) 82 5 (6.1) 13 0 (0.0)
11 1,072 77 (7.2) 74 1 (1.4) 44 1 (2.3) 56 6 (10.7) 125 13 (10.4) 215 15 (7.0) 274 23 (8.4) 209 14 (6.7) 44 1 (2.3) 31 3 (9.7)
12 922 133 (14.4) 26 4 (15.4) 12 2 (16.7) 36 6 (16.7) 94 16 (17.0) 156 28 (17.9) 267 37 (13.9) 269 35 (13.0) 62 5 (8.1) 0 0 (0.0)
Subtotal 6,824 651 (9.5) 187 7 (3.7) 109 6 (5.5) 254 21 (8.3) 754 77 (10.2) 1,199 133 (11.1) 2,005 195 (9.7) 1,818 172 (9.5) 404 29 (7.2) 94 11 (11.7)
Youngsangang 13 1,256 40 (3.2) 36 0 (0.0) 28 0 (0.0) 28 1 (3.6) 134 5 (3.7) 240 8 (3.3) 435 16 (3.7) 296 9 (3.0) 58 1 (1.7) 1 0 (0.0)
14 1,098 44 (4.0) 11 0 (0.0) 14 0 (0.0) 25 1 (4.0) 88 2 (2.3) 216 12 (5.6) 390 16 (4.1) 289 11 (3.8) 65 2 (3.1) 0 0 (0.0)
15 1,009 30 (3.0) 4 0 (0.0) 14 0 (0.0) 39 0 (0.0) 91 1 (1.1) 154 9 (5.8) 278 7 (2.5) 303 10 (3.3) 82 1 (1.2) 44 2 (4.5)
16 1,049 31 (3.0) 9 0 (0.0) 9 0 (0.0) 38 1 (2.6) 115 1 (0.9) 223 10 (4.5) 361 14 (3.9) 252 4 (1.6) 41 1 (2.4) 1 0 (0.0)
Subtotal 4,412 145 (3.3) 60 0 (0.0) 65 0 (0.0) 130 3 (2.3) 428 9 (2.1) 833 39 (4.7) 1,464 53 (3.6) 1,140 34 (3.0) 246 5 (2.0) 46 2 (4.3)
Nakdonggang 17 836 89 (10.6) 1 0 (0.0) 4 0 (0.0) 23 3 (13.0) 71 5 (7.0) 146 18 (12.3) 391 55 (14.1) 182 7 (3.8) 16 1 (6.3) 2 0 (0.0)
18 919 141 (15.3) 69 1 (1.4) 4 0 (0.0) 24 4 (16.7) 91 19 (20.9) 160 31 (19.4) 316 55 (17.4) 210 28 (13.3) 35 3 (8.6) 10 0 (0.0)
19 1,001 59 (5.9) 0 0 (0.0) 0 0 (0.0) 5 0 (0.0) 58 5 (8.6) 164 11 (6.7) 422 23 (5.5) 317 18 (5.7) 35 2 (5.7) 0 0 (0.0)
20 1,002 73 (7.3) 0 0 (0.0) 2 0 (0.0) 14 0 (0.0) 66 7 (10.6) 126 15 (11.9) 350 25 (7.1) 389 23 (5.9) 55 3 (5.5) 0 0 (0.0)
21 936 142 (15.2) 18 1 (5.6) 11 0 (0.0) 34 4 (11.8) 97 14 (14.4) 205 41 (20.0) 282 37 (13.1) 239 37 (15.5) 34 3 (8.8) 16 5 (31.3)
22 1,175 137 (11.7) 9 0 (0.0) 8 2 (25.0) 18 0 (0.0) 75 9 (12.0) 202 41 (20.3) 398 41 (10.3) 378 35 (9.3) 54 6 (11.1) 33 3 (9.1)
23 1,165 145 (12.4) 24 2 (8.3) 22 2 (9.1) 37 1 (2.7) 147 26 (17.7) 309 56 (18.1) 346 33 (9.5) 248 22 (8.9) 30 3 (10.0) 2 0 (0.0)
24 880 98 (11.1) 15 0 (0.0) 9 0 (0.0) 41 3 (7.3) 110 13 (11.8) 216 31 (14.4) 276 30 (10.9) 171 20 (11.7) 17 0 (0.0) 25 1 (4.0)
25 1,172 33 (2.8) 0 0 (0.0) 15 0 (0.0) 85 0 (0.0) 202 5 (2.5) 298 14 (4.7) 307 7 (2.3) 207 7 (3.4) 57 0 (0.0) 1 0 (0.0)
26 695 94 (13.5) 17 0 (0.0) 29 5 (17.2) 40 4 (10.0) 60 11 (18.3) 127 26 (20.5) 180 21 (11.7) 188 21 (11.2) 52 6 (11.5) 3 0 (0.0)
27 953 198 (20.8) 62 4 (6.5) 25 3 (12.0) 31 3 (9.7) 103 13 (12.6) 168 42 (25.0) 271 68 (25.1) 227 49 (21.6) 60 15 (25.0) 6 1 (16.7)
28 1,163 124 (10.7) 12 0 (0.0) 27 0 (0.0) 43 2 (4.7) 120 12 (10.0) 210 23 (11.0) 330 41 (12.4) 311 38 (12.2) 74 6 (8.1) 36 2 (5.6)
29 960 222 (23.1) 3 0 (0.0) 6 1 (16.7) 20 1 (5.0) 125 31 (24.8) 203 54 (26.6) 258 54 (20.9) 278 66 (23.7) 67 15 (22.4) 0 0 (0.0)
Subtotal 12,857 1,555 (12.1) 230 8 (3.5) 162 13 (8.0) 415 25 (6.0) 1,325 170 (12.8) 2,534 403 (15.9) 4,127 490 (11.9) 3,345 371 (11.1) 586 63 (10.8) 134 12 (9.0)
Total 31,268 2,531 (8.1) 854 15 (1.8) 498 21 (4.2) 1,132 56 (4.9) 3,433 287 (8.4) 6,024 628 (10.4) 9,508 790 (8.3) 7,833 605 (7.7) 1,562 102 (6.5) 425 27 (6.4)


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