Seroprevalence of cytotoxin-associated gene A positive Helicobacter pylori strains in Changle, an area with very high prevalence of gastric cancer in south China.
BACKGROUND
Helicobacter pylori, especially the CagA-positive strains, are closely associated with peptic ulcers and gastric cancers. We performed a large scale gastric cancer screening project and examined the prevalence of H. pylori and CagA-positive strains in Changle, China, an area with one of the World's highest gastric cancer mortality. We also compared the prevalence with that in Hong Kong which has one-tenth of the gastric cancer mortality of that in Changle.


METHODS
A total of 2424 subjects in Changle and 523 subjects in Hong Kong had endoscopic examination and venesection. Sera were tested for anti-H. pylori antibody and anti-CagA antibody and correlated with endoscopic findings.


RESULTS
In Changle, 80. 9% of the subjects were H. pylori carriers. Out of 551 carriers, 408 (74%) were positive for anti-CagA antibody. A total of 76% and 87% of the asymptomatic and gastric cancer patients were positive for anti-CagA antibody, respectively (P > 0.05). Compared to Hong Kong, there was a significantly (P < 0.0001) higher prevalence of CagA-positive strains in asymptomatic subjects in Changle (76%) than in Hong Kong (28%), but not in peptic ulcers or gastric cancers.


CONCLUSIONS
Subjects in Changle had a high prevalence of H. pylori infection and a high prevalence of the CagA-positive strains. The contrast in the prevalence of CagA-positive strains, in asymptomatic subjects in two areas with differing gastric cancer mortality, supports the pathogenic role of CagA-positive strains in gastric carcinogenesis.
Wong
B C
BC
Department of Medicine and Pathology, University of Hong Kong, Hong Kong.
Lam
S K
SK
Ching
C K
CK
Hu
W H
WH
Ong
L Y
LY
Chen
B W
BW
Gao
Z
Z
Chen
J S
JS
Jiang
X W
XW
Hou
X H
XH
Lu
J Y
JY
Wang
W H
WH
Ho
J
J
Yuen
S T
ST
Lai
K C
KC
Kwok
E
E
Hui
W M
WM
Covacci
A
A
D000293:Adolescent; D000328:Adult; D000368:Aged; D000907:Antibodies, Bacterial / Q000097:blood; D000942:Antigens, Bacterial; D001426:Bacterial Proteins / Q000235:genetics* / Q000276:immunology; D005260:Female; D016481:Helicobacter Infections / Q000097:blood / Q000453:epidemiology* / Q000382:microbiology*; D016480:Helicobacter pylori / Q000235:genetics*; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D008297:Male; D008403:Mass Screening; D008875:Middle Aged; D011446:Prospective Studies; D016036:Seroepidemiologic Studies; D013274:Stomach Neoplasms / Q000097:blood / Q000453:epidemiology* / Q000382:microbiology*
D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C080866:cagA protein, Helicobacter pylori