[Serological characteristics of a hepatitis E outbreak].
OBJECTIVE
To look into the serological characteristics of a hepatitis E outbreak.


METHODS
Sera from the first five patients with acute icteric hepatitis who developed the disease successively within ten days and the 1,675 employees routinely having their lunch in a dining hall of a department (outbreak population) were examined for anti.HEV IgM and IgG at 26th days after the outbreak, and the 883 employees of a neighboring department not having their lunch in the hall were selected as control (control population).


RESULTS
The five patients were all positive for anti-HEV IgM and IgG. The positive rates of anti-HEV IgM and IgG in outbreak population were 8.7% and 38.4% respectively, both significantly higher than those in control population which were only 0.1% and 28.6%. The numbers with abnormal ALT in the 145 individuals with anti-HEV IgM(+) of outbreak population were significantly higher than those in the IgM(-) individuals of the same group as well as in control, while the abnormal ALT ratio in the IgM(-) individuals of the outbreak was not higher than that in control. The results from the four patients' serial sera showed that the anti-HEV IgM titers declined gradually and were undetectable at about 4th month after infection, and the IgG titers increased to peak in about 2-3 months after infection, then declined very slowly. The mean IgG titer of the anti-HEV IgM(+) individuals was significantly higher than that of the IgM(-) but IgG(+) individuals in outbreak population, and the latter was significantly higher than the IgG(+) individuals in control, which suggested that the post-infection individuals' immunities to HEV were boosted during the outbreak. There was no difference between sex or age groups for the anti-HEV IgM(+) ratio, but the abnormal ALT was much more frequent in the anti-HEV IgM(+) male than in the female, and no difference was observed between age groups.


CONCLUSIONS
The pathogen of the outbreak of acute icteric hepatitis was hepatitis E virus and associated with food intake. Anti-HEV IgM and IgG were used not only for diagnosis of hepatitis E but also for surveilance in mass population. The attack risk was not associated with age or sex, but the abnormal ALT was much more frequent fresh infectors in male.
Tan
Chun-rong
CR
Department of Clinical Laboratory, Beijing Railway General Hospital, Beijing 100038, China. crtan@vip.sina.com.
Chen
Min
M
Ge
Sheng-xiang
SX
Zhang
Jun
J
Hu
Mei
M
Sun
Huan-ying
HY
Chen
Yan
Y
Peng
Geng
G
Shen
Wei
W
Zhang
Man
M
Xia
Ning-shao
NS
D000328:Adult; D004196:Disease Outbreaks; D005260:Female; D006508:Hepatitis Antibodies / Q000097:blood; D016751:Hepatitis E / Q000453:epidemiology*; D016752:Hepatitis E virus / Q000276:immunology; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D007075:Immunoglobulin M / Q000097:blood; D008297:Male; D008875:Middle Aged; D016036:Seroepidemiologic Studies
D006508:Hepatitis Antibodies; D007074:Immunoglobulin G; D007075:Immunoglobulin M