[Analysis of epidemiologic and etiology of hepatitis E in Hangzhou, 2004-2011].

OBJECTIVE: To comprehend the epidemiologic of hepatitis E and genetic characteristics of hepatitis E virus (HEV) in Hangzhou from 2004 to 2011.

METHODS: Using China information system for disease control and prevention, the incidence of hepatitis E from 2004 to 2011 in Hangzhou city, and the basic information of patients were collected. In 2011, 65 hepatitis E laboratory confirmed cases were selected by random number table sampling method from the hospitals designated infectious diseases in Hangzhou city, and acquisition of the 60 blood specimens and stool specimens of 18 copies. One city and two surrounding counties were selected by cluster random sampling method in the context of Hangzhou city, and the pig slaughters and farmers were selected as the sampling point, and acquisition of pig gallbladder specimens of 52 copies, and 30 stool samples of scatter-feed pigs, 15 stool specimens of scatter-feed rabbits. HEV was tested in samples, gene extraction and analysis of gene sequence were conducted which were compared with gene bank HEV gene sequence, and a phylogenetic tree was formed. The epidemic characteristics of hepatitis E of Hangzhou city from 2004 to 2011 were described. The difference of incidence of hepatitis E was analyzed between years and sexes in Hangzhou city.

RESULTS: There were reported a total of 3 490 cases of hepatitis E in Hangzhou from 2004 to 2011, and 3 cases of death; The average annual incidence rate was 5.79/100 000 (3 490/60 276 338). There was the overall upward trend in incidence between different years (χ² = 52.38, P < 0.01) , which the highest was 8.10/100 000 (705/8 700 373) in 2011, and the lowest incidence rate was 4.19/100 000 in 2005. The incidence of males (8.12/100 000 (2 474/30 450 990) ) was significantly higher than that of the females (3.46/100 000 (1 016/29 384 491) ) (χ² = 558.45, P < 0.05). 78 specimens of blood and stool were collected, including 16 positive samples, with positive rate 21%. There were a total of 97 specimens of pig gallbladder, pig manure and rabbit stool, including 2 positive rabbit stool samples, with positive rate of 2%. HEV genes isolated from Hangzhou were mainly type IV, with homology of 91.8% to 100%; compared with human type IV strains, the homology of nucleotide was 84.6%-96.7%; compared with type IV strain of pig genome sequence alignment, homology was 82.6%-95.2%.

CONCLUSION: Hepatitis E's incidence showed an increasing trend year by year in Hangzhou. HEV of type IV was dominant, and HEV strains in the human and swine were highly homologous.