Spread of hepatitis E virus among different-aged pigs: two-year survey in Taiwan.
Swine are reservoirs of hepatitis E virus (HEV). In this study, a 2-year survey of HEV in feces and sera of swine was conducted to determine if: 1) HEV has circulated among pigs for some time in Taiwan; 2) the spread of HEV among different-aged pigs; and 3) there exists HEV strains possibly imported through trading. From 1998-2000, 521 serum samples and 54 fecal specimens from pigs were examined by reverse transcription polymerase chain reaction. None of the 11 pigs in suckling stage (< 2 months) were serum HEV RNA positive. The highest viremia rate (4.5%) was in pigs of 2 months age, followed by 1.2% and 1.8% in pigs of growing (3-4 months) and finishing stages (5-6 months), and none in pigs older than 6 months. Viremia showed little variation in different years and areas. None of the 20 fecal samples from pigs in suckling stage were HEV RNA positive, whereas 9% of the 34 samples from pigs in growing or finishing stages were positive. Most swine HEV isolates in Taiwan clustered within the genotype 4, whereas the three HEV isolates cloned from pigs imported recently from the U.S. belonged to the genotype 3 HEV in the U.S. The results suggest that HEV may infect pigs at an early growing stage and spread unnoticed among pigs and possibly across countries through trading.
Wu
Jaw-Ching
JC
Institute of Clinical Medicine, National Yang-Ming University School of Medicine, Taipei, Taiwan. jcwu@vghtpe.gov.tw
Chen
Chuan-Mu
CM
Chiang
Tzen-Yuh
TY
Tsai
Wen-Hsuan
WH
Jeng
Wen-Juei
WJ
Sheen
I-Jane
IJ
Lin
Chen-Chun
CC
Meng
Xiang-Jin
XJ
D000367:Age Factors; D000818:Animals; D005243:Feces / Q000821:virology; D016751:Hepatitis E / Q000635:transmission / Q000662:veterinary* / Q000821:virology; D016752:Hepatitis E virus / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D006801:Humans; D008969:Molecular Sequence Data; D012367:RNA, Viral / Q000097:blood; D017422:Sequence Analysis, DNA; D013552:Swine; D013553:Swine Diseases / Q000635:transmission* / Q000821:virology; D013624:Taiwan
D012367:RNA, Viral