[Study on an epidemic caused by the vaccine-derived poliovirus circulation in Guizhou province, 2004].
OBJECTIVE
To study the circulating vaccine-derived poliovirus (cVDPVs) that occurred in Zhenfeng county, Guizhou province in 2004 and to discover wild-poliovirus, vaccine-derived poliovirus (VDPVs) and other vaccine-associated poliovirus which could cause clinical poliomyelitis.


METHODS
Field epidemiological studies at the epidemic area and collecting acute flaccid paralysis (AFP) case and contact stool specimen for virus identification and nucleotide sequencing. Analysis on data related to annual reports on stool specimens surveillance which involved AFP case and contacts in the resent years in Zhenfeng county.


RESULTS
Type-I VDPVs had been isolated from 2 AFP cases and 3 contact stool specimen in Wanlan village of Zhenfeng. After the first cVDPVs case was identified, there were 3 cases identified of having other vaccine-associated poliovirus of type-I or type-II in the 5 case of AFP that met the criteria of clinical poliomyelitis. The result of virological surveillance on polio showed that the EV isolation rate (55.1%) of Zhenfeng county was higher than the rate from the whole province of the same year (23.2%). The poliovirus (PV) isolation rate (36.8%) was obviously higher in 2004 than in the previous years. In the 16 PVs strains, the type-I accounted for 43.8% which was significantly higher than the average level (18.3%) from the whole province.


CONCLUSIONS
Data indicated that the type-I VDPVs had been circulating (cVDPVs) in Zhenfeng county in Guizhou province. Clinical poliomyelitis was caused by non-VDPVs. The increased PV infection and the decreasing rate of vaccination in the general population were responsible for the epidemic of type-I cVDPVs at this time. Monitoring and evaluation on the rate of routine immunization program and prediction of the trend of epidemic should be strenthened.
Ye
Xu-fang
XF
Center for Disease Control and Prevention of Guizhou Province, Guiyang 550004, China.
Tong
Yi-bin
YB
Su
Fei
F
Ren
Gang
G
Liu
Ming
M
Xu
Wen-bo
WB
Yan
Dong-mei
DM
Zhang
Yong
Y
Zhang
Li
L
Zhang
Da-yong
DY
Zou
Jian
J
Yu
Hao
H
D000293:Adolescent; D000818:Animals; D002460:Cell Line; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D004196:Disease Outbreaks; D005243:Feces / Q000821:virology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D010264:Paraplegia / Q000453:epidemiology* / Q000209:etiology / Q000821:virology*; D011051:Poliomyelitis / Q000517:prevention & control; D017955:Poliovirus / Q000276:immunology* / Q000502:physiology*; D023321:Poliovirus Vaccines / Q000276:immunology*; D014611:Vaccination / Q000706:statistics & numerical data*
D023321:Poliovirus Vaccines