Investigation Of Poliovirus Amongst Healthy Population And Environmental Distribution In Border Provinces In China

BackgroundAt present, the risk of WPV importation from endemic countries were still high in China, especially from those countries bordered with China and never achieved polio free status up to now. In most countries, it has proved that using the PV laboratory surveillance data would be more beneficial to assess the polio free status through the PV distribution amongst healthy population and environment. Therefore, to provide more evidences for polio free status in China, the investigation were necessary to implement in the highest risk provinces in China. The investigation will provide the technical and methods to detect poliovirus amongst healthy population and environment, utilize epidemiology analysis as well as.Objective1. To know the poliovirus distribution amongst healthy population and environment under polio free status in China.2. To update the AFP surveillance data in border provinces.MethodsThrough stratified random sampling and experience sampling, all those were selected to test poliovirus amongst healthy population divided into5subgroup,1-2y,3-4y,5-9y,10-14y and≥15y. sewage was also collected in some counties after random sampling.ResultsAs a total,749stool specimen were collected from healthy population.93were detected NPEV, the isolation rate is12.42%;6stool specimen were detected PV (Sabin-like strain PV), the isolation is0.8%. However, there are no poliovirus detected in the stool specimen collected from Guangdong, Yunnan and Xinjiang province,3type Ⅰ,1type Ⅱ and1type Ⅲ PV isolated from Heilongjiang province,1type Ⅰ PV isolated from the subgroup Ⅰ-9y in Guangxi province.35sewage samples were collected. After testing,32NPEV were isolated, the isolation rate is91.43%;29samples were detected PV (Sabin-like PV), the isolation rate is82.86%. NPEV isolation rate is100%in Guangdong, Guangxi and Yunnan province. In Heilongjiang, the isolation rate was85.71%. In Xinjing, the isolation rate was only71.43%. As a total, all52PV strains isolated were composed of14type Ⅰ PV,19type Ⅱ PV,19type Ⅲ PV. In counties level, there are100%isolation rate in Huidong, Dongxin county and Zhaoyang district, the isolation rate is only66.67%in Fujin and Kashi city.Conclusionsthe Surveillance data shown that WPV and VDPV were not detected amongst healthy population and environment. It proved that all frontier provinces investigated still keep a polio free status. The NPEV positive rate were decreased with age increased. Both NPEV and PV have a higher isolation rate from sewage and environment, which was possibly caused by OPV immunization policy. As a supplementary component for AFP surveillance, environmental surveillance is an effective tool to dynamically, timely and completely understand the circulation of pathogen in human body and outside, as well as early warning weak areas.