桂平市1例服苗接触者VAPP病例流行病学调查与处理

Investigation and treatment of a vaccine-assciated paralytic poliomyelitis case contacted with vaccinators in Guiping City

目的分析疫苗高变异株病例的发病原因,为制定防控策略提供依据。方法对1例疫苗高变异病例进行流行病学个案调查,采集病例、病例接触者和外环境的标本并进行病毒分离;开展急性弛缓性麻痹(AFP)病例主动搜索和接种率调查。结果该病例为脊髓灰质炎(脊灰)疫苗相关麻痹病例(VAPP)接触者型病例,病例双份大便标本经国家脊灰实验室检测与Sabin株相比对均为Ⅲ型脊灰病毒,有7个核苷酸变异,属脊灰疫苗高变异株病毒,病例第3份标本病毒分离阴性;病例接触者中有1人检出疫苗株病毒,病例居住外环境污水中亦检出疫苗株病毒;病例所在县接种率调查(除甲肝外)均维持在90%以上,入户AFP病例主动搜索未发现漏报病例,市级医院存在AFP病例漏报,漏报率为26.83%。结论该病例为服苗接触者高变异株病例,提高疫苗接种率可有效阻断毒株的循环,防止疫苗衍生病例的发生和流行。

Objective To analyze the causes of a high poliomyelitis vaccine variant case and provide evidence forprevention and control of acute flaccid paralysis（AFP）. Methods Survey of a high poliomyelitis vaccine variant case wasconducted by collecting biological samples from the patient, patient contacts and outside environment for isolating virus.Meanwwhile active AFP and vaccine coverage rate survey were also conducted. Results The pateint was a vaccine-assciatedparalytic poliomyelitis case contaced with vaccinators. The virus isolated from two specimens of the patient and tested bynational polio laboratory and compared with Sabin strains was type III poliomylitis virus of a high poliomyelitis vaccine variantwith seven nucleotide mutation. The result of isolation of virus from the third specimen was negative. Vaccine strain viruseswere detected from one of the contacts and external environment sewage. Vaccine immunization rates（except Hepatitis A） ofthe city in which the case was detected was over 90% and no AFP cases was discovered during active survey for missed casesas the missed reporting rate of AFP case in county hospitals was 26.83%. Conclusions The case was diagnosed a vaccine-assciated paralytic poliomyelitis case contaced with vaccinators. The circulation of poliomyelitis virus can be interrupted andthe prevalence of vaccine-associted paralytic poliomyelitis cases can be prevented by enhancement of vaccination rate in thiscounty.