Subrahmanyan T P, Lesiak J M, Appleton F, Labzoffsky N A
Bull World Health Organ. 1973;49(3):245-50.
Sporadic cases of paralytic poliomyelitis are being reported with increasing frequency, particularly in unvaccinated persons, in several countries in which the disease had been absent for several years following adequate initial vaccination programmes. In Ontario, two paralytic cases occurred in unvaccinated children after several disease-free years. Detailed studies of the strains of poliovirus type 1 isolated from these patients showed that they were not vaccine strains. Contact surveillance in one case showed that 21 originally unvaccinated contacts were also excreting virulent virus.
在一些国家,尽管最初实施了充分的疫苗接种计划,该国已多年未出现该疾病,但目前散发性麻痹性脊髓灰质炎病例的报告频率却在不断增加,尤其是在未接种疫苗的人群中。在安大略省,经过数年无病例后,两名未接种疫苗的儿童出现了麻痹病例。对从这些患者中分离出的1型脊髓灰质炎病毒毒株进行的详细研究表明,它们并非疫苗毒株。对其中一例病例的接触者监测显示,21名最初未接种疫苗的接触者也在排出强毒株。