IMMUNITY STATUS TO POLIOVIRUS IN VENETO REGION (NORTHEAST ITALY) - A SEROEPIDEMIOLOGICAL SURVEY

The immunity state to poliovirus types 1, 2, and 3 of a population age d 2 to 75 years was determined by examining 274 sera collected in the Venice mainland (North-East Italy). Altogether, the neutralizing antib ody prevalences (at a titre greater than or equal to 1:2) for poliovir us 1, 2, and 3 were 99.0 percent (geometrical mean titres [GMT]:72.1), 99.6 percent (GMT:95.9) and 98.2 percent (GMT:17.3), respectively, an d all the age groups also showed very good levels of humoral immunity. High antibody titres (greater than or equal to 1:256) to one or more types of poliovirus were demonstrated in older age groups also, possib ly indicating exposure to natural polioviruses or contact with vaccine strains. Although probably all the older subjects had practically acq uired their antibodies as a result of natural infection and those unde r 30 through vaccination, these results indicate that the humoral immu nity against poliomyelitis in our population is satisfactory, and the maintenance of such good protection level depends on an effective immu nization program.