Poliomyelitis vaccination strategies for Europe

Serological survey on immunity status against polioviruses in children and adolescents living in a border region, Apulia (Southern Italy)

BACKGROUND

In 1988 the World Health Assembly adopted the goal to eradicate poliomyelitis by routine immunization using Oral Polio Vaccine (OPV). On 21 June 2002 the WHO European Region was declared polio-free. In 2008 poliomyelitis is still endemic in 4 countries (Nigeria, India, Pakistan, and Afghanistan), where 1201 new cases were registered in 2007; 107 sporadic cases were also notified in countries where poliovirus is not endemic. The aim of this work was to verify the level of antipoliomyelitis immunity status in children and adolescents in the Apulia region (south of Italy), which may be considered a border region due to its position.

METHODS

704 blood specimens from a convenience sample were collected in six laboratories. The age of subjects enrolled was 0-15 years. The immunity against poliomyelitis was evaluated by neutralizing antibody titration in tissue culture microplates.

RESULTS

Seropositivity (neutralising antibodies titre > or = 8) for polioviruses 1, 2 and 3 was detected in 100%, 99.8% and 99.4% of collected sera. Antibody titres were not lower in subjects who received either four doses of inactivated polio vaccine (IPV) or a sequential schedule consisting of two doses of IPV and two of oral polio vaccine than in subjects who received four doses of OPV.

CONCLUSION

These results confirmed current data of vaccine coverage for poliomyelitis: during the last ten years in Apulia, the coverage in 24 months old children was more than 90%. The high level of immunization found confirms the effectiveness both of the sequential schedule IPV-OPV and of the schedule all-IPV. Apulia region has to face daily arrivals of refugees and remains subject to the risk of the importation of poliovirus from endemic areas. Surveys aimed at determining anti-polio immunity in subpopulations as well as in the general population should be carried out.

High level of immunity against poliomyelitis in Albanian refugees in southern Italy

BACKGROUND

The Apulia region (Southern Italy) may be considered a "border region" which, due to its position, has to face daily arrivals of refugees, especially from Albania. When the exodus of Albanians took place in 1991, a seroepidemiologic study revealed a low seroimmunity to poliomyelitis. In 1996, a large outbreak of paralytic poliomyelitis occurred in Albania. The aim of the study was to evaluate the poliomyelitis immunization level in a sample of Albanian refugees who arrived in the Apulia region between April and May 1997.

METHODS

Blood samples were obtained, after informed consent and on a voluntary basis, from 667 subjects housed in seven refugee camps in the Apulia region. Titration of neutralizing antibodies to the three polioviruses was carried out.

RESULTS

The findings showed that Albanian refugees had adequate levels of immunity to all polioviruses (95% for poliovirus type 1, 98.6% for poliovirus type 2 and 91.4% for poliovirus type 3). Moreover, a high immunization rate was found in all age groups irrespective of the areas of origin of the refugees and their socioeconomic conditions.

CONCLUSION

Our findings show that Albanian refugees in Apulia region have adequate levels of immunity against polioviruses and confirm the effectiveness of mass vaccination campaigns with OPV conducted by WHO in Albania following an outbreak of poliomyelitis in 1996.