Prevalence of anti-poliovirus type 1, 2 and 3 antibodies in unvaccinated Italian travelers.
BACKGROUND
Immunization against poliomyelitis is recommended for international travelers to developing countries. However, the level of antibodies varies even in previously unvaccinated persons, due to wild-type or vaccine-type infections in the eldest travelers.


METHODS
In 1999, we conducted a seroprevalence study in the Lombardy region (northern Italy), using sera collected in 1994 from a population aged 50 to 59 years. The study subjects were consecutive, randomly selected travelers enrolled in an anti-hepatitis A virus antibody study. Neutralizing antibodies were titrated on Vero cells in microtiter plates. Each serum dilution (1:8 to 1:256) was challenged against 100 tissue culture infective doses of the three Sabin strains. Titers> 1:8 were considered to be protective.


RESULTS
We studied 98 travelers, 59 male and 39 female, of mean age 54 years. Seventy-three (74.4%) reported previous travel abroad, but none had been vaccinated against polio. Dietary habits included consumption of seafood in 74.4% and raw vegetables from their own garden in 52.1%. The seroprevalences for neutralizing antibodies against poliovirus type 1, type 2 and type 3 were 86.7%, 89.9%, and 86.7%, respectively. All travelers presented protective antibody titers against at least one of the three viral types. Protective antibody titers were unrelated to travel history or dietary habit.


CONCLUSIONS
A high proportion of the previously unvaccinated adults in our sample presented protective immunity to polioviruses. This observation may have implications for cost-effectiveness analysis of generalized polio vaccination in adult Italian travelers.
Signorini
Liana
L
Institute of Infectious and Tropical Diseases, University of Brescia, Italy.
Barbi
Maria
M
Matteelli
Alberto
A
Binda
Sandro
S
Didò
Patrizia
P
Caroppo
Simona
S
Primache
Valeria
V
Pisani
Salvatore
S
Messino
Crescenzo
C
Brunelli
Maria
M
Costa
Paolo
P
Ronca
Enrico
E
Fausti
Caterina
C
Castelli
Francesco
F
D000328:Adult; D000914:Antibodies, Viral / Q000097:blood*; D005260:Female; D006801:Humans; D007558:Italy / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D011051:Poliomyelitis / Q000453:epidemiology* / Q000209:etiology / Q000276:immunology / Q000517:prevention & control*; D017955:Poliovirus / Q000276:immunology*; D016036:Seroepidemiologic Studies; D014195:Travel; D014611:Vaccination / Q000706:statistics & numerical data
D000914:Antibodies, Viral