Abstract
Sera from 1523 persons, aged 0-72 years, were examined in Chiang Mai province and Bangkok in Thailand by the Society for Medical Research in South-East Asia, Nippon Medical School in 1977-1982. These sera were studied by the micro cell culture method to determine the polio neutralizing antibody titer using Vero cells.
1) Except in the children at CCCC (Comprehensive Child Care Clinic, Chiang Mai University), who had been 100% immunized with OPV, polio antibodies (titer≥1: 4) to type 1 virus were detected in 86.5%, antibodies to type 2 in 86.0%, and antibodies to type 3 in 80.5%. These figures correspond to those of the tropical countries.
2) Except Chiang Mai 1982 CCCC the percentages of sera with positive antibody (≥1: 4) were low (0-40%) in all three types of poliovirus at the age of 1 year old; then it rose to 100% at the age of 4 years old in type 1, 90.6% at the age of 8 years in type 2 and 66.8% at the age of 5 years in type 3. Among those who were older, the percentages ranging 75-100% were observed in each type Of polioviruses.
3) Except Chiang Mai 1982 CCCC geometric mean antibody titers (log2 GM) of the sera with a positive polio neutralizing antibody to type 1 were 3.78 at the age of 1-12 months old, 6.00 at 1-5 years, 5.45-5.87 at older than 6 years; the mean titers in type 2 were 6.07 at 1-12 months old, 5.91 at 1-5 years old, 5.59-6.21 at older than 6 years; those in type 3 were 3.14 at 1-12 months old, 5.35 at 1-5 years old, 4.49-4.79 at 6-19 years old 4.87-6.81 at older than 20 years.
4) A significant difference of the percentage of sera with a positive antibody (≥1: 4) was not observed between 1977 and 1978 at Raming Tea Plantation, and between 1981 and 1982 at WKK. Geometric mean titer of the sera with the positive antibody against type 2 poliovirus was lower in 1978 than in 1977 in over 20 year old in Raming Tea Plantation; and it was lower in 1982 than in 1981 in the 10-16 year old age group in WKK.
5) The percentage of sera with a positive antibody from children in Chiang Mai 1977, 1978 was high, and the percentages were different in different groups of children from the highland.
6) Antibody positive rate of the children in the control group of CCCC was high in comparison with a group from the Chiang Mai suburbs who had no record of immunization with OPV. On the other hand, the geometric mean titer of the latter group was higher than the former group. This high antibody positive rate with low geometric mean titer observed in the children in the control group of CCCC reflects the effect of the OPV immunization.
7) Surveys of polio antibody in 628 serum samples from children at CCCC who had been immunized in a more intensive immunization program than that of the Ministry of Public Health, Thailand, showed that the antibody positive rate against type 2 poliovirus was high and the rate of children having antibodies against all of the three types (complete protection) was also high. This immunity status corresponds to that of vaccinated people in other countries.
8) There was no significant correlation between the children in the control group of CCCC and the their parents on the polio neutralizing antibody titers.
9) After pulse OPV immunization of 25 children who had not received any artificial immunization in Chiang Mai, allof them had antibodies (≥1: 4) in their sera and the geometric mean titers of the sera with positive antibody to each type of poliovirus were significantly higher than the control group.
The percentage that showed a fourfold rise or more was significantly higher than the control group in type 2 and type 3 poliovirus.
10) A low poliovirus antibody positive rate was observed among students and teachers at the Vocational School in Chiang Mai. This might be due to the fact that 94.4% of the blood donors were females.
