Level of immunoglobuin in the community against poliovirus and factors that might affect

In 1988 the World Health Assembly resolved to eradicate poliomyelitis by the year 2000, with eventual bio-containment of polioviruses and the certification of global eradication by the year 2005. Since then substantial progress towards eradication of poliomyelitis has occurred throughout the world. However, poliomyelitis continued to be a problem as evidenced by reports on acute outbreaks from various parts of the world. In Iraq after the conflict in 1991 and because of the continuing effect of economic sanction on the population, poliomyelitis has increased from a disease of very limited focal transmission to being endemic throughout the country, as evidenced by the marked increase in both the number of cases and number of districts reporting the disease, which indicates that there was a build-up of a substantial immunity deficit with continuing viral transmission and endemicity of the disease in our country and last year epidemic of poliomyelitis was a good example, this brought up the importance of determining the herd immunity against poliovirus among Iraqi children, and by using direct ELISA test which proved to be a reliable and rapid method. It was possible to study the immunity level against poliovirus and assess factors that affect immunity in particular age, sex, OPV doses, geography ....etc. In ELISA, standardization procedures were conducted for: - Antigen (2 types). A-WHO supplied poliovirus antigen, optimal reading with least non specific reaction was 1/40 dilution for type 1 antigen, and 1/50 dilution for type 2&3 antigens. B-Antigen developed from attenuated virus (Sabin Strain), optimal reading was 0.5ug/ml for the 3 serotypes. -serum: optimal reading obtained with least non-specific reaction was 1/20 dilution for the 3 serotypes. - Conjugate: optimal reading obtained with 1/1000 dilution for the 3 serotypes. Validity of the ELISA test to be tested and verified by comparison with already established test like microneutralization test. The study was conducted to evaluate the herd immunity to poliovirus and factors affecting it for the period from Feb 1998-2000, in seven health centers and one out' patient clinic (randomly selected) in Baghdad Governorate, 1592 I children < 10 years of age, both sexes, vaccinated and unvaccinated were included ; in the sample through preceded questionnaire form, anthropometric measurement i including height, weight, and blood samples were obtained for packed cell volume determination, ELISA test and part of the samples were used in micro-neutralization test. During last year outbreak of poliomyelitis, visits were paid to some affected areas to assess some factors related to the epidemic, and 12 cases of poliomyelitis with their 49 close contacts were included in a selected study through simple questionnaire form, blood samples were taken from 10 cases and all the contact for estimation of antibodies by ELISA method. Also to assess maternal immunity 83 cord blood samples were collected and antibody level to poliovirus type 1,2&3 were estimated by ELISA method and some of them by microneutralization test. Result of ELISA test:
The validity of the test was assessed by correlation with micro-neutralization test, the results were strongly correlated, the Pearson's rho and P-value for antibody to type 1 were (R-0.681 p=0.0001), for antibody to type 2 (R=0.628 p=0.0001), and for antibody to type 3 (R=0.709 p-0.0001).
Also by conflation between the 2 antigens used, the results were strongly correlated , for antibody to type 1 (R=0.501 p<0.0001), antibody to type 2 (R=0.398 p