KAIS 2007 1 - Kenya National AIDS & STI Control Programme ...

also at substantially elevated risk of tertiary syphilis, notably neurosyphilis, which can lead topsychosis and motor problems.Appendix B.13 provides sample sizes and 95% confidence intervals for estimates presented in thischapter. Throughout the chapter, the term significant indicates a chi‐square p‐value less than 0.05;marginally significant indicates a p‐value between 0.05 and 0.10, inclusive; and not significantindicates a p‐value greater than 0.10.Population estimates reported in this chapter were calculated based on the 2007 projected populationby province, age and sex reported in The Analytical Report on Population Projections, Volume II, KenyanNational Bureau of Statistics (2002). Weighted national estimates for selected indicators from the 2007KAIS were used in these calculations. Detailed methods used for calculating population estimates aredescribed in Appendix A.DATA IN CONTEXTLaboratory Testing for Syphilis in the 2007 KAISSyphilis testing was conducted using two types of laboratory tests. All serum specimens werefirst screened using a Treponema pallidum particle agglutination assay (TPPA) test. TPPAremains reactive indefinitely, even after treatment, and was thus used to screen forantibodies in order to identify participants previously exposed to syphilis. All TPPA-positivespecimens were then tested using a rapid plasma reagin (RPR) test on undiluted (i.e. neat)serum specimen. This algorithm better identifies current infection, though sometimes, areactive RPR may also reflect late syphilis that has been successfully treated. In this chapter,we refer to participants with both a positive TPPA and positive RPR test as “infected.” Forquality control purposes, all TPPA reactive specimens and 5% of nonreactive specimenswere re-tested at the quality assurance laboratory using the same TPPA/RPR algorithm. It isworth noting that the standard algorithm for serological diagnosis of syphilis is an RPR testfollowed, if reactive, by a TPHA, a test similar but not identical to TPPA. In the 2007 KAIS,the laboratory used TPPA instead of TPHA because TPPA produces fewer false positiveresults and is faster to conduct. Participants classified as seropositive on both TPPA andRPR who returned to receive their results were referred for treatment for active infection.KAIS 2007 229