3. Electronic Theses and Dissertations (ETDs) - All submissions
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Item Determinants of vaccination coverage among children aged 12-23 months in rural KwaZulu-Natal(2009-05-18T12:24:00Z) Ndirangu, James Ng'Ang'aTo evaluate the impact of maternal HIV-infection on routine childhood immunization coverage, comparison was made on the immunization status of children born to HIV-infected and HIV-uninfected women in rural KwaZulu Natal. The study population was all children enrolled in the routine demographic surveillance system as at 31st December 2005 (n=18,171) in Africa Centre Demographic Surveillance Area. Sampling of subjects was done based on the dates of birth that were between the period 1st Jan 2004 and 31st December 2005 (n=2,020). This was further divided based on maternal HIV status namely; 236 HIV (+), 777 HIV (-) and 1,007 HIV (unknown). The main outcome measure was the percent of complete routine childhood immunizations recommended by the WHO as assessed from the Road-to- Health cards or maternal recall during household interviews. For all vaccines, children born to HIV-infected mothers had lower immunization coverage than children born to HIV-negative mothers (78.21% vs. 86.52%). The children of mothers who were HIV-infected were 31-55% (P-value <0.020) less likely to be immunized compared to children of mothers who were HIVuninfected. We conclude that maternal HIV-infection is associated with childhood under immunisation. VCT health workers should encourage HIV-infected mothers to complete childhood immunization. Improving access to immunization services could benefit vulnerable populations such as children born to HIV-infected mothers.Item Molecular characterisation of Hepatitis B virus vaccine escape mutants in South Africa(2006-11-17T12:51:16Z) Crowther, PennySince the introduction of vaccination against hepatitis B virus (HBV) infection in South Africa, at least one case of infection despite vaccination has occurred. The purpose of this study was to determine whether this infection was the result of mutations within the region of the surface (S) gene encoding the a determinant epitopes of the hepatitis B surface antigen, which permitted viral vaccine-escape. HBV DNA was extracted from the serum and liver tissue of the patient and amplified within the complete 3 215 bp genome and S gene, respectively. Following cloning, sequencing revealed a minor population displaying unique or uncommon S gene mutations that resulted in C138R, C139R, K141R, P142L, T143A, N146D, and T148A amino acid substitutions in the clones from the serum, and C139Y and D144N in the clones from the liver. Such isolates may represent South African HBV vaccine-escape mutants that caused chronic infection in the host prior to their reversion to wild-type.