Doctoral Degrees (Medical Virology)

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Browsing Doctoral Degrees (Medical Virology) by Author "Van der Colf, Berta Elizabeth"

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    Seroprevalence and incidence of Toxoplasma gondii, rubella and cytomegalovirus among Namibian women of childbearing potential
    (Stellenbosch : Stellenbosch University, 2020-12) Van der Colf, Berta Elizabeth; Van Zyl, Gert U.; Reju, Sunday A.; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Pathology: Medical Virology.
    Introduction: Data on the prevalence or incidence of congenital infections in Namibia are limited. Therefore, this study aimed to determine the prevalence and model the incidence of three important vertically transmitted infectious diseases: Toxoplasma gondii (T. gondii), rubella and cytomegalovirus (CMV) infections in women of childbearing potential in Namibia. Methodology: Three hundred and forty-four consenting women attending public antenatal care in Windhoek were included in the study. Clotted blood was collected, and a questionnaire included demographic data, immunization and obstetric history data as well as information on the exposure to risk factors. Seroprevalences of IgG against T. gondii, rubella and CMV and specific IgM antibodies against CMV were determined. T. gondii IgM and T. gondii and CMV IgG avidity were determined with ELISA. Statistics: Fisher’s exact test was used for categorical associations and Kruskal Wallis test for continuous variables. Results: Anti-T. gondii IgG was found in 9 (2.61%) pregnant women. There was no association of anti-T. gondii IgG with demographic characteristics or exposure to risk factors. Anti-T. gondii IgM was positive in 1 (0.3 %) woman while 3 (0.9 %) women had borderline positive results. Specific IgG avidity was equivocal and high in 33% and 67% of seropositive women. Seroprevalence of rubella did not increase with age and the overall seroprevalence of specific IgG was 95.9%. The majority of the participants had never been vaccinated against rubella infection. The percentage of women with IgG levels of <10 IU/ml, 10-14.9 IU/ml and > 15 IU/ml were 2.0%, 2.0% and 95.9% respectively. An overall anti-rubella IgG mean level of 164.5 IU/ml (95% CI 150.4-178.7) was found in five age groups, namely 15-20 (195.8; 159-232); 21-25 (167.8; 143-193); 26-30 (165.2; 136-195); 31-35 (147.6; 116-179) and 36-47 (150.4; 107-194). Demographic factors like maternal age, gestational age and immunization history did not show significant associations with anti-rubella IgG levels. Seroprevalence of anti-CMV IgG among pregnant women was 100%. Eleven participants (3.2%) had a positive or equivocal anti-CMV IgM result. Specific IgG avidity was high in all of these cases. Neither maternal age nor gestational age was associated with a positive or equivocal zone IgM result. Incidences of infections could not be modelled due to either a very high or very low prevalence across age ranges. Conclusion: Seroprevalence of anti-T. gondii IgG is much lower in central urban Namibia than in other developing countries. Investigation into specific IgM seropositivity and IgG avidity showed that pregnant women in the central region of Namibia are at low risk of vertical transmission and development of congenital toxoplasmosis. A high percentage of pregnant women in the study were immune to rubella virus despite no history of vaccination. This is likely due to a high rate of natural infection with rubella of children before reaching child-bearing potential. This was the first study to investigate seroprevalence of CMV in Namibia. The high seroprevalence of CMV suggests a risk of reinfection or reactivation rather than primary CMV infection in pregnancy. Further studies are needed to determine the prevalence of congenital CMV in Namibia.