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Seroprevalence and incidence of Toxoplasma gondii, rubella and cytomegalovirus among Namibian women of childbearing potential

dc.contributor.advisorVan Zyl, Gert U.en_ZA
dc.contributor.advisorReju, Sunday A.en_ZA
dc.contributor.authorVan der Colf, Berta Elizabethen_ZA
dc.contributor.otherStellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Pathology: Medical Virology.en_ZA
dc.date.accessioned2020-11-26T10:18:34Z
dc.date.accessioned2021-01-31T19:40:37Z
dc.date.available2020-11-26T10:18:34Z
dc.date.available2021-01-31T19:40:37Z
dc.date.issued2020-12
dc.identifier.urihttp://hdl.handle.net/10019.1/109234
dc.descriptionThesis (DMed)--Stellenbosch University, 2020.en_ZA
dc.description.abstractIntroduction: 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.en_ZA
dc.description.abstractInleiding: Data oor die voorkoms of insidensie van aangebore infeksies in Namibië is beperk. Hierdie studie het ten doel gehad om die voorkoms te bepaal en die insidensie te modelleer van drie belangrike vertikaal oordraagbare aansteeklike siektes: Toksoplasma gondii (T. gondii), rubella en sitomegalovirus (CMV) infeksies in vroue van vrugbare potensiaal in Namibië. Metodiek: Driehonderd vier-en-veertig instemmende vroue wat die openbare voorgeboortekliniek in Windhoek besoek het, is in die studie ingesluit. Stolboed is versamel en ‘n vraelys het demografiese data, inentingsgeskiedenis en verloskundige geskiedenis sowel as inligting oor blootstelling aan risikofaktore ingesluit. Seroprevalensie van IgG teen T. gondii, rubella en CMV en spesifieke IgM teenliggampies teen CMV is bepaal. T. gondii IgM en T. gondii en CMV IgG aviditeit is bepaal met ‘n ELISA. Statistiek: Fisher se eksakte toets is gebruik vir kategoriese data en die Kruskal Wallis-toets vir aaneenlopende waardes. Resultate: Anti-T. gondii IgG is in 9 (2.61%) swanger vroue gevind. Daar was geen assosiasie van anti-T. gondii IgG met demografiese eienskappe of blootstelling aan risikofaktore nie. Anti-T. gondii IgM was positief in 1 (0.3 %) vrou terwyl 3 (0.9 %) vroue grenslyn anti-T. gondii IgM resultate getoon het. Spesifieke IgG aviditeit was dubbelsinnig en hoog in 33% en 67% van seropositiewe vroue. Seroprevalensie van rubella het nie met ouderdom toegeneem nie. Die meerderheid van die deelnemers het geen rubella-inentingsgeskiedenis gehad nie. Die persentasie vroue met IgG vlakke van <10 IU/ml, 10-14.9 IU/ml en > 15 IU/ml was 2.0%, 2.0% en 95.9% respektiewelik. ‘n Algehele anti-rubella IgG gemiddelde vlak van 164.5 IU/ml (95% CI 150.4-178.7) is gevind in vyf ouderdomsgroepe, naamlik 15-20 (195.8; 159-232); 21-25 (167.8; 143-193); 26-30 (165.2; 136-195); 31-35 (147.6; 116-179) en 36-47 (150.4; 107-194). Demografiese faktore soos moederlike ouderdom, swangerskapouderdom en inentingsgeskiedenis het nie beduidende assosiasies met hoë vlakke van anti-rubella IgG getoon nie. Seroprevalensie van anti-CMV IgG in swanger vroue was 100%. Elf deelnemers (3.2%) het ‘n positiewe of dubbelsinnige anti-CMV IgM resultaat getoon. Spesifieke IgG aviditeit was hoog in al hierdie gevalle. Moederlike ouderdom of swangerskapouderdom was nie positief geassosieer met ‘n positiewe of dubbelsinnige IgM resultaat nie. Insidensie van infeksies kon nie bepaal word nie weens of baie hoë of baie lae voorkoms oor ouderdomskategorieë. Gevolgtrekking: Seroprevalensie van anti-T. gondii IgG is baie laer in sentraal stedelike Namibië as in ander ontwikkelende lande. Ondersoek na spesifieke IgM seropositiwiteit en IgG aviditeit het getoon dat swanger vroue in die sentrale streek van Namibië ’n lae risiko vir vertikale oordrag en gevolglike aangebore toksoplasmose het. ‘n Hoë persentasie van swanger vroue in die studie was immuun teen rubella virus ten spyte van geen rubella inentingeskiedenis. Dit is waarskynlik as gevolg van ‘n hoë koers van natuurlike infeksies met rubella onder kinders voordat vrugbare ouderdom bereik word. Hierdie was die eerste studie wat die seroprevalensie van CMV in Namibië ondersoek het. Die hoë seroprevalense dui op ‘n groter kans vir herinfeksie of heraktivering as vir primêre CMV infeksie. Verdere studies is nodig om die voorkoms van aangebore CMV infeksies in Namibië te ondersoek.af_ZA
dc.format.extent213 pagesen_ZA
dc.language.isoen_ZAen_ZA
dc.publisherStellenbosch : Stellenbosch Universityen_ZA
dc.subjectCongenital infectionsen_ZA
dc.subjectNamibiaen_ZA
dc.subjectInfectious diseasesen_ZA
dc.subjectUCTDen_ZA
dc.subjectToxoplasma gondiien_ZA
dc.subjectRubella in pregnancyen_ZA
dc.subjectCytomegalovirus infectionsen_ZA
dc.titleSeroprevalence and incidence of Toxoplasma gondii, rubella and cytomegalovirus among Namibian women of childbearing potentialen_ZA
dc.typeThesisen_ZA
dc.description.versionDoctoralen_ZA
dc.rights.holderStellenbosch Universityen_ZA


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