Data was collected by 3 trained research assistants through structured interviews. Pregnant women above 24 weeks of gestation, including other pregnant women who were not registered at, nor attended the antenatal clinics of UITH were excluded from this study.Ī structured questionnaire was designed and standardised. Selection criteria included pregnant women in their first and second trimesters of pregnancy, and had never received antirubella vaccines. An informed consent form was signed by each participant.
Ethical approval was obtained from the Ethical Committee of the University of Ilorin Teaching Hospital. This study was designed to determine the significance of IgG-avidity testing in the serologic diagnosis of antenatal rubella.Ī descriptive study was carried out on a cohort group of 92 pregnant women attending the Antenatal clinics at the University of Ilorin Teaching Hospital (UITH), Ilorin, Nigeria. However this could, be significantly reduced by immunization and diagnostically-informed antenatal counselling ( 2). Despite the development of successful vaccines over four decades ago ( 7, 8), the global burden of disease as a result of Congenital rubella syndrome remains a major concern ( 3, 12). Studies carried out amongst pregnant women in Nigeria have revealed prevalence rates of 68.5% and 76% in two south-western ( 9, 10), 16.3% in a North-central region ( 2), and 54.1% in a North-western region ( 11). However, viral strains from cases of reinfection do not seem to differ from other strains ( 8). Although reasons for re-infections have not been clearly defined, cases associated with viraemia do not seem to be due to a defective immunologic response. Re-infections are generally asymptomatic and are detected by serological investigations ( 7, 6). However, a positive IgM result may not always the onset of a primary infection. Currently, laboratory confirmation of suspected cases is based on the detection of Rubella virus-specific IgM in a single serum sample collected soon after the onset of symptoms ( 8, 6). At early stages of primary infection, anti-rubella IgG antibodies have a low antigenic affinity this however matures progressively over the next 3 months ( 6).ĭifferential diagnosis of rubella infections remains unreliable ( 7). Three weeks after infection, anti-rubella virus antibodies are present in all immunoglobulin classes, including IgG, IgA, IgD, and IgE ( 6). Viral-specific IgM antibodies are first detected 10 days post infection, and peaks at about 4 weeks post infection and may persist for more than 7 months after acute infections ( 6). Virions invoke a serological response that is detectable at the onset of its characteristic rash and evolves over the next few weeks ( 6). The infectious period of the virus is from 7 days before to 5 – 7 days after the onset of rash ( 2). Rubella has an average incubation period of 12 – 18 days but can extend to 23 days ( 3, 5). Acute infections that occur in early pregnancy may induce foetal death or congenital malformations in the foetus, mostly affecting the brain, heart, eyes and ears ( 2).
Rubella remains the mildest of viral exanthems in adults and may remain sub-clinical in 25% to 50% of cases ( 4, 5). Viral particles are spread through airborne droplets, contact with oral-pharyngeal secretion of infected persons and vertically from infected mother to foetus during pregnancy ( 2, 3, 1). Rubella virus is the monotypic agent of rubella ( 1).
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