Browsing by Author "Suchard, Melinda"

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    Establishment of outbreak thresholds for Hepatitis A in South Africa using laboratory surveillance, 2017–2020
    (MDPI, 2021) Prabdial-Sing, Nishi; Motaze, Nkengafac Villyen; Manamela, Jack; McCarthy, Kerrigan; Suchard, Melinda
    As South Africa transitions from endemic to intermediate endemicity, hepatitis A surveillance needs strengthening to monitor trends in disease incidence and to identify outbreaks. We used passive laboratory-based surveillance data from the National Health Laboratory Services to calculate national hepatitis A incidence and to establish thresholds for outbreaks. Incidence was calculated by age and geographic location. The static threshold used two or three standard deviations (SDs) above the mean hepatitis A incidence in 2017–2019, and a cumulative summation (CuSum2) threshold used three SDs above the mean of the preceding seven months. These thresholds were applied to hepatitis A data for 2020. From 2017 to 2020, the mean incidence of hepatitis A IgM was 4.06/100,000 and ranged from 4.23 to 4.85/100,000 per year. Hepatitis A incidence was highest in the Western Cape province (WCP) (7.00–10.92/100,000 per year). The highest incidence was in the 1–9-year-olds. The incidence of hepatitis A in 2020 exceeded the static threshold in two districts of the WCP: Cape Winelands in January and Overberg district in August. The provincial incidence did not exceed the static and CuSum2 thresholds. District-level analysis using either threshold was sensitive enough to monitor trends and to alert district health authorities, allowing early outbreak responses.
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    Hepatitis A virus seroprevalence in South Africa - Estimates using routine laboratory data, 2005–2015
    (Public Library of Science, 2019-06-26) Mazanderani, Ahmad Haeri; Motaze, Nkengafac Villyen; McCarthy, Kerrigan; Suchard, Melinda; Du Plessis, Nicolette Marie
    Introduction: South Africa is considered highly endemic for hepatitis A virus (HAV) although few seroprevalence studies have been conducted over the past two decades. The World Health Organization recommends integrating HAV vaccination into national childhood immunization schedules where there is transition from high to intermediate endemicity. As a means of gauging age-specific rates of infection, we report HAV seroprevalence rates among specimens tested for HAV serology within South Africa’s public health sector from 2005–2015. Materials and methods: Hepatitis A serology results (Anti-HAV IgM, IgG and total antibody) from 2005–2015 were extracted from South Africa’s National Health Laboratory Service’s Corporate Data Warehouse (NHLS CDW), the central data repository of all laboratory test-sets within the public health sector. Results were extracted according to test-set, result, date of testing, health facility, name, surname, age, and sex. Anti-HAV IgG results were merged with total antibody results to reflect anti-HAV seroprevalence. Testing volume, positivity rates and age-specific anti-HAV seroprevalence rates by year and geographic distribution are described. Results and discussion: A total of 501 083 HAV IgM results were retrieved, of which 16 423 (3.3%) were positive, 484 259 (96.6%) negative and 401 (0.1%) equivocal; and 34 710 HAV total antibody/IgG tests of which 30 675 (88.4%) were positive, 4 020 (11.6%) negative and 15 equivocal. Whereas IgM positivity was highest among the 1–4 year age group (33.5%) and lowest among patients >45 years (<0.5%), total antibody positivity ranged from its lowest level of 52.7% in the 1–4 year age group increasing to levels of >90% only after 25 years of age. Conclusion: Anti-HAV total antibody testing within the South African public health sector demonstrates seroprevalence rates reach levels >90% only in adulthood, suggesting South Africa could be in transition from high to intermediate endemicity. Prospective studies with geographically representative sampling are required to confirm these findings and evaluate provincial and urban/rural heterogeneity.
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    Primary immunodeficiency diseases
    (Health and Medical Publishing Group (HMPG), 2012-08) Buldeo, Suvarna; Suchard, Melinda; Esser, Monika
    Primary immunodeficiency diseases (PIDs) are a group of disorders with defects in the development or function (or both) of the immune system. Most PIDs originate from mutations in single genes, but polygenic forms do occur.1 The global prevalence of PIDs varies between 0.3 and 12 per 100 000 population, and is higher in areas with high rates of consanguinity.2 The prevalence in South Africa is unknown, but according to prevalence data reported from the PID register,3 these diseases are either missed or not reported. The possible reasons for under-diagnosis are that patients presenting with recurrent, persistent, severe or even unusual infections are treated without investigating the underlying cause, or the diagnosis is missed in the face of the overwhelming burden of similar clinical presentations of infectious diseases such as HIV and tuberculosis. Early diagnosis is important as therapeutic options are available to treat and prevent long-term sequelae such as bronchiectasis, which will improve quality of life and decrease mortality. Basic laboratory assays to screen for PIDs are available throughout South Africa but the threshold for investigation among healthcare workers is high. This review aims to increase the clinical suspicion of PIDs in South Africa and provide an approach to the diagnosis and management.