Publications by authors named "Kalk E"

Background: Data on tuberculosis (TB) incidence and risk factors among children living with HIV (CLHIV) in the universal ART era are limited.

Methods: We analysed routinely-collected data on TB diagnoses for CLHIV age ≤5 years, born 2018-2022, in the Westen Cape, South Africa. We examined factors associated with TB diagnosis, with death and loss to follow-up as competing events.

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Background: Although prior studies of tuberculosis-preventive treatment (TPT) for pregnant people with human immunodeficiency virus (PPWH) report conflicting adverse pregnancy outcome (APO) risks, international guidelines recommend TPT for PPWH.

Methods: We used a microsimulation model to evaluate 5 TPT strategies among PPWH receiving antiretroviral therapy in South Africa: No TPT; 6 months of isoniazid (6H) or 3 months of isoniazid-rifapentine (3HP) during pregnancy (Immediate 6H or Immediate 3HP) or post partum (Deferred 6H or Deferred 3HP). The primary outcomes were maternal, fetal/infant, and combined deaths from causes potentially influenced by TPT (maternal tuberculosis, maternal hepatotoxicity, stillbirth, low birth weight [LBW], and infant tuberculosis).

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Article Synopsis
  • Lack of comprehensive data on congenital disorders (CDs) in South Africa affects resource distribution and detection of risks from harmful pregnancy exposures.
  • A study using the Western Cape Pregnancy Exposure Registry analyzed data from 2016 to 2022, finding a confirmed prevalence of major CDs at 7.2 per 1,000 births, which increased to 9.2 when including missed diagnoses.
  • Factors such as older maternal age and diabetes raised CD prevalence, while HIV status and other conditions did not significantly impact rates; improving neonatal checks and records could enhance CD detection.
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  • * A study in Cape Town, South Africa showed seroprevalence of SARS-CoV-2 rose from 39.19% in July 2020 to 67.8% by November 2021, with poorer communities experiencing higher rates and mortality.
  • * Seropositivity before the Omicron wave offered strong protection against severe disease, suggesting that effective seroprevalence research is essential for understanding true infection rates and directing public health interventions.
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Using the Data Evaluation and Preparation for HIV-Exposed Uninfected Child Cohorts project's standardized child HIV exposure definitions, 64%, 64% and 90% of children exposed to HIV in utero could be classified as HIV-uninfected with moderate or high certainty at the ages of 1 and 3 years and at the time of first infectious disease hospitalization, respectively. These definitions can be applied retrospectively to routine datasets with linked mother-child data.

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Background: Pretreatment of HIV drug resistance among children living with HIV (CLHIV) can compromise antiretroviral therapy (ART) effectiveness. Resistance may be transmitted directly from mothers or acquired following exposure to antiretrovirals consumed through breastfeeding or administered as prophylaxis.

Methods: We performed resistance testing in children aged <3 years, newly diagnosed with HIV in Western Cape, South Africa (2021-2022), who either (1) acquired HIV via possible breastfeeding transmission from mothers who received ART (any regimen) during pregnancy/postpartum and/or (2) were exposed to protease inhibitors or integrase strand transfer inhibitors (INSTIs) in utero.

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Article Synopsis
  • Pharmacovigilance (PV) is essential for monitoring medication safety during pregnancy, particularly since clinical trials typically exclude pregnant individuals, and there's a significant lack of safety data in low- and middle-income countries (LMICs).
  • A scoping review of 31 PV publications from at least 24 LMICs revealed that most studies focus on the impacts of therapeutic and vaccine exposures related to infectious diseases such as HIV, tuberculosis, and malaria among pregnant individuals.
  • The review categorized outcomes into maternal, birth, and neonatal/infant results, identifying specific relationships, such as the effects of antiretroviral therapies for HIV and antimalarial drugs during pregnancy on adverse outcomes.
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Background: In South Africa, infants who are HIV-exposed are tested for HIV at birth and 10 weeks of age. The COVID-19 pandemic lockdown restrictions resulted in reduced access to healthcare services and uncertain impact on early infant HIV testing.

Objectives: To describe the effects of the COVID-19 pandemic lockdown restrictions on early infant HIV testing and diagnosis in Cape Town, South Africa.

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Introduction: Monitoring mother-infant pairs with HIV exposure is needed to assess the effectiveness of vertical transmission (VT) prevention programmes and progress towards VT elimination.

Methods: We used routinely collected data on infants with HIV exposure, born May 2018-April 2021 in the Western Cape, South Africa, with follow-up through mid-2022. We assessed the proportion of infants diagnosed with HIV at birth (≤7 days), 10 weeks (>1 to 14 weeks) and >14 weeks as proxies for intrauterine, intrapartum/early breastfeeding and late breastfeeding transmission, respectively.

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Introduction: With the scaling up of vertical HIV transmission prevention programmes, the HIV-related population profile of children in South Africa has shifted. We described temporal changes in HIV-related characteristics of children, aged ≤3 years (up to the third birthday), with infectious disease hospitalisations across the Western Cape province.

Methods: We used routinely collected electronic data to identify children born in the Western Cape with infectious disease hospital records for lower respiratory tract infections, diarrhoea, meningitis and tuberculous meningitis, from 2008 to 2021.

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Background: The first vertical transmission of HIV prevention (VTP) programme in South Africa was launched in 1999 in Khayelitsha, Western Cape Province (WC). Since then, VTP guidelines have expanded in complexity and scope.

Objectives: To describe contemporary VTP uptake in Khayelitsha and quantify vertical transmission (VT) risk factors based on linked routine electronic health data.

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Background: Despite the close relationship between pre-pregnancy body mass index (BMI), gestational weight gain (GWG) and postpartum weight (PPW), these factors are often studied separately. There are no data characterising longitudinal weight trajectories among pregnant and postpartum women in urban African populations. We examined maternal weight trajectories from pregnancy through to 12 months postpartum, factors associated with higher weight trajectory class membership and associations of weight trajectories with infant growth at 12 months.

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The risk of HIV acquisition is higher during pregnancy and postpartum than other times. Newly acquired maternal HIV infection associated with high primary viraemia, substantially increases the risk of vertical HIV transmission. Pre-exposure prophylaxis (PrEP) reduces the risk of HIV acquisition.

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Introduction: We evaluated associations of HIV and antiretroviral therapy (ART) with birth and maternal outcomes at a province-wide-level in the Western Cape, South Africa, in a recent cohort before dolutegravir-based first-line ART implementation.

Methods: This retrospective cohort study included pregnant people delivering in 2018-2019 with data in the Western Cape Provincial Health Data Centre which integrates individual-level data on all public sector patients from multiple electronic platforms using unique identifiers. Adverse birth outcomes (stillbirth, low birth weight (LBW), very LBW (VLBW)) and maternal outcomes (early and late pregnancy-related deaths, early and late hospitalizations) were compared by HIV/ART status and adjusted prevalence ratios (aPRs) calculated using log-binomial regression.

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The aim of this scoping review was to determine the scope, objectives and methodology of contemporary published research on congenital anomalies (CAs) in sub-Saharan Africa (SSA), to inform activities of the newly established sub-Saharan African Congenital Anomaly Network (sSCAN). MEDLINE was searched for CA-related articles published between January 2016 and June 2021. Articles were classified into four main areas (public health burden, surveillance, prevention, care) and their objectives and methodologies summarized.

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Each year more than 200,000 pregnant people become sick with TB, but little is known about how to optimize their diagnosis and therapy. Although there is a need for further research in this population, it is important to recognize that much can be done to improve the services they currently receive. Following a systematic review of the literature and the input of a global team of health professionals, a series of best practices for the diagnosis, prevention and treatment of TB during pregnancy were developed.

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Introduction: CHERISH is designed to establish a long-term sustainable system for measurement of in utero and postnatal exposures and outcomes in children who are HIV-exposed uninfected (HEU) and HIV-unexposed to compare survival, hospitalisation, growth and neurodevelopment in the Western Cape, South Africa.

Methods And Analysis: During 2022-2025, the CHERISH dynamic cohort is prospectively enrolling pregnant people with and without HIV at 24-36 weeks gestation from one urban and one rural community, following mother-child pairs, including children who are HEU (target N=1200) and HIV-unexposed (target N=600) for 3 years from the child's birth. In-person visits occur at enrolment, delivery, 12 months, 24 months and 36 months with intervening 3-monthly telephone data collection.

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Article Synopsis
  • In Cape Town, South Africa, a study conducted from July 2020 to November 2021 analyzed residual blood samples to understand the prevalence of SARS-CoV-2 and its determinants in the community.
  • The research found that seroprevalence increased significantly over time, from 39.2% to 67.8%, with poorer communities experiencing higher rates of both infection and COVID-19 deaths.
  • Being seropositive before the Omicron wave provided strong protection against severe disease, especially for those who were also vaccinated, highlighting the importance of both natural immunity and vaccination in combating COVID-19.
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Purpose: The Western Cape Pregnancy Exposure Registry (PER) was established at two public sector healthcare sentinel sites in the Western Cape province, South Africa, to provide ongoing surveillance of drug exposures in pregnancy and associations with pregnancy outcomes.

Participants: Established in 2016, all women attending their first antenatal visit at primary care obstetric facilities were enrolled and followed to pregnancy outcome regardless of the site (ie, primary, secondary, tertiary facility). Routine operational obstetric and medical data are digitised from the clinical stationery at the healthcare facilities.

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Background: In the absence of clinical trials, data on the safety of medicine exposures in pregnancy are dependent on observational studies conducted after the agent has been licensed for use. This requires an accurate history of antenatal medicine use to determine potential risks. Medication use is commonly determined by self-report, clinician records, and electronic pharmacy data; different data sources may be more informative for different types of medication and resources may differ by setting.

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Background: Infants born HIV-exposed yet remain uninfected (HEU) are at increased risk of poorer growth and health compared to infants born HIV-unexposed (HU). Whether maternal antiretroviral treatment (ART) in pregnancy ameliorates this risk of poorer growth is not well understood. Furthermore, whether risks are similar across high burden HIV settings has not been extensively explored.

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Purpose: The purpose was to conduct an independent biomechanical study comparing the main types of femoral fixation adapted to short hamstring grafts in anterior cruciate ligament (ACL) reconstruction surgery and to validate their performance.

Methods: The ACLip Femoral, ToggleLoc™ Ziploop (TLZ), and Tape Locking Screw (TLS) implants were tested in tension in the following three different configurations: implant alone, implant fixed on the femur without graft, and implant fixed on the femur with graft. Grafts alone were also tested.

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Background: Although global nutrition/dietary transition resulting from industrialisation and urbanisation has been identified as a major contributor to widespread trends of obesity, there is limited data in pregnant women, including those living with HIV in South Africa. We examined food-based dietary intake in pregnant women with and without HIV at first antenatal care (ANC) visit, and associations with maternal overweight/obesity and gestational weight gain (GWG).

Methods: In an urban South African community, consecutive women living with (n = 479) and without (n = 510) HIV were enrolled and prospectively followed to delivery.

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Objectives: Increased risk of morbidity and hospitalization has been observed in children who are HIV-exposed uninfected (HEU) compared with HIV-unexposed uninfected (HUU). Studies in the era of universal maternal antiretroviral treatment (ART) are limited.

Design: Prospective cohort.

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Background: Successful scale-up of antiretroviral therapy (ART) during pregnancy has minimized infant HIV acquisition, and over 1 million infants are born HIV-exposed but uninfected (HEU), with an increasing proportion also exposed in utero to maternal ART. While benefits of ART in pregnancy outweigh risks, some studies have reported associations between in utero ART exposure and impaired fetal growth, highlighting the need to identify the safest ART regimens for use in pregnancy.

Methods: We compared birth anthropometrics of infants who were HEU with those HIV-unexposed (HU) in Cape Town, South Africa.

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