Browsing by Author "Van Zyl, Gert"
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- ItemClinical experience with severe acute respiratory syndrome Coronavirus 2-related illness in children : hospital experience in Cape Town, South Africa(Oxford University Press, 2020-11-10) van der Zalm, Marieke M.; Lishman, Juanita; Verhagen, Lilly M.; Redfern, Andrew; Smit, Liezl; Barday, Mikhail; Ruttens, Dries; da Costa, A’ishah; van Jaarsveld, Sandra; Itana, Justina; Schrueder, Neshaad; Van Schalkwyk, Marije; Parker, Noor; Appel, Ilse; Fourie, Barend; Claassen, Mathilda; Workman, Jessica J.; Goussard, Pierre; Van Zyl, Gert; Rabie, HelenaBackground: Children seem relatively protected from serious severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-related disease, but little is known about children living in settings with high tuberculosis and human immunodeficiency virus (HIV) burden. This study reflects clinical data on South African children with SARS-CoV-2. Methods: We collected clinical data of children aged <13 years with laboratory-confirmed SARS-CoV-2 presenting to Tygerberg Hospital, Cape Town, between 17 April and 24 July 2020. Results: One hundred fifty-nine children (median age, 48.0 months [interquartile range {IQR}, 12.0-106.0 months]) were included. Hospitalized children (n = 62), with a median age of 13.5 months (IQR, 1.8-43.5 months) were younger than children not admitted (n = 97; median age, 81.0 months [IQR, 34.5-120.5 months]; P < .01.). Thirty-three of 159 (20.8%) children had preexisting medical conditions. Fifty-one of 62 (82.3%) hospitalized children were symptomatic; lower respiratory tract infection was diagnosed in 21 of 51 (41.2%) children, and in 11 of 16 (68.8%) children <3 months of age. Respiratory support was required in 25 of 51 (49.0%) children; 13 of these (52.0%) were <3 months of age. One child was HIV infected and 11 of 51 (21.2%) were HIV exposed but uninfected, and 7 of 51 (13.7%) children had a recent or new diagnosis of tuberculosis. Conclusions: Children <1 year of age hospitalized with SARS-CoV-2 in Cape Town frequently required respiratory support. Access to oxygen may be limited in some low- and middle-income countries, which could potentially drive morbidity and mortality. HIV infection was uncommon but a relationship between HIV exposure, tuberculosis, and SARS-CoV-2 should be explored.
- ItemCollaborative update of a rule-based expert system for HIV-1 genotypic resistance test interpretation(Public Library of Science, 2017-07-28) Paredes, Roger; Tzou, Philip L.; Van Zyl, Gert; Barrow, Geoff; Camacho, Ricardo; Carmona, Sergio; Grant, Philip M.; Gupta, Ravindra K.; Hamers, Raph L.; Harrigan, P. Richard; Jordan, Michael R.; Kantor, Rami; Katzenstein, David A.; Kuritzkes, Daniel R.; Maldarelli, Frank; Otelea, Dan; Wallis, Carole L.; Schapiro, Jonathan M.; Shafer, Robert W.Introduction: HIV-1 genotypic resistance test (GRT) interpretation systems (IS) require updates as new studies on HIV-1 drug resistance are published and as treatment guidelines evolve. Methods: An expert panel was created to provide recommendations for the update of the Stanford HIV Drug Resistance Database (HIVDB) GRT-IS. The panel was polled on the ARVs to be included in a GRT report, and the drug-resistance interpretations associated with 160 drug-resistance mutation (DRM) pattern-ARV combinations. The DRM pattern-ARV combinations included 52 nucleoside RT inhibitor (NRTI) DRM pattern-ARV combinations (13 patterns x 4 NRTIs), 27 nonnucleoside RT inhibitor (NNRTI) DRM pattern-ARV combinations (9 patterns x 3 NNRTIs), 39 protease inhibitor (PI) DRM pattern-ARV combinations (13 patterns x 3 PIs) and 42 integrase strand transfer inhibitor (INSTI) DRM pattern-ARV combinations (14 patterns x 3 INSTIs). Results: There was universal agreement that a GRT report should include the NRTIs lamivudine, abacavir, zidovudine, emtricitabine, and tenofovir disoproxil fumarate; the NNRTIs efavirenz, etravirine, nevirapine, and rilpivirine; the PIs atazanavir/r, darunavir/r, and lopinavir/r (with “/r” indicating pharmacological boosting with ritonavir or cobicistat); and the INSTIs dolutegravir, elvitegravir, and raltegravir. There was a range of opinion as to whether the NRTIs stavudine and didanosine and the PIs nelfinavir, indinavir/r, saquinavir/r, fosamprenavir/r, and tipranavir/r should be included. The expert panel members provided highly concordant DRM pattern-ARV interpretations with only 6% of NRTI, 6% of NNRTI, 5% of PI, and 3% of INSTI individual expert interpretations differing from the expert panel median by more than one resistance level. The expert panel median differed from the HIVDB 7.0 GRT-IS for 20 (12.5%) of the 160 DRM pattern-ARV combinations including 12 NRTI, two NNRTI, and six INSTI pattern-ARV combinations. Eighteen of these differences were updated in HIVDB 8.1 GRT-IS to reflect the expert panel median. Additionally, HIVDB users are now provided with the option to exclude those ARVs not considered to be universally required. Conclusions: The HIVDB GRT-IS was updated through a collaborative process to reflect changes in HIV drug resistance knowledge, treatment guidelines, and expert opinion. Such a process broadens consensus among experts and identifies areas requiring further study.
- ItemCOVID-19 : getting ahead of the epidemic curve by early implementation of social distancing(Health & Medical Publishing Group, 2020) Preiser, Wolfgang; Van Zyl, Gert; Dramowski, AngelaThe response to the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease 2019 (COVID-19), has largely been reactive. There are a few exceptions of countries taking proactive measures. Some countries in Asia, including Taiwan and Singapore, were able to limit the spread despite close links to China,[1,2] and South Korea and China were able to mobilise to contain an initial rapidly spreading epidemic through mass testing and early interventions.[2,3] As COVID-19 has now reached Africa, South Africa (SA) could be a regional leader in its response and reduce the impact of the disease on its population by acting early.
- ItemDelays in HIV-1 infant polymerase chain reaction testing may leave children without confirmed diagnoses in the Western Cape province, South Africa(AOSIS, 2022-06) Mahlakwane, Kamela L.; Preiser, Wolfgang; Nkosi, Nokwazi; Naidoo, Nasheen; Van Zyl, GertBackground: Early diagnosis and confirmation of HIV infection in newborns is crucial for expedited initiation of antiretroviral therapy. Confirmatory testing must be done for all children with a reactive HIV PCR result. There is no comprehensive data on confirmatory testing and HIV PCR test request rejections at National Health Laboratory Service laboratories in South Africa. Objective: This study assessed the metrics of routine infant HIV PCR testing at the Tygerberg Hospital Virology Laboratory, Cape Town, Western Cape, South Africa, including the proportion of rejected test requests, turn-around time (TAT), and rate of confirmatory testing. Methods: We retrospectively reviewed laboratory-based data on all HIV PCR tests performed on children ≤ 24 months old (n = 43 346) and data on rejected HIV PCR requests (n = 1479) at the Tygerberg virology laboratory over two years (2017–2019). Data from sample collection to release of results were analysed to assess the TAT and follow-up patterns. Results: The proportion of rejected HIV PCR requests was 3.3%; 83.9% of these were rejected for various pre-analytical reasons. Most of the test results (89.2%) met the required 96-h TAT. Of the reactive initial test results, 53.5% had a follow-up sample tested, of which 93.1% were positive. Of the initial indeterminate results, 74.7% were negative on follow-up testing. Conclusion: A high proportion of HIV PCR requests were rejected for pre-analytical reasons. The high number of initial reactive tests without evidence of follow-up suggests that a shorter TAT is required to allow confirmatory testing before children are discharged.
- ItemThe effect of interventions on the transmission and spread of HIV in South Africa : a phylodynamic analysis(Nature Research, 2019-02-25) Wilkinson, Eduan; Junqueira, Dennis Maletich; Lessells, Richard; Engelbrecht, Susan; Van Zyl, Gert; De Oliveira, Tulio; Salemi, MarcoENGLISH ABSTRACT: The epidemic in South Africa is characterized by high genetic diversity driven by multiple independent introductions. The bulk of these introductions occurred between 1985–2000 during which time HIV prevalence increased exponentially. Epidemic growth has stabilized in recent years with the implementation of several interventions. Here we identified distinct HIV clades from a large sequence dataset of southern African HIV sequences (n = 15,332). Each clade was characterized using phylodynamic and phylogeographic methods to infer their growth through time and space. The estimated date of origin for the 18 clades that were found, fell between 1979–1992 with strong growth during the 1990’s. Phylogeographic reconstruction revealed wide dispersal of clades throughout the country with the city of Johannesburg as the focal point of viral dispersal. We found clear signs of decreasing growth rate in four of the clades since the advent of interventions, while other clades have continued to growth and expand. Our results demonstrate that interventions do not affect the HIV epidemic universally with major difference between different clades over time and space. Here we demonstrate the utility and flexibility of molecular epidemiological methods and demonstrate how they can potentially be a powerful tool in HIV epidemic monitoring in South Africa.
- ItemHigh positive HIV serology results can still be false positive(Elsevier, 2019) Reid, Joanna; Van Zyl, Gert; Linstrom, Michael; Korsman, Stephen; Marais, Gert; Preiser, WolfgangENGLISH ABSTRACT: The consequences of falsely reactive HIV test results can be significant, for patients and healthcare providers. This case describes a diagnostic investigation of a patient with pronounced discordant HIV serological results, to determine HIV status. The fourth generation serological screening assay (Roche COBAS Elecsys HIV combiPT) had high positive results but confirmatory testing was negative (Abbott HIV Ag/Ab Combo). Five separate samples over 13 days were tested using multiple fourth generation HIV immunoassays and molecular tests for HIV-1 and HIV-2. Potential causes of falsely reactive serological results were investigated. Samples were sent to the manufacturer for analysis. The screening assay was positive on all samples with a very high signal to cut-off ratio (S/CO) of greater than 400. However, multiple serological and molecular assays did not detect HIV-1 or HIV-2 specific antibodies, antigen or nucleic acid. A recombinant immunochromatographic assay had faint reactivity to gp41 peptide and the manufacturer investigation reported cross-reactivity to one of the screening assay’s synthetic peptides. Possible causes of the false positive result include cross reactivity to other antigens, including prior schistosomiasis infection, or the patient’s previously excised ameloblastoma (a rare germ cell tumor of the jaw). This is a rare case of false high positive results on fourth-generation HIV serology testing due to high level non-specific reactivity to an isolated synthetic peptide component of the assay. It highlights the need for confirmatory testing even in settings with HIV high prevalence and awareness that false-positive serological results may have a high S/CO.
- ItemHIV Drug Resistance (HIVDR) in antiretroviral therapy-naive patients in Tanzania not eligible for WHO Threshold HIVDR survey is dramatically high(Public Library of Science (PLoS), 2011-08-19) Kasang, Christa; Kalluvya, Samuel; Majinge, Charles; Stich, August; Bodem, Jochen; Kongola, Gilbert; Jacobs, Graeme Brendon; Mlewa, Mathias; Mildner, Miriam; Hensel, Irina; Horn, Anne; Preiser, Wolfgang; Van Zyl, Gert; Klinker, Hartwig; Koutsilieri, Eleni; Rethwilm, Axel; Scheller, Carsten; Weissbrich, Benedikt; Kallas, Esper GeorgesBACKGROUND: The World Health Organization (WHO) has recommended guidelines for a HIV drug resistance (HIVDR) survey for resource-limited countries. Eligibility criteria for patients include age below 25 years in order to focus on the prevalence of transmitted HIVDR (tHIVDR) in newly-infected individuals. Most of the participating sites across Africa have so far reported tHIVDR prevalences of below 5%. In this study we investigated whether the rate of HIVDR in patients <25 years is representative for HIVDR in the rest of the therapy-naïve population. Methods and Findings HIVDR was determined in 88 sequentially enrolled ART-naïve patients from Mwanza, Tanzania (mean age 35.4 years). Twenty patients were aged <25 years and 68 patients were aged 25–63 years. The frequency of HIVDR in the study population was 14.8% (95%; CI 0.072–0.223) and independent of NVP-resistance induced by prevention of mother-to-child transmission programs. Patients >25 years had a significantly higher HIVDR frequency than younger patients (19.1%; 95% CI 0.095–0.28) versus 0%, P = 0.0344). In 2 out of the 16 patients with HIVDR we found traces of antiretrovirals (ARVs) in plasma. Conclusions ART-naïve patients aged over 25 years exhibited significantly higher HIVDR than younger patients. Detection of traces of ARVs in individuals with HIVDR suggests that besides transmission, undisclosed misuse of ARVs may constitute a significant factor in the generation of the observed high HIVDR rate. The current WHO tHIVDR survey that is solely focused on the transmission of HIVDR and that excludes patients over 25 years of age may therefore result in substantial underestimation of the prevalence of HIVDR in the therapy-naïve population. Similar studies should be performed also in other areas to test whether the so far reported optimistic picture of low HIVDR prevalence in young individuals is really representative for the rest of the ART-naïve HIV-infected population.
- ItemHIV evolution and diversity in ART-treated patients(BioMed Central, 2018-01-30) Van Zyl, Gert; Bale, Michael J.; Kearney, Mary F.Characterizing HIV genetic diversity and evolution during antiretroviral therapy (ART) provides insights into the mechanisms that maintain the viral reservoir during ART. This review describes common methods used to obtain and analyze intra-patient HIV sequence data, the accumulation of diversity prior to ART and how it is affected by suppressive ART, the debate on viral replication and evolution in the presence of ART, HIV compartmentalization across various tissues, and mechanisms for the emergence of drug resistance. It also describes how CD4+ T cells that were likely infected with latent proviruses prior to initiating treatment can proliferate before and during ART, providing a renewable source of infected cells despite therapy. Some expanded cell clones carry intact and replication-competent proviruses with a small fraction of the clonal siblings being transcriptionally active and a source for residual viremia on ART. Such cells may also be the source for viral rebound after interrupting ART. The identical viral sequences observed for many years in both the plasma and infected cells of patients on long-term ART are likely due to the proliferation of infected cells both prior to and during treatment. Studies on HIV diversity may reveal targets that can be exploited in efforts to eradicate or control the infection without ART.
- ItemModerate levels of pre-treatment HIV-1 antiretroviral drug resistance detected in the first South African national survey(Public Library of Science, 2016) Steegen, Kim; Carmona, Sergio; Bronze, Michelle; Papathanasopoulos, Maria A.; Van Zyl, Gert; Goedhals, Dominique; MacLeod, William; Sanne, Ian; Stevens, Wendy S.Background: In order to assess the level of transmitted and/or pre-treatment antiretroviral drug resistance to HIV-1, the World Health Organization (WHO) recommends that regular surveys are conducted. This study’s objective was to assess the frequency of HIV-1 antiretroviral drug resistance in patients initiating antiretroviral treatment (ART) in the public sector throughout South Africa. Methods: A prospective cross-sectional survey was conducted using probability proportional to size sampling. This method ensured that samples from each province were proportionally collected, based on the number of patients receiving ART in each region. Samples were collected between March 2013 and October 2014. Pol sequences were obtained using RT-PCR and Sanger sequencing and submitted to the Stanford Calibrated Population Resistance tool v6.0. Results: A total of 277 sequences were available for analysis. Most participants were female (58.8%) and the median age was 34 years (IQR: 29–42). The median baseline CD4-count was 149 cells/mm3 (IQR: 62–249) and, based on self-reporting, participants had been diagnosed as HIV-positive approximately 44 days prior to sample collection (IQR: 23–179). Subtyping revealed that 98.2% were infected with HIV-1 subtype C. Overall, 25 out of 277 patients presented with ≥1 surveillance drug resistance mutation (SDRM, 9.0%, 95% CI: 6.1–13.0%). Non-nucleoside reverse transcriptase inhibitor (NNRTI) mutations were the most numerous mutations detected (n = 23). Only two patients presented with a protease inhibitor (PI) mutation. In four patients ≥4 SDRMs were detected, which might indicate that these patients were not truly ART-naïve or were infected with a multi-resistant virus. Conclusions: These results show that the level of antiretroviral drug resistance in ART-naïve South Africans has reached moderate levels, as per the WHO classification. Therefore, regular surveys of pre-treatment drug resistance levels in all regions of South Africa is highly recommended to monitor the changing levels of pre-treatment antiretroviral drug resistance.
- ItemMolecular characterisation and epidemiology of enterovirus-associated aseptic meningitis in the Western and Eastern Cape Provinces, South Africa 2018–2019(Elsevier B.V., 2021-04) Nkosi, Nokwazi; Preiser, Wolfgang; Van Zyl, Gert; Claassen, Mathilda; Cronje, Nadine; Maritz, Jean; Newman, Howard; McCarthy, Kerrigan; Ntshoe, Genevie; Essel, Vivien; Korsman, Stephen; Hardie, Diana; Smuts, HeidiBackground: Enteroviruses are amongst the most common causes of aseptic meningitis. Between November 2018 and May 2019, an outbreak of enterovirus-associated aseptic meningitis cases was noted in the Western and Eastern Cape Provinces, South Africa. Objectives: To describe the epidemiology and phylogeography of enterovirus infections during an aseptic meningitis outbreak in the Western and Eastern Cape Provinces of South Africa. Methods: Cerebrospinal fluid samples from suspected cases were screened using a polymerase chain reaction targeting the 5’UTR. Confirmed enterovirus-associated meningitis samples underwent molecular typing through species–specific VP1/VP2 primers and pan-species VP1 primers. Results: Between November 2018 and May 2019, 3497 suspected cases of aseptic meningitis were documented in the Western and Eastern Cape Provinces. Median age was 8 years (range 0–61), interquartile range (IQR=4–13 years), 405/735 (55%) male. 742/3497 (21%) cases were laboratory – confirmed enterovirus positive by routine diagnostic PCR targeting the 5’UTR. 128/742 (17%) underwent molecular typing by VP1 gene sequencing. Echovirus 4 (E4) was detected in 102/128 (80%) cases. Echovirus 9 was found in 7%, Coxsackievirus A13 in 3%. 10 genotypes contributed to the remaining 10% of cases. Synonymous mutations were found in most cases, with sporadic amino acid changes in 13 (12.7%) cases. Conclusion: The aseptic meningitis outbreak was associated with echovirus 4. Stool samples are valuable for molecular typing in CSF confirmed EV-associated aseptic meningitis.
- ItemPandemic flu (H1N1) 2009 and pregnancy(Health and Medical Publishing Group (HMPG), 2010-04) Andersson, Monique I.; Van Zyl, Gert; Preiser, Wolfgang; Langenegger, Eduard; Theron, Gerhard
- ItemA qualitative PCR minipool strategy to screen for virologic failure and antiretroviral drug resistance in South African patients on first-line antiretroviral therapy(Elsevier, 2014-08) Newman, Howard; Breunig, Lukas; Van Zyl, Gert; Stich, August; Preiser, Wolfgang; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Pathology: Medical Virology.ENGLISH ABSTRACT: Background: The high cost of commercial HIV-1 viral load tests for monitoring of patients on antiretroviral treatment limits their use in resource-constrained settings. Commercial genotypic antiretroviral resistance testing is even more costly, yet it provides important benefits. Objectives: We sought to determine the sensitivity and negative predictive value of a qualitative PCR targeting partial reverse transcriptase for detection of virologic failure when 5 patient specimens are pooled. Study Design: A total of 300 South African routine patient samples were included and tested in 60 pools of 5 samples each. A qualitative nested PCR was optimised for testing pools and individual samples from positive pools. All positive samples were sequenced to detect drug resistance-associated mutations. Results were compared to those of conventional viral load monitoring. Results: Twenty-two of 60 pools tested positive. Individual testing yielded 29 positive individual samples. Twenty-six patients had viral loads of above 1000 copies per millilitre. The pooling algorithm detected 24 of those 26 patients, resulting in a negative predictive value of 99.3%, and a positive predictive value of 89.7%. The sensitivity for detecting patients failing therapy was 92%, with a specificity of 98.9%. Of the patients failing first-line ART, 83.3% had NRTI and 91.7% NNRTI resistance mutations. Conclusions: The pooled testing algorithm presented here required 43% fewer assays than conventional viral load testing. In addition to offering a potential cost saving over individual viral load testing, it also provided drug resistance information which is not available routinely in resourced-limited settings.