Nicolette du Plessis

Prof. Nicolette du Plessis

University of Pretoria, Pretoria, South Africa
orcid

Research Focus & Metrics

Academic Career Length

13Years (2014-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

View All Publications
30 January 2021 in Viruses
Verified
Journal Article
Open access
PDF file
EREsmari Rossouw
Esmari Rossouw
MBMarieke Brauer
Marieke Brauer
Pieter MeyerPieter Meyer
Pieter Meyer
NPNicolette du Plessis
Nicolette du Plessis
TATheunis Avenant
Theunis Avenant
JMJanet Mans
Janet Mans
Background: Viral gastroenteritis remains a major cause of hospitalisation in young children. This study aimed to determine the distribution and diversity of enteric viruses in children ≤5 years, hospitalised with gastroenteritis at Kalafong Provincial Tertiary Hospital, Pretoria, South Africa, between July 2016 and December 2017. Methods: Stool specimens (n = 205) were screened for norovirus GI and GII, rotavirus, sapovirus, astrovirus and adenovirus by multiplex RT-PCR. HIV exposure and FUT2 secretor status were evaluated. Secretor status was determined by FUT2 genotyping. Results: At least one gastroenteritis virus was detected in 47% (96/205) of children. Rotavirus predominated (46/205), followed by norovirus (32/205), adenovirus (15/205), sapovirus (9/205) and astrovirus (3/205). Norovirus genotypes GI.3, GII.2, GII.3, GII.4, GII.7, GII.12, GII.21, and rotavirus strains G1P[8], G2P[4], G2P[6], G3P[4], G3P[8], G8P[4], G8P[6], G9P[6], G9P[8] and sapovirus genotypes GI.1, GI.2, GII.1, GII.4, GII.8 were detected; norovirus GII.4[P31] and rotavirus G3P[4] predominated. Asymptomatic norovirus infection (GI.3, GI.7, GII.4, GII.6, GII.13) was detected in 22% of 46 six-week follow up stools. HIV exposure (30%) was not associated with more frequent or severe viral gastroenteritis hospitalisations compared to unexposed children. Rotavirus preferentially infected secretor children (p = 0.143) and norovirus infected 78% secretors and 22% non-secretors. Conclusion: Rotavirus was still the leading cause of gastroenteritis hospitalisations, but norovirus caused more severe symptoms.

21 December 2021 in medRxiv
Verified
Preprint
Open access
PDF file
JCJeané Cloete
Jeané Cloete
AKAnnelet Kruger
Annelet Kruger
MMMaureen Masha
Maureen Masha
NPNicolette du Plessis
Nicolette du Plessis
DMDini Mawela
Dini Mawela
Ute FeuchtUte Feucht
Ute Feucht
Background: South Africa reported a notable increase in COVID-19 cases from mid-November 2021 onwards, starting in Tshwane District, linked to rapid community spread of the Omicron variant. This coincided with a rapid rise in paediatric COVID-19-associated hospitalisations. Methods: We synthesized data from five sources to describe the impact of Omicron on clinical manifestations and outcomes of hospitalized children (≤19 years) with positive SARS-CoV-2 tests in Tshwane District from 31 October to 11 December 2021, including: 1) COVID-19 line lists; 2) collated SARS-CoV-2 testing data; 3) SARS-CoV-2 genomic sequencing data; 4) COVID-19 hospitalisation surveillance; and 5) clinical data of public sector paediatric (≤13 years) COVID-19 hospitalisations. Findings: During the six-week period 6,287 paediatric (≤19 years) COVID-19 cases were recorded in Tshwane District, of these 462 (7.2%) were hospitalized in 42 hospitals (18% of overall admissions). The number of paediatric cases was higher than in the prior 3 waves, uncharacteristically preceding adult hospitalisations. Of the 75 viral specimens sequenced from the district, 99% were Omicron. Detailed clinical information obtained from 139 of 183 (76%) admitted children (≤13 years; including all public sector hospitalisations) indicated that young children (0-4 years) were most affected (62%). Symptoms included fever (47%), cough (40%), vomiting (24%), difficulty breathing (23%), diarrhoea (20%) and convulsions (20%). Length of hospital stay was short (mean 3.2 days), and in 44% COVID-19 was the primary diagnosis. Most children received standard ward care (92%), with 31 (25%) receiving oxygen therapy. Seven children (6%) were ventilated; four children died, all related to complex underlying co-pathologies. All children and majority of parents for whom data were available were unvaccinated. Interpretation: Rapid increases in paediatric COVID-19 cases and hospitalisations mirror high community transmission of SARS-CoV-2 (Omicron variant) in Tshwane District, South Africa. Continued monitoring is needed to understand the long-term impact of the Omicron variant on children. Research in context: Evidence before the study: The announcement of the new Omicron (B.1.1.529) variant of the SARS-CoV-2 virus was made on 24 November 2021. Clinical characteristics, and disease profiles of children with COVID-19 before the arrival of Omicron have been described in the literature. Added value of the study: This study describes the rapid rise in paediatric COVID-19-associated hospitalisations in Tshwane District in the Gauteng Province of South Africa – one of the first known epicentres of the new Omicron variant of the SARS-CoV-2 virus. The clinical picture as well as the steep increase in paediatric positivity rates and hospitalizations are described in detail from the perspective of a large South African health district, providing a broad overview on how the Omicron variant affects the paediatric population. Implication of all available evidence: This study describes the clinical picture and outcomes in children in the current wave of SARS-CoV-2 Omicron variant infections by incorporating data from 42 hospitals at all levels of care in a large district within the South African health system. This provides novel paediatric data to assist global preparation for the impact of the Omicron variant in the paediatric setting.

2 November 2023 in Viruses
Verified
Journal Article
Open access
PDF file
CMCaitlin MacIntyre
Caitlin MacIntyre
CLCarla Lourens
Carla Lourens
AMAdriano Mendes
Adriano Mendes
MVMaryke De Villiers
Maryke De Villiers
TATheunis Avenant
Theunis Avenant
MVMarietjie Venter
Marietjie Venter
West Nile virus (WNV), a mosquito-borne flavivirus, is endemic to South Africa. However, its contribution to acute febrile and neurological disease in hospitalized patients in South Africa is unknown. This study examined two patient cohorts for WNV using molecular testing and IgM serology with confirmation of serological results by viral neutralization tests (VNT) to address this knowledge gap. Univariate analysis was performed using collected demographic and clinical information to identify risk factors. In the first cohort, 219 cerebrospinal fluid (CSF) specimens from patients with acute neurological disease in Gauteng hospitals collected in January to June 2017 were tested for WNV. The study identified WNV in 8/219 (3.65%, 95.00% CI (1.59–7.07)) patients with unsolved neurological infections. The second cohort, from 2019 to 2021, included 441 patients enrolled between January and June with acute febrile or neurological disease from urban and rural sites in Gauteng and Mpumalanga provinces. West Nile virus was diagnosed in 40/441 (9.07%, 95.00% CI (6.73–12.12)) of patients, of which 29/40 (72.50%, 95.00% CI (56.11–85.40)) had neurological signs, including headaches, encephalitis, meningitis, and acute flaccid paralysis (AFP). Notably, most of the cases were identified in children although adolescents and senior adults had a significantly higher risk of testing WNV positive. This suggests a previously underestimated disease burden and that WNV might be underrecognized as a cause of febrile and neurological diseases in hospitalized patients in South Africa, especially in children. This emphasizes the importance of further research and awareness regarding arboviruses of public health concern.

5 March 2024 in Viruses
Verified
Journal Article
Open access
PDF file
MDMichaela Davids
Michaela Davids
SJSiobhan Johnstone
Siobhan Johnstone
AMAdriano Mendes
Adriano Mendes
GBGadean Brecht
Gadean Brecht
TATheunis Avenant
Theunis Avenant
MVMarietjie Venter
Marietjie Venter
Severe acute respiratory tract infections (SARIs) has been well described in South Africa with seasonal patterns described for influenza and respiratory syncytial virus (RSV), while others occur year-round (rhinovirus and adenovirus). This prospective syndromic hospital-based surveillance study describes the prevalence and impact of public interventions on the seasonality of other respiratory pathogens during the coronavirus disease-19 (COVID-19) pandemic. This occurred from August 2018 to April 2022, with 2595 patients who met the SARS case definition and 442 controls, from three sentinel urban and rural hospital sites in South Africa. Naso/oro-pharyngeal (NP/OP) swabs were tested using the FastTrack Diagnostics® Respiratory pathogens 33 (RUO) kit. Descriptive statistics, odds ratios, and univariate/multivariate analyses were used. Rhinovirus (14.80%, 228/1540) and Streptococcus pneumoniae (28.50%, 439/1540) were most frequently detected in NP/OP swabs and in children <1 years old (35%, 648/1876). Among others, pathogens associated with SARI cases causing disease were influenza A&B, HRV, RSV, hCoV 229e, Haemophilus influenzae, Staphylococcus aureus, and Streptococcus pneumoniae. Pre-COVID-19, seasonal trends of these pathogens correlated with previous years, with RSV and influenza A seasons only resuming after the national lockdown (2021). It is evident that stringent lockdown conditions have severe impacts on the prevalence of respiratory tract infections.

1 November 2014 in Journal of Clinical Virology
Verified
Journal Article
Closed access
MWMarianne Wolfaardt
Marianne Wolfaardt
ABAné Büchner
Ané Büchner
MMMarcelle Myburgh
Marcelle Myburgh
TATheunis Avenant
Theunis Avenant
NPNicolette du Plessis
Nicolette du Plessis
MTMaureen Taylor
Maureen Taylor

30 November 2022 in Scientific Reports
Verified
Journal Article
Open access
PDF file
NPNicolette du Plessis
Nicolette du Plessis
AMAhmad Haeri Mazanderani
Ahmad Haeri Mazanderani
NMNkengafac Villyen Motaze
Nkengafac Villyen Motaze
MNMakhosazane Ngobese
Makhosazane Ngobese
TATheunis Avenant
Theunis Avenant
Hepatitis A virus (HAV) infection is one of the most important global causes of viral hepatitis. Recent reviews suggested that HAV endemicity in South Africa could shift from high to intermediate. A hospital-based HAV seroprevalence study was conducted between February 2018 and December 2019 in Pretoria, South Africa. Systematic sampling was performed on children and adolescents (1–15 years) who attended outpatient services. Participants with a known HIV status and valid HAV serology results were included. Of the 1220 participants, the median age was 7 years (IQR: 4–11), with 648 (53.11%) males and 572 (46.89%) females. Of 628 (51.48%) HIV-infected participants, most (329, 71.83%) were both immunologically and virologically controlled or had low-level viremia (74, 16.16%). Almost three-quarters (894, 73.28%) were living in formal dwellings, and just over half (688, 56.39%) had access to clean water sources inside the house. Increasing age was associated with testing HAV IgG-positive (OR 1.25; 95% CI 1.20–1.30, p < 0.001), with 19.8% of participants one year of age compared with 86.7% of participants 15 years of age. This study suggests that South Africa has an intermediate HAV seroprevalence, with rates < 90% by 10 years of age (68.6%). Increased age and informal dwellings are statistically associated with HAV seropositivity, while HIV status does not significantly influence HAV seropositivity.