Epidemiologic and Genomic Analysis of SARS-CoV-2 Delta Variant Superspreading Event in Nightclub, the Netherlands, June 2021.

We report a severe acute respiratory syndrome coronavirus 2 superspreading event in the Netherlands after distancing rules were lifted in nightclubs, despite requiring a negative test or vaccination. This occurrence illustrates the potential for rapid dissemination of variants in largely unvaccinated populations under such conditions. We detected subsequent community transmission of this strain.

Erratum to: Direct-Acting Antiviral Treatment for Hepatitis C Genotypes Uncommon in High-Income Countries: A Dutch Nationwide Cohort Study.

[This corrects the article DOI: 10.1093/ofid/ofab006.].

Direct-Acting Antiviral Treatment for Hepatitis C Genotypes Uncommon in High-Income Countries: A Dutch Nationwide Cohort Study.

BACKGROUND: The majority of hepatitis C virus (HCV) infections are found in low- and middle-income countries, which harbor many region-specific HCV subtypes. Nevertheless, direct-acting antiviral (DAA) trials have almost exclusively been conducted in high-income countries, where mainly epidemically spread HCV subtypes are present. Recently, several studies have demonstrated suboptimal DAA efficacy for certain nonepidemic subtypes, which could hamper global HCV elimination. Therefore, we aimed to evaluate DAA efficacy in patients treated for a nonepidemic HCV genotype infection in the Netherlands. METHODS: We performed a nationwide retrospective study including patients treated with interferon-free DAAs for an HCV genotype other than 1a/1b/2a/2b/3a/4a/4d. The genotype was determined by NS5B region phylogenetic analysis. The primary end point was SVR-12. If stored samples were available, NS5A and NS5B sequences were obtained for resistance-associated substitutions (RAS) evaluation. RESULTS: We included 160 patients, mainly infected with nonepidemic genotype 2 (41%) and 4 (31%) subtypes. Most patients were from Africa (45%) or South America (24%); 51 (32%) were cirrhotic. SVR-12 was achieved in 92% (140/152) of patients with available SVR-12 data. Only 73% (8/11) genotype 3-infected patients achieved SVR-12, the majority being genotype 3b patients with 63% (5/8) SVR. Regardless of SVR, all genotype 3b patients had 30K and 31M RAS. CONCLUSIONS: The DAA efficacy we observed in most nonepidemic genotypes in the Netherlands seems reassuring. However, the low SVR-12 rate in subtype 3b infections is alarming, especially as it is common in several HCV-endemic countries. Alongside earlier results, our results indicate that a remaining challenge for global HCV elimination is confirming and monitoring DAA efficacy in nonepidemic genotypes.

High frequency and diversity of parechovirus A in a cohort of Malawian children.

Parechoviruses (PeVs) are highly prevalent viruses worldwide. Over the last decades, several studies have been published on PeV epidemiology in Europe, Asia and North America, while information on other continents is lacking. The aim of this study was to describe PeV circulation in a cohort of children in Malawi, Africa. A total of 749 stool samples obtained from Malawian children aged 6 to 60 months were tested for the presence of PeV by real-time PCR. We performed typing by phylogenetic and Basic Local Alignment Search Tool (BLAST) analysis. PeV was found in 57% of stool samples. Age was significantly associated with PeV positivity (p = 0.01). Typing by phylogenetic analysis resulted in 15 different types, while BLAST typing resulted in 14 different types and several indeterminate strains. In total, six strains showed inconsistencies in typing between the two methods. One strain, P02-4058, remained untypable by all methods, but appeared to belong to the recently reclassified PeV-A19 genotype. PeV-A1, -A2 and -A3 were the most prevalent types (26.8%, 13.8% and 9.8%, respectively). Both the prevalence and genetic diversity found in our study were remarkably high. Our data provide an important contribution to the scarce data available on PeV epidemiology in Africa.

Carriage of Blastocystis spp. in travellers - A prospective longitudinal study.

INTRODUCTION: A lack of prospective and longitudinal data on pre- and post-travel carriage of Blastocystis spp. complicates interpretation of a positive test post-travel. Therefore we studied dynamics of Blastocystis carriage in a cohort of Dutch travellers. METHODS: From the prospective, multicentre COMBAT study among 2001 Dutch travellers, a subset of 491 travellers was selected based on travel destination to 7 subregions (70 or 71 travellers each). Faecal samples taken directly before and after travel were screened for Blastocystis with qPCR, followed, when positive, by sequence analysis to determine subtypes. RESULTS: After exclusion of 12 samples with missing samples or inhibited qPCR-reactions, stool samples of 479 travellers were analysed. Before travel, 174 of them (36.3%) carried Blastocystis and in most of these, the same subtype was persistently carried. However, in 48/174 of those travellers (27.6%; CI95 20.8-36.6%) no Blastocystis or a different subtype was detected in the post-travel sample, indicating loss of Blastocystis during travel. Only 26 (5.4%; CI95 3.7%-8.0%) of all travellers acquired Blastocystis, including two individuals that were already positive for Blastocystis before travel but acquired a different subtype during travel. DISCUSSION: This study shows that Blastocystis carriage in travellers is highly dynamic. The observed acquisition and loss of Blastocystis could either be travel-related or reflect the natural course of Blastocystis carriage. We demonstrate that the majority of Blastocystis detected in post-travel samples were already carried before travel.

High frequency of Polio-like Enterovirus C strains with differential clustering of CVA-13 and EV-C99 subgenotypes in a cohort of Malawian children.

Enteroviruses (EVs) are among the most commonly detected viruses infecting humans worldwide. Although the prevalence of EVs is widely studied, the status of EV prevalence in sub-Saharan Africa remains largely unknown. The objective of our present study was therefore to increase our knowledge on EV circulation in sub-Saharan Africa. We obtained 749 fecal samples from a cross-sectional study conducted on Malawian children aged 6 to 60 months. We tested the samples for the presence of EVs using real time PCR, and typed the positive samples based on partial viral protein 1 (VP1) sequences. A large proportion of the samples was EV positive (89.9%). 12.9% of the typed samples belonged to EV species A (EV-A), 48.6% to species B (EV-B) and 38.5% to species C (EV-C). More than half of the EV-C strains (53%) belonged to subgroup C containing, among others, Poliovirus (PV) 1-3. The serotype most frequently isolated in our study was CVA-13, followed by EV-C99. The strains of CVA-13 showed a vast genetic diversity, possibly representing a new cluster, 'F'. The majority of the EV-C99 strains grouped together as cluster B. In conclusion, this study showed a vast circulation of EVs among Malawian children, with an EV prevalence of 89.9%. Identification of prevalences for species EV-C comparable to our study (38.5%) have only previously been reported in sub-Saharan Africa, and EV-C is rarely found outside of this region. The data found in this study are an important contribution to our current knowledge of EV epidemiology within sub-Saharan Africa.

Respiratory Viruses in Invasively Ventilated Critically Ill Patients-A Prospective Multicenter Observational Study.

OBJECTIVES: The presence of respiratory viruses and the association with outcomes were assessed in invasively ventilated ICU patients, stratified by admission diagnosis. DESIGN: Prospective observational study. SETTING: Five ICUs in the Netherlands. PATIENTS: Between September 1, 2013, and April 30, 2014, 1,407 acutely admitted and invasively ventilated patients were included. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Nasopharyngeal swabs and tracheobronchial aspirates were collected upon intubation and tested for 14 respiratory viruses. Out of 1,407 patients, 156 were admitted because of a severe acute respiratory infection and 1,251 for other reasons (non-severe acute respiratory infection). Respiratory viruses were detected in 28.8% of severe acute respiratory infection patients and 17.0% in non-severe acute respiratory infection (p < 0.001). In one third, viruses were exclusively detected in tracheobronchial aspirates. Rhinovirus and human metapneumovirus were more prevalent in severe acute respiratory infection patients (9.6% and 2.6% vs 4.5 and 0.2%; p = 0.006 and p < 0.001). In both groups, there were no associations between the presence of viruses and the number of ICU-free days at day 28, crude mortality, and mortality in multivariate regression analyses. CONCLUSIONS: Respiratory viruses are frequently detected in acutely admitted and invasively ventilated patients. Rhinovirus and human metapneumovirus are more frequently found in severe acute respiratory infection patients. Detection of respiratory viruses is not associated with worse clinically relevant outcomes in the studied cohort of patients.

The hepatitis C virus nonstructural protein 3 Q80K polymorphism is frequently detected and transmitted among HIV-infected MSM in the Netherlands.

OBJECTIVES: The Q80K polymorphism is a naturally occurring resistance-associated variant in the hepatitis C virus (HCV) nonstructural protein 3 (NS3) region and is likely transmissible between hosts. This study describes the Q80K origin and prevalence among HCV risk groups in the Netherlands and examines whether Q80K is linked to specific transmission networks. DESIGN AND METHODS: Stored blood samples from HCV genotype 1a-infected patients were used for PCR and sequencing to reconstruct the NS3 maximum likelihood phylogeny. The most recent common ancestor was estimated with a coalescent-based model within a Bayesian statistical framework. RESULTS: Study participants (n = 150) were either MSM (39%), people who inject drugs (17%), or patients with other (15%) or unknown/unreported (29%) risk behavior. Overall 45% was coinfected with HIV. Q80K was present in 36% (95% confidence interval 28-44%) of patients throughout the sample collection period (2000-2015) and was most prevalent in MSM (52%, 95% confidence interval 38-65%). Five MSM-specific transmission clusters were identified, of which three exclusively contained sequences with Q80K. The HCV-1a most recent common ancestor in the Netherlands was estimated in 1914 (95% higher posterior density 1879-1944) and Q80K originated in 1957 (95% higher posterior density 1942-1970) within HCV-1a clade I. All Q80K lineages could be traced back to this single origin. CONCLUSION: Q80K is a highly stable and transmissible resistance-associated variant and was present in a large part of Dutch HIV-coinfected MSM. The introduction and expansion of Q80K variants in this key population suggest a founder effect, potentially jeopardizing future treatment with simeprevir.