Controlling a human parainfluenza virus-3 outbreak in a haematology ward in a tertiary hospital: the importance of screening strategy and molecular diagnostics in relation to clinical symptoms

Molecular Epidemiology of Human Parainfluenza Virus Type 3 in Children With Acute Respiratory Tract Infection in Hangzhou

BACKGROUND

Since the outbreak of COVID-19, China has undertaken a variety of preventative and control measures, effectively reducing the incidence of numerous infectious diseases among the pediatric population in Hangzhou. We aim to investigate the genetic and epidemiological characteristics of Human parainfluenza virus-3 (HPIV-3) in pediatric patients during this period.

METHODS

A total of 1442 pharyngeal swab samples were collected from outpatients and inpatients with a diagnosis of acute respiratory tract infections (ARTIs) from November 2020 to March 2021. HPIV-3 was detected by quantitative real time polymerase chain reaction (qRT-PCR). The L gene of HPIV-3 positive samples was amplified and sequenced.

RESULTS

Among 1442 children with ARTI, the positive rate of HPIV-3 was 7.07% (102/1442). The positive detection rate was the highest in the 6-month to 1-year age group. Coinfection was observed in 36 HPIV-3-positive samples (35.29%, 36/102), and adenovirus (ADV) was the most common coinfecting virus (63.89%, 23/36). The L gene of 48 HPIV-3 positive samples was sequenced. The nucleotide sequence analysis showed high consistency (92.10%-99.40%), and all strains belonged to C3a.

CONCLUSIONS

During study periods, the positive detection rate of HPIV-3 among children is high, and the highest proportion of coinfection was observed in HPIV-3 mixed ADV infection. Phylogenetic analysis revealed that the nucleotide sequence of the L gene of HPIV-3 was highly consistent, and the main epidemic strain in this area was the C3a subtype.

Molecular epidemiology of a Parainfluenza Type 3 virus outbreak: Informing infection control measures on adult hematology wards

OBJECTIVES

Parainfluenza virus type 3 (PIV3) outbreaks among hematology patients are associated with high morbidity and mortality. Prompt implementation of infection prevention (IP) measures has proven to be the most efficacious approach for controlling PIV3 outbreaks within this patient population. The most suitable IP measures can vary depending on the mode of virus transmission, which remains unidentified in most outbreaks. We describe the molecular epidemiology of an outbreak of PIV3 among hematology patients and the development of a new method that allows for the differentiation of outbreak and community strains, from which a closed outbreak could be inferred.

METHODS

Patients were screened for respiratory viruses using multiplex-PCR. PIV3 positive samples with a cycle threshold (Ct)-value of <31 underwent a retrospective characterization via an in-house developed sequence analysis of the hemagglutinin-neuraminidase (HN) gene.

RESULTS

Between July and September 2022, 31 hematology patients were identified with PIV3. Although infection control measures were implemented, the outbreak persisted for nine weeks. Sequencing the HN gene of 27 PIV3 strains from 27 patients revealed that all outbreak strains formed a distinct cluster separate from the control strains, suggestive of a nosocomial transmission route.

CONCLUSIONS

Sequencing the HN gene of PIV3 strains in an outbreak setting enables outbreak strains to be distinguished from community strains. Early molecular characterization of PIV3 strains during an outbreak can serve as a tool in determining potential transmission routes. This, in turn, enables rapid implementation of targeted infection prevention measures, with the goal of minimizing the outbreak's duration and reducing associated morbidity and mortality.

Analysis of two sequential SARS-CoV-2 outbreaks on a haematology-oncology ward and the role of infection prevention

Two SARS-CoV-2 nosocomial outbreaks occurred on the haematology ward of our hospital. Patients on the ward were at high risk for severe infection because of their immunocompromised status. Whole Genome Sequencing proved transmission of a particular SARS-CoV-2 variant in each outbreak. The first outbreak (20 patients/31 healthcare workers (HCW)) occurred in November 2020 and was caused by a variant belonging to lineage B.1.221. At that time, there were still uncertainties on mode of transmission of SARS-CoV-2, and vaccines nor therapy were available. Despite HCW wearing II-R masks in all patient contacts and FFP-2 masks during aerosol generating procedures (AGP), the outbreak continued. Therefore, extra measures were introduced. Firstly, regular PCR-screening of asymptomatic patients and HCW; positive patients were isolated and positive HCW were excluded from work as a rule and they were only allowed to resume their work if a follow-up PCR CT-value was ≥30 and were asymptomatic or having only mild symptoms. Secondly, the use of FFP-2 masks was expanded to some long-lasting, close-contact, non-AGPs. After implementing these measures, the incidence of new cases declined gradually. Thirty-seven percent of patients died due to COVID-19. The second outbreak (10 patients/2 HCW) was caused by the highly transmissible omicron BA.1 variant and occurred in February 2022, where transmission occurred on shared rooms despite the extra infection control measures. It was controlled much faster, and the clinical impact was low as the majority of patients was vaccinated; no patients died and symptoms were relatively mild in both patients and HCW.

Predicting the next pandemic: VACCELERATE ranking of the WorldHealth Organization's Blueprint forAction toPreventEpidemics

INTRODUCTION

The World Health Organization (WHO)'s Research and Development (R&D) Blueprint for Action to Prevent Epidemics, a plan of action, highlighted several infectious diseases as crucial targets for prevention. These infections were selected based on a thorough assessment of factors such as transmissibility, infectivity, severity, and evolutionary potential. In line with this blueprint, the VACCELERATE Site Network approached infectious disease experts to rank the diseases listed in the WHO R&D Blueprint according to their perceived risk of triggering a pandemic. VACCELERATE is an EU-funded collaborative European network of clinical trial sites, established to respond to emerging pandemics and enhance vaccine development capabilities.

METHODS

Between February and June 2023, a survey was conducted using an online form to collect data from members of the VACCELERATE Site Network and infectious disease experts worldwide. Participants were asked to rank various pathogens based on their perceived risk of causing a pandemic, including those listed in the WHO R&D Blueprint and additional pathogens.

RESULTS

A total of 187 responses were obtained from infectious disease experts representing 57 countries, with Germany, Spain, and Italy providing the highest number of replies. Influenza viruses received the highest rankings among the pathogens, with 79 % of participants including them in their top rankings. Disease X, SARS-CoV-2, SARS-CoV, and Ebola virus were also ranked highly. Hantavirus, Lassa virus, Nipah virus, and henipavirus were among the bottom-ranked pathogens in terms of pandemic potential.

CONCLUSION

Influenza, SARS-CoV, SARS-CoV-2, and Ebola virus were found to be the most concerning pathogens with pandemic potential, characterised by transmissibility through respiratory droplets and a reported history of epidemic or pandemic outbreaks.