Clinical Features of Human Metapneumovirus Pneumonia in Non-Immunocompromised Patients: An Investigation of Three Long-Term Care Facility Outbreaks

Burden of respiratory syncytial virus, human metapneumovirus and influenza virus infections in Japanese adults in the Hospitalized Acute Respiratory Tract Infection study

BACKGROUND

Respiratory syncytial virus (RSV), human metapneumovirus (hMPV), and influenza virus are responsible for acute respiratory tract infections (ARTIs) in adults. We assessed the clinical burden of RSV, hMPV and influenza virus infection among Japanese adults hospitalized with ARTIs.

METHODS

The Hospitalized Acute Respiratory Tract Infection (HARTI) study was a multinational, prospective cohort study in adults with ARTIs across the 2017-2019 epidemic seasons. Enrolment in Japan began in Sept 2018 and ran until Oct 2019. The clinical diagnosis of ARTI and the decision to hospitalize the patient were made according to local standard of care practices. Viral testing was performed by reverse transcription polymerase chain reaction.

RESULTS

Of the 173 adults hospitalized with ARTI during this period at the Japan sites, 7 (4.0%), 9 (5.2%), and 11 (6.4%) were positive for influenza virus, RSV, and hMPV, respectively. RSV season was observed from Oct 2018 to Jan 2019, followed by influenza from Dec 2018 to Apr 2019. hMPV was detected across both the RSV and influenza seasons. Two patients with RSV and 1 patient with hMPV required ICU admission whereas none with influenza. Use of antibiotics, bronchodilators and inhaled corticosteroids was high amongst patients with RSV and hMPV at 1, 2, and 3 months' post-discharge compared with patients with influenza, with few exceptions.

CONCLUSION

These findings highlight the need for a high degree of clinical suspicion for RSV and hMPV infection in adults hospitalized with ARTIs.

[Respiratory infections: Additional transmission-based precautions in healthcare facilities]

INTRODUCTION

In health care, measures against cross-transmission of microorganisms are codified by standard precautions, and if necessary, they are supplemented by additional precautions.

STATE OF THE ART

Several factors impact transmission of microorganisms via the respiratory route: size and quantity of the emitted particles, environmental conditions, nature and pathogenicity of the microorganisms, and degree of host receptivity. While some microorganisms necessitate additional airborne or droplet precautions, others do not.

PROSPECTS

For most microorganisms, transmission patterns are well-understood and transmission-based precautions are well-established. For others, measures to prevent cross-transmission in healthcare facilities remain under discussion.

CONCLUSIONS

Standard precautions are essential to the prevention of microorganism transmission. Understanding of the modalities of microorganism transmission is essential to implementation of additional transmission-based precautions, particularly in view of opting for appropriate respiratory protection.

Evaluation of multiple open-source deep learning models for detecting and grading COVID-19 on chest radiographs

Purpose: Chest x-rays are complex to report accurately. Viral pneumonia is often subtle in its radiological appearance. In the context of the COVID-19 pandemic, rapid triage of cases and exclusion of other pathologies with artificial intelligence (AI) can assist over-stretched radiology departments. We aim to validate three open-source AI models on an external test set.

Approach: We tested three open-source deep learning models, COVID-Net, COVIDNet-S-GEO, and CheXNet for their ability to detect COVID-19 pneumonia and to determine its severity using 129 chest x-rays from two different vendors Phillips and Agfa.

Results: All three models detected COVID-19 pneumonia (AUCs from 0.666 to 0.778). Only the COVID Net-S-GEO and CheXNet models performed well on severity scoring (Pearson’s r 0.927 and 0.833, respectively); COVID-Net only performed well at either task on images taken with a Philips machine (AUC 0.735) and not an Agfa machine (AUC 0.598).

Conclusions: Chest x-ray triage using existing machine learning models for COVID-19 pneumonia can be successfully implemented using open-source AI models. Evaluation of the model using local x-ray machines and protocols is highly recommended before implementation to avoid vendor or protocol dependent bias.

Human metapneumovirus-associated community-acquired pneumonia in adults during the first wave of COVID-19

Objective: The clinical course of human metapneumovirus (hMPV) infection is similar to that of coronavirus 2019 disease (COVID-19). However, community-acquired hMPV infections in adults have not yet been sufficiently investigated. We examined the detection status of hMPV antigens and the clinical features of positive patients during the first wave of COVID-19, which coincided with the epidemic season of hMPV infection in Japan.

Methods: In this cross-sectional, observational, and single-center study, we recruited consecutive individuals who visited the Japan Agricultural Cooperatives Kochi Hospital due to fever, respiratory symptoms, or close contact with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infected persons during the period from January to May 2020.

Results: The positive rate of immunochromatography for hMPV antigens from nasopharyngeal swabs was 9.5% (4/42), and four positive cases were community-acquired pneumonia (CAP) (5.3% of all CAP). The positive rate of hMPV antigens in the CAP group (30.8%, 4/13) was higher than that in the non-pneumonia group (0.0%, 0/19) (p < 0.05). The average age of the four adult patients with CAP was 69.8 years (range 35–93). Mean white blood cell counts and C-reactive protein blood levels were 6,250 cells/μL (3,500–12,180) and 4.30 mg/dL (4.05–7.04), respectively. Chest computed tomography images were diverse and two patients showed dense consolidation. No multi-organ disorder was noted during the clinical course in any of the four cases, and their prognoses were good.

Conclusion: hMPV infection may be considered in the differential diagnosis of COVID-19 and CAP in Japan under the preventive measures for SARS-CoV-2 infection, at least during the epidemic season of hMPV infection.

Clinical and Radiologic Characteristics of Human Metapneumovirus Infections in Adults, South Korea

Clinical features of human metapneumovirus (HMPV) infection have not been well documented for adults. We investigated clinical and radiologic features of HMPV infection in 849 adults in a tertiary hospital in South Korea. We classified patients into groups on the basis of underlying diseases: immunocompetent patients, solid tumor patients, solid organ transplantation recipients, hematopoietic stem cell transplant recipients, hematologic malignancy patients, and patients receiving long-term steroid treatment. Of 849 HMPV-infected patients, 756 had community-acquired infections, 579 had pneumonia, and 203 had infections with other pathogens. Mortality rates were highest in hematopoietic stem cell transplantation recipients (22% at 30 days). Older age, current smoking, and underlying disease were associated with HMPV pneumonia. Body mass index and an immunocompromised state were associated with 30-day mortality rates in HMPV-infected patients. Bronchial wall thickening, ground-glass opacity, and ill-defined centrilobular nodules were common computed tomography findings for HMPV pneumonia. Macronodules and consolidation were observed in <50% of patients.

Human metapneumovirus infection: Diagnostic impact of radiologic imaging

Background

Human metapneumovirus (hMPV) is a recently detected virus, which can cause mild to severe respiratory tract infections. Through this study, we aimed to detail the outcomes of hMPV infections.

Materials/methods

Between January 2012 and November 2017, patients who had hMPV detected in nasopharyngeal or bronchoalveolar lavage by molecular respiratory pathogen tests were evaluated. The Food and Drug Administration cleared multiplexed‐polymerase chain reaction system (Idaho Technology, Salt Lake City, UT) was used for diagnosis. Chest radiography (CR) and computed tomography (CT) were evaluated by an expert radiologist.

Results

In total 100 patients were included, the mean age was 22.9 (0‐87) years, and 50% were male. The hospitalization rate was 52%. Lower respiratory system infection (LRTI) was diagnosed in 44 patients with clinical findings, and in 31 patients out of 44 the radiological findings supported the diagnosis. The LRTI rate was significantly higher in adults than children (66.7%‐32.8%; P = 0.001). In CR, peribronchovascular infiltration (PI) was the most common feature seen in 14 out of 18 patients and was generally bilateral (13 out of 18 patients). In CT imaging, ground‐glass opacity was the most common finding seen in 11 out of 16 patients and nodular consolidation in five patients. Ribavirin was given to four patients, three of whom were severe and required respiratory support. None of the patients died of hMPV infection.

Conclusions

The ground‐glass opacity in CT was similar to other respiratory virus infections, and PI in CR was very common and typical; however, nodular consolidation that may mimic bacterial infection was seen in one‐fourth of CT.

Human metapneumovirus (hMPV) is a recently detected virus which can cause mild to severe respiratory tract infections. Nodular consolidation that may mimics bacterial infection was detected in one fourth of CT administered patients. Clinicians should be alert that hMPV infection may present like a bacterial LRTI in radiologic imaging.