Human metapneumovirus infection: Diagnostic impact of radiologic imaging

Viral Pneumonias

Viral pneumonia is usually community acquired and caused by influenza, parainfluenza, respiratory syncytial virus, human metapneumovirus, and adenovirus. Many of these infections are airway centric and chest imaging demonstrates bronchiolitis and bronchopneumonia, With the exception of adenovirus infections, the presence of lobar consolidation usually suggests bacterial coinfection. Community-acquired viral pathogens can cause more severe pneumonia in immunocompromised hosts, who are also susceptible to CMV and varicella infection. These latter 2 pathogens are less likely to manifest the striking airway-centric pattern. Airway-centric pattern is distinctly uncommon in Hantavirus pulmonary syndrome, a rare environmentally acquired infection with high mortality.

Community-Acquired Pneumonia: Postpandemic, Not Post-COVID-19

The coronavirus disease 2019 (COVID-19) pandemic upended our approach to imaging community-acquired pneumonia, and this will alter our diagnostic algorithms for years to come. In light of these changes, it is worthwhile to consider several postpandemic scenarios of community-acquired pneumonia: (1) patient with pneumonia and recent positive COVID-19 testing; (2) patient with air space opacities and history of prior COVID-19 pneumonia (weeks earlier); (3) multifocal pneumonia with negative or unknown COVID-19 status; and (4) lobar or sublobar pneumonia with negative or unknown COVID-19 status. In the setting of positive COVID-19 testing and typical radiologic findings, the diagnosis of COVID-19 pneumonia is generally secure. The diagnosis prompts vigilance for thromboembolic disease acutely and, in severely ill patients, for invasive fungal disease. Persistent or recurrent air space opacities following COVID-19 infection may more often represent organizing pneumonia than secondary infection. When COVID-19 status is unknown or negative, widespread airway-centric disease suggests infection with mycoplasma, Haemophilus influenzae, or several respiratory viruses. Necrotizing pneumonia favors infection with pneumococcus, Staphylococcus, Klebsiella, and anaerobes. Lobar or sublobar pneumonia will continue to suggest the diagnosis of pneumococcus or consideration of other pathogens in the setting of local outbreaks. A positive COVID-19 test accompanied by these imaging patterns may suggest coinfection with one of the above pathogens, or when the prevalence of COVID-19 is very low, a false positive COVID-19 test. Clinicians may still proceed with testing for COVID-19 when radiologic patterns are atypical for COVID-19, dependent on the patient's exposure history and the local epidemiology of the virus.

Clinical impact of human metapneumovirus infections before and during the COVID-19 pandemic

BACKGROUND

The first outbreak of coronavirus disease 2019 (COVID-19) occurred in March 2020 in Europe, which is normally the peak incidence period of human metapneumovirus (HMPV) infections, implying cocirculation and potentially causing competition between them.

METHODS

We investigated differences in clinical characteristics and outcomes of HMPV infections in hospitalized patients before (January 2016-28 February, 2020) and HMPV and COVID-19 during part of the COVID-19 pandemic (28 February, 2020-1 April, 2020).

RESULTS

A total of 239 HMPV patients and 303 COVID-19 patients were included. Incidence of HMPV peaked in March. Despite a 324% increase in HMPV testing during the COVID-19 outbreak, incidence of HMPV remained stable. Clinical characteristics showed 25 (11%) ICU admissions and 14 (6%) deaths. History of myocardial infarction, higher age and lower BMI were independently associated with increased 30-day mortality. Clinical characteristics of HMPV-infected patients did not differ between the non-COVID-19 period and the examined COVID-19 period except for length of hospital stay (7 vs. 5 days). HMPV infection and COVID-19 shared many clinical features but HMPV was associated with female gender, elderly patients and chronic conditions (COPD and chronic heart failure). Clinical outcomes did not differ between the viruses during the COVID-19 period.

CONCLUSIONS

The clinical impact of HMPV infection did not change during the COVID-19 outbreak in terms of incidence and/or disease severity; hence, HMPV and SARS-CoV-2 are probably co-circulating independently. Despite the current clinical focus on the COVID-19 pandemic, clinicians should keep in mind that HMPV-infection may mimic COVID-19 and is also associated with serious adverse outcomes.

Lower Respiratory Tract Infection with Human Metapneumovirus: Chest CT Imaging Features and Comparison with Other Viruses

PURPOSE

Human metapneumovirus has been increasingly identified as a cause of lower respiratory tract infection in adults worldwide. The CT imaging features of human metapneumovirus in adults have not been characterized. The purpose of this paper is to determine the imaging features of human metapneumovirus and to compare them with features of other viruses.

METHODS

Two clinicians retrospectively reviewed the medical records of 104 adults with lower respiratory tract infection due to human metapneumovirus at four hospitals in the northeast USA over 32 months. CT images were evaluated by two chest radiologists for airspace consolidation, bronchiectasis, bronchial wall thickening, ground-glass opacities, pleural effusion and tree-in-bud opacities and the dominant imaging pattern. Results for human metapneumovirus were compared with results previously reported for other viruses.

RESULTS

Human metapneumovirus predominantly caused an airway-centric pattern (71-81/104, 68-77%) of infection characterized by bronchial wall thickening, tree-in-bud opacities, peri-bronchial consolidation and/or peri-bronchial ground-glass opacities. The airway-centric pattern has been previously reported with other paramyxoviridae (parainfluenza virus and respiratory syncytial virus). However, human metapneumovirus was significantly more likely (p = 0.03-0.001) to cause bronchopneumonia (46-55%) than parainfluenza virus (17%) or respiratory syncytial virus (21%). Follow-up CT in 41 (39%) patients with hMPV revealed resolution of findings in 38/41 (91%).

CONCLUSION

The paramyxoviridae, including human metapneumovirus, are known to have a propensity to infect ciliated respiratory cells and we have demonstrated this leads to a propensity to cause bronchitis, bronchiolitis and bronchopneumonia on CT scans. Of these, human metapneumovirus is most likely to cause bronchopneumonia. Healthcare providers should consider human metapneumovirus as a cause of pneumonia on chest CT.

The clinical characteristics of pneumonia patients coinfected with 2019 novel coronavirus and influenza virus in Wuhan, China

The outbreak of 2019 novel coronavirus (COVID-19) infection emerged in Wuhan, China, in December 2019. Since then the novel coronavirus pneumonia disease has been spreading quickly and many countries and territories have been affected, with major outbreaks in China, South Korea, Italy, and Iran. Influenza virus has been known as a common pathogen in winter and it can cause pneumonia. It was found clinically that very few patients were diagnosed with both COVID-19 and influenza virus. A total of 5 of the 115 patients confirmed with COVID-19 were also diagnosed with influenza virus infection, with three cases being influenza A and two cases being influenza B. In this study, we describe the clinical characteristics of those patients who got infected with COVID-19 as well as influenza virus. Common symptoms at onset of illness included fever (five [100%] patients), cough (five [100%] patients), shortness of breath (five [100%] patients), nasal tampon (three [60%] patients), pharyngalgia (three [60%] patients), myalgia (two [40%] patients), fatigue (two [40%] patients), headache (two [40%] patients), and expectoration (two [40%] patients). The laboratory results showed that compared to the normal values, the patients' lymphocytes were reduced (four [80%] patients), and liver functions alanine aminotransferase and aspartate aminotransferase (two [40%] patients and two [40%] patients) and C-reactive protein (four [80%] patients) were increased when admitted to hospital. They stayed in the hospital for 14, 30, 17, 12, and 19 days (28.4 ± 7.02), respectively. The main complications for the patients were acute respiratory distress syndrome (one [20%] patients), acute liver injury (three [60%] patients), and diarrhea (two [40%] patients). All patients were given antiviral therapy (including oseltamivir), oxygen inhalation, and antibiotics. Three patients were treated with glucocorticoids including two treated with oral glucocorticoids. One of the five patients had transient hemostatic medication for hemoptysis. Fortunately, all patients did not need intensive care unit and were discharged from the hospital without death. In conclusion, those patients with both COVID-19 and influenza virus infection did not appear to show a more severe condition because based on the laboratory findings, imaging studies, and patient prognosis, they showed similar clinical characteristics as those patients with COVID-19 infection only. However, it is worth noting that the symptoms of nasal tampon and pharyngalgia may be more prone to appear for those coinfection 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.