Most studies of human metapneumovirus (hMPV) have been done in pediatric populations. Many of these studies compare hMPV with respiratory syncytial virus or are case reports of hMPV infection in the immunosuppressed. Though there have been reports of outbreaks in nursing homes, far less is known about hMPV infections in adults. This study characterized the clinical epidemiologic characteristics of hMPV infections among inpatients at a large academic medical center.
During a three year period (20092011), we identified all adult patients with a positive hMPV culture. 89 positive cultures were identified. 69 of these cases were in inpatients. Eight of these were duplicate patient cultures. Thus, 61 unique inpatient cases were identified. Data were collected on patient demographics, comorbidities, presenting symptoms, ICU stays, intubation, bronchoscopies, radiographic findings, and discharge diagnoses. Descriptive statistics were used to determine characteristics and trends within the group.
A mean of 5.8 days was needed for a positive hMPV culture to be identified. On average, 76% of patients had already been discharged by the time the culture returned positive. 12% of cultures were sputum cultures, 9% were BAL cultures, and the remainder were detected on nasopharyngeal cultures. hMPV infections had a seasonal distribution, with the overwhelming majority of cases occurring between January through May. 17% of those with positive hMPV cultures had alternate positive cultures that could explain patient symptoms. Only 41% had significant focal chest xray abnormalities. Unsurprisingly, 80% of patients had lower respiratory symptoms and 53% had fever. Surprisingly, 24% of patients had gastrointestinal symptoms, which was more than the 19% of patients who had upper respiratory symptoms. Less common symptoms included myalgias/arthralgias (14%) and headache (10%). An equal percentage (36%) of patients were immunosuppressed or had comorbid lung disease. 24% had underlying CHF. Twelve patients with hMPV were deceased within one year of the infection, and half of those died in relation to the hospitalization in which the hMPV infection was identified. Of these half dozen cases, 2/3 of the patients were immunosuppressed. Overall, 29% of patients required an ICU stay, 20% underwent bronchoscopy, 15% required intubation, and 12% developed ARDS. 61% had a discharge diagnosis of pneumonia; 22% were diagnosed with COPD exacerbation.
hMPV is an important pathogen, especially in those who are immunosuppressed and/or those with underlying lung disease. In the latter group, the presentation was often consistent with a COPD exacerbation. While the presence of fever or respiratory symptoms is unsurprising, many patients also had GI symptoms. The lengthy 5.8 days to positive culture indicated that a switch to PCR will detect the virus significantly more quickly, which could possibly lead to decreased antibiotic use.
Figure 1Budding human metapneumovirus.
To cite this abstract:Chenoweth C, Dastidar J. The Clinical Epidemiology of Human Metapneumovirus Infections in the Adult Inpatient Population. Abstract published at Hospital Medicine 2012, April 1-4, San Diego, Calif. Abstract 97641. Journal of Hospital Medicine. 2012; 7 (suppl 2). https://www.shmabstracts.com/abstract/the-clinical-epidemiology-of-human-metapneumovirus-infections-in-the-adult-inpatient-population/. Accessed November 18, 2019.