Human Metapneumovirus Infection in HIV Patients

Abstract & Commentary

By Dean L. Winslow, MD, FACP, FIDSA, Chief, Division of AIDS Medicine, Santa Clara Valley Medical Center; Clinical Professor, Stanford University School of Medicine, is Associate Editor for Infectious Disease Alert.

Synopsis: In a prospective surveillance study, 50 HIV-positive patients who presented with febrile respiratory symptoms were evaluated for the presence of respiratory viruses by multiplex RT-PCR and a microarray assay and for atypical bacterial pathogens by PCR, in addition to sputum cultures and serologic testing. Viruses accounted for 64% of the infections. Influenza virus was identified in 22 cases, and human metapneumovirus (hMPV) was next most common, with six cases.

Source: Klein MB, et al. Viral pathogens including human metapneumovirus are the primary cause of febrile respiratory illness in HIV-infected adults receiving antiretroviral therapy. J Infect Dis. 2010;201:297-301.

Fifty consecutive patients from a large HIV clinic in Montreal, who presented with febrile respiratory symptoms (temperature > 38° C and one or more respiratory symptom) from November 2003-April 2006, were recruited for this prospective study. An in-house multiplex real-time PCR assay was originally used to test NP samples for influenza A and B, RSV, and hMPV. Frozen aliquots of the original samples were later tested for adenovirus groups A, B, C, and E; rhinovirus A and B; influenza A and B, hMPV A and B; RSV A and B; parainfluenza types 1-3; coronaviruses HKU1, 229E, NL63, and OC43; and enteroviruses A-D using a commercial microarray assay. Paired acute and convalescent sera were analyzed by complement fixation. NP samples were tested for rRNA genes of M. pneumoniae, C. pneumoniae, and L. pneumophila. From all individuals with productive cough, a sputum sample was sent for bacterial culture and sensitivity.

Twenty-two patients were found to be infected with influenza virus, 12 with noninfluenza viral pathogens, six had bacterial infections, and 16 were not diagnosed. Patients with influenza had a median CD4+ lymphocyte count of 280, and those with noninfluenza viral infections had a median CD4+ count of 484. In addition to fever and myalgias, the patients with hMPV infection had predominant lower respiratory tract symptoms, with cough, dyspnea, and wheezing in most cases. Only one of the hMPV cases was complicated by documented bacterial infection (bacteremic pneumococcal disease). While the hMPV patients were less immunosuppressed than the influenza patients, almost all had underlying asthma.

Commentary

This study, while small, highlights the potential importance of hMPV as a cause of febrile respiratory symptoms in adult patients with HIV. While some obvious caveats to the generalizability of the findings in this study apply (e.g., hMPV may or may not cause this high proportion of febrile respiratory infections in all years and in all areas of North America), the association of hMPV with prominent lower respiratory signs and symptoms, and association with underlying asthma, is notable. The authors note that despite the fact that only one hMPV-infected patient had documented bacterial superinfection, > 80% received antibiotics despite normal chest X-rays. The promise of rapid, sensitive, molecular diagnostic assays for viral pathogens in clinical use would seem to have the potential to reduce unnecessary prescription of antibiotics. However, the costs of these assays and the turn-around times need to be markedly reduced in order for this to become a reality.