Human metapneumovirus infection as an emerging pathogen causing acute respiratory distress syndrome

Epidemiological survey in a day care center following toddler sudden death due to human metapneumovirus infection

We report the sudden death of a 33-month-old child owing to acute respiratory distress syndrome due to human metapneumovirus (hMPV) infection. Of 30 children attending the same day care centre, 26% and 59% had hMPV and multiple infections, respectively; three of six children with pneumonia had a diagnosis of hMPV. hMPV infection is common in childhood viral co-infections but it can cause sudden death.

Detection of human Metapneumovirus infection in children under 18 years old hospitalized in Lima-Peru

Background

Human Metapneumovirus (hMPV) is a negative single-stranded RNA virus. Infection by hMPV mainly affects the pediatric population and can cause upper or lower respiratory tract pathologies which can develop life threating complications. This study was carried out between 2009 and 2010 in a high complexity national hospital in Lima, Peru. The time frame corresponds to the pandemic of influenza A H1N1.

Methods

A prospective study was performed between September 2009 and September 2010. Patients with a clinical diagnosis suggestive of an acute respiratory infection were included. RT-PCR was utilized to attain the amplification and identification of the hMPV.

Results

A total of 539 samples were analyzed from patients with a clinical context suggestive of an acute respiratory tract infection. Of these samples 73, (13.54%) were positive for hMPV. Out of the positive cases, 63% were under one year old, and increased to nearly 80% when considering children younger than two years old. Cough was the most frequent symptom presented by our population with a number of 62 cases (84.93%). Viral seasonality was also established, noting its predominance during the months of summer in the southern hemisphere. The infection by hMPV has an important prevalence in Peru. It mainly affects children under one year old and should be considered an important differential diagnosis in a patient with an acute respiratory infection.

Pediatric acute respiratory distress syndrome associated with human metapneumovirus and respiratory syncytial virus

OBJECTIVES

To study the incidence, risk factors, clinical course, and outcome of ARDS in children with HMP and RSV.

WORKING HYPOTHESIS

We hypothesized that ARDS in children with HMP was similar in incidence, risk factors, clinical course, and outcomes to ARDS in children with RSV.

STUDY DESIGN

Retrospective, observational study over 2 years.

PATIENT-SUBJECT SELECTION

Patients included were <18 years old with HMP or RSV detected from nasopharyngeal specimens by commercial reverse transcriptase polymerase chain reaction assay admitted to a study site.

METHODOLOGY

We described the incidence of ARDS within 1 week following the detection of HMP or RSV using recently developed Pediatric ARDS (PARDS) criteria. We also assessed risk factors, clinical course, and outcomes of children in the PICU with HMP or RSV and PARDS or non-PARDS.

RESULTS

We identified 57 patients with HMP and 161 patients with RSV: the proportions of patients with either virus who developed PARDS (HMP: 23%, RSV: 20%) and severe PARDS (HMP: 9%, RSV: 7%) were similar, as were the proportions of patients with acute (or acute-on-chronic) respiratory failure who developed PARDS (HMP: 41%, RSV: 31%). In a logistic regression model, risk factors associated with PARDS included neurologic comorbidity and PIM 3 probability of mortality, but not virus type. The risk factors, clinical course, and outcomes were similar for patients with PARDS associated with HMP and RSV.

CONCLUSIONS

About 1/3 of children with HMP or RSV and acute (or acute-on-chronic) respiratory failure developed PARDS. Children with either virus and a neurologic comorbidity or an increased PIM 3 probability of mortality were at increased risk for PARDS.

Metapneumovirus Infections and Respiratory Complications

Acute respiratory tract infections (ARTIs) are the most common illnesses experienced by people of all ages worldwide. In 2001, a new respiratory pathogen called human metapneumovirus (hMPV) was identified in respiratory secretions. hMPV is an RNA virus of the Paramyxoviridae family, and it has been isolated on every continent and from individuals of all ages. hMPV causes 7 to 19% of all cases of ARTIs in both hospitalized and outpatient children, and the rate of detection in adults is approximately 3%. Symptoms of hMPV infection range from a mild cold to a severe disease requiring a ventilator and cardiovascular support. The main risk factors for severe disease upon hMPV infection are the presence of a high viral load, coinfection with other agents (especially human respiratory syncytial virus), being between 0 and 5 months old or older than 65 years, and immunodeficiency. Currently, available treatments for hMPV infections are only supportive, and antiviral drugs are employed in cases of severe disease as a last resort. Ribavirin and immunoglobulins have been used in some patients, but the real efficacy of these treatments is unclear. At present, the direction of research on therapy for hMPV infection is toward the development of new approaches, and a variety of vaccination strategies are being explored and tested in animal models. However, further studies are required to define the best treatment and prevention strategies.

Human Metapneumovirus

Name of Virus: Human metapneumovirus