Epidemiological Patterns and Characteristics Associated with Human Metapneumovirus at the Largest United States Pediatric Hospital

Background: While varied literature exist regarding the epidemiology of Human metapneumovirus (hMPV) in pediatrics, data describing the occurrence of this disease in the state of Texas is very limited.

Objective: To describe and analyze the patterns of confirmed hMPV cases in patients seen in Texas Children’s Hospital (TCH) between January 1 and June 30, 2010.

Methods: Medical records of patients with confirmed hMPV cases (N=268) seen at TCH between January 1 to June 30, 2010, were reviewed by an infection preventionist. A standardized form was used to collect the data. The information included, but was not limited to, demographic data, risk factors, bacterial co-infections and length of stay.

Results: Of the 268 study patients, the ages ranged from 11 months to 21 years old, with a mean of 3 years and a median of 17 months. A higher percentage of males (57%) compared to females (43%) was observed in this study group. Seventy-five percent of the patients resided in Harris County, which is the largest populated county in Texas. Hispanics made up the majority of the cases (54%), followed by Whites (24%), African-Americans (18%), and Others (4%). One hundred out of the 268 cases (37%) were described to have underlying health conditions. Cancer was the leading underlying health condition (26%), followed by asthma (16%), seizures/neurological conditions (16%), cardiac disease (15%), genetic disorders (12%) and others (15%). The average length of hospital-stay was approximately 4 days. Thirty patients (11%) were admitted to Pediatric Intensive Care Unit, 88 (33%) were seen as an outpatient, and 150 (56%) were admitted to non-ICU units. Mechanical intubation was necessary in 21 (8%) of the study patients. Secondary co-infection was identified in 38 (14%) of the study patients. The causative organisms of the co-infections were divided equally between viruses and bacteria. All the specimens in this study were tested utilizing the RT-PCR method, with the positive rate of 6.7% in January, 9.2% in February, 11.7% in March, 6% in April, 3% in May and 2% in June. The mortality rate of the study population was 0.

Conclusions: In this study, hMPV occurred more frequently in males than females, and over half of the cases occurred in Hispanics. Most patients in this study (63%) were previously healthy with no underlying conditions. A drop in cases between May and June 2010 occurred for unknown reasons and may require further investigation. The mean hospital length-of-stay indicated that this was a non-severe type of disease. The result of this descriptive study provides a better understanding of this disease pattern in pediatric patients in our institution. However, more rigorous study design such as a case-control study may be necessary to further document specifics regarding this disease in pediatric populations in Texas.