Thursday, February 26, 2015

Childhood pneumonia: study pinpoints viral cause in most cases

Viral infections are much more common than bacterial ones in children diagnosed with pneumonia, and respiratory
syncytial virus is the most common cause, suggests a study
of patients across Utah and Tennessee.

The Etiology of Pneumonia in the Community (EPIC) study was led by the US Centers for Disease Control and Prevention (CDC) in collaboration with University of Utah Health Sciences, with results published in the The New England Journal of Medicine.

A total of 2,638 children with symptoms of pneumonia were
enrolled in the study between July 2010 and June 2012, at
Primary Children's Hospital in Salt Lake City, UT, and in TN,
Le Bonheur Children's Hospital in Memphis, and Monroe Carell Jr. Children's Hospital in Nashville.

Pneumonia was confirmed by X-ray in 2,222 children and their
body fluid samples were tested for bacterial and viral
pathogens. Children with recent hospitalization or severe
immunosuppression were excluded from the analysis.

Viral infections were much more common than bacterial
infections in the children in the study that had been
diagnosed with pneumonia - 73% compared with 15%.
Co-investigator Dr. Andrew Pavia, chief of the division of
pediatric infectious diseases at University of Utah School of
Medicine, says vaccines have lowered the rate of bacterial
infections, adding that it is important to understand the causes and etiology behind the hospitalizations that continue to result from childhood pneumonia.

"Over the last 3 decades, introduction of Haemophilus
influenzae type b and pneumococcal conjugate vaccines has significantly lowered the incidence of bacterial pneumonia in children," Dr. Pavia says.

"Our results are consistent with previous findings, and support
continuing immunization efforts to maintain the reduction in
bacterial pneumonia.

"It's also important to understand how causes of
pneumonia have changed so we can better approach the illness, which still leads to high rates of hospitalization among children."

The researchers remind us there is a spike in community-
acquired pneumonia during winter, because its spread is
facilitated by people being in closer contact as they retreat
indoors. The lung infection triggers:

Persistent coughing

Chest pain


Difficulty breathing.

Community-acquired pneumonia is "particularly hard on the very young and the very old," the authors say - "in fact,
pneumonia is the leading cause of hospitalization among US
children, with estimated medical costs of $1 billion annually."

"Despite this large burden of disease, critical gaps remain in
our knowledge about pneumonia in children," reads the study

Chris Stockmann, co-investigator and senior research analyst at
the University of Utah, says of the study:
"The results help define the role of viruses as major players in pediatric pneumonia and shows a need for new therapies that
can reduce the severity of viral pneumonia."

More than a dozen bacterial and viral pathogens were found in the children in the study, causing a fifth, 21%, to need treatment in intensive care.

Respiratory syncytial virus (RSV) was the most commonly
detected pathogen, and affected the under-5s more than older
children (37% versus 8%).

Children under the age of 5 years were also more vulnerable to:

Adenovirus (15% versus 3% in older children)

Human metapneumovirus (15% versus 8%).

The authors conclude:
The very youngest children were more likely to need hospital -
half of all the children hospitalized with pneumonia in the study were aged 2 years or younger.

In children between 5 and 18 years of age, the most common
pathogen was a bacterium, Mycoplasma pneumonia - 19% in
the over-5s versus 3% in the under-5s.

Rhinovirus - the predominant cause of the common cold - was
the second most commonly detected pathogen among children
with pneumonia.

"Interestingly," the researchers say, rhinovirus was also found
in a large proportion of the children who had no symptoms,
who were acting as controls in the study.

Rhinovirus was found in 22% with pneumonia, compared with 17% without, and "one interpretation is that rhinovirus infections do not commonly lead to pneumonia.

Another is that some types of rhinoviruses cause a runny nose, while others cause severe pneumonia that leads to hospitalization."

The study authors give an estimate of the total annual incidence of hospitalization for community-acquired pneumonia.

By combining their data from the three study hospitals, they
estimate a rate in children under 18 years of age of just under 16 cases for every 10,000 children in the population.