Study Shows Link Between a Virus and Croup

A New Virus Called NL63 Could Be a Cause of Croup and Other Coughs

From the WebMD Archives

Aug. 22, 2005 - A newly discovered virus could go a long way in explaining the causes of croup and other forms of children's cough.

Coronavirus is a type of virus that is typically associated with symptoms such as nasal congestion and sore throat, often referred to as upper respiratory symptoms. Identified by Dutch scientists, the new coronavirus is known as HCoV-NL63 (NL63). It is only the fourth of its kind to be found in almost 40 years.

Coronavirus NL63 causes symptoms similar to a bad cold. Unlike acute respiratory syndrome (SARS) coronavirus, which killed some 800 people and infected 8,000 during its 2002-2003 epidemic, coronavirus NL63 does not lead to pneumonia, research shows.

The new study appears in the international journal Public Library of Science Medicine.

Researchers from the University of Amsterdam, the Netherlands, and their colleagues set out to determine whether a connection existed between the new virus and a variety of symptoms in the lower respiratory tract (windpipe, airways, and lungs) and illnesses such as croup, bronchitis, and pneumonia.

Coronaviruses are responsible for one-fifth of all respiratory infections in children under the age of 5 worldwide, according to the World Health Organization.

One of the most frequent types of infection in children during the first few years of life is a respiratory infection. A variety of viruses can be responsible for these illnesses; however, according to the researchers, no one virus is detected in a substantial number of cases.

Croup is a common childhood viral illness. It usually affects children between the ages of 6 months and 3 years. In most cases, croup occurs during the winter and early spring.

Symptoms of Croup

Typically, youngsters with croup will feel fine when they go to bed. Sometime during the night, however, they will wake up coughing and experiencing trouble breathing.

Generally they will begin developing symptoms such as a runny nose within two to six days of being exposed to other children with croup. Other symptoms include:

  • Hoarse voice
  • Decreased appetite
  • Fever up to 104 degrees

A "croupy" cough differs from a dry, wet, or deep cough in that it sounds similar to a barking seal. This occurs as a result of inflammation, swelling, and mucus buildup in the windpipes and breathing tubes. As infants and young children have smaller airways, it's not surprising that they are the ones most often affected by croup.

Researcher Lia van der Hoek, one of the scientists who originally discovered the new coronavirus, and colleagues set out to determine the frequency of the virus in children under age 3 with lower respiratory symptoms.

From December 1999 to October 2001, the researchers obtained 949 mucus and saliva samples from children in four different regions of Germany.

The researchers found that 49 samples (5%) were positive for the new virus. Other common causes included respiratory syncytial virus (RSV), which accounted for a third of causes.

Most of the positive samples were collected during the winter.

A higher number of samples collected from children seen in clinics (8%) than those hospitalized (3%) tested positive for the new virus.

A Pattern Established

Previous studies have reported certain trends in croup, including:

  • Boys are more susceptible
  • Occurs most frequently in the second year of life
  • Usually occurs in winter and early spring

Each of these factors is matched by patterns of the new virus' occurrence.

With an overall incidence of 5%, it is the third most frequent cause in this group of patients, they write.

"In conclusion, HCoV-NL63 infections occur frequently in young children with LRTI [lower respiratory tract infection] and show a strong association with croup, suggesting a causal relationship," van der Hoek writes.

Show Sources

SOURCES: van der Hoek, L. Public Library of Science Medicine, Aug. 23, 2005: vol 2. News release, University Medical Center, Amsterdam.
© 2005 WebMD, Inc. All rights reserved. View privacy policy and trust info