Norovirus and medically attended gastroenteritis in U.S. children

Abstract

Background: Cases of rotavirus-associated acute gastroenteritis have declined since the introduction of rotavirus vaccines, but the burden of norovirus-associated acute gastroenteritis in children remains to be assessed.

Methods: We conducted active surveillance for laboratory-confirmed cases of norovirus among children younger than 5 years of age with acute gastroenteritis in hospitals, emergency departments, and outpatient clinical settings. The children resided in one of three U.S. counties during the years 2009 and 2010. Fecal specimens were tested for norovirus and rotavirus. We calculated population-based rates of norovirus-associated acute gastroenteritis and reviewed billing records to determine medical costs; these data were extrapolated to the U.S. population of children younger than 5 years of age.

Results: Norovirus was detected in 21% of young children (278 of 1295) seeking medical attention for acute gastroenteritis in 2009 and 2010, with norovirus detected in 22% (165 of 742) in 2009 and 20% (113 of 553) in 2010 (P=0.43). The virus was also detected in 4% of healthy controls (19 of 493) in 2009. Rotavirus was identified in 12% of children with acute gastroenteritis (152 of 1295) in 2009 and 2010. The respective rates of hospitalization, emergency department visits, and outpatient visits for the norovirus were 8.6, 146.7, and 367.7 per 10,000 children younger than 5 years of age in 2009 and 5.8, 134.3, and 260.1 per 10,000 in 2010, with an estimated cost per episode of $3,918, $435, and $151, respectively, in 2009. Nationally, we estimate that the average numbers of annual hospitalizations, emergency department visits, and outpatient visits due to norovirus infection in 2009 and 2010 among U.S. children in this age group exceeded 14,000, 281,000, and 627,000, respectively, with more than $273 million in treatment costs each year.

Conclusions: Since the introduction of rotavirus vaccines, norovirus has become the leading cause of medically attended acute gastroenteritis in U.S. children and is associated with nearly 1 million health care visits annually. (Funded by the Centers for Disease Control and Prevention.).

Figure 1

Study Enrollment and Results of Norovirus Testing.

Figure 2. Norovirus Infection among Children with Acute Gastroenteritis, According to Month of Symptom Onset, 2009 and 2010

Data are for children younger than 5 years of age. The year 2009 refers to the period from October 2008 through September 2009, and 2010 refers to the period from October 2009 through September 2010. Data are from the New Vaccine Surveillance Network.

Figure 3. Norovirus and Rotavirus Infections among Children in Hospitals, Emergency Departments, and Outpatient Clinical Settings, 2009 and 2010

The rates for emergency departments visits in Nashville are based on data gathered through June 2010; all other rates are based on surveillance data gathered through September. Data are from the New Vaccine Surveillance Network.

Figure 4. Rates of Hospitalization for Norovirus and Rotavirus Infection According to Age, 2009 and 2010

Data are from the New Vaccine Surveillance Network.