World's Hospitalizations for Rotavirus Infection Higher Than Expected
From August 2001 to July of this year, roughly 40% of hospitalizations for diarrhea in children* worldwide were caused by rotavirus, according to a report in this week's MMWR. Rotavirus infection is known to be the leading cause of severe, acute diarrhea in young children; however, previous literature reviews had implicated rotavirus in fewer pediatric hospitalizations for diarrhea, 20%-30%.
The latest data were derived from a WHO surveillance program in 35 countries in Africa, Central and South America, Eastern Europe, the Eastern Mediterranean, Southeast Asia, and the Western Pacific. Detection was based on an enzyme immunoassay for rotavirus antigen in stool samples, and strain genotypes were identified by RT-PCR. The most common strains, excepting those in the Eastern Mediterranean region and Africa, were G1P[8], G9P[8], and G2P[4]—which accounted for two thirds of the strains detected.
|
WHO Region (No. Countries) |
Median Detection Rate, % (Range) |
|
|
41 |
|
|
34 |
|
Europe (3) |
40 |
|
|
40 |
|
Southeast Asia/Western Pacific (8) |
45 |
|
Total (35) |
40 |
In trials in the Americas and Europe, 2 live, oral rotavirus vaccines—an attenuated G1P[8] human rotavirus vaccine (Rotarix; GSK Biologicals) and a live, pentavalent, human-bovine (WC3 strain) reassortment vaccine containing serotypes G1, G2, G3, G4 and P[8] (RotaTeq; Merck)—conferred 85%-98% protection against rotavirus diarrhea. These vaccines have been incorporated into the routine immunization programs in 11 countries in these regions and in Australia. Trials of these vaccines in low-income Asian and African countries are ongoing. Notably these vaccines confer protection against rotavirus serotypes that have not been included in their respective formulations.
The CDC recommends 3 doses of an FDA-approved rotavirus vaccine** between the ages of 6 and 32 weeks. An interim report indicates that, for the 2007-2008 rotavirus season in America, viral activity started much later and was much less extensive than in previous years. These changes are believed to be due to the uptake of rotavirus vaccine.
According to the MMWR, more than half a million young children in the world die each year from rotavirus-induced diarrhea; 85% of these deaths occur in low-income African or Asian countries.
RT-PCR = reverse-transcription polymerase chain reaction.
* Younger than 5 years of age.
** The tetravalent rhesus-human reassortment rotavirus vaccine (RotaShield; Wyeth) was voluntarily withdrawn from the market in 1999 owing to a low, but increased, risk of intussusception.
Transmission electron photomicrograph of intact rotavirus particles from the CDC.
