Epidemiology of rotavirus infection in Thailand

Rotavirus is a major cause of acute severe diarrhea in children worldwide a nd an important cause of death among young children in developing countries . Group A rotaviruses are antigenically complex and multiple serotypes infe ct humans. Reassortant rotavirus vaccines are now available which offer pro tection against severe illness caused by rotavirus serotypes G1-4. Before v accines are introduced into target populations, it is necessary to establis h the baseline data of the epidemiology of rotavirus infection in those cou ntries. The purpose of the present study is to provide information related to the epidemiology of rotavirus infection in Thailand. All rotavirus studi es performed in Thailand were found through Medline and Thai Index Medicus searches. A total of 26 of the most relevant studies published in internati onal and national journals are reviewed. Most studies reported that the pre valence of rotavirus infection in Thailand was 27-34%, although a few studi es have reported a prevalence above this range. The peak seasonal distribut ion of rotavirus infection among children hospitalized with diarrhea in Tha iland was seen in the dry cool seasons: October to February. The prevalence of rotavirus infection was most frequently found in children aged 6-11 mon ths up to 2 years. G1 was the most prevalent serotype in Thailand, followed by G2, G4 and G3, respectively. At least three G serotypes, mostly G1, G2 and G4, are seen to coexist in Thailand each epidemic year and in some stud ies all four G-serotypes were reported in the same epidemics. In a 1996-199 7 study, G9 was the third prevailing serotype after G1 and G2, respectively . These results indicate that rotavirus epidemics occur in Thailand every y ear and children are the most affected population. In Thailand, although G1 -G4 have been reported, G1 is the most prevalent serotype in each epidemic and G9 is becoming increasingly common.