Epidemiology of rotavirus infection in Thailand

Abstract

Rotavirus is a major cause of acute severe diarrhea in children worldwide and an important cause of death among young children in developing countries. Group A rotaviruses are antigenically complex and multiple serotypes infect humans. Reassortant rotavirus vaccines are now available which offer protection against severe illness caused by rotavirus serotypes G1-4. Before vaccines are introduced into target populations, it is necessary to establish the baseline data of the epidemiology of rotavirus infection in those countries. The purpose of the present study is to provide information related to the epidemiology of rotavirus infection in Thailand. All rotavirus studies performed in Thailand were found through Medline and Thai Index Medicus searches. A total of 26 of the most relevant studies published in international and national journals are reviewed. Most studies reported that the prevalence of rotavirus infection in Thailand was 27-34%, although a few studies have reported a prevalence above this range. The peak seasonal distribution of rotavirus infection among children hospitalized with diarrhea in Thailand was seen in the dry cool seasons: October to February. The prevalence of rotavirus infection was most frequently found in children aged 6-11 months 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 studies all four G-serotypes were reported in the same epidemics. In a 1996-1997 study, G9 was the third prevailing serotype after G1 and G2, respectively. These results indicate that rotavirus epidemics occur in Thailand every year 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.

Diarrhea Caused by Rotavirus in Children Less than 5 Years of Age in Hanoi, Vietnam

“…This pattern was not observed in the south, where there are only two seasons per year, the rainy and the dry seasons. Rotavirus infections occurred almost all year in the south, with less distinct seasonal differences (13,20,23,24). Our results are similar to those of studies conducted in Korea, China, and Thailand but differed from those of a Japanese study, in which rotavirus was rarely detected from September to December (9,20,29,33).…”

“…Moreover, our study indicated that there was a trend of decreasing rates of rotavirus infection in the older children. This might partly be explained by the fact that older children acquired protective immunity during previous exposures to rotavirus and are therefore more resistant to infection with this agent (13,20). In addition to the age distribution of rotavirus infection, many studies have indicated a higher ratio of infected males to infected females (8,24,26,28,30).…”

Molecular characterization of VP4, VP6, VP7, NSP4, and NSP5/6 genes identifies an unusual G3P[10] human rotavirus strain

“…Although epidemiological surveillance and genotype identification of rotavirus infections in human and pig populations in Chiang Mai, Thailand, have been carried out extensively over the past two decades, the P[10] genotype had never been reported previously [Maneekarn and Ushijima, 2000;Maneekarn et al, 2006;Khamrin et al, 2006bKhamrin et al, , 2007cChan-It et al, 2008]. The present study conducted in 2005 described the detection of an unusual strain of G3P[10] (CMH079/05) in a 2-year-old boy admitted to hospital with acute gastroenteritis.…”

“…The studies of rotavirus infection carried out in Thailand revealed that rotaviruses are the leading etiologic pathogens that causes diarrhea in children, and are responsible for about 27-58% of diarrheal diseases in hospitalized cases [Maneekarn and Ushijima, 2000;Jiraphongsa et al, 2005;Khamrin et al, 2006b]. Epidemiological surveillance of group A rotavirus infection conducted in Chiang Mai, Thailand, during the period of 2000-2004 [Khamrin et al, 2006b[Khamrin et al, , 2007c During these extensive epidemiological studies, rotavirus strains with unusual G-P combinations were occasionally detected in children hospitalized with acute gastroenteritis; for example, an unusual strain of human rotavirus G3P[3] (CMH222) bearing simian-like VP7 and caprine-like VP4 genes was isolated from a 2-year-old child patient in 2001 [Khamrin et al, 2006a].…”

Detection and Genetic Characterization of Group A Rotavirus Strains Circulating among Children with Acute Gastroenteritis in Japan

“…Extensive epidemiological studies of rotavirus infection worldwide indicated that G1 was the most prevalent genotype (5,13,15,19,21,28,36). However, the new variants G2 and G3 emerged to become the leading genotypes in Japan from 2001 to 2004 (24,35).…”