Norovirus Gastroenteritis in a Birth Cohort in Southern India.
BACKGROUND
Noroviruses are an important cause of gastroenteritis but little is known about disease and re-infection rates in community settings in Asia.


METHODS
Disease, re-infection rates, strain prevalence and genetic susceptibility to noroviruses were investigated in a birth cohort of 373 Indian children followed up for three years. Stool samples from 1856 diarrheal episodes and 147 vomiting only episodes were screened for norovirus by RT-PCR. Norovirus positivity was correlated with clinical data, secretor status and ABO blood group.


RESULTS
Of 1856 diarrheal episodes, 207 (11.2%) were associated with norovirus, of which 49(2.6%) were norovirus GI, 150(8.1%) norovirus GII, and 8 (0.4%) were mixed infections with both norovirus GI and GII. Of the 147 vomiting only episodes, 30 (20.4%) were positive for norovirus in stool, of which 7 (4.8%) were norovirus GI and 23 (15.6%) GII. At least a third of the children developed norovirus associated diarrhea, with the first episode at a median age of 5 and 8 months for norovirus GI and GII, respectively. Norovirus GI.3 and GII.4 were the predominant genotypes (40.3% and 53.0%) with strain diversity and change in the predominant sub-cluster over time observed among GII viruses. A second episode of norovirus gastroenteritis was documented in 44/174 (25.3%) ever-infected children. Children with the G428A homozygous mutation for inactivation of the FUT2 enzyme (se428se428) were at a significantly lower risk (48/190) of infection with norovirus (p = 0.01).


CONCLUSIONS
This is the first report of norovirus documenting disease, re-infection and genetic susceptibility in an Asian birth cohort. The high incidence and apparent lack of genogroupII specific immunity indicate the need for careful studies on further characterization of strains, asymptomatic infection and shedding and immune response to further our understanding of norovirus infection and disease.
Department of Gastrointestinal Sciences, Christian Medical College, Vellore, India.
Vipin Kumar
VK
Menon
Department of Gastrointestinal Sciences, Christian Medical College, Vellore, India.
Santosh
S
George
Department of Gastrointestinal Sciences, Christian Medical College, Vellore, India.
Rajiv
R
Sarkar
Department of Gastrointestinal Sciences, Christian Medical College, Vellore, India.
Sidhartha
S
Giri
Department of Biostatistics, Christian Medical College, Vellore, India.
Prasanna
P
Samuel
Department of Gastrointestinal Sciences, Christian Medical College, Vellore, India.
Rosario
R
Vivek
Department of Gastrointestinal Sciences, Christian Medical College, Vellore, India.
Anuradha
A
Saravanabavan
Department of Gastrointestinal Sciences, Christian Medical College, Vellore, India.
Farzana Begum
FB
Liakath
Department of Gastrointestinal Sciences, Christian Medical College, Vellore, India.
Sasirekha
S
Ramani
Virus Reference Department, Centre for Infection, Health Protection Agency, London, United Kingdom.
Miren
M
Iturriza-Gomara
Virus Reference Department, Centre for Infection, Health Protection Agency, London, United Kingdom.
James J
JJ
Gray
Virus Reference Department, Centre for Infection, Health Protection Agency, London, United Kingdom.
David W
DW
Brown
Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, United States of America.
Mary K
MK
Estes
Department of Gastrointestinal Sciences, Christian Medical College, Vellore, India.
Gagandeep
G
Kang
D017250:Caliciviridae Infections / Q000453:epidemiology* / Q000235:genetics / Q000821:virology*; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D005647:Fucosyltransferases / Q000235:genetics; D005759:Gastroenteritis / Q000453:epidemiology* / Q000235:genetics / Q000821:virology*; D020022:Genetic Predisposition to Disease; D006801:Humans; D007194:India / Q000453:epidemiology; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D058889:Molecular Typing; D029322:Norovirus / Q000145:classification / Q000235:genetics; D015995:Prevalence; D000097631:Galactoside 2-alpha-L-fucosyltransferase
D005647:Fucosyltransferases; D000097631:Galactoside 2-alpha-L-fucosyltransferase