Community based case-control study of rotavirus gastroenteritis among young children during 2008-2010 reveals vast genetic diversity and increased prevalence of G9 strains in Kolkata.
BACKGROUND
Group A Rotaviruses are a major etiologic agent of gastroenteritis in infants and young children (<5 years) worldwide. Although rotavirus vaccines have been successfully administered in many countries, in India the introduction of rotavirus vaccine in national immunization program was approved in 2014. Since high disease burden and large number of genetic variants have been reported from low income countries including India, monitoring of rotavirus was initiated prior to implementation of the vaccine in the region.


METHODS
A total number of 3,582 stool samples were collected from an urban slum community in Kolkata, among which 1,568 samples were obtained from children of ≤ 5 years of age, with moderate to severe diarrhoea and 2,014 samples were collected from age-sex matched healthy neighbourhood controls. Rotavirus positive samples were typed by multiplex semi-nested PCR and nucleotide sequencing. Circulating strains were phylogenetically analyzed.


RESULTS
Among 1,568 children with diarrhoea, 395 (25.2%), and among 2,014 asymptomatic children, 42 (2%) were rotavirus positive. G1P[8] was identified as the most common strain (32%) followed by G9P[8] (16.9%), G2P[4] (13.5%) and G9P[4] (10.75%). G12 strains with combinations of P[4], P[6] and P[8] comprised 11.9% of total positive strains. The rest (<10%) were rare and uncommon strains like G1P[4], G1P[6], G2P[8] and animal-like strains G4P[6], G6P[14] and G11P[25]. The 42 rotavirus positive samples from asymptomatic children revealed common genotypes like G1, G2 and G9.


CONCLUSIONS
This community based case-control study showed increased predominance of genotype G9 in Kolkata. It also confirmed co-circulation of a large number of genetic variants in the community. Asymptomatic rotavirus positive children though low in number can also be a source of dispersal of infection in the community. This study provides background information to the policy makers for implementation of rotavirus vaccines in this region.
National Institute of Cholera and Enteric Diseases, Kolkata, India.
Satarupa
S
Mullick
National Institute of Cholera and Enteric Diseases, Kolkata, India.
Anupam
A
Mukherjee
National Institute of Cholera and Enteric Diseases, Kolkata, India.
Santanu
S
Ghosh
National Institute of Cholera and Enteric Diseases, Kolkata, India.
Gururaja P
GP
Pazhani
National Institute of Cholera and Enteric Diseases, Kolkata, India.
Dipika
D
Sur
National Institute of Cholera and Enteric Diseases, Kolkata, India.
Byomkesh
B
Manna
Department of Paediatrics, University of Virginia, School of Medicine, Charlottesville, Virginia, United States of America.
James P
JP
Nataro
Center for Vaccine Development, University of Maryland, School of Medicine, Baltimore, Maryland, United States of America.
Myron M
MM
Levine
National Institute of Cholera and Enteric Diseases, Kolkata, India.
Thandavarayan
T
Ramamurthy
National Institute of Cholera and Enteric Diseases, Kolkata, India.
Mamta
M
Chawla-Sarkar
D017677:Age Distribution; D000956:Antigens, Viral / Q000235:genetics; D036022:Capsid Proteins / Q000235:genetics; D016022:Case-Control Studies; D002675:Child, Preschool; D005759:Gastroenteritis / Q000453:epidemiology* / Q000266:history / Q000821:virology*; D014644:Genetic Variation; D005838:Genotype; D049674:History, 21st Century; D006801:Humans; D007194:India / Q000453:epidemiology; D007223:Infant; D007231:Infant, Newborn; D008969:Molecular Sequence Data; D010802:Phylogeny; D015995:Prevalence; D012401:Rotavirus / Q000145:classification / Q000235:genetics*; D012400:Rotavirus Infections / Q000453:epidemiology* / Q000266:history / Q000821:virology*; D012621:Seasons
D000956:Antigens, Viral; D036022:Capsid Proteins; C060339:VP4 protein, Rotavirus; C050779:VP7 protein, Rotavirus