title: Prevalence of classic, MLB-clade and VA-clade Astroviruses in Kenya and The Gambia.
abstract: BACKGROUND
  Infectious diarrhea leads to significant mortality in children, with 40 % of these deaths occurring in Africa. Classic human astroviruses are a well-established etiology of diarrhea. In recent years, seven novel astroviruses have been discovered (MLB1, MLB2, MLB3, VA1/HMO-C, VA2/HMO-B, VA3/HMO-A, VA4); however, there have been few studies on their prevalence or potential association with diarrhea.
  
  
  METHODS
  To investigate the prevalence and diversity of these classic and recently described astroviruses in a pediatric population, a case-control study was performed. Nine hundred and forty nine stools were previously collected from cases of moderate-to-severe diarrhea and matched controls of patients less than 5 years of age in Kenya and The Gambia. RT-PCR screening was performed using pan-astrovirus primers.
  
  
  RESULTS
  Astroviruses were present in 9.9 % of all stool samples. MLB3 was the most common astrovirus with a prevalence of 2.6 %. Two subtypes of MLB3 were detected that varied based on location in Africa. In this case-control study, Astrovirus MLB1 was associated with diarrhea in Kenya, whereas Astrovirus MLB3 was associated with the control state in The Gambia. Classic human astrovirus was not associated with diarrhea in this study. Unexpectedly, astroviruses with high similarity to Canine Astrovirus and Avian Nephritis Virus 1 and 2 were also found in one case of diarrhea and two control stools respectively.
  
  
  CONCLUSIONS
  Astroviruses including novel MLB- and VA-clade members are commonly found in pediatric stools in Kenya and The Gambia. The most recently discovered astrovirus, MLB3, was the most prevalent and was found more commonly in control stools in The Gambia, while astrovirus MLB1 was associated with diarrhea in Kenya. Furthermore, a distinct subtype of MLB3 was noted, as well as 3 unanticipated avian or canine astroviruses in the human stool samples. As a result of a broadly reactive PCR screen for astroviruses, new insight was gained regarding the epidemiology of astroviruses in Africa, where a large proportion of diarrheal morbidity and mortality occur.
authors.affiliation: Washington University School of Medicine, Saint Louis, MO, USA. meyer_ca@kids.wustl.edu.
authors.forename: Caroline T
authors.initials: CT
authors.lastname: Meyer
authors.affiliation: Washington University School of Medicine, Saint Louis, MO, USA. Bauer_I@kids.wustl.edu.
authors.forename: Irma K
authors.initials: IK
authors.lastname: Bauer
authors.affiliation: Medical Research Council Unit, Banjul, The Gambia. mantonio@mrc.gm.
authors.forename: Martin
authors.initials: M
authors.lastname: Antonio
authors.affiliation: Medical Research Council Unit, Banjul, The Gambia. adeyemimitchell@yahoo.com.
authors.forename: Mitchell
authors.initials: M
authors.lastname: Adeyemi
authors.affiliation: Medical Research Council Unit, Banjul, The Gambia. debasish.saha@otago.ac.nz.|Center for International Health, Department of Preventive and Social Medicine, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand. debasish.saha@otago.ac.nz.
authors.forename: Debasish
authors.initials: D
authors.lastname: Saha
authors.affiliation: Kenya Medical Research Institute/Centers for Disease Control and Prevention, Kisumu, Kenya. joseph.oundo@usamru-k.org.
authors.forename: Joseph O
authors.initials: JO
authors.lastname: Oundo
authors.affiliation: Kenya Medical Research Institute/Centers for Disease Control and Prevention, Kisumu, Kenya. bochieng@kemricdc.org.
authors.forename: John B
authors.initials: JB
authors.lastname: Ochieng
authors.affiliation: Kenya Medical Research Institute/Centers for Disease Control and Prevention, Kisumu, Kenya. romore@kemricdc.org.
authors.forename: Richard
authors.initials: R
authors.lastname: Omore
authors.affiliation: University of Maryland School of Medicine, Baltimore, MD, USA. cstine@epi.umaryland.edu.
authors.forename: O Colin
authors.initials: OC
authors.lastname: Stine
authors.affiliation: Washington University School of Medicine, Saint Louis, MO, USA. davewang@wusm.wustl.edu.
authors.forename: David
authors.initials: D
authors.lastname: Wang
authors.affiliation: Washington University School of Medicine, Saint Louis, MO, USA. Holtz_L@kids.wustl.edu.
authors.forename: Lori R
authors.initials: LR
authors.lastname: Holtz
mesh_terms: D019200:Astroviridae; D019350:Astroviridae Infections / Q000453:epidemiology* / Q000821:virology*; D052676:Avastrovirus / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D016022:Case-Control Studies; D002675:Child, Preschool; D016000:Cluster Analysis; D003967:Diarrhea / Q000453:epidemiology* / Q000821:virology*; D005243:Feces / Q000821:virology; D005260:Female; D005714:Gambia / Q000453:epidemiology; D014644:Genetic Variation; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007630:Kenya / Q000453:epidemiology; D008297:Male; D001257:Mamastrovirus; D008969:Molecular Sequence Data; D010802:Phylogeny; D015995:Prevalence; D012367:RNA, Viral / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D017385:Sequence Homology
chemical_list: D012367:RNA, Viral