title: A cohort study to define the age-specific incidence and risk factors of Shigella diarrhoeal infections in Vietnamese children: a study protocol.
abstract: BACKGROUND
  Shigella spp. are one of the most common causes of paediatric dysentery globally, responsible for a substantial proportion of diarrhoeal disease morbidity and mortality, particularly in industrialising regions. Alarming levels of antimicrobial resistance are now reported in S. flexneri and S. sonnei, hampering treatment options. Little is known, however, about the burden of infection and disease due to Shigella spp. in the community.
  
  
  METHODS
  In order to estimate the incidence of this bacterial infection in the community in Ho Chi Minh City, Vietnam we have designed a longitudinal cohort to follow up approximately 700 children aged 12-60 months for two years with active and passive surveillance for diarrhoeal disease. Children will be seen at 6 month intervals for health checks where blood and stool samples will be collected. Families will also be contacted every two weeks for information on presence of diarrhoea in the child. Upon report of a diarrhoeal disease episode, study nurses will either travel to the family home to perform an evaluation or the family will attend a study hospital at a reduced cost, where a stool sample will also be collected. Case report forms collected at this time will detail information regarding disease history, risk factors and presence of disease in the household.Outcomes will include (i) age-specific incidence of Shigella spp. and other agents of diarrhoeal disease in the community, (ii) risk factors for identified aetiologies, (iii) rates of seroconversion to a host of gastrointestinal pathogens in the first few years of life. Further work regarding the longitudinal immune response to a variety of Shigella antigens, host genetics and candidate vaccine/diagnostic proteins will also be conducted.
  
  
  CONCLUSIONS
  This is the largest longitudinal cohort with active surveillance designed specifically to investigate Shigella infection and disease. The study is strengthened by the active surveillance component, which will likely capture a substantial proportion of episodes not normally identified through passive or hospital-based surveillance. It is hoped that information from this study will aid in the design and implementation of Shigella vaccine trials in the future.
authors.forename: Corinne N
authors.initials: CN
authors.lastname: Thompson
authors.forename: Katherine L
authors.initials: KL
authors.lastname: Anders
authors.forename: Le Thi Quynh
authors.initials: le TQ
authors.lastname: Nhi
authors.forename: Ha Thanh
authors.initials: HT
authors.lastname: Tuyen
authors.forename: Pham
authors.initials: P
authors.lastname: Van Minh
authors.forename: Le Thi Phuong
authors.initials: le TP
authors.lastname: Tu
authors.forename: Tran Do Hoang
authors.initials: Tdo H
authors.lastname: Nhu
authors.forename: Nguyen Thi Thanh
authors.initials: NT
authors.lastname: Nhan
authors.forename: Tran Thi Thao
authors.initials: TT
authors.lastname: Ly
authors.forename: Vu Thuy
authors.initials: VT
authors.lastname: Duong
authors.forename: Lu Lan
authors.initials: LL
authors.lastname: Vi
authors.forename: Nguyen Thi
authors.initials: NT
authors.lastname: Van Thuy
authors.forename: Nguyen Trong
authors.initials: NT
authors.lastname: Hieu
authors.forename: Nguyen Vinh
authors.initials: NV
authors.lastname: Van Chau
authors.forename: James I
authors.initials: JI
authors.lastname: Campbell
authors.forename: Guy
authors.initials: G
authors.lastname: Thwaites
authors.forename: Cameron
authors.initials: C
authors.lastname: Simmons
authors.affiliation: Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam. sbaker@oucru.org.
authors.forename: Stephen
authors.initials: S
authors.lastname: Baker
mesh_terms: D000367:Age Factors; D002675:Child, Preschool; D015331:Cohort Studies; D004405:Dysentery, Bacillary / Q000453:epidemiology*; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D008297:Male; D012107:Research Design; D012307:Risk Factors; D012760:Shigella; D014744:Vietnam / Q000453:epidemiology