Table 1.
Demographics.
| Study | Discovery cohort | Validation cohort | Endemic cohort |
|---|---|---|---|
| Identifier | OVG2009/10 | OVG2011/02 | NA |
| Location | Oxford, United Kingdom | Oxford, United Kingdom | Kathmandu, Nepal |
| Source | S. Typhi Quailes strain dose-escalation study (103 and 104CFU) (Waddington et al., 2014) | Placebo arm of randomized controlled vaccine/challenge trial (Darton et al., 2016) | Treatment trial and diagnostics sub-study (Arjyal et al., 2016; Darton et al., 2016) |
| Trial registration | NA | Clinicaltrials.gov (NCT01405521) | Clinicaltrials.gov (NCT01421693) |
| Sample size, N | 41 | 30 | 202 |
| Confirmed casesA, n (% bacteremia) | 25 (84) | 20 (100) | 100 (100) |
| Exposed, not sickB, n | 16 | 10 | NA |
| Healthy controlsC, n | 41 | 30 | 50 |
| Febrile non-typhoid bacteremia, n | NA | NA | 52D |
| Median age, yrs (interquartile range) | 27 (22–37) | 23 (21–39) | 20 (15–27)E,F |
| Number male (%) | 28 (68) | 19 (63) | 99 (49)E,G |
NA, not applicable. CFU, colony-forming units.
ACase confirmation in the challenge studies was made using clinical (oral temperature 338°C sustained for 312 h continuously) or microbiological (S. Typhi bacteraemia detected in 31 blood culture sample). All confirmed cases in the endemic cohort were confirmed to have bacteremia.
BCHIM study participants who ingested challenge agent and were monitored for 14 days but did not meet the endpoints for typhoid diagnosis (see A, above).
CHealthy controls in the challenge study were paired pre-challenge samples from the same individual.
DPathogens isolated (n) were: Staphylococcus aureus (20), Escherichia coli (16), Streptococcus pneumoniae (6), Enterococcus sp. (5), Acinetobacter sp. (3), Streptococcus sp. (1), Klebsiella sp. (1).
EMissing data = 6/202 healthy controls.
FTyphoid patients, 16 (10–20); Healthy controls, 22.5 (19–26.25); Febrile controls, 40 (22–56.75).
GTyphoid patients, 67 (67%); Healthy controls, 11 (22%); Febrile controls, 21 (40%).