A human volunteer challenge model using frozen bacteria of the new epidemic serotype, V. cholerae O139 in Thai volunteers.
A total of 35 volunteers were recruited for an IRB-approved inpatient dose-escalation challenge. The goal was to identify a dose that produced an observed cholera attack rate > or =80% and an illness of sufficient severity during the defined study period such that the model would be useful for determining vaccine protection. Volunteers were challenged in groups of 5 with V. cholerae O139 that had been reconstituted immediately before use. Only 2 out of 5 volunteers who received the lowest dose (4.3 x 10(4) cfu) had diarrhea. As the inoculum size increased, the attack rate of diarrhea increased to 3-4 of 5 volunteers. At the highest dose tested, approximately 5 x 10(7) cfu, the attack rate was 73%. We recommend the use of frozen V. Cholera O139 in a human experimental challenge model to assess cholera vaccine efficacy (VE) in a cholera endemic area but with 4 days observation period before initiation of tetracycline to allow assessment of severity.
Pitisuttithum
P
P
Vaccine Trial Centre [VTC], Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand. tmppt@mahidol.ac.th
Cohen
M B
MB
Phonrat
B
B
Suthisarnsuntorn
U
U
Bussaratid
V
V
Desakorn
V
V
Phumratanaprapin
W
W
Singhasivanon
P
P
Looareesuwan
S
S
Schiff
G M
GM
Ivanoff
B
B
Lang
D
D
D000328:Adult; D000907:Antibodies, Bacterial / Q000097:blood; D002771:Cholera / Q000453:epidemiology / Q000276:immunology / Q000517:prevention & control; D022121:Cholera Vaccines / Q000494:pharmacology; D015169:Colony Count, Microbial; D004196:Disease Outbreaks; D005243:Feces / Q000382:microbiology; D005260:Female; D005615:Freezing; D006801:Humans; D008297:Male; D008954:Models, Biological; D012703:Serotyping; D013785:Thailand / Q000453:epidemiology; D014734:Vibrio cholerae / Q000145:classification* / Q000276:immunology / Q000472:pathogenicity*
D000907:Antibodies, Bacterial; D022121:Cholera Vaccines