Kinetics of delayed-type hypersensitivity to tuberculin induced by bacille Calmette-Guérin vaccination in northern Malawi.
During 1986-1989, a bacille Calmette-Guérin (BCG) vaccine trial was carried out in northern Malawi. The effects of age, sex, and prevaccination delayed-type hypersensitivity (DTH) on the time course of the DTH response over 1-36 months after vaccination were studied in 2418 persons. DTH response increased rapidly, to peak at 31-90 days after vaccination, when most persons had a measurable response. This was followed by a marked decline by 181-365 days, particularly in those <15 years old at vaccination, followed by a more gradual decline. Prevaccination DTH was the single best predictor of postvaccination DTH. BCG-induced DTH responsiveness appears to decline more rapidly in tropical than in temperate environments. This may reflect high prevalence of exposure to other infections, which induce a Th2 bias or compete for "space" within the T lymphocyte compartment. The inability of some persons to mount a persistent DTH response probably reflects genetic background and/or environmental exposure history.
Department of Infectious and Tropical Diseases, Infectious Diseases Epidemiology Unit, London School of Hygiene and Tropical Medicine, London, United Kingdom. sian.floyd@lshtm.ac.uk
Sian
S
Floyd
Jorg M
JM
Pönnighaus
Lyn
L
Bliss
Prince
P
Nkhosa
Lifted
L
Sichali
Glyn
G
Msiska
Paul E M
PE
Fine
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D001500:BCG Vaccine / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D006968:Hypersensitivity, Delayed / Q000453:epidemiology / Q000276:immunology*; D007700:Kinetics; D016015:Logistic Models; D008295:Malawi / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D013997:Time Factors; D014373:Tuberculin / Q000276:immunology*; D014374:Tuberculin Test
D001500:BCG Vaccine; D014373:Tuberculin