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. Author manuscript; available in PMC: 2010 Jul 30.
Published in final edited form as: Clin Infect Dis. 2007 Apr 9;44(10):1349–1357. doi: 10.1086/515397

Figure 3.

Figure 3

Tuberculin purified protein derivative (PPD) skin test responses in guinea pigs exposed and not exposed to ward air. The frequency distribution of induration diameter at 48 h for PPD skin tests is shown for quarantined animals (760 tests in 308 animals over 3 months) (A), unexposed negative control animals on the roof (287 tests in 50 animals over 13 months) (B), animals exposed to ward air (1564 tests in 292 animals over 16 months) (C), and animals exposed to ward air as in C, with the y axis truncated at 30 mm to emphasize the distribution of large responses ≥7.5 mm (D).