a. Swallowing water from a hose
b. Eating rare meat
c. Cleaning dirt from a bird roost
d. Handling unwashed fruits
164. Which finding when a PPD is read 2 1⁄2 days after it is planted indicates a positive reaction?
a. Reddened area 10 mm in diameter
b. Indurated area 12 mm in diameter
c. Blistered area 4 mm in diameter
d. Blanched area of at least 8 mm in diameter
163. Correct answer: c.
The causative organism of histoplasmosis is the fungus Histoplasma capsulatum, which is found in bird feces so cleaning a bird roost is a source of exposure. It is not passed person to person. Neither is it contracted by swal-lowing water, eating rare meat, or handling unwashed fruit.
164. Correct answer: b.
Ten mm or more of induration is highly significant for past or present infection with the tubercle bacillus. Erythema alone does not indicate a positive result. Blistering or blanching do not indicate a positive result.