"Special stains were used for microscopic examination of brain tissue from patients with clinical cases of meningitis. The black objects seen in these images is fungus."
Provenance
Picture retrieved on 2012-11-21.
This picture on the CDC website is linked from the "digital press kit" page of the fungal meningitis outbreak page: [2]
Other pictures on this page are also in the CDC "PHIL" database, [3] and have similar metadata as this picture. I cannot find this specific picture on the "PHIL" database, but it is probably there somewhere.
Those other pictures are explicitly labeled as being in the public domain.
This picture is explicitly in the "press kit," implying authorization to copy.
This picture is on the US government CDC web site and is not marked as not being in the public domain.