Acanthamoeba kills immunocompetent man after six months of necrotic lesions

A 78-year-old man developed progressive black lesions and deep ulcers across his body over six months, with tissue destruction severe enough to perforate his palate into the nasal cavity and obliterate an eyelid. Doctors at Yale eventually identified Acanthamoeba, a free-living amoeba commonly present in tap water, as the cause. Treatment came too late, and the case is now documented in Emerging Infectious Diseases.

What makes the case unusual is the patient profile. Disseminated Acanthamoeba infections almost exclusively strike immunocompromised hosts — HIV/AIDS patients, cancer patients, transplant recipients on immunosuppressants. This man had none of those risk factors, leaving the trigger for systemic spread unexplained.

The organism is more commonly associated with localized harm: keratitis in contact lens wearers who skip proper disinfection, sinus infections in people who rinse with unboiled tap water, and rare granulomatous brain infections. Sampling has detected Acanthamoeba and related amoebae in over half of US tap water supplies, making exposure routine even though severe disease remains vanishingly rare.