A-Z Index × Submit A-Z Index × Submit A-Z Index Search Dropdown × Submit Facebook Twitter LinkedIn Syndicate Emerging Infectious Disease journal ISSN: 1080-6059 Disclaimer: Early release articles are not considered as final versions. Any changes will be reflected in the online version in the month the article is officially released.
We describe a case of Acanthamoeba encephalitis with chronic lymphocytic leukemia (CLL) in the United States and summarize the Free-Living Ameba database to highlight CLL as the most common underlying malignancy for Acanthamoeba infections. CLL patients are more likely to have improved survival and nondisseminated cutaneous disease than those with other cancers.
Acanthamoeba is a free-living amoeba (FLA) transmitted via inhalation or direct contact with the eyes or skin ( 1 ) that can cause keratitis and granulomatous amebic encephalitis (GAE) ( 2 ). GAE occurs most often in immunocompromised patients; risk factors include hematologic malignancy and immunosuppressive drugs ( 2 ). Chronic lymphocytic leukemia (CLL), the most common leukemia ( 3 ), can lead to immune dysfunction from immunosuppressive treatments and hypogammaglobulinemia, as well as impairments in complement activity, cell-mediated immunity, and neutrophil function ( 4 ). The 5-year risk for severe infections in CLL is as high as 57% when IgG levels are low ( 5 ). Ibrutinib, a Bruton tyrosine-kinase inhibitor ( 6 ), is an immunomodulatory drug used for CLL treatment that increases the risk for invasive infections up to 11.4% during the first year of treatment through innate immune system impairment ( 7 – 9 ). We report a case of Acanthamoeba GAE in a patient with CLL managed with ibrutinib. Using a retrospective analysis of data from the Centers for Disease Control and Prevention (CDC) Free-Living Ameba database ( Appendix ), we sought to determine the frequency of Acanthamoeba infections among patients with CLL and to compare clinical characteristics with those of patients without CLL.
Figure . Acanthamoeba immunoassay from study of Acanthamoeba encephalitis and chronic lymphocytic leukemia, United States. Arrow indicates free-living amebic trophozoites of small to medium size that have rare double-walled cysts...
A 71-year-old man with CLL who was receiving ibrutinib sought care for fever, encephalopathy, and focal right-sided weakness. Neuroimaging showed a rapidly enlarging left frontal lesion with surrounding edema; test results for bacterial, viral, and parasitic pathogens were unremarkable ( Appendix Table). Brain biopsy demonstrated necrosis, inflammation, and rare Periodic acid-Schiff–positive organisms ( Figure ). CDC testing confirmed Acanthamoeba infection. Despite initiation of azithromycin, sulfadiazine, flucytosine, fluconazole, and miltefosine, the patient died 23 days after symptom onset.
To further investigate the possible role of CLL in this patient’s course, we examined all US cases of Acanthamoeba infection reported to the CDC FLA database during 1956–2023 ( Appendix ). This activity was reviewed by CDC, deemed not research, and was conducted consistent with applicable federal law and CDC policy (see e.g., 45 C.F.R. part 46, 21 C.F.R. part 56; 42 U.S.C. §241(d); 5 U.S.C. §552a; 44 U.S.C. §3501 et seq.).
The mean age of diagnosis was 48 years for all case-patients with Acanthamoeba infection and 68 years in the CLL subgroup ( Table ). Among the 16 Acanthamoeba cases in CLL patients with known sex, 14 occurred in male…