Cryptococcus gattii Infections in Multiple States Outside the US Pacific Northwest

Julie R. Harris

, Shawn R. Lockhart, Gail Sondermeyer, Duc J. Vugia, Matthew B. Crist, Melissa Tobin D’Angelo, Brenda Sellers, Carlos Franco-Paredes, Monear Makvandi, Chad Smelser, John Greene, Danielle Stanek, Kimberly Signs, Randall J. Nett, Tom Chiller, and Benjamin J. Park

Author affiliations: Centers for Disease Control and Prevention, Atlanta, Georgia, USA (J.R. Harris, S.R. Lockhart, R.J. Nett, T. Chiller, B.J. Park); California Department of Public Health, Richmond, California, USA (G. Sondemeyer, D.J. Vugia); Georgia Department of Public Health, Atlanta (M.B. Crist, M.T. D’Angelo); Phoebe Putney Memorial Hospital, Albany, Georgia, USA (B. Sellers, C. Franco-Paredes); Hospital Infantil Federico Gomez, Mexico City, Mexico (C. Franco-Paredes); New Mexico Department of Health, Santa Fe, New Mexico, USA (M. Mkvandi, C. Smelser); Moffitt Cancer Center, Tampa, Florida, USA (J. Greene); Florida Department of Health, Tallahassee, Florida, USA (D. Stanek); Michigan Department of Community Health, Lansing, Michigan, USA (K. Signs); Montana Department of Public Health and Human Services, Helena, Montana, USA (R.J. Nett)

Abstract

Clonal VGII subtypes (outbreak strains) of Cryptococcus gattii have caused an outbreak in the US Pacific Northwest since 2004. Outbreak-associated infections occur equally in male and female patients (median age 56 years) and usually cause pulmonary disease in persons with underlying medical conditions. Since 2009, a total of 25 C. gattii infections, 23 (92%) caused by non–outbreak strain C. gattii, have been reported from 8 non–Pacific Northwest states. Sixteen (64%) patients were previously healthy, and 21 (84%) were male; median age was 43 years (range 15–83 years). Ten patients who provided information reported no past-year travel to areas where C. gattii is known to be endemic. Nineteen (76%) patients had central nervous system infections; 6 (24%) died. C. gattii infection in persons without exposure to known disease-endemic areas suggests possible endemicity in the United States outside the outbreak-affected region; these infections appear to differ in clinical and demographic characteristics from outbreak-associated C. gattii. Clinicians outside the outbreak-affected areas should be aware of locally acquired C. gattii infection and its varied signs and symptoms.

Cryptococcus gattii, a fungal pathogen found in the environment, is associated with soil and decaying organic debris. Infection in humans results from inhalation of spores from the environment and typically causes pneumonia or meningitis (1,2); the incubation period is thought to be 2–13 months, although it may be longer (3,4). Unlike the related species C. neoformans, which is distributed globally and is a common opportunistic infection in HIV-infected or severely immunocompromised persons, C. gattii typically affects patients without HIV infection (1,2,5–8), and its environmental distribution is thought to be more limited (9–11). C. gattii infection is typically considered more difficult to treat than C. neoformans infection and requires longer and more aggressive treatment (1,7,8,12,13).
Before 1999, clinical isolates of C. gattii were rare in North America; a small number of cases were reported, mostly in southern California and in Hawaii (9,10,14,15). However, since 2004, an outbreak of C. gattii cryptococcosis has been ongoing in British Columbia, Canada, and the US Pacific Northwest states of Washington and Oregon (2,5). Approximately 100 C. gattii cases have been reported from Washington and Oregon. The US Pacific Northwest outbreak is characterized by infection with 3 clonal C. gattii strains (VGIIa, VGIIb, and VGIIc), 2 of which are uncommon outside this region and 1 (VGIIc) that is unique to the region (16). Previously reported cases of C. gattii infection were in otherwise healthy patients who had severe central nervous system (CNS) disease (1). In contrast, most patients associated with the US Pacific Northwest outbreak have had respiratory symptoms and preexisting immunocompromising or other serious underlying medical conditions before becoming infected with C. gattii (2).
The outbreak in the US Pacific Northwest has increased interest in C. gattii among public health authorities and the US health community and resulted in efforts by the Centers for Disease Control and Prevention (CDC; Atlanta, GA, USA) to collect surveillance data on C. gattii infections from states outside that region. Whether these reported cases are an effect of the US Pacific Northwest outbreak on other areas of the United States and the implications for clinical care and broader surveillance have not been addressed. We summarize C. gattii cases reported to CDC from non–US Pacific Northwest states and discuss their implications.