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Cryptococcus gattii in the United States: clinical aspects of infection with an emerging pathogen
J R Harris1, S R Lockhart, E Debess
1Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA. ggt5@cdc.gov
Background:
Cryptococcus gattii (Cg) has caused increasing infections in the US Pacific Northwest (PNW) since 2004. We describe this outbreak and compare clinical aspects of infection in the United States among patients infected with different Cg genotypes.
Methods:
Beginning in 2005, PNW state health departments conducted retrospective and prospective passive surveillance for Cg infections, including patient interviews and chart reviews; clinical isolates were genotyped at the US Centers for Disease Control and Prevention (CDC). We examined symptom frequency and underlying conditions in US patients with Cg infection and modeled factors associated with death.
Results:
From 1 December 2004 to July 2011, 96 Cg infections were reported to the CDC. Eighty-three were in patients in or travelers to the PNW, 78 of which were genotypes VGIIa, VGIIb, or VGIIc (outbreak strains). Eighteen patients in and outside the PNW had other molecular type Cg infections (nonoutbreak strains). Patients with outbreak strain infections were more likely than those with nonoutbreak-strain infections to have preexisting conditions (86% vs 31%, respectively; P < .0001) and respiratory symptoms (75% vs 36%, respectively; P = .03) and less likely to have central nervous system (CNS) symptoms (37% vs 90%, respectively; P = .008). Preexisting conditions were associated with increased pneumonia risk and decreased risk of meningitis and CNS symptoms. Nineteen (33%) of 57 patients died. Past-year oral steroid use increased odds of death in multivariate analysis (P = .05).
Conclusions:
Clinical differences may exist between outbreak-strain (VGIIa, VGIIb, and VGIIc) and nonoutbreak-strain Cg infections in the United States. Clinicians should have a low threshold for testing for Cg, particularly among patients with recent travel to the PNW.
Insights
Cryptococcus gattii (Cg) infections are increasing in the US Pacific Northwest. Outbreak strains (VGIIa, VGIIb, VGIIc) are linked to more underlying conditions and respiratory symptoms, while non-outbreak strains cause more CNS disease.
Area of Science:
- Medical Mycology
- Infectious Diseases
- Epidemiology
Background:
- Cryptococcus gattii (Cg) infections have risen in the US Pacific Northwest since 2004.
- This study details the Cg outbreak and compares clinical features of infections in the US based on Cg genotype.
Purpose of the Study:
- To describe the Cryptococcus gattii outbreak in the US Pacific Northwest.
- To compare clinical characteristics of Cg infections in the US, differentiating between outbreak and non-outbreak strains.
Main Methods:
- Passive surveillance (retrospective and prospective) of Cg infections by state health departments from 2005 to 2011.
- Clinical isolates were genotyped by the CDC; patient interviews and chart reviews were conducted.
- Analysis of symptom frequency, underlying conditions, and factors associated with mortality in US patients with Cg infection.
Main Results:
- 96 Cg infections reported; 78 were outbreak strains (VGIIa, VGIIb, VGIIc) in patients in or traveling to the Pacific Northwest.
- Outbreak strain infections were associated with more preexisting conditions (86%) and respiratory symptoms (75%) compared to non-outbreak strains (31% and 36%).
- Outbreak strains were less likely to cause CNS symptoms (37%) than non-outbreak strains (90%). Mortality was 33% (19/57), with oral steroid use increasing death risk.
Conclusions:
- Distinct clinical presentations may differentiate outbreak (VGIIa, VGIIb, VGIIc) and non-outbreak Cg infections in the US.
- Clinicians should consider Cg testing, especially in patients with recent Pacific Northwest travel.
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