Soil Spores and Fungal Infections

Cryptococcus gattii infections seen beyond Pacific Northwest outbreak tied to soil spores

/ Author:  / Reviewed by: Joseph V. Madia, MD Beth Bolt, RPh

(RxWiki News) Dirt does more than stain your clothes and carpets; it also can carry some harmful substances, including things that can lead to disease. New reserach traced cases of a rare infection caused by a type of fungus found in soil.

According to the authors of a new study, the fungi Cryptococcus gattii has been causing an outbreak of illness in the Pacific Northwest since 2004.

The researchers explored instances of C. gattii infections outside of this region and found cases in a number of other US regions, cases which differed in demographics and outcomes from the Pacific Northwest infections.

The researchers called for greater medical awareness of C. gattii infections outside of the outbreak region.

"Contact a doctor if you have changes in vision or trouble breathing."

Cryptococcosis, or infection with the C. gattii fungi, was very rare in the US before 1999. But 100 cases have been reported in the states of Washington and Oregon since 2004.

The study authors, led by Julie R. Harris, PhD, of the Centers for Disease Control and Prevention (CDC) in Atlanta, explained that C. gattii is found naturally in the environment and is associated with soil and decaying organic material. Humans can develop a fungal infection when they breathe in C. gattii spores from the environment. Pneumonia and meningitis are common results of cryptococcosis.

Three specific strains of C. gattii have been involved in the Pacific Northwest outbreak. The average age of patients was 56 years old, and the infections seemed to occur equally in men and women. 

Respiratory problems were a frequent issue for the Pacific Northwest cryptococcosis patients, and most of them had underlying medical conditions before they became ill with cryptococcosis.

In their study, Dr. Harris and colleagues aimed to explore C. gattii infections outside of the Pacific Northwest region in an attempt to understand similarities, differences and whether or not there is a need for greater surveillance of the fungus.

To do so, the researchers depended on data reported to the CDC. All of the explored cases involved patients who became ill between January 2009 and May 2012 and were not residents of Washington or Oregon.

The study authors reported that since 2009, 25 known infections with C. gattii were seen in eight states outside of the Pacific Northwest. California reported 13 infections, Georgia reported five, New Mexico reported two, and Alabama, Florida, Hawaii, Michigan and Montana reported one infection each.

In 23 of the cases (92 percent), cryptococcosis was associated with strains of C. gattii other than the three connected with the Pacific Northwest outbreak. For the 10 patients with known travel history, none visited Washington or Oregon in the year prior to becoming ill.

The most common symptoms seen were headache (in 67 percent of cases), blurred vision (in 62 percent of cases) and nausea (in 46 percent of cases). One patient did not report any symptoms.

Sixteen of the patients (64 percent) had no underlying health issues and were healthy before their infection. The age range of the patients stretched from 15 to 83 years old, with the average age being 43 years old. Most of the patients (84 percent) were male.

Outcomes tended to be serious in the patients, with 23 requiring hospitalization (92 percent), 19 (76 percent) developing infections of the central nervous system and six patients (24 percent) dying.

Dr. Harris and colleagues noted that these cases differed in many ways from those seen in the Pacific Northwest, and were unlikely to be related to that outbreak. The reasons for these differences are not yet completely understood.

The study authors did note that the data might not represent complete information on all C. gattii infections.

"[C]ase reporting was carried out only in areas where laboratory staff, clinicians, or state health departments were aware of and interested in participating in CDC C. gattii surveillance," the researchers explained.

Furthermore, the exact incubation period of C. gattii is unknown, so there is a chance that travel to the Pacific Northwest earlier than a year before becoming ill could be involved in the development of cryptococcosis.

"Although this case series might represent an emerging public health issue in states outside the US Pacific Northwest, it also might represent previously unrecognized disease in these states," wrote Dr. Harris and colleagues.

Regardless of which situation is at play, the study authors concluded, "Clinicians outside the outbreak-affected areas should be aware of locally acquired C. gattii infection and its varied signs and symptoms."

This study was published September 11 in the CDC's Emerging Infectious Diseases journal. No conflicts of interest were reported.

Review Date: 
September 9, 2013
Last Updated:
September 11, 2013