Valley Fever on the Rise and Spreading, CDC Says

Troy Brown, RN

September 19, 2019

The number of Coccidioidomycosis cases, also known as valley fever, has risen nearly 75% since 2014, according to the Centers for Disease Control and Prevention (CDC). Most of those cases were from Arizona and California, but the Coccidioides fungus has been found as far north as central Washington.

The reasons for the increase are unclear but could be related to environmental factors, such as weather and changes in land use, as well as changes in the at-risk population and surveillance.

The report, by Kaitlin Benedict, MPH, from the CDC, and colleagues from the Arizona Department of Health Services in Phoenix and the California Department of Public Health in Richmond and in Sacramento, was published online today in Morbidity and Mortality Weekly Report.

"Despite the limited scope and depth of current coccidioidomycosis surveillance practices, these data indicate that the disease persists as an important national public health problem, with cases occurring across the country, and a major public health problem for parts of Arizona and California, where rates of reported cases in some counties exceed 100 per 100,000 population," the authors explain.

A total of 95,371 cases from 26 states and the District of Columbia were reported to the CDC from 2011 to 2017. After falling from 22,634 cases in 2011 to 8232 cases in 2014, the number of reported cases increased steadily to 14,364 in 2017.

At the state level, the reported incidence in Arizona fell from 261 per 100,000 persons in 2011 to 101 in 2017. In contrast, the incidence increased from 15.7 to 18.2 in California during the same period. Incidence rates were relatively steady in other states.

Patient demographic characteristics resembled those in previous years. Valley fever was concentrated among males and among adults older than 60 years in Arizona and among adults aged 40 to 59 years in California.

The authors urge healthcare providers to consider Coccidioides infection in patients who reside or work in or who have traveled to affected areas. Clinicians should understand that those areas may extend farther than previously thought.

Coccidioidomycosis surveillance needs to expand to more states to enable officials to identify emerging at-risk areas, the authors write. They urge officials in Arizona and California ― where the majority of cases occur ― to take a systematic approach in collecting more detailed data on patient characteristics and illness severity. This could shed light on reasons for changes in incidence trends.

Valley fever is a potentially fatal infection caused by the Coccidioides fungus, which is found in soil in warm, dry regions. Seen largely in the southwestern United States, the fungus has been found as far north as central Washington. The fungus usually causes respiratory illness, although it can also cause disseminated illness.

It is unknown whether antifungal medications lessen symptom duration or intensity in patients with uncomplicated pulmonary coccidioidomycosis; therefore, additional research is needed to identify the best treatment for these patients.

The collection of accurate, timely information that can be compared across public health jurisdictions will provide a more complete understanding of the infection's epidemiology, critical for improving prevention and treatment.

"Ongoing public health efforts aimed at increasing awareness among the public and among health care providers are essential for helping patients receive a diagnosis and appropriate treatment more quickly," the researchers write.

"Research on understanding and reducing human exposures, individual susceptibility to disease, and vaccines could lead to more effective primary prevention strategies," they conclude.

The authors have disclosed no relevant financial relationships.

Morb Mortal Wkly Rep. Published online September 19, 2019. Full text

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