Advocating for Coccidioidomycosis to Be a Reportable Disease Nationwide in the United States and Encouraging Disease Surveillance across North and South America

Discovery of novel antifungal drugs via screening repurposing libraries against Coccidioides posadasii spherule initials

Coccidioidomycosis or valley fever is a treatment-limited fungal infection endemic to the alkaline deserts of North and South America for which two classes of antifungals are typically used: the polyenes and the triazoles. In light of the limited usefulness of the echinocandins and a growing trend of azole resistance, it is essential that we identify novel antifungals. In this study, we have developed and optimized a screening methodology for identifying potential antifungals effective against Coccidioides spherule initials using a metabolic assay, used it to screen four diverse drug libraries with limited drug overlap, and established safety and efficacy data for a majority of the compounds, including the Broad Repurposing Hub, Prestwick Chemicals 1520, Selleck L8200 Anti-parasitic, and MedChemExpress CNS Penetrants libraries. Hits were defined as compounds with strong metabolic inhibition (≥70%), which were significantly different compared to the median plate readout (B-scores ≤ -3). We identified 30 promising hits and found 12 compounds exhibiting half-maximal inhibitory concentrations below 6 µM. Among these, oxethazaine, niclosamide ethanolamine, 10058-F4, niclosamide (NIC), and pentamidine isethionate showed synergy with amphotericin B, suggesting their potential use in combination therapy. Further assessment of lead compounds' effects on spherules was conducted by image flow cytometry. Additionally, we explored the potential to use an attenuated, Biosafety Level 2 containment mutant, C. posadasii ∆cts2/∆ard1/∆cts3 (∆T), as a surrogate model for drug screening. Overall, our findings provide a foundation for future research focused on screening and developing novel coccidioidomycosis treatments.IMPORTANCEThe antifungal treatment arsenal is especially limited against Coccidioides. Due to toxicity concerns, amphotericin B is generally reserved for triazole-recalcitrant infections. Recent laboratory susceptibility tests show an increase in fluconazole resistance, highlighting a need for new treatments. We have developed a large-scale metabolic screening assay under Biosafety Level 3 containment to identify existing drugs with novel activity against Coccidioides spherules. This drug-repurposing approach represents a convenient and cost-effective strategy to increase the available antifungals effective against these infections.

Coccidioidomycosis: a growing global concern

Coccidioidomycosis (CM) has been a recognized disease for about 130 years. The organisms (Coccidioides spp. fungi) inhabit desert soil in the southwestern USA, Mexico, and parts of Central and South America. Natural events such as dust storms, wildfires or outdoor activities including construction and gardening can disrupt the fungal arthroconidia, which easily become airborne and inhaled by the host. Approximately 60% of those exposed to arthroconidia are asymptomatic and do not require medical attention, but 30% show signs of pulmonary infection with symptoms ranging from a flu-like illness to pneumonia. In 5%-10% of cases serious or disseminated disease develops, which requires prompt diagnosis and management. About 1%-3% of infections disseminate to the CNS and if not appropriately treated are often fatal. There is an urgent need for improved diagnostics and treatments.

Estimating coccidioidomycosis endemicity while accounting for imperfect detection using spatio-temporal occupancy modeling

Coccidioidomycosis, or Valley fever, is an infectious disease caused by inhaling Coccidioides fungal spores. Incidence has risen in recent years, and it is believed the endemic region for Coccidioides is expanding in response to climate change. While Valley fever case data can help us understand trends in disease risk, using case data as a proxy for Coccidioides endemicity is not ideal because case data suffer from imperfect detection, including false positives (eg, travel-related cases reported outside of endemic area) and false negatives (eg, misdiagnosis or underreporting). We proposed a Bayesian, spatio-temporal occupancy model to relate monthly, county-level presence/absence data on Valley fever cases to latent endemicity of Coccidioides, accounting for imperfect detection. We used our model to estimate endemicity in the western United States. We estimated high probability of endemicity in southern California, Arizona, and New Mexico, but also in regions without mandated reporting, including western Texas, eastern Colorado, and southeastern Washington. We also quantified spatio-temporal variability in detectability of Valley fever, given an area is endemic to Coccidioides. We estimated an inverse relationship between lagged 3- and 9-month precipitation and case detection, and a positive association with agriculture. This work can help inform public health surveillance needs and identify areas that would benefit from mandatory case reporting. This article is part of a Special Collection on Environmental Epidemiology.

From soil to clinic: current advances in understanding Coccidioides and coccidioidomycosis

SUMMARYCoccidioides immitis and Coccidioides posadasii are fungal pathogens that cause systemic mycoses and are prevalent in arid regions in the Americas. While C. immitis mainly occurs in California and Washington, C. posadasii is widely distributed across North and South America. Both species induce coccidioidomycosis (San Joaquin Valley fever or, more commonly, Valley fever), with reported cases surging in the United States, notably in California and Arizona. Moreover, cases in Argentina, Brazil, and Mexico are on the rise. Climate change and environmental alterations conducive to Coccidioides spp. proliferation have been recently explored. Diagnostic challenges contribute to delayed treatment initiation, compounded by limited therapeutic options. Although antifungal drugs are often effective treatments, some patients do not respond to current therapies, underscoring the urgent need for a vaccine, particularly for vulnerable populations over 60 years old relocating to endemic areas. Despite recent progress, gaps persist in the understanding of Coccidioides ecology, host immune responses, and vaccine development. This review synthesizes recent research advancements in Coccidioides ecology, genomics, and immune responses, emphasizing ongoing efforts to develop a human vaccine.

Spatiotemporal analysis of lung immune dynamics in lethal Coccidioides posadasii infection

Coccidioidomycosis, or Valley fever, is a lung disease caused by inhalation of Coccidioides fungi, prevalent in the Southwestern United States, Mexico, and parts of Central and South America. Annually, the United States reports 10,000-20,000 cases, although those numbers are expected to increase as climate change expands the fungal geographic range. While 60% of infections are asymptomatic, 40% symptomatic infections are often misdiagnosed due to similarities with bronchitis or pneumonia. A small subset of infection progress to severe illness, necessitating a better understanding of immune responses during lethal infection. Using single-cell RNA sequencing and spatial transcriptomics, we characterized lung responses during Coccidioides infection. We identified monocyte-derived Spp1-expressing macrophages as potential mediators of tissue remodeling and fibrosis, marked by high expression of profibrotic and proinflammatory transcripts. These macrophages showed elevated TGF-β and IL-6 signaling, pathways involved in fibrosis pathogenesis. Additionally, we observed significant neutrophil infiltration and defective lymphocyte responses, indicating severe adaptive immunity dysregulation in lethal, acute infection. These findings enhance our understanding of Coccidioides infection and suggest new therapeutic targets.IMPORTANCECoccidioidomycosis, commonly known as Valley fever, is a lung disease caused by the inhalation of Coccidioides fungi, which is prevalent in the Southwestern United States, Mexico, and parts of Central and South America. With climate change potentially expanding the geographic range of this fungus, understanding the immune responses during severe infections is crucial. Our study used advanced techniques to analyze lung responses during Coccidioides infection, identifying specific immune cells that may contribute to tissue damage and fibrosis. These findings provide new insights into the disease mechanisms and suggest potential targets for therapeutic intervention, which could improve outcomes for patients suffering from severe Valley fever.

Suspected Acute Pulmonary Coccidioidomycosis in Traveler Returning to Switzerland from Peru

We report a suspected case of acute pulmonary coccidioidomycosis contracted in Peru, where the disease is not known to occur, in a patient from Switzerland. Although not confirmed by direct diagnostic testing, the clinical manifestations and serologic testing results of this case are highly suggestive of coccidioidomycosis.

Coccidioidomycosis in Immunocompromised at a Non-Endemic Referral Center in Mexico

The incidence and distribution of coccidioidomycosis are increasing. Information scarcity is evident in Mexico, particularly in non-endemic zones and specific populations. We compared the treatment and outcomes for patients with isolated pulmonary infections and those with disseminated coccidioidomycosis, including mortality rates within six weeks of diagnosis. Of 31 CM cases, 71% were male and 55% were disseminated. For 42% of patients, there was no evidence of having lived in or visited an endemic region. All patients had at least one comorbidity, and 58% had pharmacologic immunosuppressants. The general mortality rate was 30%; without differences between disseminated and localized disease. In our research, we describe a CM with a high frequency of disseminated disease without specific risk factors and non-significant mortality. Exposure to endemic regions was not found in a considerable number of subjects. We consider diverse reasons for why this may be, such as climate change or migration.

Epidemiology of coccidioidomycosis in Argentina, an update

The National Reference Laboratory in Clinical Mycology of Argentina conducted a retrospective review of human coccidioidomycosis cases diagnosed by the National Mycology Laboratory Network of Argentina between 2010 and 2022 to determine the burden of the disease in the country. A total of 100 human coccidioidomycosis cases were documented, with a higher prevalence in male patients (male-to-female ratio of 1.9:1), with a median age of 41 years. Comparing the number of cases between two 10-year periods (2000-2009 and 2010-2019), the increase was 36.51% (from 63 to 86 cases). Among the 100 recorded cases, 79 tested positive using the double immunodiffusion test. Spherules were observed in 19 cases through histopathology or direct microscopic examination and the fungus was isolated in 39 cases. Thirty-six isolates were identified as Coccidioides posadasii through partial sequencing of the Ag2/PRA gene. Catamarca province had the highest number of cases, comprising 64% of the total, with an incidence rate above 1.0-2.5/100,000 inhabitants until 2018. However, there has been a recent downward trend in the region from 2018 to 2022. It is concerning that more than half of diagnosed cases were chronic pulmonary or disseminated forms, indicating a lack of early disease detection. To rectify this issue, it is imperative to conduct targeted training programs for healthcare personnel and enhance public awareness within the endemic area. This will contribute to a better understanding of the true burden of coccidioidomycosis and enable the implementation of appropriate sanitary control measures.

Coccidioidomycosis-Related Hospital Visits, Texas, USA, 2016-2021

We analyzed hospital discharge records of patients with coccidioidomycosis-related codes from the International Classification of Diseases, 10th revision, Clinical Modification, to estimate the prevalence of hospital visits associated with the disease in Texas, USA. Using Texas Health Care Information Collection data for 2016-2021, we investigated the demographic characteristics and geographic distribution of the affected population, assessed prevalence of hospital visits for coccidioidomycosis, and examined how prevalence varied by demographic and geographic factors. In Texas, 709 coccidioidomycosis-related inpatient and outpatient hospital visits occurred in 2021; prevalence was 3.17 cases per 100,000 total hospital visits in 2020. Geographic location, patient sex, and race/ethnicity were associated with increases in coccidioidomycosis-related hospital visits; male, non-Hispanic Black, and Hispanic patients had the highest prevalence of coccidioidomycosis compared with other groups. Increased surveillance and healthcare provider education and outreach are needed to ensure timely and accurate diagnosis and treatment of coccidioidomycosis in Texas and elsewhere.

The dog as a sentinel and animal model for coccidioidomycosis

Coccidioidomycosis is a potentially fatal fungal disease of humans and animals that follows inhalation of Coccidioides spp. arthroconidia in the environment. The disease in dogs resembles that in people, and because dogs may be at increased risk of exposure due to their proximity to the ground and digging behavior, they are valuable models for the disease in humans. Dogs have been sentinels for identification of new regions of endemicity in Washington and Texas. Canine serosurveillance has also been used to predict variables associated with environmental presence of Coccidioides spp. Expansion of the endemic region of coccidioidomycosis with climate change-along with predicted population increases and increased development in the southwest United States-may result in 45.4 million additional people at risk of infection by 2090. Here we provide an overview of the value of dogs as sentinels for the disease and encourage the routine reporting of coccidioidomycosis cases in dogs to public health agencies. We also highlight the value of dogs as naturally occurring models for studying novel treatment options and preventatives, such as a novel live avirulent coccidioidomycosis vaccine.

Epidemiology of Coccidioidomycosis in the Veterans Health Administration, 2013-2022

We describe the epidemiology of coccidioidomycosis among a national cohort of Veterans. Using electronic health record data from adults tested for coccidioidomycosis between 1 January 2013 and 31 December 2022, we analyzed differences in baseline demographics (age, sex, race/ethnicity, birth country, comorbidities, residence, and Charlson Comorbidity Index score) between 4204 coccidioidomycosis-test-positive and 63,322 test-negative Veterans. Log-binomial regression models with adjusted risk ratios (aRRs) were used to evaluate risk factors associated with coccidioidomycosis including dissemination, hospitalization, and mortality. Case counts and incidence rates were highest in select counties in Arizona and California where Coccidioides is endemic. Coccidioidomycosis-positive Veterans were younger, more likely to be male, and Philippine-born. The risk factors most highly associated with being coccidioidomycosis-positive included Native Hawaiian/Pacific Islander (aRR 1.068 [95%CI: 1.039-1.098]), Asian (aRR 1.060 [95%CI: 1.037-1.083]), Black (aRR 1.029 [95%CI: 1.022-1.036]), American Indian/Alaska Native (aRR 1.026 [95%CI: 1.004-1.048]) race, and Hispanic/Latino ethnicity (aRR 1.021 [95%CI: 1.013-1.028]). Black race (aRR: 1.058 [95%CI: 1.037-1.081]) and Hispanic/Latino ethnicity (aRR 1.018 [95%CI: 1.0003-1.036]) were also associated with disseminated coccidioidomycosis, strengthening the evidence for the association of coccidioidomycosis, including severe infections, with specific racial and ethnic groups. There were no statistically significant differences in hospitalization within 45 days of testing or 30-day all-cause mortality. Improving our understanding of coccidioidomycosis risk factors is important for targeted prevention strategies and to reduce delays in diagnosis and ineffective treatment.