Coccidioidomycosis in Tulare County, California, 1991: reemergence of an endemic disease

The Known and Unknown "Knowns" of Human Susceptibility to Coccidioidomycosis

Coccidioidomycosis occurs after inhalation of airborne spores of the endemic, dimorphic fungus, Coccidioides. While the majority of individuals resolve the infection without coming to medical attention, the fungus is a major cause of community-acquired pneumonia in the endemic region, and chronic pulmonary and extrapulmonary disease poses significant personal and economic burdens. This review explores the literature surrounding human susceptibility to coccidioidomycosis, including chronic pulmonary and extrapulmonary dissemination. Over the past century of study, themes have emerged surrounding factors impacting human susceptibility to severe disease or dissemination, including immune suppression, genetic susceptibility, sex, pregnancy, and genetic ancestry. Early studies were observational, frequently with small numbers of cases; several of these early studies are highly cited in review papers, becoming part of the coccidioidomycosis "canon". Specific genetic variants, sex, and immune suppression by TNF inhibitors have been validated in later cohort studies, confirming the original hypotheses. By contrast, some risk factors, such as ABO blood group, Filipino ancestry, or lack of erythema nodosum among black individuals, are repeated in the literature despite the lack of supporting studies or biologic plausibility. Using examination of historical reports coupled with recent cohort and epidemiology studies, evidence for commonly reported risk factors is discussed.

Race and ethnicity: Risk factors for fungal infections?

Racial and ethnic identities, largely understood as social rather than biologic constructs, may impact risk for acquiring infectious diseases, including fungal infections. Risk factors may include genetic and immunologic differences such as aberrations in host immune response, host polymorphisms, and epigenomic factors stemming from environmental exposures and underlying social determinants of health. In addition, certain racial and ethnic groups may be predisposed to diseases that increase risk for fungal infections, as well as disparities in healthcare access and health insurance. In this review, we analyzed racial and ethnic identities as risk factors for acquiring fungal infections, as well as race and ethnicity as they relate to risk for severe disease from fungal infections. Risk factors for invasive mold infections such as aspergillosis largely appear related to environmental differences and underlying social determinants of health, although immunologic aberrations and genetic polymorphisms may contribute in some circumstances. Although black and African American individuals appear to be at high risk for superficial and invasive Candida infections and cryptococcosis, the reasons for this are unclear and may be related to underling social determinants of health, disparities in access to healthcare, and other socioeconomic disparities. Risk factors for all the endemic fungi are likely largely related to underlying social determinants of health, socioeconomic, and health disparities, although immunologic mechanisms likely play a role as well, particularly in disseminated coccidioidomycosis.

Update on the Epidemiology, Diagnosis, and Treatment of Coccidioidomycosis

Coccidioidomycosis is a fungal infection caused by Coccidioides immitis and Coccidioides posadasii. The dimorphic fungi live in the soils of arid and semi-arid regions of the western United States, as well as parts of Mexico, Central America, and South America. Incidence of disease has risen consistently in recent years, and the geographic distribution of Coccidioides spp. appears to be expanding beyond previously known areas of endemicity. Climate factors are predicted to further extend the range of environments suitable for the growth and dispersal of Coccidioides species. Most infections are asymptomatic, though a small proportion result in severe or life-threatening forms of disease. Primary pulmonary coccidioidomycosis is commonly mistaken for community-acquired pneumonia, often leading to inappropriate antibacterial treatment and unnecessary healthcare costs. Diagnosis of coccidioidomycosis is challenging and often relies on clinician suspicion to pursue laboratory testing. Advancements in diagnostic tools and antifungal therapy developments seek to improve the early detection and effective management of infection. This review will highlight recent updates and summarize the current understanding of the epidemiology, diagnosis, and treatment of coccidioidomycosis.

Sex Differences in the Susceptibility to Coccidioidomycosis

To assess sex-specific differences in coccidioidomycosis, a retrospective analysis of human patients, nonhuman primates, and veterinary patients (including the neutered status of the animal) was performed. We found higher rates of infection and severity in males. This observed increased infection risk suggests deeper biological underpinnings than solely occupational/exposure risks.

Viral, bacterial, and fungal infections of the oral mucosa: Types, incidence, predisposing factors, diagnostic algorithms, and management

For millions of years, microbiota residing within us, including those in the oral cavity, coexisted in a harmonious symbiotic fashion that provided a quintessential foundation for human health. It is now clear that disruption of such a healthy relationship leading to microbial dysbiosis causes a wide array of infections, ranging from localized, mild, superficial infections to deep, disseminated life-threatening diseases. With recent advances in research, diagnostics, and improved surveillance we are witnessing an array of emerging and re-emerging oral infections and orofacial manifestations of systemic infections. Orofacial infections may cause significant discomfort to the patients and unnecessary economic burden. Thus, the early recognition of such infections is paramount for holistic patient management, and oral clinicians have a critical role in recognizing, diagnosing, managing, and preventing either new or old orofacial infections. This paper aims to provide an update on current understanding of well-established and emerging viral, bacterial, and fungal infections manifesting in the human oral cavity.

Coccidioides ecology and genomics

Although the natural history and ecology of Coccidioides spp. have been studied for over 100 years, many fundamental questions about this fungus remain unanswered. Two of the most challenging aspects of the study of Coccidioides have been the undefined ecological niche and the outdated geographic distribution maps dating from midcentury. This review details the history of Coccidioides ecological research, and discusses current strategies and advances in understanding Coccidioides genetics and ecology.

Coccidioidomycosis Among American Indians and Alaska Natives, 2001-2014

Background

American Indians and Alaska Natives (AI/ANs) may be uniquely vulnerable to coccidioidomycosis given the large population residing in the Southwestern United States. We describe coccidioidomycosis-associated hospitalizations and outpatient visits during 2001-2014 in the Indian Health Service (IHS) system and compare hospitalizations with data from the Agency for Healthcare Research and Quality's National (Nationwide) Inpatient Sample (NIS).

Methods

We identified hospitalizations in the IHS and the NIS and outpatient visits in the IHS using International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) codes 114.0-114.9. We calculated average annual hospitalization and outpatient visit rates per 1 000 000 population and used Poisson regression to calculate rate ratios (RRs) and 95% confidence intervals (CIs). We used multivariable logistic regression to assess factors associated with IHS hospitalization.

Results

AI/ANs had the highest average annual hospitalization rate (58.0; 95% CI, 49.5-66.6) of any racial/ethnic group in the NIS, compared with 13.4 (95% CI, 12.7-14.2) for non-Hispanic whites. IHS data showed a hospitalization rate of 37.0; the median length of stay (interquartile range) was 6 (3-10) days. The average annual outpatient visit rate in IHS was 764.2, and it increased from 529.9 in 2001 to 845.9 in 2014. Male sex, age ≥65 years, diabetes, and extrapulmonary or progressive coccidioidomycosis were independently associated with increased risk for hospitalization. Twenty-four percent of patients had ICD-9-CM codes for community-acquired pneumonia in the 3 months before coccidioidomycosis diagnosis.

Conclusions

AI/ANs experience high coccidioidomycosis-associated hospitalization rates, high morbidity, and possible missed opportunities for earlier diagnosis. Yearly trends in IHS data were similar to the general increase in hospitalizations and reported cases nationwide in the same period.

Coccidioidomycosis Dynamics in Relation to Climate in the Southwestern United States

Valley fever is endemic to the southwestern United States. Humans contract this fungal disease by inhaling spores of Coccidioides spp. Changes in the environment can influence the abundance and dispersal of Coccidioides spp., causing fluctuations in valley fever incidence. We combined county-level case records from state health agencies to create a regional valley fever database for the southwestern United States, including Arizona, California, Nevada, New Mexico, and Utah. We used this data set to explore how environmental factors influenced the spatial pattern and temporal dynamics of valley fever incidence during 2000-2015. We compiled climate and environmental geospatial data sets from multiple sources to compare with valley fever incidence. These variables included air temperature, precipitation, soil moisture, surface dust concentration, normalized difference vegetation index, and cropland area. We found that valley fever incidence was greater in areas with warmer air temperatures and drier soils. The mean annual cycle of incidence varied throughout the southwestern United States and peaked following periods of low precipitation and soil moisture. From year-to-year, however, autumn incidence was higher following cooler, wetter, and productive springs in the San Joaquin Valley of California. In southcentral Arizona, incidence increased significantly through time. By 2015, incidence in this region was more than double the rate in the San Joaquin Valley. Our analysis provides a framework for interpreting the influence of climate change on valley fever incidence dynamics. Our results may allow the U.S. Centers for Disease Control and Prevention to improve their estimates of the spatial pattern and intensity of valley fever endemicity.

Characteristics of patients with mild to moderate primary pulmonary coccidioidomycosis

In Arizona, USA, primary pulmonary coccidioidomycosis accounts for 15%-29% of community-acquired pneumonia. To determine the evolution of symptoms and changes in laboratory values for patients with mild to moderate coccidioidomycosis during 2010-2012, we conducted a prospective 24-week study of patients with primary pulmonary coccidioidomycosis. Of the 36 patients, 16 (44%) were men and 33 (92%) were White. Median age was 53 years, and 20 (56%) had received antifungal treatment at baseline. Symptom scores were higher for patients who received treatment than for those who did not. Median times from symptom onset to 50% reduction and to complete resolution for patients in treatment and nontreatment groups were 9.9 and 9.1 weeks, and 18.7 and 17.8 weeks, respectively. Median times to full return to work were 8.4 and 5.7 weeks, respectively. One patient who received treatment experienced disseminated infection. For otherwise healthy adults with acute coccidioidomycosis, convalescence was prolonged, regardless of whether they received antifungal treatment.

Coccidioidomycosis: epidemiology

Coccidioidomycosis consists of a spectrum of disease, ranging from a mild, self-limited, febrile illness to severe, life-threatening infection. It is caused by the soil-dwelling fungi, Coccidioides immitis and C. posadasii, which are present in diverse endemic areas. Climate changes and environmental factors affect the Coccidioides lifecycle and influence infection rates. The incidence of coccidioidomycosis has risen substantially over the past two decades. The vast majority of Coccidioides infections occur in the endemic zones, such as California, Arizona, Mexico, and Central America. Infections occurring outside those zones appear to be increasingly common, and pose unique clinical and public health challenges. It has long been known that elderly persons, pregnant women, and members of certain ethnic groups are at risk for severe or disseminated coccidioidomycosis. In recent years, it has become evident that persons with immunodeficiency diseases, diabetics, transplant recipients, and prisoners are also particularly vulnerable.

Coccidioidomycosis in African Americans

Coccidioidomycosis is caused by Coccidioides species, a fungus endemic to the desert regions of the southwestern United States, and is of particular concern for African Americans. We performed a PubMed search of the English-language medical literature on coccidioidomycosis in African Americans and summarized the pertinent literature. Search terms were coccidioidomycosis, Coccidioides, race, ethnicity, African, black, and Negro. The proceedings of the national and international coccidioidomycosis symposia were searched. All relevant articles and their cited references were reviewed; those with epidemiological, immunologic, clinical, and therapeutic data pertaining to coccidioidomycosis in African Americans were included in the review. Numerous studies documented an increased predilection for severe coccidioidal infections, coccidioidomycosis-related hospitalizations, and extrapulmonary dissemination in persons of African descent; however, most of the published studies are variably problematic. The immunologic mechanism for this predilection is unclear. The clinical features and treatment recommendations are summarized. Medical practitioners need to be alert to the possibility of coccidioidomycosis in persons with recent travel to or residence in an area where the disease is endemic.

Atmospheric movement of microorganisms in clouds of desert dust and implications for human health

Billions of tons of desert dust move through the atmosphere each year. The primary source regions, which include the Sahara and Sahel regions of North Africa and the Gobi and Takla Makan regions of Asia, are capable of dispersing significant quantities of desert dust across the traditionally viewed oceanic barriers. While a considerable amount of research by scientists has addressed atmospheric pathways and aerosol chemistry, very few studies to determine the numbers and types of microorganisms transported within these desert dust clouds and the roles that they may play in human health have been conducted. This review is a summary of the current state of knowledge of desert dust microbiology and the health impact that desert dust and its microbial constituents may have in downwind environments both close to and far from their sources.

The population biology of coccidioides: epidemiologic implications for disease outbreaks

Studies of field- and patient-derived isolates conducted over the past 75 years have provided a general picture of the population structure of Coccidioides, the cause of coccidioidomycosis. Premolecular studies provided a general outline of the geographical range, epidemiology and distribution of the fungus. Recent studies based on molecular markers have demonstrated that the genus is comprised of two genetically diverse, and genetically isolated, species: Coccidioides immitis and C. posadasii. Both species are composed of biogeographically distinct populations. Structure for two of these populations (C. immitis from central California, and C. posadasii from southern Arizona) indicates that frequent genetic recombination occurs within the entire geographic range of each population, even though sex has never been observed in the genus. Outbreaks of coccidioidomycosis are not the result of the spread of a single clonal isolate, but are caused by a diversity of genotypes. Although it is now possible to match patient isolates to populations, the lack of apparent structure within each population and the current paucity of environmental isolates limit map-based epidemiological approaches to understanding outbreaks. Therefore, a comprehensive database comprised of soil-derived isolates from across the biogeographic range of Coccidioides will improve the utility of this approach. Appropriate collection of environmental isolates will assist the investigation of remaining questions regarding the population biology of Coccidioides. The comparative genomics of representative genotypes from both species and all populations of Coccidioides will provide a thorough set of genetic markers in order to resolve the population genetics of this pathogenic fungus.

Adverse health effects of outdoor air pollutants

Much research on the health effects of outdoor air pollution has been published in the last decade. The goal of this review is to concisely summarize a wide range of the recent research on health effects of many types of outdoor air pollution. A review of the health effects of major outdoor air pollutants including particulates, carbon monoxide, sulfur and nitrogen oxides, acid gases, metals, volatile organics, solvents, pesticides, radiation and bioaerosols is presented. Numerous studies have linked atmospheric pollutants to many types of health problems of many body systems including the respiratory, cardiovascular, immunological, hematological, neurological and reproductive/ developmental systems. Some studies have found increases in respiratory and cardiovascular problems at outdoor pollutant levels well below standards set by such agencies as the US EPA and WHO. Air pollution is associated with large increases in medical expenses, morbidity and is estimated to cause about 800,000 annual premature deaths worldwide [Cohen, A.J., Ross Alexander, H., Ostro, B., Pandey, K.D., Kryzanowski, M., Kunzail, N., et al., 2005. The global burden of disease due to outdoor air pollution. J Toxicol Environ Health A. 68: 1-7.]. Further research on the health effects of air pollution and air pollutant abatement methods should be very helpful to physicians, public health officials, industrialists, politicians and the general public.

Hospitalizations for endemic mycoses: a population-based national study

We performed a retrospective cohort study, using the 2002 Nationwide Inpatient Sample, a national database of hospital inpatient stays, to describe the incidence and epidemiology of endemic mycoses requiring hospitalization. An estimated 332 pediatric and 6003 adult patients with endemic mycoses required hospitalization (4.6 and 28.7 cases per 1 million children and adults, respectively). Crude mortality rates were 5% and 7% among children and adults, respectively.

Incidence of coccidioides infection among dogs residing in a region in which the organism is endemic

OBJECTIVE

To determine the incidence of Coccidioides infection among dogs residing in a region in which the organism is endemic (Pima and Maricopa counties, Arizona) and estimate the rate of clinical illness.

DESIGN

Community-based longitudinal and cross-sectional studies.

ANIMALS

124 healthy 4- to 6-month-old seronegative puppies (longitudinal study) and 381 4- to 18-month-old dogs with unknown serostatus (cross-sectional study).

PROCEDURE

Dogs in the longitudinal study were tested at 6-month intervals for at least 1 year for anticoccidioidal antibodies. Dogs that became ill were evaluated for coccidioidomycosis. Dogs in the cross-sectional study were tested for anticoccidioidal antibodies once, and clinical abnormalities were recorded.

RESULTS

28 of the 104 (27%) dogs that completed the longitudinal study developed anticoccidioidal antibodies. Thirty-two of the 381 (8%) dogs in the cross-sectional study had anticoccidioidal antibodies. Five seropositive dogs in the longitudinal study and 13 seropositive dogs in the cross-sectional study had clinical signs of disease. The remaining seropositive dogs were otherwise healthy and were classified as subclinically infected. Survival analysis indicated that the cumulative probability of infection by 2 years of age was 28%, and the cumulative probability of clinical infection by 2 years of age was 6%. Titers for clinically and subclinically infected dogs overlapped.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that young dogs living in the study area had a high likelihood of becoming infected with Coccidioides spp, but few developed clinical illness. Serologic testing alone was insufficient for a diagnosis of clinical disease because of the overlap in titers between clinically and subclinically infected dogs.

Coccidioidomycosis: host response and vaccine development

Coccidioidomycosis is caused by the dimorphic fungi in the genus Coccidioides. These fungi live as mycelia in the soil of desert areas of the American Southwest, and when the infectious spores, the arthroconidia, are inhaled, they convert into the parasitic spherule/endospore phase. Most infections are mild, but these organisms are frank pathogens and can cause severe lethal disease in fully immunocompetent individuals. While there is increased risk of disseminated disease in certain racial groups and immunocompromised persons, the fact that there are hosts who contain the initial infection and exhibit long-term immunity to reinfection supports the hypothesis that a vaccine against these pathogens is feasible. Multiple studies have shown that protective immunity against primary disease is associated with T-helper 1 (Th-1)-associated immune responses. The single best vaccine in animal models, formalin-killed spherules (FKS), was tested in a human trial but was not found to be significantly protective. This result has prompted studies to better define immunodominant Coccidioides antigen with the thought that a subunit vaccine would be protective. These efforts have defined multiple candidates, but the single best individual immunogen is the protein termed antigen 2/proline-rich antigen (Ag2/PRA). Studies in multiple laboratories have shown that Ag2/PRA as both protein and genetic vaccines provides significant protection against mice challenged systemically with Coccidioides. Unfortunately, compared to the FKS vaccine, it is significantly less protective as measured by both assays of reduction in fungal CFU and assays of survival. The capacity of Ag2/PRA to induce only partial protection was emphasized when animals were challenged intranasally. Thus, there is a need to define new candidates to create a multivalent vaccine to increase the effectiveness of Ag2/PRA. Efforts of genomic screening using expression library immunization or bioinformatic approaches to identify new candidates have revealed at least two new protective proteins, expression library immunization antigen 1 (ELI-Ag1) and a beta-1,3-glucanosyltransferase (GEL-1). In addition, previously discovered antigens such as Coccidioides-specific antigen (CSA) should be evaluated in assays of protection. While studies have yet to be completed with combinations of the current candidates, the hypothesis is that with increased numbers of candidates in a multivalent vaccine, there will be increased protection. As the genome sequences of the two Coccidioides strains which are under way are completed and annotated, the effort to find new candidates can increase to provide a complete genomic scan for immunodominant proteins. Thus, much progress has been made in the discovery of subunit vaccine candidates against Coccidioides and there are several candidates showing modest levels of protection, but for complete protection against pulmonary challenge we need to continue the search for additional candidates.

Trends in mortality due to invasive mycotic diseases in the United States, 1980-1997

To determine national trends in mortality due to invasive mycoses, we analyzed National Center for Health Statistics multiple-cause-of-death record tapes for the years 1980 through 1997, with use of their specific codes in the International Classification of Diseases, Ninth Revision (ICD-9 codes 112.4-118 and 136.3). In the United States, of deaths in which an infectious disease was the underlying cause, those due to mycoses increased from the tenth most common in 1980 to the seventh most common in 1997. From 1980 through 1997, the annual number of deaths in which an invasive mycosis was listed on the death certificate (multiple-cause [MC] mortality) increased from 1557 to 6534. In addition, rates of MC mortality for the different mycoses varied markedly according to human immunodeficiency virus (HIV) status but were consistently higher among males, blacks, and persons > or =65 years of age. These data highlight the public health importance of mycotic diseases and emphasize the need for continuing surveillance.

The potential impacts of climate variability and change on health impacts of extreme weather events in the United States

Extreme weather events such as precipitation extremes and severe storms cause hundreds of deaths and injuries annually in the United States. Climate change may alter the frequency, timing, intensity, and duration of these events. Increases in heavy precipitation have occurred over the past century. Future climate scenarios show likely increases in the frequency of extreme precipitation events, including precipitation during hurricanes, raising the risk of floods. Frequencies of tornadoes and hurricanes cannot reliably be projected. Injury and death are the direct health impacts most often associated with natural disasters. Secondary effects, mediated by changes in ecologic systems and public health infrastructure, also occur. The health impacts of extreme weather events hinge on the vulnerabilities and recovery capacities of the natural environment and the local population. Relevant variables include building codes, warning systems, disaster policies, evacuation plans, and relief efforts. There are many federal, state, and local government agencies and nongovernmental organizations involved in planning for and responding to natural disasters in the United States. Future research on health impacts of extreme weather events should focus on improving climate models to project any trends in regional extreme events and as a result improve public health preparedness and mitigation. Epidemiologic studies of health effects beyond the direct impacts of disaster will provide a more accurate measure of the full health impacts and will assist in planning and resource allocation.

Risk factors for severe pulmonary and disseminated coccidioidomycosis: Kern County, California, 1995-1996

Surveillance for coccidioidomycosis (CM) and a case-control study for risk factors among adults were conducted in Kern County, California. From January 1995 through December 1996, 905 cases of CM were identified, for an annual incidence of 86 cases per 100,000 population. A total of 380 adults were enrolled in the case-control study: 77 had severe pulmonary disease, 33 had disseminated disease, and 270 control patients had mild disease. Independent risk factors for severe pulmonary disease included diabetes, recent history of cigarette smoking, income of < $15,000 per year, and older age. Oral antifungal therapy before hospitalization was associated with a reduced risk of CM pneumonia. Risk factors for disseminated disease were black race, income of < $15,000 per year, and pregnancy. Early treatment of CM with oral antifungal agents may prevent severe pulmonary disease in groups considered to be at high risk, such as elderly individuals, persons with diabetes, and smokers. Persons at risk for severe CM may benefit from vaccination once an effective CM vaccine is available.

Prevalence of skin reactivity to coccidioidin and associated risks factors in subjects living in a northern city of Mexico

BACKGROUND

Coccidioidomycosis is a reemerging fungal disease seen mainly in the states located at the Mexican-U.S. border. The finding of advanced cases of the disease are now more frequent.

METHODS

A cross-sectional study was conducted to determine the prevalence of skin reactivity to coccidioidin in the city of Torreón, Coahuila, Mexico, located in the northern region of the country. A multifactorial association of environmental, social, and health conditions was analyzed. A total of 1,653 coccidioidin skin tests was applied in male and female subjects older than 8 years of age.

RESULTS

The overall rate of positive reactivity in this city was 40.2%, with a 95% confidence interval of 37.8-42.5. This was related to time/life exposure risk and to the habitat of unpaved streets. No statistically significant difference regarding gender, socioeconomic level, and working activities was found. The highest reactivity was observed in subjects between 30 and 65 years of age.

CONCLUSIONS

Positive results were related to exposure risk and habitat, principally in the southeast region of the city. These results were applied both to residents and outsiders with no differences between the groups. Of the total, 87.5% were considered high-risk subjects. It is recommended that future surveys be carried out in other northern cities of Mexico to obtain more useful data concerning the extent of the infection and mainly to establish preventive measures, such as appropriate reforestation and urbanization procedures.