Effects of season and weather on blastomycosis in dogs: Northern Wisconsin, USA

Changing Patterns of Disease Severity in Blastomyces dermatitidis Infection, Quebec, Canada

The increase in severe cases might be related to an increased number of immunosuppressed patients; climate change might also play a role.

This retrospective multicenter cohort study assessed temporal changes in the severity and mortality rate of blastomycosis in Quebec, Canada, and identified risk factors for death in patients with blastomycosis in 1988–2016. The primary outcome was 90-day all-cause deaths. Among 185 patients, 122 (66%) needed hospitalization and 30 (16%) died. We noted increases in the proportion of severe cases, in age at diagnosis and in the proportion of diabetic and immunocompromised patients over time. Independent risk factors for death were age (adjusted odds ratio [aOR] 1.04, 95% CI 1.00–1.07), immunosuppression (aOR 4.2, 95% CI 1.5–11.6), and involvement of >2 lung lobes (aOR 5.3, 95% CI 1.9–14.3). There was no association between the Blastomyces genotype group and all-cause mortality. The proportion of severe cases of blastomycosis has increased in Quebec over the past 30 years, partially explained by the higher number of immunosuppressed patients.

The Consequences of Our Changing Environment on Life Threatening and Debilitating Fungal Diseases in Humans

Human activities have significantly impacted the environment and are changing our climate in ways that will have major consequences for ourselves, and endanger animal, plant and microbial life on Earth. Rising global temperatures and pollution have been highlighted as potential drivers for increases in infectious diseases. Although infrequently highlighted, fungi are amongst the leading causes of infectious disease mortality, resulting in more than 1.5 million deaths every year. In this review we evaluate the evidence linking anthropomorphic impacts with changing epidemiology of fungal disease. We highlight how the geographic footprint of endemic mycosis has expanded, how populations susceptible to fungal infection and fungal allergy may increase and how climate change may select for pathogenic traits and indirectly contribute to the emergence of drug resistance.

A global view on fungal infections in humans and animals: infections caused by dimorphic fungi and dermatophytoses

Fungal infections are still underappreciated and their prevalence is underestimated, which renders them a serious public health problem. Realistic discussions about their distribution, symptoms, and control can improve management and diagnosis and contribute to refinement of preventive actions using currently available tools. This article represents an overview of dermatophytes and endemic fungi that cause infections in humans and animals. In addition, the impact of climate change on the fungal spread is discussed. The endemic fungal infections characterized in this article include coccidioidomycosis, histoplasmosis, blastomycosis, lobomycosis, emergomycosis and sporotrichosis. Moreover the geographic distribution of these fungi, which are known to be climate sensitive and/or limited to endemic tropical and subtropical areas, is highlighted. In turn, dermatophytes cause superficial fungal infections of skin, hairs and nails, which are the most prevalent mycoses worldwide with a high economic burden. Therefore, the possibility of causing zoonoses and reverse zoonoses by dermatophytes is highly important. In conclusion, the article illustrates the current issues of the epidemiology and distribution of fungal diseases, emphasizing the lack of public programmes for prevention and control of these types of infection.

Prevalence, distribution, and risk factors for canine blastomycosis in Michigan, USA

Blastomycosis is a systemic fungal infection that most commonly affects dogs and humans. The disease is thought to be endemic in southern regions of Michigan, USA, but epidemiologic investigations have not been reported in detail for this state. The primary aims of this study were to investigate the prevalence and distribution of canine blastomycosis cases in Michigan and to identify risk factors for infection. Over 200 primary care veterinary clinics throughout the state were surveyed regarding blastomycosis prevalence, and demographic information was obtained from medical records of affected dogs that were evaluated at these clinics. A retrospective case control study was conducted for an additional 49 dogs with blastomycosis that were evaluated at specialty referral centers located in the southern mid-Michigan region. Prevalence rates were calculated for each county, and cases were mapped using geocoding software. Univariable and multivariable analyses were used to identify risk factors for infection. Prevalence rates were ≥100 cases per 100,000 dogs in five counties. Most blastomycosis cases originated from the Upper Peninsula or from a high-density area in the northern Lower Peninsula. Multivariable regression analysis identified travel or residence north of the 45^th parallel as a strong risk factor for infection (P < .001). Blastomycosis was uncommon in southern counties. These results refute previous speculations and should be of value to both human and animal health. Given that many heightened risk areas are popular tourist destinations, practitioners across the USA should be mindful of the spatial distribution of blastomycosis in Michigan.

Spatial epidemiology of blastomycosis hospitalizations: detecting clusters and identifying environmental risk factors

Blastomycosis is a disease caused by endemic fungi that ranges from severe pulmonary or disseminated to mild or asymptomatic. Environmental factors associated with it are not well described throughout the endemic area. We used the intramural State Inpatient Database from the Agency for Healthcare Research and Quality and ArcMap GIS to identify geographic high-risk clusters of blastomycosis hospitalizations in 13 states in the US endemic regions (AR, IA, IL, IN, KY, LA, MI, MN, MO, MS, OH, TN, and WI). We then used logistic regression to identify risk factors associated with these high-risk clusters. We describe six clusters of counties in which there was an elevated incidence of blastomycosis hospitalizations. We identified maximum mean annual temperature, percentage of persons aged ≥65 years, and mercury and copper soil content as being associated with high-risk clusters. Specifically, the odds of a county being part of a high-risk cluster was associated with increasing percentage of population over age 65, decreasing maximum temperature, increasing mercury, and decreasing copper soil content. Healthcare providers should be aware of these high-risk areas so that blastomycosis can be included, as appropriate, in a differential diagnosis for patients currently or previously residing in these areas.

Incidence and trends of blastomycosis-associated hospitalizations in the United States

We used the State Inpatient Databases from the United States Agency for Healthcare Research and Quality to provide state-specific age-adjusted blastomycosis-associated hospitalization incidence throughout the entire United States. Among the 46 states studied, states within the Mississippi and Ohio River valleys had the highest age-adjusted hospitalization incidence. Specifically, Wisconsin had the highest age-adjusted hospitalization incidence (2.9 hospitalizations per 100,000 person-years). Trends were studied in the five highest hospitalization incidence states. From 2000 to 2011, blastomycosis-associated hospitalizations increased significantly in Illinois and Kentucky with an average annual increase of 4.4% and 8.4%, respectively. Trends varied significantly by state. Overall, 64% of blastomycosis-associated hospitalizations were among men and the median age at hospitalization was 53 years. This analysis provides a complete epidemiologic description of blastomycosis-associated hospitalizations throughout the endemic area in the United States.

The ecology of pneumocystis: perspectives, personal recollections, and future research opportunities

I am honored to receive the second Lifetime Achievement Award by International Workshops on Opportunistic Protists and to give this lecture. My research involves Pneumocystis, an opportunistic pulmonary fungus that is a major cause of pneumonia ("PcP") in the immunocompromised host. I decided to focus on Pneumocystis ecology here because it has not attracted much interest. Pneumocystis infection is acquired by inhalation, and the cyst stage appears to be the infective form. Several fungal lung infections, such as coccidiomycosis, are not communicable, but occur by inhaling < 5 μm spores from environmental sources (buildings, parks), and can be affected by environmental factors. PcP risk factors include environmental constituents (temperature, humidity, SO2 , CO) and outdoor activities (camping). Clusters of PcP have occurred, but no environmental source has been found. Pneumocystis is communicable and outbreaks of PcP, especially in renal transplant patients, are an ongoing problem. Recent evidence suggests that most viable Pneumocystis organisms detected in the air are confined to a patient's room. Further efforts are needed to define the risk of Pneumocystis transmission in health care facilities; to develop more robust preventive measures; and to characterize the effects of climatological and air pollutant factors on Pneumocystis transmission in animal models similar to those used for respiratory viruses.

Clinical and molecular epidemiology of veterinary blastomycosis in Wisconsin

Background

Several studies have shown that Blastomyces dermatitidis, the etiologic agent of blastomycosis, is a genetically diverse pathogen. Blastomycosis is a significant health issue in humans and other mammals. Veterinary and human isolates matched with epidemiological case data from the same geographic area and time period were used to determine: (i) if differences in genetic diversity and structure exist between clinical veterinary and human isolates of B. dermatitidis and (ii) if comparable epidemiologic features differ among veterinary and human blastomycosis cases.

Results

Genetic typing of 301 clinical B. dermatitidis isolates produced 196 haplotypes (59 unique to veterinary isolates, 134 unique to human isolates, and 3 shared between canine and human isolates). Private allelic richness was higher in veterinary (median 2.27) compared to human isolates (median 1.14) (p = 0.005).

Concordant with previous studies, two distinct genetic groups were identified among all isolates. Genetic group assignment was different between human and veterinary isolates (p < 0.001), with more veterinary isolates assigned to Group 2.

The mean age of dogs diagnosed with blastomycosis was 6 years. Thirty cases were in male dogs (52%) and 24 were females (41%). The breed of dog was able to be retrieved in 38 of 58 cases with 19 (50%) being sporting breeds. Three of four felines infected with blastomycosis were domestic shorthair males between ages 6–12, and presented with disseminated disease. The other was a lynx with pulmonary disease. The equine isolate was from an 11-year-old male Halflinger with disseminated disease. Disseminated disease was reported more often in veterinary (62%) than human cases (19%) (p < 0.001).

Conclusions

Isolates from all hosts clustered largely into previously identified genetic groups, with 3 haplotypes being shared between human and canine isolates confirming that B. dermatitidis isolates capable of infecting both species occur in nature. Allelic diversity measures trended higher in veterinary samples, with a higher number of total alleles and private alleles. Veterinary isolates of B. dermatitidis contributed a substantial amount of diversity to the overall population genetic structure demonstrating the importance of including veterinary isolates in genetic studies of evolution and virulence in this organism.