Dennis J. Baumgardner

The epidemiology of blastomycosis in dogs: north central Wisconsin, USA

The epidemiological features of 59 consecutive cases of blastomycosis in domestic dogs, from a single veterinary practice in Eagle River, Wisconsin over a 3-year period, were examined by owner interview. The control sample included: (i) all porcupine quill-injured dogs during this time period (outdoor exposed dogs); and (ii) every sixth dog receiving a rabies vaccination during the second year of study (representative of all dogs in the practice). The estimated mean annual incidence of blastomycosis in dogs in this region was 1420:100,000. Blastomycosis cases were more likely to reside within 400 m of a waterway (95%) than quill-injured dogs (63%, P < 0.001) or vaccinated dogs (74%, P = 0.001). Exposure to an excavation was significantly more likely among blastomycosis cases compared to quill-injured dogs, however, no differences were found for age, sex, hunting, swimming and reported exposure to beavers. The geographical clustering of cases in dogs is similar to that previously reported for humans in this region. A close proximity to waterways and an exposure to excavation are significant risk factors for blastomycosis.

Soil-Related Bacterial and Fungal Infections

A variety of classic and emerging soil-related bacterial and fungal pathogens cause serious human disease that frequently presents in primary care settings. Typically, the growth of these microorganisms is favored by particular soil characteristics and may involve complex life cycles including amoebae or animal hosts. Specific evolved virulence factors or the ability to grow in diverse, sometimes harsh, microenvironments may promote pathogenesis. Infection may occur by direct inoculation or ingestion, ingestion of contaminated food, or inhalation. This narrative review describes the usual presentations and environmental sources of soil-related infections. In addition to tetanus, anthrax, and botulism, soil bacteria may cause gastrointestinal, wound, skin, and respiratory tract diseases. The systemic fungi are largely acquired via inhalation from contaminated soil and near-soil environments. These fungal infections are particularly life-threatening in those with compromised immune systems. Questions regarding soil exposure should be included in the history of any patient with syndromes consistent with tetanus, botulism or anthrax, traumatic wounds, recalcitrant skin lesions, gastroenteritis, and nonresponsive, overwhelming, or chronic pneumonia.

Diagnosis and management of pneumonia and bronchitis in outpatient primary care practices

AIMS To understand which clinical criteria physicians use to diagnose pneumonia compared to bronchitis and upper respiratory tract infection (URTI). METHODS Retrospective chart review of adults diagnosed with pneumonia, bronchitis, or URTI. RESULTS Logistic regression analysis identified rales, a temperature > 100 degrees F (37.8 degrees C), chest pain, dyspnoea, rhonchi, heart rate, respiratory rate, and rhinorrhoea, as the best explanation for the variation in diagnosis of pneumonia compared to either of the alternative diagnoses (R2 = 59.3), with rales and a temperature > 100 degrees F explaining 30% of the variation. Rales, chest pain, and a temperature > 100 degrees F best predicted the ordering of a chest x-ray (R2 = 20.0). However, 35% (59/175) of patients diagnosed with pneumonia had a negative chest x-ray. Abnormal breath sounds were the best predictors for prescribing antibiotics (R2 = 38%). A significant number of patients with acute bronchitis (93% excluding sinusitis) and URTI (42%) were given antibiotics. CONCLUSIONS The presence of abnormal breath sounds and a temperature > 100 degrees F were the best predictors of a diagnosis of pneumonia.

Real-Time PCR Assay for Identification of Blastomyces dermatitidis in Culture and in Tissue

ABSTRACT The TaqMan real-time PCR assay was developed from the Blastomyces dermatitidis BAD1 gene promoter. The assay identified all haplotypes of B. dermatitidis and five of six positive paraffin-embedded tissues. The assay sensitivity threshold was 1 pg genomic DNA of the mold form and 2 CFU of the yeast form of B. dermatitidis. No cross-reactivity was observed against other fungal DNA. The assay allowed rapid (5-h) identification of B. dermatitidis from culture and from clinical specimens.

Blastomycosis in indoor cats: Suburban Chicago, Illinois, USA

Blastomyces dermatitidis, the etiologic agent of blastomycosis, a potentially life-threatening systemic mycosis of humans and animals, is acquired from a yet incompletely defined environmental niche. There is controversy regarding the potential for contact with the fungus in or near one’s home, particularly in urban areas. We investigated an outbreak of blastomycosis among five urban, indoor cats diagnosed at three veterinary clinics March 3–July 13, 2005, in suburban Chicago, Illinois, by owner interviews, site visits, environmental cultures for B. dermatitidis, GIS analysis, and analysis of local weather data. There were no environmental exposures common to the five cats that lived a median of 300 m from nearest body of water, in homes on a loam soil. Closest and farthest case home sites were 3.4 and 26.1 km, respectively. All cats were confined indoors except one cat that averaged 15 min/week in his backyard and was exposed to excavation. B. dermatitidis was not isolated from any of 60 environmental samples. The annualized incidence rate March through July 2005 among 6,761 cats in these practices was 178/100,000, compared to none in the previous 4 years, and 0.14/100,000 cat visits from a nationwide animal hospital registry. Precipitation January through June 2005 was 9.30 versus period mean of 14.05 ± 1.69 inches the previous 4 years (P = 0.01). Circumstantial evidence suggests acquisition of B. dermatitidis from the home site environment in five cats. Relative drought may have contributed to an apparent outbreak of blastomycosis in this urban locale.

Studies on the molecular ecology of Blastomyces dermatitidis

The microecology of Blastomyces dermatitidis, the dimorphic etiologic agentof the potentially fatal systemic fungal infection, blastomycosis, is not well defined.Blastomyces dermatitidis may occur periodically at natural sites, perhaps aided by rotting organic material, animal droppings and physical changes. Semi-quantitative growth studies of B. dermatitidis on 2% agar plates determined the ability toutilize or tolerate a variety of substrates including simple and complex molecules as carbon source, and organic and inorganic nitrogen sources. Allantoin, creatinine, quanidoacetic acid, guanidine and cysteine may be used as sole nitrogen source. Allantoin in combination with dextrose, glycerol, lichenen, celloboise and other wood by-products support growth of B. dermatitidis at room temperature. The nutritional conversion of the fungus to the yeast form at room temperature, well demonstrated on allantoin/glycerol/yeast extract media, appears to be affected by certain inorganic compounds. The organism tolerates low to moderate levels of alpha-pinene, tannic acid, shikimic acid, veratryl alcohol, vanillic acid, and polyethyleneglycol-200. There are significant differences among isolates regarding growth on various substances at 20° and 37° centigrade. It appears that a variety of wood by-products and animal waste substrates, in combination, support the growth of B. dermatitidis. Their role in the ecological niche of B. dermatitidis, and the importance of nutritional dimorphism in the natural environment warrants further investigation.

Symptoms of pulmonary blastomycosis: northern Wisconsin, United States.

OBJECTIVE Pulmonary disease is the most common manifestation of the systemic fungal infection, blastomycosis. This study examines symptoms of pulmonary blastomycosis and possible age and gender differences in a 22-year case series. METHODS Laboratory-confirmed cases of blastomycosis were identified from mandatory reports to the Vilas County Health Department (1984--2001) and from hospital records and case contacts before mandated reports (November 1979--1983). Symptoms were ascertained by interviews of respondent cases (or next of kin) by using a standard form. Proportions were compared with the chi-square test or Fisher exact test. RESULTS One hundred seventy cases of blastomycosis (mean age 44, 56% male) were identified and pulmonary manifestations were present in 154 (91%). Of the 118 interviewed cases, the following symptoms were common: cough (90%), fever (75%), night sweats (68%), weight loss (66%), chest pain (63%), dyspnea (54%), and aches (50%). Hemoptysis occurred in 18%, and nearly all queried patients had fatigue. The dyad of cough and fever occurred in 73%, and triads of fever-cough-night sweats, fever-cough-weight loss, and fever-cough-chest pain occurred in 58%, 57%, and 51%, respectively. Among men, fever (P = .03), cough and fever (P = .03), fever-cough-weight loss (P = .03), and fever-cough-night sweats (P = .03) were less common in those 50 years of age and older. Symptoms did not vary by duration of illness. CONCLUSIONS Cough, fever, night sweats, weight loss, chest pain, dyspnea, and aches are common symptoms of pulmonary blastomycosis. Symptom constellations that included fever were less common in men 50 years of age and older. There was no apparent difference in symptoms between acute and chronic blastomycosis.

Identification of Blastomyces dermatitidis in the stool of a dog with acute pulmonary blastomycosis

We report the identification of Blastomyces dermatitidis by microscopic examination of a direct faecal smear from a dog with pulmonary blastomycosis. A simultaneously obtained faecal culture grew Blastomyces dermatitidis. The fungus was also cultured from a transtracheal sample from this same dog. This report suggests that yeast-phase cells of B. dermatitidis may be recovered in the stool of dogs with pulmonary blastomycosis following transit through the gastrointestinal tract of swallowed infected sputum. Implications regarding the ecology of Blastomyces dermatitidis are discussed.

GEOGRAPHIC ANALYSIS OF DIAGNOSIS OF ATTENTION-DEFICIT/HYPERACTIVITY DISORDER IN CHILDREN: EASTERN WISCONSIN, USA

Objective: To perform a novel geographic analysis of Attention-Deficit/Hyperactivity Disorder (ADHD) diagnosis in Midwest United States. Method: Primary care children age 5–17 with ADHD diagnosis (N = 6833; 13.5%) were compared to those receiving well child care without ADHD diagnosis (N = 43,630) in a Wisconsin integrated medical system. Street addresses, demographic, and block group level U.S. Census 2000 data were mapped and analyzed using ArcGIS, CrimeStat III, and SaTScan. Lead levels from a State database were linked to 2,837 subjects. Univariate analysis was done by chi-square test or Mann-Whitney U test, multivariate analysis by logistic regression. Results: ADHD cases were 74% male (p = 0.0001), and more frequently diagnosed in White children (17.3%) than Blacks (10.6%), Hispanics (9.4%), or Asians (3.7%; all p values < 0.001). Overall, male gender, white race, lower block group median household income and population density, and greater distance to nearest park and airport were more predictive of ADHD (p values < 0.001). In urban Milwaukee County (865 cases/10,493 controls) male gender, white race, suburban residence, and younger age were more predictive of ADHD (p values < 0.01). Among children with ADHD diagnosis and linked lifetime lead values, those with a maximum level of 10 μg/dl or more differed significantly from controls (9.3% vs. 5.6%; p = 0.003); elevated lead remained a significant predictor of ADHD diagnosis in multivariate analysis. Conclusions: Further studies are needed to determine if geographic distribution of ADHD diagnosis can be partially explained by differential efficiency of referral for diagnosis by school districts, by race/ethnicity, and/or built environment.

Genetic diversity in Blastomyces dermatitidis: implications for PCR detection in clinical and environmental samples.

Blastomycosis is a serious and potentially fatal infection caused by the thermally dimorphic fungus Blastomyces dermatitidis. Polymerase chain reaction (PCR) assays targeting the BAD-1 virulence gene promoter have been developed to aid in the detection of the pathogen in clinical and environmental samples. However, little is known regarding the genetic diversity of B. dermatitidis and how this might affect the performance characteristics of these assays. We explored the genetic relatedness of 106 clinical and environmental isolates of B. dermatitidis using a previously described rDNA PCR restriction fragment length polymorphism (RFLP) assay. In addition, we looked for polymorphisms in the promoter region upstream of BAD-1. RFLP analysis showed that all isolates fell into one of five genotypic groups, designated A through E. Genotypic groups A and B predominated, comprising 50/106 (47.2%) and 51/106 (48.1%) of isolates, respectively. Three of 106 (2.8%) isolates were genotype C. Genotypes D and E represented novel genotypes and were each associated with single clinical isolates. PCR of the BAD-1 promoter revealed significant size differences among amplification products. Fifty-one of 106 isolates (50/50 RFLP genotypic group A and 1/51 genotypic group B) had amplicons of 663-bp, nearly twice the size of the expected product. Sequence analysis of amplification products from 17 representative isolates revealed four haplotypes and showed that the size disparity was due to two large insertions. Because these insertions were present in a high percentage of isolates, the utility of the PCR assays for diagnostic purposes could be affected. However, the novel RFLP genotypes and multiple BAD-1 haplotypes may prove useful as markers in population genetic studies.