Serum 25-hydroxyvitamin D concentrations and mortality in dogs with blastomycosis

Blastomycosis is a prominent fungal disease in the United States. Vitamin D status has been found to be altered in critical illness and various infectious diseases. The objectives of this study were to compare serum 25-hydroxyvitamin D (25[OH]D) concentrations in dogs with blastomycosis and healthy controls, to assess the change in serum 25(OH)D concentrations in dogs with blastomycosis after 30 days of treatment, and to determine if baseline serum 25(OH)D concentrations in dogs with blastomycosis were associated with in-hospital, 30-day, or end-of-study mortality. In this prospective cohort study, 19 dogs newly diagnosed with blastomycosis had serum 25(OH)D concentrations measured with a commercially available validated radioimmunoassay at the time of diagnosis and 30 days after start of treatment. These values were compared to 24 healthy control dogs. Serum 25(OH)D concentrations at the time of diagnosis were lower in dogs with blastomycosis (median, 203 nmol/L; range, 31-590 nmol/L) than in clinically healthy control dogs (259.5 nmol/L, 97-829 nmol/L; P = 0.01). Despite clinical improvement, there was no significant change in serum 25(OH)D concentrations from baseline to 30-day follow-up. Dogs with baseline serum 25(OH)D concentrations <180.5nmol/L had a greater odds of death during hospitalization (odds ratio [OR], 15.0; 95% confidence interval [CI], 1.4-191.3; P = 0.04) and at 30 days follow-up (OR, 30.0; 95% CI, 2.5-366.7; P = 0.006). These findings highlight the need for further studies evaluating the prognostic value of vitamin D status in dogs with blastomycosis at diagnosis and throughout treatment and remission.

Mortality From Fungal Diseases in the US Air Force From 1970 to 2013

We review a unique set of documents, death certificates, catalogued in the US Air Force Mortality Registry, which tracks deaths for current and retired Air Force service members. We screened the records for all deaths caused by fungal diseases between 1970 and 2013. There were 216 deaths caused by a variety of diseases such as aspergillosis, blastomycosis, candidiasis, coccidioidomycosis, cryptococcosis, histoplasmosis, mucormycosis, pneumocystosis, sporotrichosis, and zygomycosis. The single most common identified cause of death was opportunistic candidiasis. Of the total 216 deaths, only 7 were active duty or active reserve personnel.

Blastomycosis mortality rates, United States, 1990-2010

Risks for illness and death caused by the Blastomyces dermatitidis fungus are affected by demographic, geographic, and behavioral factors.

Blastomycosis is a potentially fatal fungal infection endemic to parts of North America. We used national multiple-cause-of-death data and census population estimates for 1990–2010 to calculate age-adjusted mortality rates and rate ratios (RRs). We modeled trends over time using Poisson regression. Death occurred more often among older persons (RR 2.11, 95% confidence limit [CL] 1.76, 2.53 for those 75–84 years of age vs. 55–64 years), men (RR 2.43, 95% CL 2.19, 2.70), Native Americans (RR 4.13, 95% CL 3.86, 4.42 vs. whites), and blacks (RR 1.86, 95% CL 1.73, 2.01 vs. whites), in notably younger persons of Asian origin (mean = 41.6 years vs. 64.2 years for whites); and in the South (RR 18.15, 95% CL 11.63, 28.34 vs. West) and Midwest (RR 23.10, 95% CL14.78, 36.12 vs. West). In regions where blastomycosis is endemic, we recommend that the diagnosis be considered in patients with pulmonary disease and that it be a reportable disease.

Blastomycosis in solid organ transplant recipients

BACKGROUND

Blastomyces dermatitidis, the etiologic agent of blastomycosis, causes severe disease and substantial mortality in those immunocompromised by acquired immunodeficiency syndrome or malignancy. In solid organ transplant recipients, the epidemiology, clinical features, and outcomes have not been fully described.

METHODS

We conducted a retrospective case-series at the University of Wisconsin Hospital and Clinics. Case patients were solid organ transplant recipients with blastomycosis.

RESULTS

From 1986 to 2004, we identified 11 cases of post-transplant blastomycosis with 64% occurring between 2000 and 2004. Onset of infection occurred a median of 26 months post transplantation with near equal distribution before and after the first year of transplantation. Rejection did not precede any case of post-transplant blastomycosis. Opportunistic co-infections were common, occurring in 36% of patients. Pneumonia was the most common clinical presentation and was frequently complicated by acute respiratory distress syndrome (ARDS). Extrapulmonary disease predominantly involved the skin and spared the central nervous system. The overall mortality rate was 36%; however, this increased to 67% in those with ARDS. None of the surviving patients relapsed or received routine secondary antifungal prophylaxis.

CONCLUSION

Blastomycosis is an uncommon infection following solid organ transplantation that is frequently complicated by ARDS, dissemination, and opportunistic co-infection. After cure, post-transplant blastomycosis may not require lifelong antifungal suppression.

Cardiovascular involvement in 8 dogs with blastomyces dermatitidis infection

BACKGROUND

Blastomycosis is a common systemic fungal infection in dogs.

HYPOTHESIS

Dogs with cardiovascular involvement may have abnormalities in electrical conduction and valvular function, and may have a worse prognosis.

ANIMALS

Eight client-owned animals.

METHODS

Dogs with cardiovascular lesions caused by blastomycosis were identified from retrospective evaluation of medical records.

RESULTS

Five dogs had de novo infections and 3 had recurrences of previously treated infections. Harsh labored breathing, lethargy, and anorexia were the most common historic complaints. Three dogs had syncope. Physical examination and clinicopathologic data were typical of blastomycosis and included dyspnea, increased lung sounds, and lethargy. In addition, 3 dogs had heart murmurs and 1 had a third-degree atrioventricular block. Four dogs had myocarditis and 2 had pericarditis or epicarditis. Two dogs had cardiac signs attributed to extracardiac compression by fungal granulomas and clinical signs were relieved by treatment. Half of the remaining 6 dogs were euthanized; 2 of these were not treated. Of the remaining 3 dogs, 1 dog died acutely while sleeping; the second died intraoperatively during an attempt to place an epicardial pacemaker; and the third had Blastomyces-induced endocarditis and died of heart failure.

CONCLUSIONS AND CLINICAL IMPORTANCE

Blastomycosis should be considered in the differential diagnosis of dogs from endemic areas with inflammatory myocarditis, heart block, heart base or intracardiac mass lesions, syncope, or endocarditis.

Clinical aspects of natural infection withBlastomyces dermatitidisin cats: 8 cases (1991–2005)

OBJECTIVE

To evaluate clinical and laboratory findings, treatment, and clinical outcome in cats with blastomycosis.

DESIGN

Retrospective case series.

ANIMALS

8 cats with naturally occurring blastomycosis.

PROCEDURES

Medical records of the University of Illinois Veterinary Teaching Hospital were searched for cases of blastomycosis in cats diagnosed via cytologic or histopathologic findings. Clinical and laboratory findings, treatment, and clinical outcome were determined. Radiographs were reviewed for the 8 cases.

RESULTS

All cats were systemically ill. Respiratory tract signs and dermal lesions were most commonly observed. All cats had radiographic evidence of respiratory tract disease. Seven of the 8 cats had ill-defined soft-tissue opacities (nodules or masses) or alveolar consolidation of the lungs. Antemortem diagnosis was achieved cytologically in 6 of the 8 cats, and 3 were successfully treated and survived.

CONCLUSIONS AND CLINICAL RELEVANCE

In contrast to previous reports, diagnosis was achieved antemortem in most of the cats (all by cytologic identification of the organism). Clinical signs, laboratory findings, and outcome were similar to previous descriptions of this rare disease in cats.

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.

IL-12 is required for induction but not maintenance of protective, memory responses to Blastomyces dermatitidis: implications for vaccine development in immune-deficient hosts

Cellular immunity mediated by T lymphocytes, in particular CD4(+) and CD8(+) type 1 (T1) cells, is the main defense against pathogenic fungi. IL-12 initiates T1 cell development and cell-mediated immunity, but it is unclear whether IL-12 contributes to the maintenance of an antifungal T1 response. In this study, we addressed the role of IL-12 for vaccine-induced memory T cell development against experimental pulmonary blastomycosis. CD4(+) T cells absolutely required IL-12 to control a live genetically engineered attenuated strain of Blastomyces dermatitidis given s.c. as a vaccine, whereas CD8(+) T cells were significantly less dependent on IL-12. Despite differential dependency of T cell subsets on IL-12 during vaccination, neither subset acquired memory immunity in the absence of IL-12. In contrast, adoptive transfer of immune CD4 T cells from wild-type mice into IL-12(-/-) mice showed that CD4(+) T1 memory cells sustained a T1 cytokine profile and remained protective over a period of 6 mo posttransfer. Similarly, memory CD8 cells elicited in IL-12(-/-) mice with killed yeast and transient rIL-12 treatment (during vaccination) remained durable and protective after animals were rested for 3 mo. In conclusion, these studies demonstrate that once CD4 and CD8 cells have acquired a protective T1 phenotype they no longer require the presence of IL-12 to maintain antifungal protective memory.

The epidemiology of blastomycosis in Illinois and factors associated with death

BACKGROUND

Blastomycosis is a systemic fungal disease that may be asymptomatic or progressive and may lead to death.

METHODS

In response to a reported increase in the number of cases of blastomycosis in Illinois, surveillance data reported to the Illinois Department of Public Health from January 1993 to August 2003 were analyzed and the medical records of 4 patients who died were reviewed.

RESULTS

Among the 500 cases reported, the median age of the patients was 43 years (range, 4-87 years), and 34 patients (7%) died. Higher rates of mortality were observed among persons who were black, who were > or =65 years of age, and who were male. The median time from onset of illness to diagnosis was 128 days (range, 12-489 days). Death was associated with a time from onset of illness to diagnosis of > or =128 days (OR, 2.1; 95% CI, 1.0-4.8). During the period from 1993 through 2002, the number of cases reported per year increased from 24 to 87 (P<.05).

CONCLUSIONS

The incidence of blastomycosis has been increasing in Illinois. To reduce mortality related to delay in diagnosis and treatment, medical providers need to be educated about blastomycosis, with an emphasis on symptom recognition, methods of diagnosis, and appropriate antifungal treatment.

Immunological basis for susceptibility and resistance to pulmonary blastomycosis in mouse strains

The immunological basis for a >10-fold resistance of outbred CD-1 mice compared to inbred BALB/c mice to pulmonary blastomycosis was investigated. Bronchoalveolar macrophages (BAM) from CD-1 mice killed yeast cells of Blastomyces dermatitidis (Bd) by 25% and this increased to 59% when activated by IFN-gamma. In contrast, BAM from BALB/c mice lacked significant killing (5%) of Bd but could be activated by IFN-gamma for enhanced killing (19%). Peritoneal macrophages (PM) from CD-1 mice had significant fungicidal activity for Bd (43%) and this increased to 63% with IFN-gamma treatment. By contrast, PM from BALB/c mice did not significantly kill Bd (14%) but were activated by IFN-gamma for significant killing (24%). Fungicidal activity of peripheral blood polymorphonuclear neutrophils (PMN) from CD-1 (87%) was greater than that of BALB/c (75%) (P<0.05). Macrophage inflammatory protein-1alpha (MIP-1alpha) production by BAM from BALB/c was significantly less than that from CD-1 in response to co-culture with Bd. IFN-gamma production by CD-1 spleen cells in response to concanavalin A (Con A, 1microg/ml) was 8-fold greater than that by BALB/c spleen cells. In contrast, BAM and PM from BALB/c mice in co-culture with Bd secreted several-fold more TNFalpha than BAM or PM from CD-1 mice. IL-2 production by BALB/c spleen cells in response to Con A was 3- to 4-fold greater than that by CD-1 spleen cells. Depressed IL-2 production by Con A stimulated CD-1 spleen cells correlated with depressed proliferative responses. Resistance of CD-1 mice to pulmonary blastomycosis correlates with enhanced fungicidal activity of BAM, PM, PMN, and IFN-gamma production by Con A stimulated spleen cells, compared to BALB/c mice. Consistent with the in vitro enhancement of effector cell function by IFN-gamma, in vivo therapy with IFN-gamma significantly (P<0.0001) improved survival of BALB/c mice with pulmonary blastomycosis.

Epidemiology and clinical spectrum of blastomycosis diagnosed at Manitoba hospitals

Blastomyces dermatitidis is a dimorphic fungus endemic to Canada and the United States. Few reports regarding blastomycosis in Canada have been published. We retrospectively reviewed the medical charts of 143 patients with confirmed cases of blastomycosis diagnosed in hospitals in Manitoba, Canada, from 1988 through 1999. The annual incidence rate of blastomycosis in Manitoba was 0.62 cases per 100,000 population, compared with 7.11 cases per 100,000 population in the Kenora, Ontario district. The average age of patients was 38.0 years, and males accounted for 65.0% of cases. An increased incidence of blastomycosis was observed in the Aboriginal subpopulation. Organ systems involved were as follows: respiratory system (93.0% of cases), skin (21.0%), bone (13.3%), genitourinary tract (1.4%), and the central nervous system (1.4%); 6.3% of patients died, and death was associated with a short clinical course. This study provides a summary of the current status of blastomycosis in this area of endemicity in Canada.

Acute respiratory distress syndrome and blastomycosis: presentation of nine cases and review of the literature

Mississippi has the highest prevalence of blastomycosis in the country. In 20 years and 5 months there were 123 patients treated for blastomycosis at the University of Mississippi Medical Center. Among these, 107 patients had lung involvement and nine patients (8.4%) developed acute respiratory distress syndrome. Seven of the nine patients (78%) died of respiratory failure. In six patients, the lungs were the only organs involved. The three other patients had involvement of other organs as well. Average survival after the onset of acute respiratory distress syndrome was 6.9 days (range, 2 to 17 days). Acute respiratory distress syndrome can be triggered by pulmonary infections caused by bacterial diseases and other fungi. Massive proliferation of yeasts in the pulmonary parenchyma is the typical finding of patients with blastomycosis and acute respiratory distress syndrome. Underlying diseases that lead to immunodepression were present in only one patient and probable partial immunodepression was present in two other patients. Data from 19 other cases reported in the literature are discussed. Ann Diagn Pathol 5:1-9, 2001.

Immunogenicity and protective efficacy of the WI-1 adhesin of Blastomyces dermatitidis

People infected with Blastomyces dermatitidis develop strong immunity to the yeast surface adhesin WI-1, including antibody responses to the adhesive domain, a 25-amino-acid repeat, and cellular responses to the N terminus. We studied the immunogenicity of WI-1 and the ability of anti-WI-1 immune responses to protect against lethal pulmonary infection in mice. WI-1 immunization, given in Freund's adjuvant subcutaneously in two doses 2 weeks apart, evoked delayed hypersensitivity responses in a concentration-dependent manner. Immunized mice also had anti-WI-1 antibody responses, with titers reaching an endpoint dilution of approximately 1:800,000. Anti-WI-1 immunoglobulin G (IgG) antibody subclasses were IgG1 > IgG2b > IgG2a > IgG3, indicating a mixed T helper 1 and T helper 2 immune response. In protection experiments, WI-1 immunization significantly prolonged the survival of C57BL/6 and BALB/c mice compared to controls following intranasal administration of a lethal dose of B. dermatitidis yeasts (Kaplan-Meier survival curve P values of 0.027 to 0.0002) and also protected a proportion of the animals from death due to progressive pulmonary blastomycosis. Taken together, our results suggest that administration of WI-1 raises antibody and cell-mediated immune responses, which enhance resistance against pulmonary infection with B. dermatitidis. Mechanisms of vaccine-induced resistance require further investigation.

Treatment of blastomycosis with itraconazole in 112 dogs

One hundred twelve client-owned dogs with blastomycosis were treated with itraconazole, 5 or 10 mg/kg/d. The first group of 70 dogs treated in 1987 and 1988 received 10 mg/kg/d (group 1), and the second group of 42 dogs treated after October 1988 received 5 mg/kg/d (group 2). Even though the groups were treated at different times, the dogs were similar in age and gender distribution, number of sites involved, and percent and severity of pulmonary involvement. The proportion of dogs cured with a 60-day course of itraconazole was similar for both groups (53.6% versus 54.3%) and for a second historical control group treated with amphotericin B (57%); the recurrence rate was also similar, 20%, 21.4%, and 20%, respectively. Dogs treated with itraconazole had similar mortality rates (25.7% at 5 mg/kg/d; 25% at 10 mg/kg/day) to those treated with amphotericin B (23%). Seventeen of the 23 dogs that died (74%), did so during the first week of treatment; these early deaths were usually attributed to respiratory failure. The only site of infection that was significantly associated with failure (death or recurrence) was the brain. There was a marked difference in survival times between dogs without lung disease or with mild lung disease compared with dogs with moderate or severe lung disease. Serum itraconazole concentrations reached steady state by 14 days of treatment. Dogs receiving 5 mg/kg/d of itraconazole (group 2) had mean serum concentrations of 3.55 +/- 2.81 mg/mL (range, 0.67 to 10.8 micrograms/mL), whereas dogs receiving 10 micrograms/kg/d (group 1) had mean concentrations of 13.46 +/- 8.49 micrograms/mL (range, 1.8 to 28 micrograms/mL) (P < or = .001). There was no association between cure and serum itraconazole concentrations. Dogs in group 1 had significantly more adverse effects than dogs in group 2 (P = .046). Anorexia was the most common adverse effect, occurring in 14.9% of dogs in group 1. Only 8% of dogs in group 2 had adverse effects. Serum concentrations of itraconazole were positively correlated with serum alkaline phosphatase and alanine aminotransferase activities. Our findings indicate that itraconazole administered at a dose of 5 mg/kg/d is the drug of choice for blastomycosis in dogs.

Blastomycosis and human immunodeficiency virus: three new cases and review

Reports of blastomycosis in individuals infected with the human immunodeficiency virus (HIV) are increasing. We report on 3 patients co-infected with blastomycosis and HIV (to add to the previously reported 21), and review important clinical aspects and outcomes in all cases. The percentage of patients co-infected with blastomycosis and HIV who had disseminated blastomycosis (63%) was similar to the blastomycosis patients in the general population (67%); however, as a group the patients with HIV were severely immunosuppressed and fared poorly. Severe immunodeficiency was indicated by CD4 counts < 200/mm3 in 85% of co-infected patients. Central nervous system (CNS) involvement occurred in 46% of this group, approximately 5 to 10 times more frequently than in individuals not infected with HIV previously reported at 5% to 10%. The mortality rate from blastomycosis for patients with both HIV infection and blastomycosis is 54%, about 5 times the mortality rate of blastomycosis patients in the general population, previously reported at < 10%. Disseminated blastomycosis in individuals with HIV may appear as deep cutaneous ulcers, as was the case in two of our patients. Although blastomycosis is not an AIDS-defining infection, it may be reasonable to consider HIV testing and measurement of CD4 counts in patients with blastomycosis. Such testing could help identify individuals who are HIV positive but asymptomatic who have blastomycosis, as well as provide useful information regarding a possible association between CD4 cell deficiency and various clinical manifestations of blastomycosis. Patients with HIV and blastomycosis should be examined carefully for any evidence of CNS involvement. Lifetime therapy with ketoconazole or itraconazole is likely to be of benefit to patients with HIV who have been treated successfully for blastomycosis.

Blastomycosis in patients with the acquired immunodeficiency syndrome

OBJECTIVE

To describe the clinical, demographic, radiographic, diagnostic, and therapeutic aspects of blastomycosis in patients with the acquired immunodeficiency syndrome (AIDS).

DESIGN

A retrospective survey.

SETTING

Ten university medical centers and community hospitals, six in geographic areas endemic for Blastomyces dermatitidis, and four outside the endemic area.

PATIENTS

We identified 15 patients with blastomycosis and positive serologic test results for human immunodeficiency virus (HIV).

MEASUREMENTS

A diagnosis of blastomycosis was based on a positive culture (14 patients) or typical histopathologic features (one patient) for B. dermatitidis in clinical specimens.

RESULTS

Twelve of 15 patients had a previous or concomitant AIDS-defining illness at the time of diagnosis of blastomycosis, and only one patient had a CD4 lymphocyte count of greater than 200 cells/mm3. Two patterns of disease emerged: localized pulmonary involvement (seven patients), and disseminated or extrapulmonary blastomycosis (eight patients). Central nervous system involvement was common (40%). Six patients died within 21 days of presentation with blastomycosis, including four patients with disseminated and two with fulminant pulmonary disease. Among the nine patients who survived longer than 1 month, all received amphotericin B as initial antifungal therapy, and most received subsequent therapy with ketoconazole. Only two of these nine patients died with evidence of progressive blastomycosis.

CONCLUSIONS

Blastomycosis is a late and frequently fatal infectious complication in a few patients with AIDS. In these patients, overwhelming disseminated disease including involvement of the central nervous system is common, and it is associated with a high early mortality. Initial therapy with amphotericin B is appropriate in patients with AIDS and presumptive blastomycosis.

Fungal-strain-dependent alterations in the time course and mortality of chronic murine pulmonary blastomycosis

Intratracheal injection of 10(4) conidia of Blastomyces dermatitidis strain M1-A into mice was shown in previous work to induce chronic pulmonary and disseminated infection with histopathologic features of chronic human blastomycosis. Furthermore, 10-fold variations in inoculum density produced marked changes in mean survival times (MSTs), i.e., 32 days at 10(6), 36 days at 10(5), 97 days at 10(4), and 172 days at 10(3). A second strain (M1-B) failed to induce death in this model. To assess fungal-strain-dependent virulence, we extended these previous studies to 11 additional human isolates. Groups of male BALB/cByJ mice (6 to 8 weeks old) were injected intratracheally with 10(4) conidia from each of the 13 strains; the mice were weighed weekly and monitored for mortality, and their lungs were examined histopathologically. Infection rate and mortality were 100% in all groups except for the M1-B inoculated mice. For strains M1-B and M1-A, MST and mortality curves were not significantly different from those observed in our previously reported experiments. Four different survival patterns were noted in infected mice. The shortest MSTs were produced by strains M2-E, M2-B, M2-K, M2-H, and M2-A (24, 26, 26, 27, and 31 days, respectively), and the longest MST was seen in animal groups inoculated with strains M2-J and M2-G (130 and 134 days, respectively). Strains M2-I, M2-F, and M2-D produced intermediate MSTs of 65, 79, and 80 days, respectively. The 107-day MST induced by M1-A did not differ from strain M2-C-induced MST but differed significantly from the MST produced by the other strains. Pulmonary histopathology was similar in all animals dying with blastomycosis. The wide spectrum in survival times was not related to differences in clinical status of the patient from whom the isolate had been obtained, to fungal inoculum viability, or to individual mouse weight at inoculation. Strain-dependent virulence factors present in these fungal isolates alter the disease course in inbred mice in a fashion similar to that induced by 10-fold inoculum variation of strain M1-A conidia. These 13 isolates of B. dermatitidis, 1 avirulent and 12 with differing levels of virulence, provide tools for future studies into the nature of fungal virulence determinants in chronic blastomycosis.

Chronic murine pulmonary blastomycosis induced by intratracheally inoculated Blastomyces dermatitidis conidia

Groups of 6-wk-old male BALB/cByJ mice were injected intratracheally (IT) with viable conidia from Blastomyces dermatitidis strains (FW or CR) harvested from 2-wk-old cultures (Pine-Drouhet agar at 30 degrees C) and separated from hyphal elements by polycarbonate filtration (5 micron). Inocula (0.05 ml) were 93 to 97% conidia in nonpyrogenic normal saline (NPNS) with greater than 90% viability. Quantitative cultures of the lungs and trachea of mice killed immediately after injection of 10(4) conidia (FW) confirmed that the inoculum was evenly distributed between the lungs, with virtually no conidia retained in the trachea. Animals were observed for 354 days for weight change, mortality, extrapulmonary dissemination and histopathologic changes. Mice inoculated with 10(4) FW began dying on Day 44, with a median survival of 92 days. A decrease in mean weight compared with that in control mice was noted by Day 55. In contrast, mice inoculated with 10(4) CR or NPNS neither died with blastomycosis nor lost weight in 329 days. Variation of the FW inoculum by tenfold increments produced comparable dose-dependent alterations in both mortality rate and weight change curves. Fifty percent survival was 32, 36, 92, or 172 days for mice inoculated with 10(6), 10(5), 10(4), or 10(3) conidia, respectively. Dissemination from the lungs to the liver, spleen, kidney, testis, and brain was found in the cachectic mice that were killed. Pathologic features of pulmonary and disseminated infections were comparable to those in human disease. This quantitative, reproducible model of chronic murine blastomycosis mimics the human disease in many respects and should provide a basis for future studies of the immunology, pathogenesis, and therapy of chronic blastomycosis.

Failure of ketoconazole in two patients with blastomycosis

Two patients with severe pulmonary blastomycosis were treated with ketoconazole. One patient developed disseminated disease while receiving this drug. After responding to incomplete treatment with amphotericin B, this patient relapsed while continuing ketoconazole therapy. The second patient failed to respond to ketoconazole and died shortly after treatment with amphotericin B was instituted. We conclude that it is dangerous to use ketoconazole as initial treatment in patients with severe forms of blastomycosis. Death, relapse, and prolonged morbidity may be the result. In such cases, amphotericin B is still the drug of first choice despite its toxicity, inconvenience, and expense of administration.

Protection against pulmonary blastomycosis: correlation with cellular and humoral immunity in mice after subcutaneous nonlethal infection

A model of pulmonary blastomycosis in the mouse, in which the portal of entry is the same as natural human infection, was used to study resistance to challenge after subcutaneous infection. One week after subcutaneous infection, mice were partially resistant to pulmonary challenge, and mice challenged two weeks after infection were resistant. Measurement of cellular and humoral immune responses to Blastomyces dermatitidis antigens after subcutaneous infection showed the following. (i) Delayed-type hypersensitivity appeared 1 week after infection, and responses increased for 3 weeks thereafter. (ii) Proliferative responses in vitro appeared in spleen cells at 1 week and in contralateral lymph node cells at 3 weeks, (iii) Serum antibody, detected by an enzyme-linked immunosorbent assay, appeared 1 week after infection and then increased in titer. (iv) Peritoneal macrophages were activated to inhibit replication of B. dermatitidis in vitro by the first week after infection. Prior subcutaneous infection also resulted in rapid clearing of a second subcutaneous challenge, as well as resistance to a lethal intraperitoneal challenge. This resistance was associated with the development of cell-mediated and humoral immune responses. These data provide a chronological framework for selective transfer experiments.

Susceptibility differences of inbred strains of mice to blastomycosis

The susceptibility of inbred strains of mice to pulmonary blastomycosis was studied to derive information relevant to host resistance and genetic background. Initial studies with eight strains with various H-2 backgrounds revealed the C3H/HeJ strain to be highly susceptible and DBA/1J mice to be resistant. These observations were confirmed with various challenge inocula. These differences were not dependent on the size of the challenge, the strain of Blastomyces dermatitidis, host age, or ability of the challenge to penetrate to the lower airways. Differences between the susceptible and resistant strains in lymphocyte proliferation in vitro and delayed-type hypersensitivity in vivo after nonlethal subcutaneous infection were not demonstrated; the susceptible strain made a significantly greater antibody response to blastomyces antigens as determined by an enzyme-linked immunosorbent assay. The resistance of the C3H/HeN strain of mice, which differs from the C3H/HeJ in sensitivity to lipopolysaccharide and lacks the macrophage cytotoxicity defect of the latter, suggests that the susceptibility of C3H/HeJ mice is not related to their C3H background or the H-2 locus. As the A/HeJ strain, which also has a macrophage cytotoxicity defect, was found in this study to be the second most susceptible strain, this also suggests macrophages as the subject for further study with respect to the mechanism of genetic resistance to this infection.

Enhanced efficacy of amphotericin B and rifampicin combined in treatment of murine histoplasmosis and blastomycosis

Amphotericin B in combination with rifampicin was more effective in the treatment of murine histoplasmosis and blastomycosis than either agent alone. The increased therapeutic effects were not accompanied by an increase in toxicity.

Clinical aspects of blastomycosis

Blastomycosis is a specific granulomatous disease which tends to be chronic and indolent. It frequently presents in extrapulmonary form by means of haematogenous dissemination from the lungs. It has been shown that tuberculosis, histoplasmosis and coccidioidomycosis are, in the majority of cases, mild and subclinical in effect and often heal without therapy. It is probable that blastomycosis behaves in a like manner. The exact mortality is not known but is probably in the range of 13% in hospitalized cases with disseminated disease (Blastomycosis Cooperative Study of the Veterans Administration, 1964). The most effective form of therapy in active disease is amphotericin B; 2-hydroxy-stilbamidine is also used.

Blastomycosis has largely been considered to be a disease of the American continent. However, cases have been reported from Africa and Europe and therefore a wider appreciation of this disease is considered pertinent. The relevant literature has been reviewed and four illustrative cases are presented.