Molecular evidence of recurrent histoplasmosis with 9-year latency in a patient with Addison's disease

Histoplasmosis in Taiwan: Case Summary and Literature Review

Histoplasmosis is a global infection caused by the thermally dimorphic fungus, Histoplasma capsulatum complex. It is endemic in the United States, as well as in Central and South America. In Taiwan, histoplasmosis is rare, with the first reported case not occurring until 1977. We summarized a total of 17 cases reported in Taiwan over the past 40 years and provided detailed descriptions for four probable indigenous cases. Due to the lack of rapid diagnostic tools and clinical suspicion, histoplasmosis may be underdiagnosed in Taiwan. We recognize that a limitation of our review is the lack of data on the environmental surveillance for H. capsulatum complex in Taiwan. Conducting a further phylogenetic analysis on both environmental and clinical isolates would provide valuable evidence for the region.

Metagenomic next-generation sequencing identified Histoplasma capsulatum in the lung and epiglottis of a Chinese patient: A case report

Histoplasmosis is an endemic disease mainly occurring in North America and is rare in China. Confirmation of histoplasmosis should be based on a compatible clinical scenario and a positive culture or histopathology. However, there are still many cases that are misdiagnosed or missed, especially in individuals from non-endemic areas. In recent years, metagenomic next-generation sequencing (mNGS) has led to the accurate and timely diagnosis of some rare and complicated infectious diseases. We describe the case of a 27-year-old Chinese man who had chronic progressive pulmonary lesions without any symptoms for more than 1year, until the lesions reached the epiglottis and led to progressive pharyngeal pain. There were no positive results from bronchoalveolar lavage fluid (BALF) and epiglottis tissue cultures, or from epiglottis and lung pathological examinations, but mNGS was able to identify Histoplasma capsulatum in the epiglottis tissues and BALF as the cause of the lesions. The patient was treated successfully with itraconazole.

How Environmental Fungi Cause a Range of Clinical Outcomes in Susceptible Hosts

Environmental fungi are globally ubiquitous and human exposure is near universal. However, relatively few fungal species are capable of infecting humans, and among fungi, few exposure events lead to severe systemic infections. Systemic infections have mortality rates of up to 90%, cost the US healthcare system $7.2 billion annually, and are typically associated with immunocompromised patients. Despite this reputation, exposure to environmental fungi results in a range of outcomes, from asymptomatic latent infections to severe systemic infection. Here we discuss different exposure outcomes for five major fungal pathogens: Aspergillus, Blastomyces, Coccidioides, Cryptococcus, and Histoplasma species. These fungi include a mold, a budding yeast, and thermal dimorphic fungi. All of these species must adapt to dramatically changing environments over the course of disease. These dynamic environments include the human lung, which is the first exposure site for these organisms. Fungi must defend themselves against host immune cells while germinating and growing, which risks further exposing microbe-associated molecular patterns to the host. We discuss immune evasion strategies during early infection, from disruption of host immune cells to major changes in fungal cell morphology.

Chronic cavitary pulmonary histoplasmosis in a non-HIV and immunocompromised patient without overseas travel history

Korea is not known as an endemic area for Histoplasma. However, we experienced a case of histoplasmosis in a person who had never been abroad. A 65-year-old female was admitted to the hospital for evaluation of multiple lung nodules. A computed tomography (CT) scan of the chest showed multiple ill-defined consolidations and cavitations in all lobes of both lungs. The patient underwent a CT-guided lung biopsy, and a histopathology study showed findings compatible with histoplasmosis. Based on biopsy results and clinical findings, the patient was diagnosed with chronic cavitary pulmonary histoplasmosis. The patient recovered completely following itraconazole treatment. This is the first case report of pulmonary histoplasmosis unconnected with either HIV infection or endemicity in Korea.

Genetic diversity of Histoplasma capsulatum strains isolated from Argentina based on nucleotide sequence variations in the internal transcribed spacer regions of rDNA

The internal transcribed spacer (ITS) regions of rDNA genes of 49 Histoplasma capsulatum (48 from clinical samples and one from soil) isolates were examined. Nucleotide sequence heterogeneity within this region was useful for phylogenetic classification of H. capsulatum and species identification. Thus, in 45 of 49 isolates we observed higher percentages of identity in the nucleotide sequences of ITS regions when the isolates studied herein were compared with those reported in our country in the South America B clade. Phylogenetic analyses of rDNA sequences corresponding to the 537 bp of the ITS region obtained from H. capsulatum isolates assigned South America type B clade (45 isolates), North America type 1 and Asia clade (2 isolates each one). H. capsulatum strains isolated from soil and from patients living in Argentina (45 of 49) clustered together with the H. capsulatum isolates of the South America B clade. The high level of genetic similarity among our isolates suggests that almost one genetic population is present in the microenvironment. Isolates described as H. capsulatum var. capsulatum or var. farciminosum (2 isolates) did not form a monophyletic group and were found in the Asia clade. Subsequent studies are needed to properly identify these isolates.

Vulvar histoplasmosis as a rare cause of genital ulceration

BACKGROUND

Histoplasmosis is an infection caused by the dimorphic fungus Histoplasma capsulatum and primarily presents with pulmonary symptoms. Immunocompromised individuals are at high risk for contracting disseminated histoplasmosis, which can be fatal if left untreated.

CASE

We present a case involving a 50-year-old woman with acquired immunodeficiency syndrome with an ulcerated vulvar lesion concerning for carcinoma. Extensive workup revealed disseminated histoplasmosis without pulmonary manifestations. She was treated with an extended course of an antifungal agent. Her vulvar lesion resolved.

CONCLUSION

Vulvar histoplasmosis is a rare etiology of vulvar pathology but one that should be considered in immunocompromised patients.

Localized Histoplasma capsulatum osteomyelitis of the fibula in an immunocompetent teenage boy: a case report

Background

Infection of local bone with Histoplasma capsulatum is rare and difficult to diagnosis, and occurs particularly in immunocompetent subjects, who are more likely to be affected by a wide range of organisms.

Case presentation

An 11-year-old boy presented with localized histoplasmosis osteomyelitis in the left fibula without any evidence of abnormal immunological function or systemic disease. After surgical clearance of the lesion and homologous cancellous bone, the patient was treated orally with voriconazole for 6 months. The patient completely recovered with full function of his left leg during the 5-year follow-up.

Conclusions

Histoplasmosis osteomyelitis can occasionally occur in immunocompetent individuals and can be complete cured by surgical clearance of the lesion and antibiotic treatment.

Histoplasmosis: a new endemic fungal infection in China? Review and analysis of cases

Histoplasmosis occurs in specific endemic areas, including the mid-western United States, Africa and most of Latin America. Sporadic cases have also been reported in China. The aim of this study was to summarise the epidemiological and clinical data of histoplasmosis in China. We searched the PubMed, CBMdisk and CNKI databases to identify publications related to histoplasmosis in China. Case reports/series on patients with histoplasmosis were included. A comprehensive literature review identified additional cases. The relevant material was evaluated and reviewed. Overall, 300 cases of histoplasmosis were reported in China from 1990 to 2011, and 75% were from regions through which the Yangtze River flows. Most of the patients were autochthonous infections. Of these, 43 patients had pulmonary histoplasmosis and 257 patients had disseminated histoplasmosis. Common underlying diseases included HIV infection, diabetes mellitus and liver diseases. Fever was the most frequently reported clinical feature in disseminated histoplasmosis, followed by splenomegaly and hepatomegaly. Cases of histoplasmosis had a prominent geographical distribution in China. Histoplasmosis should be considered in the diagnosis of patients with relevant symptoms and a history of travel to or residence in these areas.