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A case series of histoplasmosis patients with elevated serum soluble interleukin-2 receptor levels
Tatsuro Hirayama1, Takahiro Takazono2, Kazuma Iwata3
1Second Department of Internal Medicine, Nagasaki University Hospital, Nagasaki, Japan; Department of Respiratory Medicine, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
Abstract:
Histoplasmosis is a common endemic mycosis that is usually asymptomatic but occasionally results in severe illness. Histoplasmosis and its causative agent, Histoplasma capsulatum, are found worldwide but rarely in Japan. In recent years, however, the number of histoplasmosis patients in Japan has increased. In addition, to our knowledge, there are no previous reports of increased serum soluble interleukin-2 receptor (sIL-2R) levels in patients with histoplasmosis. We report a case series of histoplasmosis in three Japanese temporary workers in Manzanillo, Mexico. All three patients developed a persistent high fever and general fatigue. Laboratory tests showed increased C-reactive protein levels and mild liver dysfunction. All patients also showed increased soluble interleukin-2 receptor (sIL-2R) levels. Chest computed tomography revealed multiple nodules in both lung fields. All patients were positive for serum anti-Histoplasma antibodies, and two patients were positive for Histoplasma on polymerase chain reaction tests. After treatment that included antifungals, their conditions gradually improved and laboratory data normalized. Although one patient developed respiratory failure, this patient recovered with antifungal therapy in combination with methylprednisolone. Serum sIL-2R levels in all patients gradually declined to normal levels, indicating their recovery from Histoplasma infection. From our experience with these patients, sIL-2R levels may be a useful biomarker for patients with histoplasmosis.
Insights
This study highlights increased serum soluble interleukin-2 receptor (sIL-2R) levels in Japanese histoplasmosis patients. These levels may serve as a valuable biomarker for diagnosing and monitoring Histoplasma infections.
Area of Science:
- Mycology
- Infectious Diseases
- Immunology
Background:
- Histoplasmosis, caused by Histoplasma capsulatum, is a globally endemic fungal infection, rarely reported in Japan.
- Recent years have seen an increase in histoplasmosis cases in Japan.
- No prior studies have reported elevated serum soluble interleukin-2 receptor (sIL-2R) in histoplasmosis patients.
Observation:
- A case series of three Japanese temporary workers in Mexico with histoplasmosis presented with persistent fever and fatigue.
- Laboratory findings included elevated C-reactive protein, mild liver dysfunction, and notably, increased serum sIL-2R levels.
- Chest CT scans revealed bilateral pulmonary nodules in all patients.
Findings:
- All patients tested positive for anti-Histoplasma antibodies, with two positive for Histoplasma DNA via PCR.
- Treatment with antifungals led to gradual clinical improvement and normalization of laboratory values.
- Serum sIL-2R levels decreased to normal ranges post-treatment, correlating with recovery.
Implications:
- Elevated serum sIL-2R levels may represent a novel and useful biomarker for histoplasmosis diagnosis and management.
- This finding is significant given the increasing incidence of histoplasmosis in Japan.
- Further research is warranted to validate sIL-2R as a reliable biomarker in a larger cohort.