Talaromycosis
Le T., Dat VQ., van Doorn HR.
Talaromycosis is an invasive fungal infection affecting primarily immunosuppressed individuals. Talaromycosis is caused by the thermally dimorphic fungus Talaromyces marneffei that is endemic in Southeast Asia, southern China, and northeastern India. Its intersection with the HIV epidemic in Southeast Asia has transformed talaromycosis from a rare human disease to a leading cause of death in people with advanced HIV disease. At least 288,000 cases and 87,900 deaths have been reported in the literature in 33 countries to date, and an estimate of 17,300 cases and 4900 deaths occur annually. Ninety percent of global cases occur in HIV-infected individuals, and 0.5% occur in infants and children. Incidence is increasing in non-HIV-infected individuals with secondary immunodeficiency due to increasing use of immunosuppressive therapies. Talaromycosis is increasingly reported in travelers to and immigrants from the endemic region. The clinical features are diverse, ranging from primary pulmonary to localized to disseminated infections involving multiple organ systems. Current diagnosis is based on culture isolation of T. marneffei demonstrating the temperature-dependent morphological switch between the mold and yeast forms. Culture isolation takes up to 28 days, leading to delays in treatment and high mortality. Promising molecular amplification and antigen detection methods offer improved sensitivities and speed and are undergoing clinical validation for clinical use. Induction therapy with amphotericin B reduces mortality, and is associated with faster fungal clearance from blood and reduced incidence of relapse and other complications compared to itraconazole. Amphotericin B is recommended as first line induction therapy regardless of disease severity. The mortality with treatment is high, and treatment options remain limited. Strategies for early diagnosis using non-culture diagnostics, use of effective but less toxic antifungal regimens, and more cost-effective disease prevention are critical to reduce morbidity and mortality.