Mucormycosis in Asia

Abstract

Mucormycosis, also called “Fungal Emergency,” is a rare disease across the world except Asia. In Asia, especially in India, the alarmingly high incidence of mucormycosis in uncontrolled diabetic population is a cause for concern. In contrast, the majority of mucormycosis cases in western world occur in the patients with hematological malignancies and neutropenia. Recently in a study from India, the incidence of mucormycosis is estimated at a rate of 0.14 cases/1000 population, means 70 times to the incidence in wetern world. Other than India, few case series have been reported from Taiwan, Korea, Indonesia, and Japan. The population of Asia is not homogenous. The prevalence of infectious diseases varies with economy, geography, behaviour, and hospital practices. However, the majority of Asian population avoid periodic health checkup and it is reflected in the fact that 16–23% of our mucormycosis patients in India were unaware of background diabetes. Asian mucormycosis cases have certain unique features. Contrary to pulmonary mucormycosis, rhino-cerebral presentation is commonest in Asia. In India and China, a distinct group of population without any risk factor has been reported with isolated kidney involvement. These patients are young and immunocompetent. It is not clear how and why these patients acquire isolated renal mucormycosis. The spectrum of agents causing mucormycosis in Asia is also wide. Though Rhizopus oryzae is the commonest agent isolated, Apophysomyces variabilis ranks the second. Other new species isolated in Asia include Saksenaea vasiformis, Rhizopus homothallicus, Mucor irregularis, and Thamnostylum lucknowense. In an environmental survey, R. oryzae was the commonest agent isolated, followed by Lichtheimia and Cunninghamella species. The rare agents like A. variabilis and Rhizopus homothallicus were isolated in high numbers in alkaline soils. On multivariate analysis low nitrogen content, alkaline pH of soil was found to be significantly associated with A. variabilis isolation. The mortality due to mucormycosis remains high in Asian population. A large section of Asian patients fail to afford liposomal amphotericin B and the disease is managed with conventional amphotericin B deoxycholate. More studies are required from Asian countries to know the exact prevalence of the disease, the pathogenesis of renal mucormycosis, and the relation of environmental and clinical isolates.