Emergomycosis in Africa: Time to Pay Attention to This Emerging Deadly Fungal Infection

Abstract

Emergomycosis is an emerging deadly infectious disease caused primarily by a little-known airborne pathogen Emergomyces africanus, which can cause clinical management challenge especially in patients with advanced HIV disease. This minireview describes Es. africanus as the main cause of emergomycosis in Africa as well as considers contributing factors to the difficulties encountered in managing this infection. Emergomycosis is common in HIV-positive persons with low CD4 lymphocyte count and has an estimated fatality of 50%. The infection exhibits airborne transmission with pulmonary and extrapulmonary manifestations leading to skin lesions. However, the pathogenesis of Es. africanus is still poorly understood. The management of the infection is complicated due to lack of defined diagnostic and therapeutic guidelines. Limited expertise, poor research funding, and lack of awareness and national surveillance are thought to impact the recognition and prioritisation of the infection. These factors may ultimately assign emergomycosis a 'neglected infection status' even as it is suspected to be prevalent in more African countries than previously recognised. Increased awareness and integrated and targeted strategies such as mobilising manpower in clinical mycology are of paramount importance in managing emergomycosis in Africa and beyond.

Keywords: Es. africanus; HIV; emergomycosis; epidemiology; pathogenesis.

Figure 1

A model for Emergomyces infection and clinical manifestation. Emergomyces species (Es. africanus, Es. pasteurianus, Es. canadensis, Es. europaeus and Es. orientalis) have been reported - using Es. africanus - to exist in the soil as saprophytic moulds that produce spores (conidia). The conidia adapt for wind dispersal and can remain airborne for lengthy periods. Humans inhale the conidia (1) which then lodged in the terminal regions of the lungs where they undergo morphological transition to the infective phase - budding yeast (2). The yeast phase causes pulmonary infection in susceptible individuals especially in patients with advanced HIV infection which can lead to disseminated infections. From the lungs, the yeast cells can spread (3) throughout the body through haematogenous dissemination in neutrophils and infect virtually any organ including the skin, heart, bone marrow, spleen, and lymph node. Figure created with BioRender.com.