Molecular detection of airborne Emergomyces africanus, a thermally dimorphic fungal pathogen, in Cape Town, South Africa.

Ilan S Schwartz,Dilys Berman,Chris Kenyon,Josh D Mcloud,Robert Colebunders,Alfred Botha,Estelle Levetin,Barbra Lerm

doi:10.1371/journal.pntd.0006174

Abstract

Emergomyces africanus is a thermally dimorphic fungus that causes a systemic mycosis in immunocompromised persons in South Africa. Infection is presumed to follow inhalation of airborne propagules. We developed a quantitative PCR protocol able to detect as few as 5 Es. africanus propagules per day. Samples were collected in Cape Town, South Africa over 50 weeks by a Burkard spore trap with an alternate orifice. We detected Es. africanus in air samples from 34 days (10%) distributed over 11 weeks. These results suggest environmental exposure to airborne Es. africanus propagules occurs more commonly in endemic areas than previously appreciated.

Highlights

Emergomyces africanus is an emerging opportunistic dimorphic fungal pathogen that causes emergomycosis, a systemic and often-fatal HIV-associated mycosis in South Africa [1,2]
We developed a highly specific and sensitive protocol for the molecular detection and quantification of Es. africanus, and tested air samples collected over a 50-week period from an urban area of Cape Town, Western Cape, South Africa, where the disease is endemic
In addition to Emergomyces africanus, which has been reported from South Africa and Lesotho [1,2,3], the genus includes Emergomyces pasteurianus and Emergomyces orientalis

Summary

Introduction

Emergomyces africanus is an emerging opportunistic dimorphic fungal pathogen that causes emergomycosis, a systemic and often-fatal HIV-associated mycosis in South Africa [1,2]. It is a member of a newly-described genus within the family Ajellomycetaceae called Emergomyces, so-named because of the striking appearance or recognition of new dimorphic fungal pathogens reported globally [2]. Disease caused by Es. africanus is relatively common: only described in 2013 (as Emmonsia species [1]), Es. africanus is recognized to cause the most frequently diagnosed dimorphic fungal infection in South Africa [10]. In Cape Town, a clinical and laboratory surveillance study at public hospitals over a 15-month period identified 14 cases of cultureproven emergomycosis [13]

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Discussion

Conclusion