By Eloise Ballard

What is Emergomyces africanus?

It is not often that completely novel pathogens are identified, but in 2013 this is exactly what happened in South Africa. The fungal pathogen identified was named Emergomyces africanus, which is a bit of a mouthful. But, it can be broken down to mean ‘Emergo’ as in emerging, ‘myces’ denoting fungus and ‘africanus’ indicating African origin.

The fungus was identified because it was causing a range of serious systemic fungal infections in patients with weakened immune systems (specifically patients with HIV). Interestingly, Emergomyces africanus is a thermally dimorphic fungus, which means at different temperatures it exists as different forms. Namely, either a hyphae- or yeast-like form. The difference between hyphae and yeast is mainly the shape and composition of the cell type. As shown below, hyphae are long and branched whereas yeasts are single circular/oval shaped cell.

Fig 1. Diagram showing the structures of hyphae and yeasts (Source: BioRender software).

How can Emergomyces africanus infect patients?

It is believed that inhalation of Emergomyces africanus causes the infection and that the fungus cannot be transmitted person to person. But this requires validation.

What are the signs and symptoms?

Symptoms of this infection include skin lesions, fever, weight loss and lung disease. The number of cases of Emergomyces africanus infection reported are fewer than 100. But tragically, of these cases approximately 50% of patients have died. If diagnosed early, this infection is treatable using available antifungal agents. It is important to note that this infection only affects individuals with weakened immune systems, individuals with healthy immune systems need not worry. More information can be found on the National Institute for Communicable Diseases website.

Where is the fungus coming from?

Having identified infections caused by this mysterious fungus, researchers’ next question was to determine the environmental reservoir of this fungus. After extensive searching, researchers identified the fungus to be present in the soil. This identification was done using molecular techniques, namely polymerase chain reaction (PCR), which enables determination of whether DNA of specific organisms is present in a sample. Out of 60 South African soil samples tested using this technique, 18 contained Emergomyces africanus. The majority of these soil samples were obtained in the Western Cape of South Africa shown below. Studies have now also been done to positively identify the prevalence of this fungus in the air in South Africa.

Fig 2. Map of South Africa (Source: Wikimedia Commons).

Final thoughts

Further research is required to gain more information on this emerging fungal pathogen. There is still a lot we do not understand about this deadly fungus. Where is it coming from, how does it cause infection and importantly whether it will develop resistance to antifungal drugs? However, as the prevalence of Emergomyces africanus globally remains unknown, it is important that we monitor this fungus to prepare for potential future outbreaks. The Centers for Disease Control and Prevention do a lot of work monitoring fungal infections worldwide, more information can be found on their website.

Further reading

Schwartz et al. Emergomyces africanus in Soil, South Africa. Emerg Infect Dis 24(2):377-380 (2018).

Schwartz et al. Molecular detection of airborne Emergomyces africanus, a thermally dimorphic fungal pathogen, in Cape Town, South Africa. PLoS Negl Trop Dis 12(1):e0006174 (2018).

About me

I am a final year PhD student at the MRC Centre for Medical Mycology at the University of Aberdeen. My research focuses on the human fungal pathogen Aspergillus fumigatus and how it adapts to the human lung environment during infection.

Before beginning my PhD, I completed a BSc in Biochemistry at the University of St Andrews (UK). Outside of the lab, I enjoy science blogging on The Microbe Diaries.

You can find me on Twitter @eballard123.