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New study finds emerging pathogen inside brown locusts

17 February 2025 | Story Andre Damons | Photo Supplied

Prof Carolina Pohl-Albertyn — Prof Carlien Pohl-Albertyn is the NRF SARChI Research Chair in Pathogenic Yeasts at the UFS.

A new study by researchers from the University of the Free State (UFS), the National Health Laboratory Service, and the University of Venda has confirmed for the first time that common brown locusts are carriers of pathogenic yeasts that can cause severe infections in humans – especially in people with compromised immune systems or who are seriously ill.

The study, ‘South African brown locusts, Locustana pardalina, hosts fluconazole resistant, Candidozyma (Candida) auris (Clade III)’, highlights for the first time the presence of the pathogenic (disease-producing) fungal yeast C. auris in the digestive tract of the locusts, and shows their potential in disseminating this emerging pathogen. The research started in April 2022, when 20 gregarious (swarming) adult locusts were collected during a large locust outbreak which occurred from September 2021 to May 2022 in the semi-arid Eastern Karoo region in the Eastern Cape. The study is still under peer review.

According to Prof Carlien Pohl-Albertyn, National Research Foundation (NRF) SARChI Research Chair in Pathogenic Yeasts, three C. auris strains were isolated from three different adult locusts, two of which also harboured strains of another potentially pathogenic yeast, Candida orthopsilosis. “The fact that we were able to isolate C. auris from 15% of the sampled locusts, using non-selective media and a non-restrictive temperature of 30°C, may indicate that C. auris is abundant in the locusts and that specific selective isolation is not mandatory,” Prof Pohl-Albertyn said.

“Interestingly, C. auris was isolated from the fore- and hindgut of the locusts. Isolation from the foregut, which is dedicated to food intake and storage, filtering and partial digestion, indicates that C. auris was probably obtained by the locusts via feeding activities. Isolation from the hindgut confirms that C. auris can survive the digestive processes in the midgut and is likely to be released back into the environment via faeces.”

Healthy humans are not at great risk

One of the C. auris strains was studied in more detail. This strain was not resistant to disinfectants but showed decreased susceptibility to the common antifungal drug fluconazole. This is a characteristic of this yeast species and thus not surprising. Most of the emerging pathogenic yeasts show this intrinsic resistance. This highlights the urgent need to discover and develop new antifungal drugs.

Prof Pohl-Albertyn, also a Professor of Microbiology in the UFS Department of Microbiology and Biochemistry, says, “Healthy humans are not at great risk for infection by this yeast and there is currently no proof that ingestion may be harmful to them. This is unfortunately not the case for people with compromised immune systems or who are seriously ill. However, few susceptible people come into direct contact with the locusts in South Africa.”

She added that there are treatment options available, using other antifungal drugs, but C. auris can become resistant to all the currently available antifungal drugs.

Importance of the study

“The fact that locusts are a food source for other animals, such as birds, could lead to eventual distribution of the yeast to people. In other countries, wild locusts are a food source for humans and there more direct transmission may be possible,” Prof Pohl-Albertyn said.

She explained that this study tries to answer questions regarding the natural hosts of this emerging pathogen and how it may facilitate the spread of the pathogen to the rest of the environment. The study is one part of the puzzle regarding how new pathogens may emerge from the environment and spread to people.

“One of the questions in the field of pathogenic yeasts is how C. auris was able to emerge as a pathogen in several different countries in a relatively short period. It is well known as a hospital-acquired pathogen, but it is not known where in the environment it occurs naturally, and which environmental factors may have shaped its evolution and ability to cause human infections. This has implications for the prevention of the spread of this specific yeast species, as well as our preparedness for new pathogenic yeasts that may be emerging from the environment.”

News Archive

UFS professor addresses genetically modified food in South Africa in inaugural lecture

2016-09-23

Description: Chris Viljoen inaugural lecture Tags: Chris Viljoen inaugural lecture

At the inaugural lecture were, from the left front,
Prof Lis Lange, Vice Rector: Academic;
Prof Chris Viljoen; Prof Gert van Zyl,
Dean: Faculty of Health Sciences; back: Prof Marius Coetzee,
Head of Department of Haematology and Cell Biology;
and Dr Lynette van der Merwe, Undergraduate
Programme Director.
Photo: Stephen Collett

The first genetically modified (GM) crops in South Africa were planted in 1998. Eighteen years later, the country is one of the largest producers of GM food in the world. Those in support of genetically modified crops say this process is the only way to feed a rapidly growing world population. But those who criticise GM food describe it as a threat to the environment and safety of the population. Who is right? According to Prof Chris Viljoen of the Department of Haematology and Cell Biology at the University of the Free State, neither position is well-founded.

GM crops play a vital role in food security
While GM crops have an important role to play in increasing food production, the technology is only part of the solution to providing sufficient food for a growing world population. The major genetically modified crops produced in the world include soybean, cotton, maize and canola. However, the authenticity of food labelling and the long-term safety of GM food are issues that consumers are concerned about.

Safety and labelling of GM food important in South Africa
In his inaugural lecture on the subject “Are you really going to eat that?” Prof Viljoen addressed the importance of the safety and labelling of GM food in the country. “In order for food to be sustainable, production needs to be economically and environmentally sustainable. On the other hand, food integrity, including food quality, authenticity and safety need to be ensured,” Prof Viljoen said.

Labelling of food products for genetic modification was mandatory in South Africa, he went on to say. “It allows consumers the right of choice whether to eat genetically modified foods or not.” The Consumer Protection Act of 2008 requires food ingredients containing more than 5% of GM content to be labelled.

GMO Testing Facility world leader in food diagnostic testing
In 1999, Prof Viljoen spearheaded research in developing a GM diagnostic testing platform, and in 2003, a commercial diagnostic platform for GM status certification, called the GMO Testing Facility, was founded. The facility is a licensed Eurofins GeneScan laboratory a world leader in food diagnostic testing and provides diagnostic detection and quantification of genetically modified organisms (GMOs) in grain and processed foods for the local and international market.

Molecular diagnostic technology the future of food integrity, authenticity and safety
With GM labelling now well-established in South Africa, the next challenge is to establish the use of molecular diagnostic technology to ensure that food integrity, including food authenticity and safety is maintained, said Prof Viljoen.

“To the question ‘Are you really going to eat that?’ the answer is ‘yes’, but let’s continue doing research to make sure that what we eat is safe and authentic.”

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