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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

Research into surrogate milk important to wildlife conservation

2017-05-08

Prof Gary Osthoff from the UFS Department of
Microbial, Biochemical and Food Biotechnology,
will soon work on a milk formula for elephants.
Photo: Supplied

Research is being done at the University of the Free State (UFS) to analyse and synthetically imitate the unique milk of various wildlife species. This research is not only of scientific value, but also serves the conservation of South Africa’s wildlife species. At the forefront of this research is Prof Garry Osthoff from the Department of Microbial, Biochemical and Food Biotechnology.

Orphaned rhino calf pulled through with surrogate milk
“There is still a lot of research to be done. Naturally the research is of scientific importance, but with surrogate milk having the same composition as the mother’s milk of a specific species, orphaned calves or cubs of that species could be pulled through during a difficult time of weaning. Bearing in mind that exotic animals fetch thousands and even millions of rands at auctions, it goes without saying a game farmer will do everything possible to provide only the best nourishment to such an orphaned animal. In such a case, synthetically-manufactured milk would be the right choice,” says Prof Osthoff.

The fruits of his research were recently demonstrated in Germany when a rhino calf was left orphaned in the Leipzig Zoo. Prof Osthoff’s article: “Milk composition of a free-ranging white rhinoceros during late lactation” was used as a directive for applying surrogate milk for horse foals (which is already commercially available), since the composition of horse and rhino milk largely corresponds. The surrogate milk was used with great success and the rhino calf is flourishing. He mentions that such an orphan is often given the wrong nourishment with the best intentions, resulting in the starvation of the animal despite the amount of cow’s milk it devours.

With surrogate milk having the same
composition as the mother’s milk of a
specific species, orphaned calves or
cubs of that species could be pulled
through during the difficult time
of weaning.

Milk formula for baby elephants in the pipeline
With baby elephants left orphaned due to the increase in elephant poaching for their ivory, several attempts have been made to create a milk formula in order to feed these elephants. To date, many elephants have died in captivity from side effects such as diarrhoea as a result of the surrogate formula which they were fed.

Prof Osthoff recently received a consignment of frozen milk which he, together with researchers from Zimbabwe, will use to work on a milk formula for elephants. They are studying the milk in a full lactation period of two years. During lactation, the composition of the milk changes to such an extent that a single surrogate formula will not be sufficient. Four different formulas should probably be designed.

Prof Osthoff says that of the different species he has researched, elephants are the most interesting and deviate most from the known species.

Although his research to develop surrogate milk is adding much value to the wildlife industry, and although he finds this part of his work very exciting, his research focus is on food science and nutrition. “What is currently authentic in milk research is the study of the fat globules with content, the structure and composition of the casein micelle, and the prebiotic sugars. The knowledge which is gained helps to improve the processing, development of new food products, and development of food products for health purposes,” says Prof Osthoff.

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