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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

#Women'sMonth: Save the children

2017-08-10

Dr Trudi O’Neill, Senior lecturer in the Department of
Microbial, Biochemical and Food Biotechnology.
Photo: Anja Aucamp

Dr Trudi O’Neill, Senior lecturer in the Department of Microbial, Biochemical and Food Biotechnology, is conducting research on rotavirus vaccines.

Dr O’Neill was inspired to conduct research on this issue through her fascination with the virus. “The biology of rotaviruses, especially the genome structure and the virus’ interaction with the host, is fascinating.”

“In fact, it is estimated that, globally, ALL children will be infected with rotavirus before the age of five, irrespective of their socio-economic standing. However, infants and young children in poor countries are more vulnerable due to inadequate healthcare. The WHO estimates that approximately 215 000 deaths occur each year. This roughly equates to eight Airbus A380 planes, the largest commercial carrier with a capacity of approximately 500 seats, filled with only children under the age of five, crashing each week of every year.”

Alternative to expensive medicines
“Currently, there are two vaccines that have been licensed for global use. However, these vaccines are expensive and poor countries, where the need is the greatest, are struggling to introduce them sustainably. It is therefore appealing to study rotaviruses, as it is scientifically challenging, but could at the same time have an impact on child health,” Dr O’Neill said.

The main focus of Dr O’Neill’s research is to develop a more affordable vaccine that can promote child vaccination in countries/areas that cannot afford the current vaccines.

All about a different approach
When asked about the most profound finding of her research, Dr O’Neill responded: “It is not so much a finding, but rather the approach. My rotavirus research group is making use of yeast as vehicle to produce a sub-unit vaccine. These microbes are attractive, as they are relatively easy to manipulate and cheap to cultivate. Downstream production costs can therefore be reduced. The system we use was developed by my colleagues, Profs Koos Albertyn and Martie Smit, and allows for the potential use of any yeast. This enables us to screen a vast number of yeasts in order to identify the best yeast producer.”

Vaccination recently acquired a bad name in the media for its adverse side effects. As researcher, Dr O’Neill has this to say: “Vaccines save lives. By vaccinating your child, you don’t just protect your own child from a potentially deadly infection, but also other children in your community that might be too young to be vaccinated or have pre-existing health problems that prevents vaccination.”

A future without rotavirus vaccination?
Dr O’Neill believes a future without rotavirus vaccination will be a major step backwards, as the impact of rotavirus vaccines has been profound. “Studies in Mexico and Malawi actually show a reduction in deaths. A colleague in Mozambique has commented on the empty hospital beds that amazed both clinicians and scientists only one year after the introduction of the vaccine in that country. Although many parents, mostly in developed countries, don’t have to fear dehydrating diarrhoea and potential hospitalisation of their babies due to rotavirus infection anymore, such an infection could still be a death sentence in countries that have not been able to introduce the vaccine in their national vaccination programmes,” she said.

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