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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

To tan or not to tan: a burning issue

2009-12-08

Prof. Werner Sinclair

“Some evidence exists which implies that sunscreens could indeed be responsible for the dramatic rise in the incidence of melanoma over the past three decades, the period during which the use of sunscreens became very popular,” says Prof. Werner Sinclair, Head of the Department of Dermatology at the University of the Free State. His inaugural lecture was on the topic Sunscreens – Curse or Blessing?

Prof. Sinclair says the use of sunscreen preparations is widely advocated as a measure to prevent acute sunburn, chronic sun damage and resultant premature skin aging as well as skin malignancies, including malignant melanoma. There is inconclusive evidence to prove that these preparations do indeed achieve all of these claims. The question is whether these preparations are doing more harm than good?

He says the incidence of skin cancer is rising dramatically and these tumours are induced mostly by the ultra-violet rays.

Of the UV light that reaches the earth 90-95% belongs to the UVA fraction. UVC is normally filtered out by the ozone layer. UVB leads to sunburn while UVA leads to pigmentation (tanning). Because frequent sunburn was often associated with skin cancer, UVB was assumed, naively, to be the culprit, he says.

Exposure to sunlight induces a sense of well-being, increases the libido, reduces appetite and induces the synthesis of large amounts of vitamin D, an essential nutritional factor. The use of sunscreen creams reduces vitamin D levels and low levels of vitamin D have been associated with breast and colon cancer. Prof. Sinclair says the 17% increase in breast cancer from 1981 to 1991 parallels the vigorous use of sunscreens over the same period.

Among the risk factors for the development of tumours are a family history, tendency to freckle, more than three episodes of severe sunburn during childhood, and the use of artificial UV light tanning booths. He says it remains a question whether to tan or not. It was earlier believed that the main carcinogenic rays were UVB and that UVA merely induced a tan. The increase in UVA exposure could have severe consequences.

Prof. Sinclair says the UV light used in artificial tanning booths consists mainly of pure UVA which are highly dangerous rays. It has been estimated that six per cent of all melanoma deaths in the UK can be directly attributed to the use of artificial tanning lights. The use of an artificial tanning booth will double the melanoma risk of a person. “UVA is solely responsible for solar skin aging and it is ironical that tanning addicts, who want to look beautiful, are inflicting accelerated ageing in the process,” he says.

On the use of sunscreens he says it can prevent painful sunburn, but UVA-induced damage continues unnoticed. UVB blockers decrease vitamin D synthesis, which is a particular problem in the elderly. It also prevents the sunburn warning and therefore increases the UVA dosage that an individual receives. It creates a false sense of security which is the biggest problem associated with sunscreens.

Evidence obtained from the state of Queensland in Australia, where the heaviest and longest use of sunscreens occurred, boasted the highest incidence of melanoma in the world. A huge study in Norway has shown a 350% increase in melanoma for men and 440% for women. This paralleled the increase in the use of UVB blocking sunscreens while there was no change in the ozone layer. It did however, occur during that time when tanning became fashionable in Norway and there was an increase especially in artificial tanning.

Prof. Sinclair says: “We believe that sunscreen use does not directly lead to melanoma, but UVA exposure does. The Melanoma Epidemic is a reality. Sunscreen preparations are not the magical answer in the fight against melanoma and the irresponsible use of these preparations can worsen the problem.”

Media Release
Issued by: Mangaliso Radebe
Assistant Director: Media Liaison
Tel: 051 401 2828
Cell: 078 460 3320
E-mail: radebemt.stg@ufs.ac.za
7 December 2009

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