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14 August 2024 | Story Martinette Brits | Photo Supplied
Dr Luther van der Mescht
Dr Luther van der Mescht, Senior Lecturer in the Department of Zoology and Entomology.

Ticks that feed on South Africa’s cattle are developing resistance to the only effective pesticides, making them increasingly difficult to control. If this issue is not addressed, the spread of these parasites and their resistance to pesticides could significantly impact farmers' incomes and food security.

According to a study by Dr Luther van der Mescht, Senior Lecturer in the Department of Zoology and Entomology, many tick populations in South Africa are resistant to at least two of the three main types of acaricides (chemical classes) used in the country.

Dr Van der Mescht notes that with around 12 million cattle in South Africa, these ticks not only lower meat and milk production but also carry pathogens that can cause potentially fatal diseases. He estimates that the economic losses from tick-borne diseases and the use of acaricides could reach up to R670 million annually in the cattle industry alone.

He adds that South Africa's agricultural sector is unique due to its dual farming system, which includes both subsistence and commercial farmers, amplifying the impact of ticks. “The country is also home to a wide variety of tick species that transmit numerous pathogens across a diverse range of habitats and climates in which cattle are farmed. Consequently, the effects of ticks and tick-borne diseases in South Africa may be more severe compared to those in developed countries.”

Dr Van der Mescht highlights that ticks are developing resistance primarily due to poor farm management practices, such as underdosing, overdosing, and excessive use of acaricides. “Additionally, insufficient government support in educating farmers and managing resistance exacerbates the problem.”

Managing acaricide resistance

Dr Van der Mescht explains that while ticks will inevitably develop resistance to acaricides, this usually happens much slower if pesticides are used strategically. To slow the development of resistance, several measures can be implemented: 

• Minimise the number of acaricide treatments.
• Assess tick diversity and acaricide resistance at the farm level and monitor it regularly. The study found that acaricide resistance was highly variable across South Africa, likely due to different farm management practices; hence it should be assessed at the farm level.
• Quarantine animals when transferring them to a new farm, ensuring they are free of ticks before releasing them.
• Rotate acaricides from different chemical classes, with a gap of at least two years between applications.

• Government veterinary services should raise awareness about acaricide resistance and provide support, particularly to under-resourced farmers. Establishing acaricide resistance testing laboratories would help monitor resistance and offer guidance to farmers.

Expert in parasitology

Dr Van der Mescht is particularly fascinated by the fact that most animals on earth follow a parasitic way of life. He graduated with a PhD in Conservation Ecology from the Department of Conservation Ecology and Entomology at Stellenbosch University in 2015, focusing on rodent parasites.

Career highlights include receiving the Wilhelm Neitz Memorial Scholarship in Parasitology from the Parasitological Society of Southern Africa (PARSA) for study abroad, and the Blaustein Centre for Scientific Cooperation Postdoctoral Fellowship in 2016 from Ben-Gurion University of the Negev, Israel, to conduct research on the experimental evolution of host specialisation. He also received the Claude Leon Foundation Postdoctoral Fellowship in 2019 to study the cat flea at Stellenbosch University’s Department of Botany and Zoology.

With over four years of experience in the industry at a contract research organisation, he has conducted more than 40 clinical studies for international pharmaceutical companies and published over 50 peer-reviewed scientific articles.

Making research visible, impactful, and relevant to society

Dr Van der Mescht recently published an article for The Conversation and participated in interviews with eNCA, Newzroom Afrika, and Cape Talk to discuss his research. “This effort aligns with the Vision 130 strategy of being a regionally engaged university and supports one of the key pillars of research development at the University of the Free State (UFS), which is to make our research visible, impactful, and relevant to society.”

He also highlighted the significance of popular science, noting that it helps scientists communicate their research to a broader audience, build their professional reputation, enhance their funding opportunities, and improve their research outcomes.

News Archive

Stem cell research and human cloning: legal and ethical focal points
2004-07-29

   

(Summary of the inaugural lecture of Prof Hennie Oosthuizen, from the Department of Criminal and Medical Law at the Faculty of Law of the University of the Free State.)

 

In the light of stem cell research, research on embryo’s and human cloning it will be fatal for legal advisors and researchers in South Africa to ignore the benefits that new bio-medical development, through research, contain for this country.

Legal advisors across the world have various views on stem cell research and human cloning. In the USA there is no legislation that regulates stem cell research but a number of States adopted legislation that approves stem cell research. The British Parlement gave permission for research on embryonic stem cells, but determined that it must be monitored closely and the European Union is of the opinion that it will open a door for race purification and commercial exploitation of human beings.

In South Africa the Bill on National Health makes provision for therapeutical and non therapeutical research. It also makes provision for therapeutical embryonical stem cell research on fetuses, which is not older than 14 days, as well as for therapeutical cloning under certain circumstances subject to the approval of the Minister. The Bill prohibits reproductive cloning.

Research on human embrio’s is a very controversial issue, here and in the rest of the world.

Researchers believe that the use of stem cell therapy could help to side-step the rejection of newly transplanted organs and tissue and if a bank for stem cell could be built, the shortage of organs for transplants would become something of the past. Stem cells could also be used for healing of Alzheimer’s, Parkinson’s and spinal injuries.

Sources from which stem cells are obtained could also lead to further ethical issues. Stem cells are harvested from mature human cells and embryonic stem cells. Another source to be utilised is to take egg cells from the ovaries of aborted fetuses. This will be morally unacceptable for those against abortions. Linking a financial incentive to that could become more of a controversial issue because the woman’s decision to abort could be influenced. The ideal would be to rather use human fetus tissue from spontaneous abortions or extra-uterine pregnancies than induced abortions.

The potential to obtain stem cells from the blood of the umbilical cord, bone-marrow and fetus tissue and for these cells to arrange themselves is known for quite some time. Blood from the umbilical cord contains many stem cells, which is the origin of the body’s immune and blood system. It is beneficial to bank the blood of a newborn baby’s umbilical cord. Through stem cell transplants the baby or another family member’s life could be saved from future illnesses such as anemia, leukemia and metabolic storing disabilities as well as certain generic immuno disabilities.

The possibility to withdraw stem cells from human embrio’s and to grow them is more useable because it has more treatment possibilities.

With the birth of Dolly the sheep, communities strongly expressed their concern about the possibility that a new cloning technique such as the replacement of the core of a cell will be used in human reproduction. Embryonic splitting and core replacement are two well known techniques that are associated with the cloning process.

I differentiate between reproductive cloning – to create a cloned human embryo with the aim to bring about a pregnancy of a child that is identical to another individual – and therapeutically cloning – to create a cloned human embryo for research purposes and for healing human illnesses.

Worldwide people are debating whether to proceed with therapeutical cloning. There are people for and against it. The biggest ethical objection against therapeutical cloning is the termination of the development of a potential human being.

Children born from cloning will differ from each other. Factors such as the uterus environment and the environment in which the child is growing up will play a role. Cloning create unique children that will grow up to be unique individuals, just like me and you that will develop into a person, just like you and me. If we understand this scientific fact, most arguments against human cloning will disappear.

Infertility can be treated through in vitro conception. This process does not work for everyone. For some cloning is a revolutionary treatment method because it is the only method that does not require patients to produce sperm and egg cells. The same arguments that were used against in vitro conception in the past are now being used against cloning. It is years later and in vitro cloning is generally applied and accepted by society. I am of the opinion that the same will happen with regard to human cloning.

There is an argument that cloning must be prohibited because it is unsafe. Distorted ideas in this regard were proven wrong. Are these distorted ideas justified to question the safety of cloning and the cloning process you may ask. The answer, according to me, is a definite no. Human cloning does have many advantages. That includes assistance with infertility, prevention of Down Syndrome and recovery from leukemia.

 

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