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23 August 2022 | Story André Damons | Photo Supplied
Dr Walter Janse van Rensburg
Dr Walter Janse van Rensburg, Senior Lecturer in the Human Molecular Biology Unit, Department of Haematology and Cell Biology in the UFS School of Biomedical Sciences, says new research found that men of European descent over the age of 50 are the most vulnerable for the development of atherosclerosis.

A new study by researchers in the Human Molecular Biology Unit in the School of Biomedical Sciences at the University of the Free State (UFS) into atherosclerosis in the South African population found that men of European descent over the age of 50 are the most vulnerable for the development of atherosclerosis – the most common disorder associated with cardiovascular diseases (CVDs). Nearly half of men in this group had visible signs of atherosclerosis in the coronary arteries of the heart. 

This was in contrast to the only roughly one-tenth of the African-descent males and females in the same age bracket. More than a third of women of European descent over 50 had visible atherosclerosis in their coronary arteries. One hypothesis regarding a possible explanation for this discrepancy is based on the theory that socioeconomic status may be a driving force behind CVD.

Risks factor for cardiovascular diseases

Dr Walter Janse van Rensburg, Senior Lecturer in the Human Molecular Biology Unit at the School of Biomedical Sciences, UFS, and principal researcher, says the study was conceptualised during 2020s COVID-19 pandemic, due to reports of excessive blood clots associated with both acute COVID-19 infection and some of the SARS-CoV2 vaccines. However, limited data existed in our region regarding the other underlying causes for blood clot formation, such as atherosclerotic plaque rupture. The data was collected during a couple of months in 2021. The data was collected out of more than 10,000 case files spanning 10 years. The study is still ongoing.

“Atherosclerosis remains a major risk factor for CVD, and thus, believed to be a good indicator of the CVD profile in a population, yet little is known on its prevalence in sub-Saharan African populations. We aimed to determine the prevalence of atherosclerosis in a diverse South African population as found in post-mortem investigations. A retrospective file audit was done on 10,240 forensic post-mortem reports done at a forensic pathology mortuary in South Africa, over 10 years,” writes Dr Janse van Rensburg in the Abstract of the research article. 

According to him, cardiovascular diseases are reportedly the No 1 cause of mortality worldwide. According to the latest report from Stats SA, diseases of the circulatory system account for nearly a fifth of all deaths in South Africa.
“CVD is a multifactorial disorder, however, the presence of atherosclerosis (an inflammatory condition of artery walls) is the most common disorder associated with CVD. In order to assist in the prevention of the formation and progression of atherosclerosis, one can manage factors that have been associated with a higher risk for atherosclerosis, such as the use of tobacco, hypertension, elevated cholesterol, obesity, HIV infection and diabetes,” says Dr Janse van Rensburg.

Reasons behind different population’s mortality rate

It has been proposed, says Dr Janse van Rensburg, that socioeconomic status is possibly one of the essential roleplayers in CVD aetiology. The socioeconomic inequality in South Africa is well known, with an economic inequality Gini coefficient of 0.63 (the highest in the world). One study reported that in the Free State province, in the non-agricultural sector, the average household income for a European-descent household is roughly 4.35-times higher than the average African-descent household income. 

“Therefore, it is postulated that wealthier people, in the South African context, historically people of European descent, have the means to afford and adopt lifestyles that contribute to the increased risk of lifestyle diseases such as obesity, hypercholesterolaemia and diabetes, which are associated with a higher risk to develop CVD.

“We postulate that CVD-related deaths are traditionally lower among South Africans of African descent compared to the other ethnic populations due to the historical socioeconomic discrepancy between people of African descent and other population groups in higher-income countries.”

The study also found that the prevalence of CVDs and the incidence of premature CVD-related deaths are steadily increasing in both rural and urban communities and across the socioeconomic spectrum. The theory of epidemiological transition says that in populations with improved living conditions and better access to healthcare, the proportion of deaths caused by infectious diseases will decrease, and the proportion of deaths due to more chronic “man-made” lifestyle-related diseases, such as CVD, will increase.

However, our population’s socioeconomic status is not the only driving force behind CVD. Therefore, we theorise there has been an upward trend in South Africa across all regions to improve the access to better food and better healthcare, consequently resulting in an increase in CVD-related morbidity and mortality statistics.

“For all population groups, males are more affected than females within their demographic group. This may also be possibly attributed to the socioeconomic status and access to the healthcare gender-gap differential in the country.”

Studies are vital in raising public awareness

Dr Janse van Rensburg says that studies such as this are vital in raising public awareness regarding disorders associated with the lifestyle choices people make. However, a multidisciplinary approach is needed to ultimately create a lasting impact. 

“We hope that our findings will assist in identifying specific groups with a possible increased risk for CVD, and that we will inspire more focused research to identify potential high-risk behaviours within these groups that may eventually result in the enhancement of public health policies and awareness campaigns in our region.

“Recently, another article has been accepted for publication regarding the prevalence of excessive blood clots (thrombosis) as the underlying cause of death in our study cohort, further contributing to our understanding of the origins and contributory factors of CVDs in our region.”

News Archive

Inaugural lecture: Prof Robert Bragg, Dept. of Microbial, Biochemical and Food Biotechnology
2006-05-17



Attending the inaugural lecture were in front from the left Prof Robert Bragg (lecturer at the Department of Microbial, Biochemical and Food Biotechnology) and Frederick Fourie (Rector and Vice-Chancellor).  At the back from the left were Prof James du Preez (Departmental Chairperson:  Department of Microbial, Biochemical and Food Biotechnology) and Prof Herman van Schalkwyk (Dean: Faculty of Natural and Agricultural Sciences). Photo: Stephen Collett
 

A summary of an inaugural lecture delivered by Prof Robert Bragg at the University of the Free State:

CONTROL OF INFECTIOUS AVIAN DISEASES – LESSONS FOR MAN?

Prof Robert R Bragg
Department of Microbial, Biochemical and Food Biotechnology
University of the Free State

“Many of the lessons learnt in disease control in poultry will have application on human medicine,” said Prof Robert Bragg, lecturer at the University of the Free State’s (UFS) Department of Microbial, Biochemical and Food Biotechnology during his inaugural lecture.

Prof Bragg said the development of vaccines remains the main stay of disease control in humans as well as in avian species.  Disease control can not rely on vaccination alone and other disease-control options must be examined.  

“With the increasing problems of antibiotic resistance, the use of disinfection and bio security are becoming more important,” he said.

“Avian influenza (AI) is an example of a disease which can spread from birds to humans.  Hopefully this virus will not develop human to human transmission,” said Prof Bragg.

According to Prof Bragg, South Africa is not on the migration route of water birds, which are the main transmitters of AI.  “This makes South Africa one of the countries less likely to get the disease,” he said.

If the AI virus does develop human to human transmission, it could make the 1918 flu pandemic pale into insignificance.  During the 1918 flu pandemic, the virus had a mortality rate of only 3%, yet more than 50 million people died.

Although the AI virus has not developed human-to-human transmission, all human cases have been related to direct contact with infected birds. The mortality rate in humans who have contracted this virus is 67%.

“Apart from the obvious fears for the human population, this virus is a very serious poultry pathogen and can cause 100% mortality in poultry populations.  Poultry meat and egg production is the staple protein source in most countries around the world. The virus is currently devastating the poultry industry world-wide,” said Prof Bragg.

Prof Bragg’s research activities on avian diseases started off with the investigation of diseases in poultry.  “The average life cycle of a broiler chicken is 42 days.  After this short time, they are slaughtered.  As a result of the short generation time in poultry, one can observe changes in microbial populations as a result of the use of vaccines, antibiotics and disinfectants,” said Prof Bragg.   

“Much of my research effort has been directed towards the control of infectious coryza in layers, which is caused by the bacterium Avibacterium paragallinarum.  This disease is a type of sinusitis in the layer chickens and can cause a drop in egg product of up to 40%,” said Prof Bragg.

The vaccines used around the world in an attempt to control this disease are all inactivated vaccines. One of the most important points is the selection of the correct strains of the bacterium to use in the vaccine.

Prof Bragg established that in South Africa, there are four different serovars of the bacterium and one of these, the serovar C-3 strain, was believed to be unique to Southern Africa. He also recently discovered this serovar for the first time in Israel, thus indicating that this serovar might have a wider distribution than originally believed.

Vaccines used in this country did not contain this serovar.  Prof Bragg established that the long term use of vaccines not containing the local South African strain resulted in a shift in the population distribution of the pathogen.

Prof Bragg’s research activities also include disease control in parrots and pigeons.   “One of the main research projects in my group is on the disease in parrots caused by the circovirus Beak and Feather Disease virus. This virus causes serious problems in the parrot breeding industry in this country. This virus is also threatening the highly endangered and endemic Cape Parrot,” said Prof Bragg.

Prof Bragg’s research group is currently working on the development of a DNA vaccine which will assist in the control of the disease, not only in the parrot breeding industry, but also to help the highly endangered Cape Parrot in its battle for survival.

“Not all of our research efforts are directed towards infectious coryza or the Beak and Feather Disease virus.  One of my Masters students is currently investigating the cell receptors involved in the binding of Newcastle Disease virus to cancerous cells and normal cells of humans. This work will also eventually lead to a possible treatment of cancer in humans and will assist with the development of a recombinant vaccine for Newcastle disease virus,” said Prof Bragg.

We are also currently investigating an “unknown” virus which causes disease problems in poultry in the Western Cape,” said Prof Bragg.
 
“Although disinfection has been extensively used in the poultry industry, it has only been done at the pre-placement stage. In other words, disinfectants are used before the birds are placed into the house. Once the birds are placed, all use of disinfectants stops,” said Prof Bragg.

“Disinfection and bio security can be seen as the ‘Cinderella’ of disease control in poultry.  This is also true for human medicine. One just has to look at the high numbers of people who die from hospital-acquired infections to realise that disinfection is not a concept which is really clear in human health care,” said Prof Bragg.

Much research has been done in the control of diseases through vaccination and through the use of antibiotics. “These pillars of disease control are, however, starting to crumble and more effort is needed on disinfection and bio security,” said Prof Bragg.

Prof Bragg has been working in close co-operation with a chemical manufacturing company in Stellenbosch to develop a unique disinfectant which his highly effective yet not toxic to the birds.

As a result of this unique product, he has developed the continual disinfection program for use in poultry. In this program the disinfectant is used throughout the production cycle of the birds. It is also used to ensure that there is excellent pre-placement disinfection.

“The program is extensively used for the control of infectious diseases in the parrot-breeding industry in South Africa and the product has been registered in 15 countries around the world with registration in the USA in the final process,” said Prof Bragg.

“Although the problem of plasmid mediated resistance to disinfectants is starting to rear its ugly head, this has allowed for the opening of a new research field which my group will hopefully exploit in the near future,” he said.

 

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