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UFS PhD study focuses on improving life expectancy of HIV/Aids patients

11 December 2019 | Story Leonie Bolleurs

According to Global Statistics, there were approximately 37,9 million people across the globe with HIV/Aids in 2018. They also state that in 2018, an estimated 1,7 million individuals worldwide became newly infected with HIV.

In the city of Masvingo, Zimbabwe, Claris Shoko is a Statistics lecturer at the Great Zimbabwe University. In her PhD thesis at the University of the Free State (UFS) in the Department of Mathematical Statistics and Actuarial Sciences, she presented the argument that the inclusion of both the CD4 cell count and the viral-load counts in the monitoring and management of HIV+ patients on antiretroviral therapy (ART), is helping in reducing mortality rates, leading to improved life expectancy for HIV/Aids patients.

She received her doctoral degree at the December UFS Graduation Ceremonies, with her thesis: Continuous-time Markov modelling of the effects of treatment regimens on HIV/Aids immunology and virology.

CD4 cell count and viral-load count

Dr Shoko explains: “When the human immunodeficiency virus (HIV) enters the human body, the virus attacks the CD4 cells in their blood. This process damages CD4 cells, causing the number of white blood cells in the body to drop, making it difficult to fight infections.”

“Clinical markers such as CD4 cell count and viral-load count (number of HIV particles in a ml of blood) provide information about the progression of HIV/Aids in infected individuals. These markers fully define the immunology and the virology of HIV-infected individuals, thereby giving us a clear picture of how HIV/Aids evolve within an individual.”

Dr Shoko continues: “The development of highly active antiretroviral therapy (HAART) has helped substantially to reduce the death rate from HIV. HAART reduces viral load-count levels, blocking replication of HIV particles in the blood, resulting in an increase of CD4 cell counts and the life expectancy of individuals infected with HIV. This has made CD4 cell counts and viral-load counts the fundamental laboratory markers that are regularly used for patient management, in addition to predicting HIV/Aids disease progression or treatment outcomes.”

In the treatment of HIV/Aids, medical practitioners prescribe combination therapy to attack the virus at different stages of its life cycle, and medication to treat the opportunistic infections that may occur. “The introduction of combined antiretroviral therapy (cART) has led to the dramatic reduction in morbidity and mortality at both individual level and population level,” states Dr Shoko.

Once HIV-positive patients are put on cART, the effectiveness of treatment is monitored after the first three months and a further follow-up is done every six months thereafter. During the monitoring stages, CD4 cell count and viral load is measured. Patients are also screened for any tuberculosis (TB) co-infection and checked for any signs of drug resistance. These variables determine whether or not there is a need for treatment change.

She continues: “Previous studies on HIV modelling could not include both CD4 cell count and viral load in one model, because of the collinearity between the two variables. In this study, the principal component approach for the treatment of collinearity between variables is used. Both variables were then included in one model, resulting in a better prediction of mortality than when only one of the variables is used.”

“Viral-load monitoring helps in checking for any possibilities of virologic failure or viral rebound, which increases the rate of mortality if not managed properly. CD4 cell count then comes in to monitor the potential development of opportunistic infections such as TB. TB is extremely fatal, but once detected and treated, the survival of HIV/Aids patients is assured,” Dr Shoko explains.

Markov model

She applied the Markov model in her study. The model, named after the Russian mathematician Andrey Markov, represents a general category of stochastic processes, characterised by six basic attributes: states, stages, actions, rewards, transitions, and constraints.

According to Dr Shoko, Markov models assume that a patient is always in one of a finite number of discrete states, called Markov states. All events are modelled as transitions from one state to another. Each state is assigned a utility, and the contribution of this utility to the overall prognosis depends on the length of time spent in each state. For example, for a patient who is HIV positive, these states could be HIV+ (CD4 cell count above 200 cells/mm3), Aids (CD4 cell count below 200 cells/mm3) and Dead.

“Markov models are ideal for use in HIV/Aids studies, because they estimate the rate of transition between multiple-disease states while allowing for the possible reversibility of some states,” says Dr Shoko, quoting Hubbard and Zhou.

“Relatively fewer HIV modelling studies include a detailed description of the dynamics of HIV viral load count during stages of HIV disease progression. This could be due to the unavailability of data on viral load, particularly from low- and middle-income countries that have historically relied on monitoring CD4 cell counts for patients on ART because of higher costs of viral load-count testing,” Dr Shoko concludes

News Archive

UFS to investigate implementation of quality-monitoring system for SA food industry

2006-02-07

Some of the guests who attended the workshop were from the left Prof James du Preez (Chairperson: Department of Biotechnology at the UFS); Prof Lodewyk Kock (Head: South African Fryer Oil Initiative (SAFOI) at the UFS)); Mrs Ina Wilken (Chairperson: South African National Consumer Union (SANCU)); Prof Herman van Schalkwyk (Dean: Faculty of Natural and Agricultural Sciences at the UFS) and Mr Joe Hanekom (Managing Director of Agri Inspec).
Photo: Stephen Collet

UFS to investigate implementation of quality-monitoring system for SA food industry

The University of the Free State (UFS) will be investigating the implementation of a quality-monitoring service for the South African food industry.

This was decided during a workshop to discuss the external quality monitoring in the edible oil industry of South Africa, which was recently held at the UFS.

Major role players in the fast-food sector like Nando's, Spur, Captain
Dorego's, King Pie Holdings, Black Steer Holdings, etc and various oil
distributors like Felda Bridge Africa, Refill Oils, PSS Oils and Ilanga Oils attended
the workshop. Also present was Mrs Ina Wilken, Chairperson of the South African National Consumer Union (SANCU) and key-note speaker of this workshop. She represented the consumer.

These role players all pledged their support to the implementation of this quality- monitoring system for the whole food industry.

The decision to implement this system follows the various malpractices reported in the press and on TV concerning food adulteration (eg the recent Sudan Red Scare), misrepresentation (eg olive oil scandal exposed in 2001) and the misuse of edible frying oils by the fast-food sector.

“One of the basic rights of consumers is the right to safe food. Consumers must be protected against foods and food production processes which are hazardous to their health. Sufficient guarantee of the safety of all food products and food production processes should be implemented. It does not help to have adequate food standards and legislation and there is no manpower to do the necessary investigation or monitoring,” said Mrs Wilken.

The South African Fryer Oil Initiative (SAFOI), under the auspices of the UFS Department of Microbial, Biochemical and Food Biotechnology, currently monitors edible oils in the food industry and makes a seal of quality available to food distributors.

“Last week’s decision to implement the quality-monitoring system implies that we will now be involving also other departments in the UFS Faculty of Natural and Agricultural Sciences who are involved in various aspects of the food chain in an endeavor to implement this quality monitoring system,” said Prof Herman van Schalkwyk, Dean: Faculty of Natural and Agricultural Sciences at the UFS and one of the main speakers at the workshop.

Prof van Schalkwyk said that the main aim of such a system will be to improve the competitiveness of the South African food industry. “It is clear that the role players attending the workshop are serious about consumer service and that they agree that fraudulent practice should be monitored and corrected as far as possible. Although some of the food outlets have the capacity to monitor the quality of their food, it may not seem to the consumer that this is an objective process. The proposed external monitoring system would counteract this perception amongst consumers,” said Prof van Schalkwyk.

The workshop was also attended by representatives from SAFOI and Agri Inspec, a forensic investigation company collaborating with inter-state and government structures to combat fraud and international trade irregularities.

Agri Inspec has been working closely with SAFOI for a number of years to test the content of edible oils and fats. “Extensive monitoring and control actions have been executed in the edible oil industry during the past four years to ensure that the content and labeling of oil products are correct. Four years ago almost 90% of the samples taken indicated that the content differed from what is indicated on the label. This has changed and the test results currently show that 90% of the products tested are in order. However, to maintain this quality standard, it is necessary that quality monitoring and educational campaigns are continuously performed,” said Mr Joe Hanekom, Managing Director of Agri Inspec.

“The seal of quality presented by SAFOI should also be extended to include all the smaller oil containers used by households,” Mrs Wilken said.

The SAFOI seal of quality is currently displayed mainly on some oil brands packed in bigger 20 liter containers, which include sunflower oil, cottonseed oil, palm oil etc which are used by restaurants and fast food outlets. “Any oil type is eligible to display the seal when meeting certain standards of authenticity. In order to display the seal, the distributor must send a sample of each oil batch they receive from the manufacturer to SAFOI for testing for authenticity, ie that the container’s content matches the oil type described on the label. This is again double checked by Agri Inspec, which also draws samples countrywide from these certified brands from the end-user (restaurant or fast food outlets). If in breach, the seal must be removed from the faulty containers,” said Prof Lodewyk Kock, Head of SAFOI.

“It should however be taken into account that oils without a seal of quality from the UFS can still be of high quality and authentic. Other external laboratories equipped to perform effective authenticity tests may also be used in this respect,” said Prof Kock.

“It is also important to realise that any oil type of quality such as sunflower oil, cottonseed oil, palm oil etc can be used with great success in well controlled frying processes,” he said.

Further discussions will also be held with the Department of Health, the SA National Consumer Union and Agri Inspec to determine priority areas and to develop the most effective low-cost monitoring system.

More information on the UFS oil seal of quality and oil use can be obtained at www.uovs.ac.za/myoilguide

Media release
Issued by: Lacea Loader
Media Representative
Tel: (051) 401-2584
Cell: 083 645 2454
E-mail: loaderl.stg@mail.uovs.ac.za
6 February 2006

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