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11 December 2019 | Story Leonie Bolleurs
Aids read more

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 establishes a Postgraduate office
2007-07-18

The University of the Free State (UFS) will establish a postgraduate office that will serve as a one-stop service for the co-ordination of academic support services for postgraduate students.

According to the Director: Research Development at the UFS, Prof Frans Swanepoel, the primary purpose of the Postgraduate Office is to provide co-ordination and support services for postgraduate students and postdoctoral fellows, as well as academic staff across the University.

“Guided by values such as intellectual inquiry, innovation, collegiality, integrity and efficiency, the Postgraduate Office will seek to foster a challenging, inclusive and supportive environment for postgraduate teaching, learning, research and scholarship; and will strive to engage students in the vibrant life of a research university”, Prof Swanepoel said.

All sectors of the University, namely students, faculties and staff, stand to benefit from the establishment of this office. Amongst other benefits for these sectors, postgraduate students and postdoctoral research fellows will have their interests promoted in synergy with faculty and departmental facilities. On the other hand, the office will provide a critical resource to the faculties in the form of a single database of postgraduate students, postgraduate topics, supervisors and funding opportunities. Furthermore, it will serve as a useful resource and base for training and information for younger and less experienced staff members.

The establishment of this office will be undertaken in two phases. The first phase will focus on the most critical areas that will make an immediate impact and the second phase on those areas that are not as urgent.

Areas that will be prioritised include the appointment of a manager and co-ordination of stakeholders, the provision of information and communication, useful resources for the UFS, policy administration and monitoring, postgraduate supervisors’ facilitation, recruitment activities, advice and referral, and postgraduate scholarship and bursary management.

The less urgent components of the office will be the development and implementation of academic and professional support programmes, the formation of a research information commons to create an integrated learning environment for postgraduate students, and the development of a postgraduate association or a postgraduate students’ liaison committee to provide a recognised channel of communication between postgraduate students and the University authorities.

The Postgraduate Office will form a vital component of the Directorate Research Development (DRD) at the UFS because of its experience and a noteworthy track record with regard to a facilitative and co-ordinating role that would be essential for the office.

“Establishing the Postgraduate Office as part of the Directorate would give the Centre the necessary links to the research-related issues that are important to most of the postgraduate students at the UFS. Of essential importance will be the linkages with the full spectrum of Strategic Clusters”, Prof Swanepoel explained.

“An important component of the Postgraduate Office will be related to international students and international opportunities for UFS postgraduate students. As the Office for Internationalisation has similarly been placed within the Directorate, the work of the Postgraduate Office will be facilitated by similar placement within the same Directorate”, he concluded.

Media release
Issued by: Mangaliso Radebe
Assistant Director: Media Liaison
Tel: 051 401 2828
Cell: 078 460 3320
E-mail: radebemt.stg@mail.ufs.ac.za  
18 July 2007
 

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