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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

Open letter from Prof Jonathan Jansen to all UFS students

2014-02-22

Dear Students of the University of the Free State

In the past four years there has emerged a new consensus on the three campuses of the University of the Free State (UFS) about the things that divide us – such as racism, sexism and homophobia. Students and campus leaders have worked hard to develop this new consensus in residences and in the open spaces on campus. There can be no doubt that new bonds of friendship have developed across the markers of race, ethnicity, class, religion and sexual orientation. I bear witness to these new solidarities every day on the campus.

You chose a white student to head up the transformation portfolio on the SRC. You chose a black captain to head up the university’s first team in rugby. You chose a white “prime” as head of residence to lead a predominantly black men’s residence. You chose a South African woman of Indian descent as Rag Queen and last week, a black student from Cape Town as the men’s Rag winner—choices not possible and never made before in our campus history. Many of you have intimate friends who come from different social or cultural or religious backgrounds. You learn together, share rooms together, pray together and party together. In other words, in the day to day workings of this university campus, you have demonstrated to campus, city and country that we can overcome the lingering effects of racism and other maladies in this new generation. You have helped create a university community inclusive of people of diverse religions, abilities, class and sexual orientation.

I have said this repeatedly that from time to time this new consensus will be tested – when a minority of students, and they are a small and dwindling minority, still act as if these are the days of apartheid. And when that consensus is tested as it was this week, and as it will be tested in the future, only then we will be able to assess the strength and durability of our progress in creating a new South African campus culture of human togetherness based on respect, dignity and embrace.

The real test of our leadership, including student leadership, is how we respond when our transformation drive is threatened.

Let me say this: I have absolute faith in you, as students of this great university, to stand together in your condemnation of these vile acts of violence and to move together in your determination to maintain the momentum for the Human Project of the University of the Free State. We have come too far to allow a few criminals to derail what you have built together in recent years.

There will, no doubt, be unscrupulous people on all sides of the political spectrum wanting to milk this tragedy for their own narrow purposes. There will be false information, rumours and exaggerations by those who wish to inflame a bad situation to gain mileage for their agendas. That is inevitable in a country that is still so divided.

I ask you, through all of this, to keep perspective. Two or ten or even twenty students behaving badly do not represent 30,000 students; a minority of violent and hateful persons do not represent the ideals, ambitions and commitments of the majority. At the same time, let us be realistic – anyone who thinks you can drive transformation without resistance clearly does not understand the difficult process of change.

The events of the week remind us, however, that we still have a long road to walk in deepening social and academic transformation at our university. Yes, we have invested hundreds of hours in training and mentorship; we have created new structures – such as the Institute for Reconciliation and Social Justice – to capture the energy and imagination of students driving transformation; we have created many opportunities for students to study and travel on this and other continents to enable cross-cultural learning; we have established formal and informal opportunities to dialogue about difficult issues on and off campus between students and their leaders; and we crafted new curricula to enable teaching and learning on the big questions of our times.

But this is clearly not enough, and so I have decided on the following immediate next steps:

We will meet for several hours next week to think about how we can deepen the transformation of our university after this terrible incident.
We will arrange a University Assembly on the events of the past week so that we speak with one voice on human wrongs and to re-commit to human rights and we will continue with open forum discussions during the months to come.
We will review the entire spectrum of programmes, from orientation to residence life to the undergraduate curriculum, to determine how effective our interventions really are in reaching all students with respect to basic issues of human rights.
We will review our media and communications strategy to determine how far and deep our messages on human rights travel across all sectors of the university community. In this regard it is important that the campus be blanketed on a regular basis with our condemnation of human wrongs and our commitment to human rights.
We will commission the Institute for Reconciliation and Social Justice to review the events of the past week and make recommendations on how we can improve the campus environment so that all students are protected from harm inside residences, classrooms and in open spaces of the campus.
We will take the questions raised during this week into the academic community and to the general staff of the university so that all personnel also engage with our own roles and responsibilities with respect to campus transformations.
We undertake to make annual report-backs on transformation to all stakeholders in public forums so that students and staff and external communities can track the progress of the university on matters of human rights on campus.

I wish to thank my staff for acting firmly as soon as this tragic event came to our attention. We worked through the night to find and identify the perpetrators. We traced the two students and immediately handed them to the police. They were expelled. And throughout this process we offered counselling and support to the victim of this violent act.

The two former students were expelled and will now face justice in the criminal courts. It is hoped that in the course of time they will come to their senses and seek restoration and reconciliation with the student they so callously harmed. They are not part of the university community anymore.

That is the kind of university we are.

Jonathan D Jansen
Vice-Chancellor and Rector
University of the Free State
20 February 2014

Note: The use of the word ‘campus’ refers to all three campuses of the UFS, namely the Bloemfontein Campus, South Campus and Qwaqwa Campus.

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