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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

Media: ANC can learn a lesson from Moshoeshoe
2006-05-20


27/05/2006 20:32 - (SA) 
ANC can learn a lesson from Moshoeshoe
ON 2004, the University of the Free State turned 100 years old. As part of its centenary celebrations, the idea of the Moshoeshoe Memorial Lecture was mooted as part of another idea: to promote the study of the meaning of Moshoeshoe.

This lecture comes at a critical point in South Africa's still-new democracy. There are indications that the value of public engagement that Moshoeshoe prized highly through his lipitso [community gatherings], and now also a prized feature in our democracy, may be under serious threat. It is for this reason that I would like to dedicate this lecture to all those in our country and elsewhere who daily or weekly, or however frequently, have had the courage to express their considered opinions on pressing matters facing our society. They may be columnists, editors, commentators, artists of all kinds, academics and writers of letters to the editor, non-violent protesters with their placards and cartoonists who put a mirror in front of our eyes.

There is a remarkable story of how Moshoeshoe dealt with Mzilikazi, the aggressor who attacked Thaba Bosiu and failed. So when Mzilikazi retreated from Thaba Bosiu with a bruised ego after failing to take over the mountain, Moshoeshoe, in an unexpected turn of events, sent him cattle to return home bruised but grateful for the generosity of a victorious target of his aggression. At least he would not starve along the way. It was a devastating act of magnanimity which signalled a phenomenal role change.

"If only you had asked," Moshoeshoe seemed to be saying, "I could have given you some cattle. Have them anyway."

It was impossible for Mzilikazi not to have felt ashamed. At the same time, he could still present himself to his people as one who was so feared that even in defeat he was given cattle. At any rate, he never returned.

I look at our situation in South Africa and find that the wisdom of Moshoeshoe's method produced one of the defining moments that led to South Africa's momentous transition to democracy. Part of Nelson Mandela's legacy is precisely this: what I have called counter-intuitive leadership and the immense possibilities it offers for re-imagining whole societies.

A number of events in the past 12 months have made me wonder whether we are faced with a new situation that may have arisen. An increasing number of highly intelligent, sensitive and highly committed South Africans across the class, racial and cultural spectrum confess to feeling uncertain and vulnerable as never before since 1994. When indomitable optimists confess to having a sense of things unhinging, the misery of anxiety spreads. It must have something to do with an accumulation of events that convey the sense of impending implosion. It is the sense that events are spiralling out of control and no one among the leadership of the country seems to have a handle on things.

I should mention the one event that has dominated the national scene continuously for many months now. It is, of course, the trying events around the recent trial and acquittal of Jacob Zuma. The aftermath continues to dominate the news and public discourse. What, really, have we learnt or are learning from it all? It is probably too early to tell. Yet the drama seems far from over, promising to keep us all without relief, and in a state of anguish. It seems poised to reveal more faultlines in our national life than answers and solutions.

We need a mechanism that will affirm the different positions of the contestants validating their honesty in a way that will give the public confidence that real solutions are possible. It is this kind of openness, which never comes easily, that leads to breakthrough solutions, of the kind Moshoeshoe's wisdom symbolises.

Who will take this courageous step? What is clear is that a complex democracy like South Africa's cannot survive a single authority. Only multiple authorities within a constitutional framework have a real chance. I want to press this matter further.

Could it be that part of the problem is that we are unable to deal with the notion of "opposition". We are horrified that any of us could become "the opposition". In reality, it is time we began to anticipate the arrival of a moment when there was no longer a single [overwhelmingly] dominant political force as is currently the case. Such is the course of change. The measure of the maturity of the current political environment will be in how it can create conditions that anticipate that moment rather than ones that seek to prevent it. This is the formidable challenge of a popular post-apartheid political movement.

Can it conceptually anticipate a future when it is no longer overwhelmingly in control, in the form in which it currently is and resist, counter-intuitively, the temptation to prevent such an eventuality? Successfully resisting such an option would enable its current vision and its ultimate legacy to our country to manifest itself in different articulations of itself, which then contend for social influence.

In this way, the vision never really dies, it simply evolves into higher, more complex forms of itself. If the resulting versions are what is called "the opposition" that should not be such a bad thing - unless we want to invent another name for it. The image of flying ants going off to start other similar settlements is not so inappropriate.

I do not wish to suggest that the nuptial flights of the alliance partners are about to occur: only that it is a mark of leadership foresight to anticipate them conceptually. Any political movement that has visions of itself as a perpetual entity should look at the compelling evidence of history. Few have survived those defining moments when they should have been more elastic, and that because they were not, did not live to see the next day.

I believe we may have reached a moment not fundamentally different from the sobering, yet uplifting and vision-making, nation-building realities that led to Kempton Park in the early 1990s. The difference between then and now is that the black majority is not facing white compatriots across the negotiating table. Rather, it is facing itself: perhaps really for the first time since 1994. It is not a time for repeating old platitudes. Could we apply to ourselves the same degree of inventiveness and rigorous negotiation we displayed up to the adoption or our Constitution?

Morena Moshoeshoe faced similarly formative challenges. He seems to have been a great listener. No problem was too insignificant that it could not be addressed. He seems to have networked actively across the spectrum of society. He seems to have kept a close eye on the world beyond Lesotho, forming strong friendships and alliances, weighing his options constantly. He seems to have had patience and forbearance. He had tons of data before him before he could propose the unexpected. He tells us across the years that moments of renewal demand no less.

  • This is an editied version of the inaugural Moshoeshoe Memorial Lecture presented by Univeristy of Cape Town vice-chancellor Professor Ndebele at the University of the Free State on Thursday. Perspectives on Leadership Challenges In South Africa

 

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