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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

Professor launches his book, opposition parties attend

2011-03-22

Prof. Hussein Solomon
Photo: Stephen Collett

“We are good in opposing people, but we’re less good in opposing ideas.” This was how Prof. Jonathan Jansen, Vice-Chancellor and Rector of the University of the Free State (UFS) introduced the book launch of Against all Odds: Opposition Politics in Southern Africa.

The event was hosted in collaboration with the publisher under the title: Are opposition parties in South Africa in a crisis? This formed part of a series of dialogue sessions, organised by the Centre for Africa Studies, in the run up to the local elections.

Amongst those interested who attended the evening in the Senate Hall of the CR Swart Building on the Main Campus were various politicians, students, staff en a panel consisting of academics and the respective provincial representatives of the ANC and DA.

Dr Mcebisi Ndletyana from the Human Sciences Research Council (HSRC), acted as arbiter.

Proff. Hussein Solomon, author of Against all Odds: Opposition Politics in Southern Africa, also lecturer at the UFS, as well as Dirk Kotzé, Head of the Department of Political Science at Unisa, delivered enriching lectures on the stance and positioning of opposition parties.

Prof. Hussein, who spoke first, circumscribed the context of the political climate in the country, based on his book. “The problem that political science encounters is that everybody becomes experts on the internet, while they have no experience of what is happening in South Africa.” He said that when political parties in the country are under discussion, voters often allow myths and/or stereotyping to influence their concept of it. ‘’If there are no opposition parties, there is no democracy and people are deprived of their vote.”

Prof. Kotzé stated in his speech that it was not only opposition parties who had to make the government watch its step, but also the status that the country acquired, amongst others, from its connections, i.e. collaborative agreements such as BRICSA and the country’s inclusion in the G20. He left the audience with a question about how they were going to become involved in politics, and with his rhetoric question referred to options like social networks and movements.

Mr Sibongile Besani, the ANC'S secretary in the Free State, said the DA grew due to it’s swallowing of other parties; something he claims is taking the country backwards. He also described the use of personalities by opposition parties as means of association a weakness. He added that voters will continue voting for the ANC because they can associate themselves with the party’s vision.

In contrast, Mr Roy Jankielsohn, provincial leader of the DA, said voters and parties unite under their core vision for the country as like in the case of the ANC during the liberation struggles.

During the question-and-answer session, which followed after Mr Jankielson’s speech, Prof. Kwandiwe Kondlo, upon completion and summary of the discussions, stated firmly that the opposition parties are in a crisis. “The start of the solution is to recognise the problem. That is why our democracy finds itself in the state in which it is; because the opposition does not fulfil the role that they are supposed to fulfil.“ Prof. Kondlo is the head of the Centre of Africa Studies at the UFS.

He concluded by stating that the economic basis in the country was not transformed. “We cannot say that people determine their futures if they posses nothing. Opposition parties must start to communicate at this level in order to table something new. Our democracy must become more inclusive at political and material level.”

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