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05 September 2022 | Story Andrè Damons | Photo Andrè Damons
Prof Abdon Atangana
Prof Abdon Atangana, Professor of Applied Mathematics in the Institute for Groundwater Studies (IGS) and a highly cited mathematician for the years 2019-2021, says existing mathematical models are used to first fit collected data and then predict future events. It is for this reason he introduced a new concept that can be used to test whether the spread will have one or several waves.

With a new outbreak of the Ebola Virus Disease (EVD) reported this year in Democratic Republic of the Congo (DRC) – the 14th EVD outbreak in the country – researchers at the University of the Free State (UFS) introduced a new concept that can be used to test whether the spread will have one or several waves. They believe the focus should be to identify the source or the hosts of this virus for it to be a complete eradication. 

According to the Centers for Disease Control and Prevention (CDC), the Ministry of Health in the Democratic Republic of the Congo (DRC) declared an outbreak of Ebola in Mbandaka health zone, Equateur Province on April 23, 2022. EVD, formerly known as Ebola haemorrhagic fever, is a severe, often fatal illness affecting humans and other primates. The virus is transmitted to people from wild animals (such as fruit bats, porcupines and non-human primates) and then spreads in the human population through direct contact with the blood, secretions, organs or other bodily fluids of infected people, and with surfaces and materials (e.g. bedding, clothing) contaminated with these fluids, according to the World Health Organisation (WHO).
 
Prof Abdon Atangana, Professor of Applied Mathematics in the Institute for Groundwater Studies (IGS), says existing mathematical models are used to first fit collected data and then predict future events. Predictions help lawmakers to take decisions that will help protect their citizens and their environments. The outbreaks of COVID-19 and other infectious diseases have exposed the weakness of these models as they failed to predict the number of waves and in several instances; they failed to predict accurately day-to-day new infections, daily deaths and recoveries.

Solving the challenges of the current models

In the case of COVID-19 in South Africa, it is predicted that the country had far more infections than what was recorded, which is due to challenges faced by the medical facilities, poverty, inequality, and other factors. With Ebola in the DRC, data recorded are not far from reality due to the nature of the virus and its symptoms. However, the predictions show although some measures have been put in place in DRC and other places where the Ebola virus spread, they will still face some challenges in the future, as the virus will continue to spread but may have less impact. 

“To solve the challenges with the current models, we suggested a new methodology. We suggested that each class should be divided into two subclasses (Detected and undetected) and we also suggested that rates of infection, recovery, death and vaccination classes should be a function of time not constant as suggested previously. These rates are obtained from what we called daily indicator functions. For example, an infection rate should be obtained from recorded data with the addition of an uncertain function that represents non-recorded data (Here more work is still to be done to get a better approximation).

“I introduced a new concept called strength number that can be used to test whether the spread will have one or several waves. The strength number is an accelerative force that helps to provide speed changes, thus if this number is less than zero we have deceleration, meaning there will be a decline in the number of infections. If the number is positive, we have acceleration, meaning we will have an increase in numbers. If the number is zero, the current situation will remain the same,” according to Prof Atangana. 

To provide better prediction, he continues, reliable data are first fitted with the suggested mathematical model. This helps them to know if their mathematical model is replicating the dynamic process of the spread. The next step is to predict future events, to do this, we create three sub-daily indicator functions (minimum, actual, and maximum). These will lead to three systems, the first system represents the worst-case scenario, the second is the actual scenario, and the last is a best-case scenario.

Virus will continue to spread but with less impact

Using this method, Prof Atangana, a highly cited mathematician for the years 2019-2021, says he and Dr Seda Igret Araz, postdoctoral student, were able to predict that, although some measures have been put in place in DRC and other places where the Ebola virus spreads, they will still face some challenges in the future as the virus will continue to spread but may have less impact. 

To properly achieve the conversion from observed facts into mathematical formulations and to address these limitations, he had to ask fundamental questions such as what is the rate of infection, what is the strength of the infection, what are the crossover patterns presented by the spread, how can day-to-day new infected numbers be predicted and what differential operator should be used to model a dynamic process followed by the spread?

This approach was tested for several infectious diseases where we present the case of Ebola in Congo and Covid-19 in South Africa.  

News Archive

Studies to reveal correlation between terrain, energy use, and giraffe locomotion
2016-11-18



More than half of giraffes in captivity in Europe are afflicted by lameness. This high prevalence represents an important welfare issue, similar to other large zoo animals.

According to Dr Chris Basu, a veterinarian at the Royal Veterinary College in the UK, giraffes in captivity are often afflicted by overgrown hooves, laminitis and joint problems. Diagnosis and treatment is limited by our understanding of anatomy and function, more specifically the locomotion of these animals. Although the giraffe is such a well-known and iconic animal, relatively little has been studied about their locomotor behaviour.

Dr Basu recently visited South Africa to do fieldwork on the locomotion of giraffes as part of his PhD studies under the mentorship of world-renowned Professor of Evolutionary Biomechanics, Prof John Hutchinson. This project is a joint venture between Dr Basu and Dr Francois Deacon, researcher in the Department of Animal, Wildlife, and Grassland Sciences at the UFS. Dr Deacon is a specialist in giraffe habitat-related research. 

Together Prof Hutchinson and Drs Deacon and Basu form a research group, working on studies about giraffe locomotion.

Wild giraffe population decrease by 40% in past decade

“Locomotion is one of the most common animal behaviours and comes with a significant daily energetic cost. Studying locomotion of wild animals aids us in making estimates of this energetic cost. Such estimates are useful in understanding how giraffes fit into ecosystems. Future conservation efforts will be influenced by knowledge of the energy demands in giraffes.

“Understanding aspects of giraffe locomotion also helps us to understand the relationships between anatomy, function and evolution. This is relevant to our basic understanding of the natural world, as well as to conservation and veterinary issues,” said Dr Deacon.

Locomotion study brings strategy for specialist foot care

On face value it seems as if foot disease pathologies are more common in zoo giraffes than in wild giraffes. “However, we need a good sample of data from both populations to prove this assumption,” said Dr Basu. 

This phenomenon is not well understood at the moment, but it’s thought that diet, substrate (e.g. concrete, straw, sand and grass) and genetics play a part in foot disease in giraffes. “Understanding how the feet are mechanically loaded during common activities (standing, walking, running) gives our research group ideas of where the highest strains occur, and later how these can be reduced through corrective foot trimming,” said Dr Basu.

Through the studies on giraffe locomotion, the research group plans to devise strategies for corrective foot trimming. At the moment, foot trimming is done with the best evidence available, which is extrapolation from closely related animals such as cattle. “But we know that giraffes’ specialist anatomy will likely demand specialist foot care,” Dr Basu said.

Studying giraffes in smaller versus larger spaces

The research group has begun to study the biomechanics of giraffe walking by looking at the kinematics (the movement) and the kinetics (the forces involved in movement) during walking strides. For this he studied adult giraffes at three zoological parks in the UK. 

However, due to the close proximity of fencing and buildings, it is not practical to study fast speeds in a zoo setting. 

A setting such as the Willem Pretorius Nature Reserve, near Ventersburg in the Free State, Kwaggafontein Nature Reserve, near Colesberg in the Karoo, and the Woodland Hills Wildlife Estate in Bloemfontein are all ideal for studying crucial aspects such as “faster than walking” speeds and gaits to measure key parameters (such as stride length, step frequency and stride duration). These studies are important to understand how giraffe form and function are adapted to their full range of locomotor behaviours. It also helps to comprehend the limits on athletic capacity in giraffes and how these compare to other animals. 

Drones open up unique opportunities for studying giraffes

The increasing availability of unmanned aerial vehicles (UAVs)/drones opens up unique opportunities for studying locomotion in animals like giraffes. Cameras mounted onto remotely controlled UAVs are a straightforward way to obtain high-quality video footage of giraffes while they run at different speeds.

“Using two UAVs, we have collected high definition slow motion video footage of galloping giraffes from three locations in the Free State. We have also collected detailed information about the terrain that the giraffes walked and ran across. From this we have created 3D maps of the ground. These maps will be used to examine the preferred terrain types for giraffes, and to see how different terrains affect their locomotion and energy use,” said Dr Deacon.

“The raw data (videos) will be digitised to obtain the stride parameters and limb angles of the animals. Later this will be combined with anatomical data and an estimation of limb forces to estimate the power output of the limbs and how that changes between different terrains,” said Dr Basu.


Related articles:

23 August 2016: Research on locomotion of giraffes valuable for conservation of this species
9 March 2016:Giraffe research broadcast on National Geographic channel
18 Sept 2015 Researchers reach out across continents in giraffe research
29 May 2015: Researchers international leaders in satellite tracking in the wildlife environment

 

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