Tick-Borne Diseases Under the Mathematical Microscope

Research, using stochastic epidemic models, into the role of wildlife in the distribution of tick-borne pathogens provided the foundation for
Dr Milliward Maliyoni’s PhD in Applied Mathematics which he received from UKZN.

Tick-borne diseases have serious health and economic consequences, causing several diseases to humans, livestock, as well as domestic and wild animals worldwide.

Using stochastic epidemic models, Maliyoni explored the dynamics of tick-transmitted pathogens and a tick-borne disease, human monocytic ehrlichiosis, with respect to disease extinction and persistence. He was interested in establishing the impact of randomness inherent in host-tick interactions on tick-borne disease (TBD) dynamics, especially since the dynamics of all biological systems are influenced by stochastic forces which are often not considered in mathematical models of disease transmission dynamics.

‘These interactions are extremely important because they inform the interventions that are crucial in mitigating the impact of TBDs, providing more information about the ticks’ complex biology,’ said Maliyoni.

‘TBD outbreaks are on the rise around the world, posing a threat to public health and economies. Because the transmission cycle of TBDs are complex, involving vertebrate hosts and ticks that interact in constantly changing settings, they are difficult diseases to control. This makes understanding the complex interaction between ticks and their hosts important for developing and implementing prevention and control measures.’

Maliyoni’s work provided important insights into TBD dynamics and highlighted specific areas requiring attention for effective control efforts. Contrary to his initial opinion that eliminating tick populations would be the solution to preventing TBD, he found that tick hosts play an important role in functioning as reservoirs for the disease. He recommended, therefore, that intervention strategies aimed at mitigating or eliminating TBDs focus on the infected host population, rather than the infected ticks.

He found that controlling or prohibiting host movement between patches, particularly during a disease outbreak, increases the probability of disease extinction and that prevention and control can be aided by screening of infected hosts in protected wildlife reserves and farms before they migrate to other areas.

These findings will be beneficial to livestock or deer farmers, wildlife or game park managers, veterinary officials and more in their planning or development of intervention strategies to prevent, control or eliminate TBDs.

Maliyoni recommended that the application of stochastic epidemic models in TBD studies be applied to further research in this area. He also indicated that the findings and models formulated in his study could provide useful information about stochastic models and TBDs to researchers in mathematical biology, epidemiology, public health, biology, conservation biology, veterinary science, ecology and more.

He plans to continue with his research, and is now a lecturer in Mathematics at the University of Malawi. Born and schooled in Malawi, he completed his undergraduate studies at the country’s Mzuzu University and his Master’s in Mathematical Modelling at the University of Dar es Salaam in Tanzania.

The shift from his field of deterministic modelling to stochastic modelling for his PhD was a challenging one, but Maliyoni said the encouragement of his supervisor, Dr Faraimunashe Chirove, inspired him to work hard and achieve his PhD, while attendance at a workshop also helped him hone his skills.

During his studies, Maliyoni received second prize for his poster presentation at the Postgraduate Research and Innovation Symposium in 2016.

Maliyoni thanked God for guidance and protection during his studies, and also his supervisors Chirove, Professor Kesh Govinder and Professor Holly Gaff for their support. He acknowledged UKZN and the University of Malawi for financial assistance, and thanked his wife, Grace Maliyoni, for her invaluable support.

He also thanked his parents Halex and Annie Maliyoni, his siblings, in-laws, workmates and friends for their unconditional support.

Maliyoni encouraged current and prospective PhD hopefuls to work hard and apply focus, determination, endurance, independence and commitment to achieve their degrees.

Words: Christine Cuénod 

Photograph: Gugu Mqadi