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Calculating malaria

Using mathematical biology to help control infectious diseases


By Susan Flanagan

Can a Memorial University mathematical model predict and help control the spread of malaria in Africa?

Dr. Xiunan Wang, who uses mathematical models to study biological problems, thinks so.

From left are Drs. Xiaoqiang Zhao and Xiunan Wang.
From left are Drs. Xiaoqiang Zhao and Xiunan Wang.
Photo: Mike Ritter

Author of four papers on vector-borne infectious diseases (those not transmitted directly from person to person, like malaria and Lyme disease), Dr. Wang proposes that mathematical modelling can provide suggestions for controlling disease.

“To date there is no effective vaccine for malaria that can be widely used,” said Dr. Wang, who came to Memorial in 2014 on the recommendation of her PhD supervisor, Dr. Xiaoqiang Zhao, a Memorial University research professor in the Department of Mathematics and Statistics, Faculty of Science, who acted as defence chair on her master’s thesis.

“Professor Zhao is a great mathematician with broad interests and valuable experience in dynamical systems and mathematical biology,” said Dr. Wang. “His enthusiasm in research and teaching has always motivated me. He has provided me with encouragement and advice, not only in my studies, but also in daily life. I am very lucky.”

Preventing the spread

Dr. Zhao, whose research is funded by the Natural Sciences and Research Council of Canada (NSERC), is an expert in dynamical systems and mathematical biology.

He has recently developed a new theory for periodic and time-delayed compartmental model systems. It is this theory which Dr. Wang uses in her research to help prevent the spread of malaria.

“Malaria to them is like flu to us.” — Dr. Xiunan Wang

“We can use numerical simulations to help control malaria transmission in sub-Saharan African countries like Mozambique and Nigeria,” said Dr. Wang, admitting that one of the greatest challenges is getting the local population on board.

“Malaria to them is like flu to us,” she said. “They don’t care a lot about it and this makes it difficult to eliminate. Malaria used to be in Europe, but it is now eradicated. (In certain areas of Africa) bed nets are distributed to keep people safe from mosquito bites, but the people are so poor, they use the nets for fishing.”

Monthly means

By using the monthly mean temperatures in affected areas, Drs. Wang and Zhao estimated the mosquito biting rate, death rate and the basic reproduction ratio. This in turn allowed them to predict the times when area residents have the greatest chance of becoming infected.

In a nutshell, the team has proven that if people in malaria-prone areas can be convinced to use bed nets when the mosquitoes are biting, then the chances of eradicating malaria in those areas are much greater.

“Through mathematical methods, we can solve some problems biology cannot explain.” — Dr. Xiunan Wang

“If over 75 per cent of humans in Port Harcourt, Nigeria, use bed nets, malaria may be eliminated from this area,” said Dr. Wang, who completed her PhD thesis defence in April and will go to the University of Western Ontario in September to work as a post-doctoral research associate.

“For some branches of science, results can be obtained from repeated experiments in labs. But for infectious diseases, we can develop models to explain and predict disease transmission and provide practical suggestions for the control of the disease. Through mathematical methods, we can solve some problems biology cannot explain.”

This story first appeared in the Aug. 21, 2017 edition of The Telegram as part of a regular summer series on research at Memorial University.

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