Following a conversation with Walter Focke of UP’s Institute for Sustainable Malaria Control, Peter Middleton finds out more about Malaria and highlights a truly inspiring African success story.
Before talking to Walter Focke for the SAIChE IChemE member profile this month, my personal experience of malaria was limited to choosing the tablets to take when visiting the Kruger Park, while bemoaning the inconvenience and the cost – and, of course, taking measures to avoid mosquito bites; always a good idea.
Focke tells of a much scarier and personal experience, however, which nearly caused the death one of his relatives. This prompted him to join a community of committed scientists and engineers seeking sustain- able and longer-lasting ways of reducing the disease’s impact.
According to the November 2017 World Malaria Report, there were 216-million cases of malaria in 2016, up from 211-million cases in 2015. The estimated number of malaria deaths stands at 445 000, similar to the 2015 number (446 000). Children younger than 5-years old account for 72% of the fatalities, while 90% of cases and 91% of deaths occur in sub-Saharan Africa.
Although these numbers are horrific, deaths from the disease are falling. Since the year 2000, the numbers cited above represent a 22% decrease in malaria cases and 50% fewer deaths. But according to the WHO, the disease is 100% preventable and curable.
Malaria is caused by parasites that are transmitted to people through the bites of infected female mosquitoes. In terms of treatment, early and accurate diagnosis is essential to prevent it becoming deadly, with the best available treatment for the most dangerous Plasmodium falciparum malaria being artemisinin-based combination therapy (ACT). The artemisinin is fast acting and combining it with other classes of drugs reduces the likelihood of the parasite developing resistance.
Key outstanding problems with respect to treatment, however, include delivery and access to drugs at the point of need, and their cost. Hence the focus on reducing transmission and infections by seeking ways of preventing mosquitoes from biting people and surviving to infect other people.
Only female mosquitoes bite people and they do not feed on blood. They are looking for a ‘blood meal’ to nurture their eggs, which they lay in water, each species having its own preferred aquatic habitat. The rainy season in wet and warm climates, therefore, is the most dangerous.
Transmission is also more intense in places where the mosquito lifespan is longer; because this gives the parasites more time develop. The long lifespan and strong human-biting habit of African species is the main reason why nearly 90% of the world’s malaria cases are in Africa.
For people living in malaria-susceptible areas, partial immunity is developed over years of exposure, and while it never provides complete protection, it does reduce the risk that the disease will be severe. For this reason, most malaria deaths in Africa occur in young children, whereas in areas with less transmission and low immunity, all age groups are at equal risk.
The work described by UP professor Walter Focke in this issue of MechChem Africa is all about prevention and ‘vector control’, as key ways to reduce malaria transmission.
WHO recommends two basic forms of vector control: insecticide-treated mosquito nets and indoor residual spraying. It emphasises the need for long- lasting insecticidal nets (LLINs) provided free of charge to ensure equal access for all, along with behaviour change to ensure that all people at risk sleep under a properly maintained LLIN every night.
Indoor residual spraying (IRS) of insecticides, according the WHO, is also a powerful way to rapidly reduce malaria transmission; but only when at least 80% of the houses in targeted areas are sprayed. Currently available sprays can be effective for 3- to 6-months, depending on the insecticide formulation used and the type of surface on which it is sprayed.
In South Africa, Focke works with a team from the University of Pretoria’s Institute for Sustainable Malaria Control, along with some 50 students, to develop African solutions for this African scourge. In particular, his polymer expertise is being applied to bed nets and other fabrics to enable insecticides to be trapped and stored in the polymer chains for slow and effective release over a longer time period.
In addition, though, Homa Izada, a chemical engineering student at UP, has come up with a novel formulation for mosquito repellents and insecticides. Using a mixture of two carefully selected mosquito repellent substances, he has made a negative pseudo- azeotrope: a mixture that, on evaporation, produces a lower vapour pressure than either of the parent compounds. This reduces the release rate of the repellent, also giving it a longer life.
With the development of bed nets, anklets, bracelets, socks and wall linings from carefully crafted polymers, along with Izada’s novel repellent formulations, UP’s Institute for Sustainable Malaria Control is contributing to saving thousands of lives in Africa, which is a truly inspiring African success story.
