MechChem Africa May 2018

Peter Middleton Malaria: African solutions to an African scourge B efore talking toWalter Focke for the SAIChE IChemE member profile this month, my personal experience of malaria was limited to choosing the tablets to takewhen visiting

main reason why nearly 90% of the world’s malaria cases are in Africa. For people living inmalaria-susceptible areas, par- tial immunity is developed over years of exposure, and while it never provides complete protection, it does reduce the risk that the diseasewill 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. Thework described by UP professorWalter Focke in this issue of MechChemAfrica is all about prevention and ‘vector control’, as key ways to reduce malaria transmission. WHO recommends two basic forms of vector control: insecticide-treatedmosquito nets and indoor residual spraying. It emphasises the need for long- lasting insecticidal nets (LLINs) provided freeof 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, ac- cording 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 slowand effective release over a longer time period. In addition, though, Homa Izada, a chemical en- gineering 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 hasmade a negative pseudo- azeotrope: amixture that, on evaporation, produces a lower vapour pressure than either of the parent com- pounds. This reduces the release rate of the repellent, also giving it a longer life. With the development of bed nets, anklets, brace- lets, socks and wall linings from carefully crafted polymers, along with Izada’s novel repellent formula- tions, UP’s Institute for Sustainable Malaria Control is contributing to saving thousands of lives in Africa, which is a truly inspiring African success story. q

the Kruger Park, while bemoaning the inconvenience and the cost – and, of course, takingmeasures to avoid mosquito bites; always a good idea. Focke tells of a much scarier and personal experi- ence, however, which nearly caused the death one of his relatives. This prompted him to join a community of committed scientists andengineers 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 from211-million cases in2015. The estimat- ednumber ofmalariadeaths stands at 445000, similar to the 2015number (446000). Children younger than 5-years oldaccount for 72%of the fatalities, while90% ofcasesand91%ofdeathsoccurinsub-SaharanAfrica. Although these numbers are horrific, deaths from the disease are falling. Since the year 2000, the num- bers 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. Malariaiscausedbyparasitesthataretransmittedto peoplethroughthebitesofinfectedfemalemosquitoes. In terms of treatment, early and accurate diagnosis is essential to prevent it becoming deadly, with the best availabletreatmentforthemostdangerous Plasmodium falciparum malaria being artemisinin-based combina- tion 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 treat- ment, 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 preventingmosquitoes frombiting 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 themosquito lifespan is longer; because this gives the parasites more time develop. The long lifespan and strong human-biting habit of African species is the

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