Improving methodologies for the detection and identification of malaria parasites in human blood

The life cycle of Plasmodium malaria parasites was revealed more than 100 years ago but distinguishing parasite species accurately has become an important part of diagnosis as different drugs are used to treat different species.

In 1999 around a fifth of malaria cases in Borneo had been identified as Plasmodium malariae but a test failed to identify this parasite. A team of researchers from the School, in conjunction with Malaysian partners, decided to test this and in 2004 they found that nearly 60% of 208 blood samples tested positive for the simian parasite Plasmodium knowlesi.

Nearly 2,000 cases of knowlesi malaria were correctly identified and treated in Borneo between 2004 and 2012 because of these findings. And thanks to the School’s research, P. knowlesi became the fifth form of malaria known to infect humans. 

Difficulties in identifying P. ovale infection led to the surprising finding that this type of malaria is caused by two related but distinct species. Further research showed that these species occur across Africa, much of Asia and the South West Pacific. These findings have influenced understanding of malaria epidemiology in countries such as Angola, Ethiopia, Uganda and Bangladesh, and it is now generally accepted that six forms of parasite cause human malaria.

In 2007 the School began to trial a new piece of kit for malaria detection, finding that the loop-mediated isothermal amplification kit’s diagnostic accuracy was comparable to the standard polymerase chain reaction test. The tests are less complex than the standard test and can be performed by non-specialist health workers, do not need refrigeration and take less than an hour, and are currently being deployed in The Philippines.

The tests attracted widespread media coverage leading to inquiries from countries including Malaysia, Sierra Leone, India, Tanzania and Kenya.

Studies of antimalarial drug efficacy on the Thai-Cambodian border have shown that data from the first 72 hours following treatment provide a crucial indicator of drug failure. These findings came from six-hourly blood sampling, a technique not suitable in Africa, where the majority of cases occur in children. Sutherland and researcher Khalid Beshir developed a simple quantitative polymerase chain reaction test, which worked well in a 2009 trial in Kenya.

The School joined up with a consortium of West African and European researchers to deploy the test in a large-scale study of antimalarial drug efficacy in children in Guinea, Mali and Burkina Faso, again with excellent results.

Researchers worked with NHS Blood and Transplant to develop a method of detecting tiny amounts of parasite DNA in blood donations. The increased sensitivity of the test means that fewer units of blood will be discarded.