But it’s really just another evolutionary pressure, at least when followed by an exterminating medicine:
Cheap rapid tests for malaria have helped drive down the prevalence of the disease in many parts of Africa. But just 15 years or so after their introduction, “stealthy” malaria parasites have evolved that can no longer be detected by the standard rapid tests.
“This is a major threat to malaria control,” says Jane Cunningham at the World Health Organization Global Malaria Programme in Geneva.
In many African countries, only people whose rapid test results are positive get treated. But in Eritrea around 2016, health workers noticed that many children who appeared to be really sick with malaria were testing negative. When medics looked at blood samples under a microscope, they could see many of the children were indeed infected.
“It was a crisis situation,” says Cunningham. “They thought there was something wrong with the test.”
Instead, her team found that up to 80 per cent of the malaria parasites in the area have mutations that mean they no longer produce the two proteins – called pfhrp2 and pfhrp3 – detected by the rapid tests. [“Parasite evolution is making it harder to detect and treat malaria,” Michael Le Page, NewScientist (2 October 2021)]
A fascinating change, isn’t it? Although the operational characteristics suggest that this is not a case of the mutation surviving the medication, but rather that the medicating never occurs. I do not know enough about detection tests to guess if this means a carrier only carried the mutation, or if the mutation simply outnumbers the predecessor.
