Access to an accurate and timely diagnosis is critical to preventing a malaria infection from progressing to severe illness and death. WHO recommends prompt malaria diagnosis either through microscopy or rapid diagnostic tests (RDTs) for all patients with suspected malaria. The hundreds of millions of RDTs sold each year are designed to detect a specific protein in a person’s blood. Parasites that have mutated to no longer express that protein can evade detection by RDTs. Such mutated parasites have now been reported in more than 35 countries – mainly in Africa and South America – and they are complicating malaria diagnosis and treatment. This video describes the problem of Histidine Rich Protein 2 (HRP2) gene deletions and what can be done to address it.