However, since HRP2 persists in the blood for up to five weeks after an infection is treated, an HRP2 test sometimes cannot distinguish whether someone currently has malaria or previously had it. Additionally, some P. falciparum parasites in the Amazon region lack the HRP2 gene, complicating detection. RDTs are fast and easily deployed to places without full diagnostic laboratories. However they give considerably less information than microscopy, and sometimes vary in quality from producer to producer and lot to lot.Serological tests to detect antibodies against Plasmodium from the blood have been developed, but are not used for malaria diagnosis due to their relatively poor sensitivity and specificity. Highly sensitive nucleic acid amplification tests have been developed, but are not used clinically due to their relatively high cost, and poor specificity for active infections. Classification
Malaria is classified into either "severe" or "uncomplicated" by the World Health Organization (WHO). It is deemed severe when any of the following criteria are present, otherwise it is considered uncomplicated.
Malaria was once common in the United States, but the US eliminated malaria from most parts of the country in the early 20th century using vector control programs, which combined the monitoring and treatment of infected humans, draining of wetland breeding grounds for agriculture and other changes in water management practices, and advances in sanitation, including greater use of glass windows and screens in dwellings. The use of the pesticide DDT and other means eliminated malaria from the remaining pockets in southern states of the US the 1950s, as part of the National Malaria Eradication Program. Most of Europe, North America, Australia, North Africa and the Caribbean, and parts of South America, Asia and Southern Africa have also eliminated malaria. The WHO defines "elimination" (or "malaria-free") as having no domestic transmission (indigenous cases) for the past three years. They also define "pre-elimination" and "elimination" stages when a country has fewer than 5 or 1, respectively, cases per 1000 people at risk per year. In 1955 the WHO launched the Global Malaria Eradication Program (GMEP), which supported substantial reductions in malaria cases in some countries, including India. However, due to vector and parasite resistance and other factors, the feasibility of eradicating malaria with the strategy used at the time and resources available led to waning support for the program. WHO suspended the program in 1969. Target 6C of the Millennium Development Goals included reversal of the global increase in malaria incidence by 2015, with specific targets for children under 5 years old.