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Malaria rapid diagnostic tests (RDTs)
This document discusses malaria rapid diagnostic tests (RDTs). It explains that RDTs detect specific malaria antigens or proteins to identify if malaria parasites are present. There are three main types of antigens detected: HRP2, pLDH, and aldolase. RDTs are useful for diagnosis, case management, epidemiology, and screening donated blood. Their strengths are ease of use, rapid results, and not requiring refrigeration. Challenges include shorter shelf life and lower sensitivity than laboratory tests. Key factors for choosing an RDT are the Plasmodium species, accuracy, shelf life, ease of use, and cost. Guidelines recommend testing and monitoring RDT batches, manufacturer quality practices, cold chain transport
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Malaria rapid diagnostic tests (RDTs)
- 1. MALARIA: Rapid diagnostic tests DrJerin Kuruvilla
- 2. What is MalariaRDT??? •A malaria RDT or “dipstick RDT detects specific antigens or protiens developed by malaria parasites •Principle-lateral flow or immunochromatographic stick method •Signifies presence of an antigen by colour change on adsorbing nitrocellulose strip. •RDTs sensitive to malarial antibodies-used for screening of donated blood
- 3. Types Of MalariaRDTs •Three main group of antigens detected by commercially available RDTs are: Histidine rich protien(HRP2)-specific to plasmodium Soluble,heat stable antigen present abundantly in cytoplasm and membrane of affected erythocytes. Parasite specific Lactate dehydrogenase(pLDH)-falciparum specific,pan specific or vivax specific Aldolase(pan specific)-conserved major enzymes in malarial glycolytic pathway
- 4. Appropriate use ofRDTS •Diagnosis-to identify ,confirm or rule out malaria in symptomatic patients •Case Management-accurate prescription of therapeutic interventions and to monitor treatment •Epidemiology-to detect and monitor incidence and prevalence of malaria for targetting prevention and evaluating health programmes •Available formats: Plastic cassette, card, dip stick, hybrid cassette dipsticks
- 7. Strengths of MalariaRDTs Challenges of Malaria RDTs Relatively easy to use with minimal training required Costs per test may exceed those of microscopy Relatively rapid, giving timely results Short shelf-life, requiring efficient procurement, transportation, storage and distribution systems Little or no manipulation of sample required, can be performed in places without laboratories Most tests are qualitative (i.e. gives a yes or no answer). Any quantification of parasitemia will require further laboratory-based tests Most of the RDTs do not require refrigeration, hence tests can be performed where there is no power supply Intensity of test band varies with amount of antigen present at low parasite densities-this may lead to reader variation in test results Uses whole blood (prick or venous blood-prick preferred) less sensitive than lab tests
- 8. Choosing a MalariaRDT •The plasmodium species to be detected •Accuracy(sensitivity and specificity) •Shelf life and temperature stability during storage,transport and use ( -minimum of 18 months) •Ease of use (including format of tests) •Cost
- 9. Plasmodium species tobe detected •Zone 1 -Plasmodium falciparum only(Sub Saharan Africa & Papua New Guinea) – HRP2 kits preferred •Zone 2 –Falciparum and non falciparum infections occur as single species infection(endemic areas of Asia and Americas) •Zone 3 –non falciparum malaria only(mainly vivax only)(areas of east asia and central asia)
- 11. Despite all theseadvances, malaria will likely be with us as long as there are humans on this earth.
- 13. Guidelines for useof Malaria RDTs in health programmes •Batches of RDTs should be tested and monitored throughout shelf life •Evidence of good manufacturing practice(GMP) and good field experience of manufacturer •Cold chain for transport and storage •Health worker training and monitoring •Clear guidelines & diagnostic as well as treatment guidelines
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- 15. Treatment of Chloroquineresistant malaria Quinine + tetracycline or clindamycin or Fansidar (sulfadoxine and pyrimethamine) Malarone (paludrine/atovaquone) Mefloquine (a quinoline methanol) Qinghaosu (artemesinin)
- 16. Malaria Prevention Mosquito avoidance- evening and night behavior - mosquito nets - air conditioning - screens - mosquito repellants - pyrethrin coils Mosquito killing - destroying breeding sites - fog spraying - residual spraying Plasmodium killing - chemoprophylaxis