Malaria screening: Difference between revisions
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==Screening== | ==Screening== | ||
Screening for malaria infection is important in: | |||
* Sub-Saharan refugees | |||
* Blood donor screening | |||
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Medical and laboratory screening after arrival | Medical and laboratory screening after arrival | ||
A sub-optimal alternative to presumptive therapy is to test newly arriving | A sub-optimal alternative to presumptive therapy is to test newly arriving for malaria infection. Although microscopic examination of a properly stained blood smear remains the standard for diagnosis of Plasmodium infection in symptomatic individuals presenting in the U.S., studies have demonstrated that a single malaria thick-and-thin blood smear lacks sensitivity (<40%) for detecting asymptomatic or sub-clinical malaria in these populations. 8 9 Three separate blood films taken at 12 to 24 hour intervals, the standard recommendation for diagnosis of clinical malaria, has a greater sensitivity. However, this approach is rarely feasible for screening newly arriving refugee populations because of cost constraints and the need for multiple visits. A rapid diagnostic test (RDT) was recently approved by the U.S. Food and Drug Administration (NOW-MalariaÔ) for use in diagnosis of symptomatic malaria in the United States. Although this test has excellent sensitivity for P. falciparum in symptomatic patients preliminary data suggests it is less than 30% sensitive in the diagnosis of asymptomatic P. falciparum in newly arrived refugees. 9 When a refugee does not receive presumptive therapy they should be monitored for signs or symptoms of disease, particularly during the initial 3 months after arrival, regardless of the post-arrival testing results. | ||
Although this document addresses individuals with no signs or symptoms of malaria, it is worth noting hematologic and physical examination findings that may be noted on screening in asymptomatic individuals and which have a high positive predictive value for malaria. Two studies have demonstrated that no parameters, including anemia and/or thrombocytopenia, consistently predict persons with infection (poor sensitivity and negative predictive value).8 10 However, when thrombocytopenia or splenomegaly are present among individuals in these populations, they frequently indicate malaria (high specificity and positive predictive value). 10 Refugees with these clinical signs, even when not symptomatic, should receive appropriate evaluation for clinical malaria. | Although this document addresses individuals with no signs or symptoms of malaria, it is worth noting hematologic and physical examination findings that may be noted on screening in asymptomatic individuals and which have a high positive predictive value for malaria. Two studies have demonstrated that no parameters, including anemia and/or thrombocytopenia, consistently predict persons with infection (poor sensitivity and negative predictive value).8 10 However, when thrombocytopenia or splenomegaly are present among individuals in these populations, they frequently indicate malaria (high specificity and positive predictive value). 10 Refugees with these clinical signs, even when not symptomatic, should receive appropriate evaluation for clinical malaria. | ||
Revision as of 22:23, 24 July 2014
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Malaria Microchapters |
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Diagnosis |
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Treatment |
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Case studies |
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Malaria screening On the Web |
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American Roentgen Ray Society Images of Malaria screening |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Screening
Screening for malaria infection is important in:
- Sub-Saharan refugees
- Blood donor screening