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Clinical signs and symptoms not sufficient to diagnose endemic and returning travelers' malaria

Clinical Question:
Can clinical signs and symptoms be used to accurately diagnose malaria in patients returning from endemic areas?

Bottom Line:
No symptoms or examination findings have sufficient accuracy to reliably diagnose malaria. Laboratory testing is still required for this potentially fatal illness. (LOE = 2a)

Reference:
Taylor SM, Molyneux ME, Simel DL, Meshnick SR, Juliano JJ. Does this patient have malaria? JAMA 2010;304(18):2048-2056.  [PMID:21057136]

Study Design:
Systematic review

Funding:
Government

Setting:
Various (meta-analysis)

Synopsis:
To determine the clinical accuracy of the history and physical for diagnosing malaria these investigators searched MEDLINE and EMBASE for English-language studies that reported the value of specific clinical signs and symptoms and used the thick or thin blood smear for the detection of malaria parasites as the reference standard. Two individuals independently evaluated studies for inclusion and methodological quality using standard criteria. The search identified 14 studies of endemic malaria and 11 of those studies met the criteria for level 1 evidence and the remainder met the criteria for levels 2 and 3. Thirty-three studies of imported malaria met inclusion criteria (n = 33,000) with most patients (n = 30,000) coming from a single level 1 study. In endemic areas, the likelihood of malaria is not substantially increased by the presence of any specific symptoms, including chills, rigors, or headache. Similarly, the absence of cough, dyspnea, vomiting, or diarrhea does not make malaria more likely. On physical examination, the presence of splenomegaly (positive likelihood ratio [LR+] = 3.3; 95% CI, 2-4.7), hepatomegaly (LR+ = 2.4; 1.6-3.6), or pallor in children (LR+ = 2.0; 1.2-2.8) increases the likelihood of malaria. In travelers returning from endemic areas, the median number of days to presentation after return was significantly sooner in those with malaria than in those without malaria (13; 12-14 vs 21; 21-22, respectively). Useful symptoms for increasing the likelihood of malaria include fever or history of fever (LR+ = 5.1; 4.9-5.3). The absence of fever (negative likelihood ratio [LR-] = 0.12; 0.10-0.15), headache (LR- = 0.40; 0.32-0.49), or chills or rigors (LR- = 0.47; 0.38-0.59) and the presence of cough (LR- = 0.04; 0- 0.56) or diarrhea (LR- = 0.60; 0.38-0.95) decrease the likelihood of malaria. On physical examination, splenomegaly (LR+ = 6.5; 3.9-11), jaundice or icterus (LR+ = 4.5; 1.7-12) or pallor (LR+ = 2.8; 1.7-4.6) increase the likelihood of malaria. On laboratory tests, thrombocytopenia (LR+ = 74; 9.2-601) and hyperbilirubinemia (LR+ = 11; 8-15) increase the likelihood of malaria.

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