C-229. Value of Demographic Data, Clinical Indicators, and Non-Specific Laboratory Parameters in Diagnosis of Imported Malaria

A. M. A. R. El-Moamly, M. A. Al-Sweify;
Suez Canal Univ., Ismailia, EGYPT.

Background: No evidence-based information exists to guide clinical practitioners for giving treatment to returning travelers from malaria-endemic areas when malaria is strongly suspected on clinical ground but microscopic confirmation is not available. Certain clinical and lab. features could predict the disease. The study aimed to determine the value of the non-specific lab. tests and the clinical and demographic data in the diagnosis of malaria as a practical, helpful non-microscopic way for diagnosis of imported malaria in non-endemic areas, where the experience with the disease and the available methods of diagnosis is lacking. Methods: Blood samples were collected from 872 febrile patients returned from malaria-endemic regions (Southern Saudi Arabia,Yemen, Sudan, India, Pakistan, Sub-Saharan Africa) and admitted to ER in Iman G. Hosp., Riyad, Saudi Arabia. A prospective case-control study was performed to compare the results of the routine biological parameters in the malaria-infected patients (77) and in those with other reasons of fever (795). Malaria was diagnosed by the microscopic examination of thin and thick blood films and by the immunochromatographic P-LDH assay "OptiMal".Results: Certain predictives were associated with diagnosis of malaria with significant difference between the means of the two studied groups (P<0.001). Total leucocytic count of <8x109 /L (odd ratio(OR)= 3.6, 95% CI, 0.58- 0.72), low platelet count of <150x109/L (OR = 19.3.0, 95%CI, 0.85-0.89), low cholesterol of <3 mmol/L (OR=171.5(95% CI, 0.83- 0.93), high bilirubin of >17 µmol/L (OR = 7.3, 95% CI, 0.55- 0.70), high LDH >190 U/L (OR= 57.8, 95% CI, 0.51-0.67), fever ≥38.5 (OR=45, 95% CI, 0.77- 0.84), and the triad of (fever, vomiting, and rigors, OR= 47.5, 95% CI, 0.79- 0.90).
Diagnostic features of malaria predictors.

Predictor

Sensitivity%
(95% CI)

Specificity%(95%CI)

PPV%
(95%CI)

NPV%
(95%CI)

+LR

-LR

WBC <8x109/L

69 (0.58-0.79)

62(0.52- 0.72)

58(0.48- 0.68)

72(0.63-0.82)

1.8

0.5

Low platelets

71(0.61-0.82)

89(0.86-0.91)

35(0.28-0.43)

97(0.96-0.99)

6.2

0.3

Low cholesterol

98(0.95-1.01)

78(0.70-0.86)

82(0.75-0.89)

98(0.94-1.01)

4.5

0.0

High bilirubin

88(0.79- 0.97)

50(0.40-0.60)

47(0.37-0.57)

89(0.81-0.97)

1.8

0.2

High LDH

100 (1 - 1)

37(0.27-0.47)

47(0.37- 0.56)

100(1 - 1)

1.6

0.6

Fever>=38.5 °C

92(0.86-0.98)

79(0.76-0.82)

32(0.26-0.38)

99(0.98-100)

4.4

0.1

Fever,vomiting
rigor

71(0.61-0.82)

95(0.91-0.99)

92(0.85-0.99)

81(0.74-
0.88)

14.3

0.3


Conclusion: The results suggest that, in febrile patients who have travel history to a malaria endemic region with negative thin and thick blood smears for malaria, it is recommended to consider the above clinical and biological lab predictors as suggestive of malaria infection, and reevaluate carefully subsequent blood smears, or to give a theraputic trial to avoid misdiagnosis of malaria.