Evaluation of the Performance of Standard Tests in the Differential Diagnosis of Malaria and Typhoid Fever

Malaria and typhoid fever are microbial conditions that share almost similar symptoms including hyperthermia. These diseases are endemic in sub-Saharan Africa where resources for proper control are scarce and biological diagnosis fundamentally based on direct and indirect screening tests. The present investigation aims to evaluate the performance of the usual tests for the differential diagnosis of malaria and typhoid fever, in connection with a few conducive environmental determinants of hygiene and sanitation. We conducted a descriptive cross-sectional study over a period of three months at the Bangangté District Hospital and the Cliniques Universitaires des Montagnes. The study population consisted of patients presenting with hyperthermia. Participant’s blood and stool specimens were subjected for screening according to standard protocols. The size of the study population was 90, with age average, 36 years. Men were relatively more represented than women (sex ratio1.04). The alleged most commonly water source was the tap (36.7%). Assessment of various tests and temperature displayed positive correlation (R=0.212; P=0.044) between the Plasmodium load and the increased temperature. The Widal-et-Felix test yielded 75% sensitivity, 51% specificity, 90% positive-predictive value and 97% negative-predictive value compared to stool culture for Salmonella Typhi. Concerning the SD Bioline RDT, 79% sensitivity, 70% specificity, 65% positive-predictive value and 82% negative-predictive value compared to the thick blood smear for Plasmodium were recorded. Biological crossed pieces of information (Blood Smear/stool culture) for malaria/typhoid fever co-infection were observed in 7.4% of cases. The rapid diagnostic tests assessment resulted in 34.78% false positives and 17.74% of false-negatives, while the Widal-et-Felix showed 90.74% of false-positives and 3.03% of false-negatives. The Youden index for the Widal-et-Felix (degree of inaccuracy, 0.26, far from 1) implied that this test is not appropriate for the diagnosis of typhoid fever alone.