Relevance of the Widal Agglutination Test in Malaria Endemic Region

Abstract

Malaria and typhoid fevers are twin diseases that plague many Sub-Saharan African and Asian countries at epidemic proportions with almost a third of all deaths occurring in Nigeria in the last decade. Diagnosis of malaria in Nigeria relies heavily on the simple and inexpensive microscopy and the Widal agglutination test is commonly used in resource-poor settings where cultures fail or unavailable for typhoid fever diagnosis. The study was conceived to determine the relevance of the Widal agglutination test in a malaria endemic region. Patients who had previously received artemisinin combination therapy (ACT) with unremitting febrile illness who gave consent were enlisted into the study. Blood samples were collected for blood films, examined microscopically for the presence of malaria parasites. Widal agglutination test was carried out on each separated serum with the rapid slide agglutination test and titre was determined for sera showing agglutination with tube dilution assay. Malaria parasites were present in 236/429(55.0%) of the blood samples of which 41.7% had parasitemia density of ≤5000/mL of blood. Parasitemia density higher than 5000/µL of blood accounted for 13.4%. Widal agglutination titres as high as 320 were recorded in patients with malaria parasites as wells as those without malaria parasitemia. Malaria is a major cause of febrile illness in the study population which can be carefully excluded with the inexpensive blood film microcopy to enable proper evaluation for typhoid fever to be undertaken.