Abstract
BackgroundMalaria is a major world health issue and its continued burden is due, in part, to difficulties in the diagnosis of the illness. The World Health Organization recommends confirmatory testing using microscopy-based techniques or rapid diagnostic tests (RDT) for all cases of suspected malaria. In regions where Plasmodium species are indigenous, there are multiple etiologies of fever leading to misdiagnoses, especially in populations where HIV is prevalent and children. To determine the frequency of malaria infection in febrile patients over an 8-month period at the Regional Hospital in Bamenda, Cameroon, we evaluated the clinical efficacy of the Flourescence and Staining Technology (FAST) Malaria stain and ParaLens AdvanceTM microscopy system (FM) and compared it with conventional bright field microscopy and Giemsa stain (GS).MethodsPeripheral blood samples from 522 patients with a clinical diagnosis of “suspected malaria” were evaluated using GS and FM methods. A nested PCR assay was the gold standard to compare the two methods. PCR positivity, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were determined.ResultsFour hundred ninety nine samples were included in the final analysis. Of these, 30 were positive via PCR (6.01%) with a mean PPV of 19.62% and 27.99% for GS and FM, respectively. The mean NPV was 95.01% and 95.28% for GS and FM, respectively. Sensitivity was 26.67% in both groups and specificity was 92.78% and 96.21% for GS and FM, respectively. An increased level of diagnostic discrepancy was observed between technicians based upon skill level using GS, which was not seen with FM.ConclusionsThe frequency of malarial infections confirmed via PCR among patients presenting with fever and other symptoms of malaria was dramatically lower than that anticipated based upon physicians’ clinical suspicions. A correlation between technician skill and accuracy of malaria diagnosis using GS was observed that was less pronounced using FM. Additionally, FM increased the specificity and improved the PPV, suggesting this relatively low cost approach could be useful in resource-limited environments. Anecdotally, physicians were reluctant to not treat all patients symptomatically before results were known and in spite of a negative microscopic diagnosis, highlighting the need for further physician education to avoid this practice of overtreatment. A larger study in an area with a known high prevalence is being planned to compare the two microscopy methods against available RDTs.
Highlights
Malaria is a major world health issue and its continued burden is due, in part, to difficulties in the diagnosis of the illness
Given that Plasmodium falciparum is indigenous to this area and the fact that all samples confirmed by Polymerase chain reaction (PCR) were reviewed by two clinical pathologists and determined to be P. falciparum based upon microscopy, it was not considered cost-effective to further
This study showed that there was a low number of malaria-positive patients of those presenting with a presumptive diagnosis of malaria at the Bamenda Regional Hospital in 2011
Summary
Malaria is a major world health issue and its continued burden is due, in part, to difficulties in the diagnosis of the illness. In Cameroon, malaria is perennial, rainfalldependent and the prevalence is 42.5% in children under 5 years of age, 31.5% in those between 5 and 15 years of age, and 10.5% in those older than 15 years. It causes 50% morbidity in children under 5 years old, and is implicated in 40% to 50% of medical consultations [1]. While malaria is a preventable disease, there are seemingly insurmountable issues with proper diagnosis and treatment throughout endemic regions, leading to its continued prevalence and increasing drug resistance. Due to inadequate resources, inexperienced technical personnel, poor diagnostic standards, and the lack of clinician confidence in diagnostics currently available, the disease may be misdiagnosed and individuals treated unnecessarily with antimalarial agents
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