Malaria misdiagnosis in the routine health system in Arba Minch area district in southwest Ethiopia: an implication for malaria control and elimination

Abstract Background Microscopy and Rapid Diagnostic Test (RDT) are the two widely used malaria diagnostic tools in Ethiopian health facilities. Accurate diagnosis is vital for appropriate treatment of cases to interrupt its transmission. Missing malaria cases, species misdiagnosis and false positive or negative reports might compromise the control and elimination effort. Therefore, this study assessed the status of species-specific misdiagnosis by microscope compared with polymerase chain reaction (PCR). Methods A cross-sectional survey based on health facilities was conducted from November 2019 to January 2020. Results A total of 254 microscopically negative and 193 microscopically positive malaria cases were included. Of the 193 malaria positive cases, 46.1% (95% confidence interval (CI): 38.9–53.4) (89/193) were Plasmodium falciparum infection, 52.3% (95% CI: 45.0-59.5) (101/193) were P. vivax infection, and 1.6% (3/193) had mixed infection of P. falciparum and P. vivax. Of the microscopically positive cases of P. falciparum, 84.3% (75/89) were confirmed as P. falciparum, 3.4% (3/89) were P. vivax and 11.2% (10/89) were mixed infections with P. falciparum and P. vivax and only one case was negative molecularly. Similarly, of the microscopically positive cases of P. vivax cases, 92.1% (93/101) were confirmed as P. vivax, 5.9% (6/101) were P. falciparum and 1% (1/101) was mixed infection. Single case was negative by molecular technique. Of the 254 microscopically negative cases, 0.8% of cases were tested positive for P. falciparum and 2% for P. vivax. Considering molecular technique as a reference, the sensitivity of microscopy for detecting P. falciparum was 89.2 and for P. vivax, it was 91.2. The specificity of microscopy for detecting P. falciparum was 96.1 and for P. vivax, it was 97.7. However, the sensitivity of microscopy in detecting mixed infection of P. falciparum and P. vivax was low (8.3%). Conclusion Based on our results, many P. falciparum and P. vivax mixed infections were microscopically overlooked and underreported in the routine healthcare system. In addition, there were cases left untreated or inappropriately treated. Therefore, to minimise this problem, the gaps in the microscopic-based malaria diagnosis should be identified and regularly monitored to ensure the accuracy of the diagnosis.