Misidentification of Plasmodium mixed-infections leads to an overestimation of falciparum malaria

Despite the fact that malaria elimination is nearing in several countries, we continue to struggle with accurate diagnosis and thus treatment. The purpose of this study was to determine the rate of Plasmodium species misidentification (MI) by microscopy (MS). The study was based on previously published reports in which MS-PCR pairs were analysed to identify Plasmodium misidentification rates (by MS). Region- and species-wise misidentification rates were also estimated. A total of 2706 MS-PCR pairs were extracted from 16 different locations across 11 Indian states. MS-PCR pair analysis revealed 15% misidentification rate (408/2706). Surprisingly, microscopy misidentified more than 98% of mixed infections (400/405) as mono-infections (almost all as P. falciparum mono infections). The study identifies Jharkhand and Madhya Pradesh as major contributors (>20%) to Plasmodium species misidentification by microscopy. These findings suggest that we are overestimating P. falciparum burden, potentially wasting elimination resources, and underestimating non-falciparum species. The study also addresses an important issue concerning analysis of misidentification & sub-microscopic infection data (SMI). The proposed analysis (for MI and SMI) will aid in deciphering MI and SMI data in a more granular manner, generating actionable data for elimination programmes in various countries. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This study did not receive any funding ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The study is a secondary data analysis of published studies in the field I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present work are contained in the manuscript. In addition, the methods used to create the database that was used to include studies for this manuscript can be found here .