Repeat malaria test positivity among symptomatic children with an initial negative test at Bombo General Military Hospital, Luwero District, Uganda

Abstract

Background: Prompt malaria diagnosis is recommended by WHO for all patients with suspected malaria before receiving treatment. Rapid diagnostic tests (mRDT) and malaria microscopy are used, microscopy being the gold standard. Missed malaria diagnosis increases the risk of severe malaria, hospitalization and death. Missed malaria diagnosis on single testing can be due to type of mRDTs, low parasite densities, incorrect use of mRDTs, inadequate experience and skill of the microscopist. Repeat testing showed reduced missed malaria diagnosis by Centers of Disease Control (CDC) and Clinical and Laboratory Standard institute. WHO guidelines and Uganda malaria policy lack guidance on repeat testing hence need for the study. Study Objective: To determine the frequency and factors associated with missed malaria diagnosis on single malaria testing among symptomatic children attending Bombo General Military Hospital. Methods: Prospective longitudinal study. Symptomatic children for malaria 3months – 17years were enrolled after written imformed consent from caregivers and assent from older children at General Military Hospital, Bombo from June - December ,2024. Blood was obtained by a finger prick and parallel testing with both Pan-RDT and a thick smear microscopy was done. Those that tested Positive were given antimalarials. Repeat testing was done at 24, 48 and 72 hours for the negative cases until found positive, or remained negative at 72 hours. Participants were also investigated for other causes of the symptoms and treated accordingly. Caregivers would come back when a child became sicker or for follow up testing. Transport was refunded and compensation fee was given. Participants’ characteristics and independent variables were obtained by semi structured questionnaire. Data analysis was done with STATA 17. Frequency of missed diagnosis was reported as a proportion of those found positive on subsequent tests at 24,48 and 72 hours following an initial negative test for malaria divided by all children found negative after the initial test. Kaplan Meier curve was used to determine the probability of remaining malaria negative or probability of being misdiagnosed for malaria over time. Cox regression was used to analyse factors associated with missed malaria diagnosis. Results: The participants were mean age 6.67years (5.62) and 160 (54.2 %) were male. Of the 295 participants recruited into the study, 7 were lost to follow-up and 63 (21.9%) of the remaining 288 had missed malaria diagnosis and 225 had no missed malaria diagnosis. For x

every 100 persons observed, there was a 7.12% chance of a misdiagnosis per day which equated to 71.2 misdiagnoses per 1,000 person-days. The decline in the probability of remaining correctly diagnosed over time was steepest between 24 and 48 hours, highlighting this window as particularly critical for repeat testing. Factors associated with missed malaria diagnosis were high monthly household income that reduced the risk of misdiagnosis (AHR = 0.490, 95% CI: 0.249 – 0.967, p-value = 0.040) and Other presenting symptoms other than fever such as cough, flue, diarrhoea, vomiting, abdominal pain and others (AHR = 1.583, 95%CI: 1.2741 – 1.9668, p-value < 0.001) that indicated 58.3% increased risk of misdiagnosis. Conclusion and Recommendations: There is substantial incidence of repeat malaria positivity following an initial negative test. The incidence rate of 7% observed translates to a significant risk of misdiagnosis in clinical practice. The probability of remaining malaria-negative declined sharply within the first 48 hours. Diagnostic delays affected children with non-specific symptoms and children from high income showed reduced risk of misdiagnosis. Therefore, reliance on a single test is insufficient in high-burden settings. This study highlights the need for policy and practice changes to improve malaria diagnosis in high-transmission settings through mandating repeat testing in National guidelines with high clinical Suspicion, subsidized diagnostics and treatment for low-income households and integrating malaria testing into broader febrile illness management to ensure comprehensive care for children with co-infections thus improving malaria diagnosis and treatment outcomes for children with malaria in Uganda.