Malaria Parasite burden in areas of northern Uganda where Indoor Residual spraying has been withdrawn
Authors: Okek Erick Jacob , Wakunga Erick , Obondo Sande James , Adera Doreen Atoo , Ssemwanga deogratius , Tukwasibwe Steven , Olobo Joseph , Kayondo Jonathan , Echodu Richard , Ocan Moses 
Published: January 2024

Introduction: Northern Uganda has one of the highest malaria burdens in Uganda and globally. Indoor residual spraying (IRS) for mosquito malaria vector control was last conducted in this region in 2014. The Government of the republic of Uganda intends to re-introduce IRS alongside RTS,S/AS01 malaria vaccine in this area as a strategy to achieve the ambitious goal of global malaria elimination by 20230. There is need to ascertain current parasite burden within selected areas of the region in order to predict the impact of future co-deployment of IRS and RTS,S/AS01.
Methods: 3–4 mls of whole blood was collected in an EDTA tube from 353 participants who consented/assented to the blood draw and interviews. Participants were patients seeking for medical care at Gulu Regional Referral Hospital and were drawn from Acholi and Lango districts. Attending clinicians documented disease symptoms and severity. Blood samples were tested for malaria parasite using rapid diagnostics tests and confirmed by microscopy thick smear. Thin blood smears were made, stained, and examined to quantify the parasites. Data was entered into excel and later exported to GraphPad prism (ver8) and STATA where analysis was done. The non-parametric t test was used to compare means of parasitemia across two variables/characteristics while one way ANOVA was used to compare means of parasitemia across three groups and above. 2x2 contingency table of malaria related symptoms versus test outcome was drawn and odd ratios were calculated to identify which symptoms are most associated with malaria in northern Uganda.
Results: Test positivity rate was 63.34% at enrollment with 93.21% of participants having fever as well. 258 of the 353 participants were children below 5 years while majority were females (60.3%). Vomiting, diarrhea, prostration, and seizures (indicators of severe malaria )were identified among children < 5 years only. There was no significant difference in parasite burden between male and female participants. Thick smear is an accurate measure of parasitaemia as there was a performance agreement between its quantification and that of a thin smear. There was no significant difference in the parasite count across different age categories. There is a very high association between joint pain and malaria, while fever is least associated with malaria among symptoms selected.
Conclusion: This study found malaria test positivity rate to be within the normal range for endemic regions like northern Uganda indicating that the additive effect of Indoor residual spraying is temporal and insignificant in the long run if inconsistently applied. Amidst sustained interventions, malaria test positivity rate always fluctuates within a narrow range in areas of stable transmission. We are not certain if the introduction of RTS,S/AS01 or R21 matrix vaccine will come with real additional benefits. Children and infants under 5 years still carry the highest parasite and severe malaria burden. This finding nullifies the hypothesis that cases of severe malaria was shifting from younger to older ages in areas with stable transmission & vector control measures such as northern Uganda.