Advancing malaria reactive case detection in a Zambia-like setting: A modeling study

In Zambia-like settings, asymptomatic and clinical carriers not seeking treatment further complicate malaria elimination, making reactive case detection (RCD) essential for identifying undetected infections. However, RCD faces operational hurdles, including resource shortages, logistical challenges, limited community health workers (CHWs), and limitations in availability and sensitive rapid diagnostic tests (RDTs). Prioritizing specific improvement measures is critical to enhance intervention outcomes. A mathematical model of malaria transmission for low-transmission areas (fewer than 200 cases per 1,000 annually) was developed using published data to simulate RCD. This model assessed the impact of potential improvement measures designed to address the identified operational challenges affecting RCD. Improvement measures included increasing CHWs, adjusting response times, improving RDT sensitivity, and incorporating focal mass drug administration (fMDA). A shortage of CHWs and limited availability of RDTs have the most negative impact on RCD's ability to reduce cases. In scenarios where CHWs or RDT availability for RCD were reduced by 50%, annual cases increased by approximately 22%. Only the incorporation of fMDA as an improvement measure succeeded countering the situation, resulting in a 43% reduction. Increasing CHWs to offset RCD inefficiencies caused by limited RDT sensitivity and difficulties finding individuals reduced cases by approximately 13 and 14%, respectively, reducing more cases than improving reaction time or increasing the screening radius. Although RCD is prone to challenges, the manipulation of improvement measures such as CHWs and fMDA provides promise for RCD to contribute towards malaria elimination. However, the participation of CHWs is voluntary and primarily motivated by informal incentives, often provided by donors. Finding sustainable means to ensure the sufficient availability of CHWs may guarantee continued RCD contributions toward maintaining stable malaria prevalence. More research is required to explore the application of RCD in archetypical transmission areas suitable for RCD as improvement measures to the identified challenges hindering RCD.