Utility of rapid diagnostic tests and microscopy to detect malaria in health facilities across the Solomon Islands.

Background: Accurate and efficient malaria diagnosis is critical for effective malaria control and elimination. Rapid diagnostic tests (RDTs) have been deployed over the last decade, particularly in rural and low-and-middle-income countries, as an alternative to microscopy-based diagnosis.

Methods: This study analysed retrospective health data from the Solomon Islands District Health Information System (DHIS2) for 2017-2019, focusing on factors affecting diagnostic test selection and positivity rates for microscopy versus RDTs.

Results: The national Annual Parasite Incidence (API) of malaria declined over the 3 years, with localised increases in specific health zones. The choice of malaria diagnostic test was associated with administrative division, patient age, health facility type and year. Overall, RDTs had higher malaria positivity rates than microscopy for both Plasmodium falciparum (microscopy, 6%; RDT, 11%) and Plasmodium vivax (microscopy, 10%; RDT, 14%).

Conclusions: RDTs were more widely used than microscopy in health facilities and had higher test positivity rates. This study highlights the factors influencing diagnostic test selection and underscores the importance of considering detection limits and potential overdiagnosis when interpreting positivity rates from different diagnostic methods.