Detection of Asymptomatic Plasmodium Falciparum Infections by PCR: A Cross-sectional Survey during the Malaria Elimination Programme in Jazan Province, Saudi Arabia

Background: While the world has made great strides against malaria continuing to be a public health challenge, especially in areas approaching elimination, the situation in the Jazan Province of Saudi Arabia is a bit more optimistic. Saudi Arabia has spent significant efforts since 2004 controlling Plasmodium falciparum transmission and as a result has lowered the rate of locally acquired P. falciparum cases to only two recorded cases as of 2018. That being said, asymptomatic and submicroscopic cases could undermine elimination efforts. This study examined the prevalence of asymptomatic infections in a low transmission setting through molecular diagnostics. Methods: A cross-sectional community-based survey was carried out In Samtah Province in southeastern Jazan. Blood samples were collected from 230 healthy, asymptomatic individuals ages 2–65 and were tested by microscopy, by Rapid Diagnostic Tests (RDTs) and by real time Polymerase Chain Reaction (PCR). DNA was extracted from dried blood spots using the QIAamp DNA Mini Kit (Hilden, Germany) and the samples were analyzed using the FTD Malaria PCR Kit (Cat# FTD-39-64, Luxembourg). Results: By microscopy and RDTs, we found no malaria and a 0% prevalence with standard methods. The PCR detection showed P. falciparum DNA in three individuals, equating to a 1.3%-point prevalence. These infections were asymptomatic, submicroscopic infections which were also not detected by routine diagnostics. While local transmission appears to be decreasing, imported cases and hidden reservoirs present some of the greatest challenges to elimination. Conclusion: surveillance systems should incorporate molecular diagnostics that identify low-density infections in order to eradicate and sustain malaria. Active case detection and the integration of sensitive tools into national programs should to be prioritized, especially in low-endemic conditions.