Background: Serological tools for the accurate detection of recent malaria exposure are needed to guide and monitor malaria control efforts. IgG responses against P. vivax and P. falciparum merozoite surface protein-10 (MSP10) were measured as a potential way to identify recent malaria exposure in the Peruvian Amazon. Methods: A field-based study included 470 participants in a longitudinal cohort who completed a comprehensive evaluation: light microscopy and PCR on enrollment; at least one monthly follow-up by light microscopy; a second PCR; and serum and dried blood spots for serological analysis at the end of the follow-up. IgG titers against novel mammalian cell-produced recombinant PvMSP10 and PfMSP10 were determined by ELISA. Results: During the follow-up period, 205 participants were infected, including 171 with P. vivax, 26 with P. falciparum, 6 with infections by both species but at different times, and 2 with mixed infections. Exposure to P. vivax was more accurately identified when serological responses to PvMSP10 were obtained from serum (sensitivity, 58.1%; specificity, 81.8%; AUC: 0.76) than from dried blood spots (sensitivity, 35.2; specificity, 83.5%; AUC: 0.64) (PAUC < 0.001). Sensitivity was highest (serum, 82.9%; dried blood spot, 45.7%) with confirmed P. vivax infections occurring 7-30 days before sample collection; sensitivity decreased significantly in relation to time since last documented infection. PvMSP10 serological data did not show evidence of inter-species cross-reactivity. Anti-PfMSP10 responses poorly discriminated between P. falciparum exposed- and non-exposed individuals (AUC = 0.59, P > 0.05). Conclusions: Anti-PvMSP10 IgG indicates recent exposure to P. vivax at the population level in the Amazon region. Serum, not dried blood spots, should be used for such serological tests.
Angel Rosas-Aguirre, Kailash P. Patra, Maritza Calderón, Katherine Torres, Dionicia Gamboa, Edith Arocutipa, Edith Málaga, Katherine Garro, Carlos Fernández, Grace Trompeter, Yossef Alnasser, Alejandro Llanos-Cuentas, Robert H. Gilman, Joseph M. Vinetz