Sympatric Occurrence of Plasmodium ovale curtisi and Plasmodium ovale wallikeri in Archived Samples in Saharevo in the Eastern Foothill Area of Madagascar
1 Unité de Parasitologie, Institut Pasteur de Madagascar, Antananarivo 101, Madagascar;
2 Faculté des Sciences, Université de Toliara, Toliara 601, Madagascar
3 School of Life Science and Technology, Jiangning Campus, China Pharmaceutical University, Nanjing 210009, China
4 Institut de Parasitologie et de Pathologie Tropicale de Strasbourg, 3, rue Koeberlé, 67000 Strasbourg, Bas-Rhin, France;
5 Laboratoire Mayo Bio, Biogroup Océan Indien, Résidence Jardin Créole, 97600 Mamoudzou, Mayotte, France
* Author to whom correspondence should be addressed.
Received: 9 Oct 2025 / Accepted: 31 Mar 2026 / Published: 15 Apr 2026
Abstract
Introduction: Four Plasmodium species that infect humans coexist on the island of Madagascar. P. falciparum and P. vivax are predominant while P. malariae and P. ovale remain rare. Recently, two subspecies of P. ovale were discovered through molecular analysis: P. o curtisi and P. o. wallikeri. Thus, we undertook a study that aims to assess P. o. curtisi and P. o. wallikeri infection in archived blood samples using nested PCR. Methods: Whole blood samples collected from patients with suspected malaria in Saharevo (eastern foothill area) from 1996 to 2005 were analyzed. These samples were stored at −20 °C until use. Microscopy examination of these samples had already been performed previously. Results: Of the 557 examined samples, 438 malaria infections were confirmed using nested PCR [78.6%, 95%CI: 74.9–81.9%]. Among these malaria cases, twelve patients presented singularly with P. ovale [2.7%, 95%CI: 1.5–4.9%] including six P. o. curtisi, five P. o. wallikeri, and one co-infection of P. o. curtisi + P. o. wallikeri. Conclusion: This study provides the first molecular evidence of the sympatric occurrence of P. o. curtisi and P. o. wallikeri in Madagascar. Sequencing provided definitive genotyping, confirming the nested PCR findings. Therefore, further studies assessing the prevalence of the rare species such as P. ovale are needed to better understand the distribution of this species to guide malaria control strategies.
Keywords: ; ; Nested-PCR; sympatric infection; Madagascar
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CITE
Randriamiarinjatovo, D.N.A.L.; Rabearivony, A.N.N.Z.; Abou-Bacar, A.; Randrianarivelojosia, M. Sympatric Occurrence of Plasmodium ovale curtisi and Plasmodium ovale wallikeri in Archived Samples in Saharevo in the Eastern Foothill Area of Madagascar. AJPME 2026, 3, 12.
Randriamiarinjatovo DNAL, Rabearivony ANNZ, Abou-Bacar A, Randrianarivelojosia M. Sympatric Occurrence of Plasmodium ovale curtisi and Plasmodium ovale wallikeri in Archived Samples in Saharevo in the Eastern Foothill Area of Madagascar. AJPME. 2026; 3(2):12.
Randriamiarinjatovo, Dina Ny Aina Liantsoa; Rabearivony, Anjara Nomena Ny Zo; Abou-Bacar, Ahmed; Randrianarivelojosia, Milijaona. 2026. "Sympatric Occurrence of Plasmodium ovale curtisi and Plasmodium ovale wallikeri in Archived Samples in Saharevo in the Eastern Foothill Area of Madagascar." AJPME 3, no. 2: 12.
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