Malaria chemoprevention using mefloquine has become the WHO standard regimen for military personnel who stay in the endemic area for an extended period of time. We reported a case of Plasmodium ovale infection in a young Indonesian Soldier following one year mefloquine prophylaxis 250 mg weekly. Typical fever and chills were experienced two weeks after returning from one year duty in Congo, West-Central Africa. The diagnosis of ovale malaria was made by peripheral blood smear, and 35/250 parasites in small microscopic view was found. Then, he recovered after dihydroartemisin and primaquine combination therapy. This was an unusual case of long-term prophylaxis failure since mefloquine has been recognized as the agent for malaria prevention, even multi-drug-resistance Plasmodium. Dormant stage of Plasmodium ovale, quinoline-resistance potential, and the efficacy of mefloquine itself are discussed as the cause of that phenomenon.

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Kemoprofilaksis malaria menggunakan meflokuin telah menjadi regimen standar WHO bagi anggota militer yang berada di daerah endemik dalam jangka waktu cukup panjang. Dalam laporan kasus ini disajikan kasus infeksi Plasmodium ovale pada anggota muda militer Indonesia yang telah mendapat profilaksis meflokuin 250 mg/minggu selama satu tahun. Pasien tersebut mengalami demam mengigil yang tipikal setelah kembali dua minggu dari tugas di Kongo, Afrika Barat-Tengah. Diagnosis malaria ovale ditegakkan melalui pulasan darah tepi, dan ditemukan 35/250 parasit dalam lapang pandang kecil mikroskop. Kasus kegagalan profilaksis jangka panjang pada dasarnya jarang ditemui, mengingat meflokuin telah menjadi obat pencegahan malaria, bahkan untuk kasus Plasmodium multi-resisten. Diduga, stadium dorman dari Plasmodium ovale, resistensi golongan obat kuinolin, dan efikasi meflokuin menjadi penyebab terjadinya fenomena tersebut.