Background Malaria and dengue are the most prevalent vector-borne diseases worldwide. Both diseases are endemic in similar tropical regions. Each infection has a specific mosquito vector. Hence, overlapping of the habitat cannot be easily available. In co-infection, the clinical features were more like dengue mono-infection than malaria mono-infection. Therefore, clinically, it is difficult to diagnose co-infection dengue and malaria. Case Illustration A 42-yo Javanese man, presented with 10-days of fever that was clinically and serologically consistent with symptoms of vivax malaria. Plasmodium vivax was found in the ring, trophozoite and schizonts form in the thick blood smear examination with parasitemia index 84.410 parasite/?l. In the course of the disease, patients were found to have a mixed infection with Plasmodium ovale. The patients also experience complications of spontaneous bleeding, thrombocytopenia and worsening respiratory conditions leading to acute respiratory distress syndrome (ARDS) which increases suspicion of co-infection with dengue virus. Laboratory tests to enforce dengue infection are carried out with the results obtained positive IgG and IgM that indicate recurrent infections. The patient is then given the management of severe malaria and expanded dengue syndrome according to the Indonesia Ministry of Health of guideline. On the 11th day of hospitalizations, the patients showed a significant cure rate and continuing ambulatory therapy with Primaquine 15 mg oral until day 14th. Conclusion The incidence of heavy bleeding in malaria patients is very low. Thus, malaria patients who experience unclear fever patterns and heavy bleeding should be systematically investigated for suspicion of dengue virus co-infection.

Co-infection; Malaria vivax; Malaria ovale; Dengue; Expanded dengue syndrome