No simian Plasmodium detected in populations living in the equatorial rainy forest of the Democratic Republic of Congo

Background
Malaria remains the most deadly parasitic disease to date, especially in sub-Saharan Africa, which comprises the majority of cases collected per year. It has long been accepted that four species of Plasmodium (P. falciparum, P. vivax, P. malariae and P. ovale) were responsible for the disease in humans. But quite recently, a fifth species, Plasmodium Knowlesi, has been identified as naturally infecting humans. Indeed, known for decades as naturally parasitizing the monkey Macaca fascicularis, P. knowlesi has long been confused, in terms of its evolutionary stage, with P. malariae or P. falciparum, which it resembles morphologically and it was not possible to properly differentiate them until the advent of molecular biology. To date, P. Knowlesi has only been identified in Southeast Asia and a similar phenomenon of natural transmission of simian plasmodium to humans has not been reported elsewhere. We therefore conducted this study to investigate the possible transmission of simian plasmodium to humans in populations living near the rainforest of the Democratic Republic of Congo (DRC) where several species of primates lives.
Methods & Materials
Three villages (Wenji-Secli, Bongonde, and Bolenge) in the Province of Ecuador (North-eastern DRC) were selected because of their geographical location. Blood samples spotted on filter paper were collected from 100 people randomly taken in each village. Two successive RT- PCR were performed. A first one using a single probe able to diagnose all plasmodium spp. and a second using four species-specific probes for the diagnosis of the four conventional human plasmodium species. Positivity in the first RT- PCR with negativity in the second RT- PCR would suggest the presence of plasmodium species other than the four conventional.
Results
P. falciparum was correctly identified in 44.6 % of samples. No other species of human plasmodium or not has been identified.
Conclusion
This preliminary study did not detect the presence of simian plasmodium in human populations living in the rainforest of the DRC. Studies with larger samples and with more advanced techniques should still be conducted.
Keywords: Malaria, simian plasmodium, DR Congo