Predictors of antimalarial self-medication in illegal gold miners in French Guiana: a pathway towards artemisinin resistance.

BACKGROUND: Malaria is endemic in French Guiana (FG), South America. Despite the decrease in cases in the local population, illegal gold miners are very affected by malaria (22.3% of them carried Plasmodium spp.). Self-medication seems to be very common, but its modalities and associated factors have not been studied. The aim of this study was to evaluate parasite susceptibility to drugs and to document behaviours that could contribute to resistance selection in illegal gold miners. METHODS: This multicentric cross-sectional study was conducted in resting sites along the FG-Surinamese border. Participating gold miners working in FG completed a questionnaire and provided a blood sample. RESULTS: From January to June 2015, 421 illegal gold miners were included. Most were Brazilian (93.8%) and 70.5% were male. During the most recent malaria attack, 45.5% reported having been tested for malaria and 52.4% self-medicated, mainly with artemisinin derivatives (90%). Being in FG during the last malaria attack was the main factor associated with self-medication (adjusted OR = 22.1). This suggests that access to malaria diagnosis in FG is particularly difficult for Brazilian illegal gold miners. Treatment adherence was better for persons who reported being tested. None of the 32 samples with Plasmodium falciparum presented any mutation on the pfK13 gene, but one isolate showed a resistance profile to artemisinin derivatives in vitro. CONCLUSIONS: The risk factors for the selection of resistance are well known and this study showed that they are present in FG with persons who self-medicated with poor adherence. Interventions should be implemented among this specific population to avoid the emergence of artemisinin resistance.

[Importance of a regional observatory of malarial chemoresistance, an emerging public health problem in the Guyanas region]. / Intérêt d'un observatoire régional de la chimiorésistance du paludisme, problème émergent de santé publique dans la région des Guyanes.

A regular implementation of prophylactic and therapeutic decision trees was organized on a consensus basis in Cayenne, French Guiana in 1990, 1995 and 2002. The updated recommendations were based on the knowledge of the in vitro chemosensitivity profiles of the local isolates, mainly coming from big rivers (Maroni and Oyapock, frontiers with Suriname and Brazil, respectively; and more recently Approuague). Most of the patients infected by Plasmodium falciparum were followed by the medical staff of the main hospitals (Cayenne and Saint-Laurent) and of the peripheral health centers in remote areas. Consequently the epidemiological situation and evolution of chemoresistance have been widely observed on a long-term (since 1994) basis in the Maroni region. Yet, we have only partial information coming from the Oyapock valley, even though an important (most of the time) illegal immigration has been developing since the 90s' leading to a notable modification of the epidemiological status of malaria in this eastern region, including a regular increase of P. vivax infections. Presently very little P. vivax chloroquine (and mefloquine) resistance has been identified but this result could lead to a real public health problem in a near future. As such, the National Reference Center on Plasmodium Chemoresistance in the French West Indies and Guiana (CNRCP-AG in French) is a unique observatory of malaria chemoresistance in the Guyanese shield which works with research laboratories of the Institut Pasteur, Paris. This network strategy offers a very attractive perspective for applications of modern tools, including the validation of chemoresistance molecular markers, for malaria control at both medical and public health levels. Some examples related to chloroquine and artemether resistance are given.

Monkeys of the rainforest in French Guiana are natural reservoirs for P. brasilianum/P. malariae malaria.

Monkey blood samples were collected from 214 monkeys relocated as part of the wildlife rescue organized in French Guiana during the filling of the Petit Saut Dam on the Sinnamary River. These samples were tested for malaria parasites by microscopy of thick blood filsm and by nested PCR for small subunit rRNA genes (SSUrRNA). Parasitic blood forms similar to Plasmodium brasilianum were detected in 4 monkey species: Alouatta seniculus macconnelli, Saguinus midas midas, Pithecia pithecia and Ateles paniscus paniscus, with the highest prevalence in Alouatta monkeys. PCR was more sensitive than the conventional method for detecting low-grade parasitaemia in positive monkeys. The examination of blood films indicated that 5.6% of the animals carried parasites whereas the nested PCR for ribosomal DNA indicated a prevalence of 11.3%. The P. brasilianum SSUrRNA gene sequence was analysed and aligned with those from P. malariae, P. falciparum and P. vivax. This suggested that P. brasilianum and P. malariae are very closely related. Similar results were obtained from analysis of the sequences in P. malariae and P. brasilianum isolates of a polymorphic gene fragment analogous to the merozoite surface protein-1 (MSP-1) gene of P. falciparum. The P. brasilianum/P. malariae sequences were more similar to those of P. vivax than to those of P. falciparum, at least in the gene region examined. The high degree of DNA homology in the sequences of the SSUrRNA and msp1-like genes is consistent with other characterizations demonstrating a taxonomic relationship between P. brasilianum and P. malariae species. Our results provide further evidence that P. brasilianum and P. malariae are virtually identical and should probably be considered to be a single malaria species. This raises the question as to whether monkeys living in the rainforest are natural reservoirs for both simian and human malaria. These results have implications for the interpretation of the current epidemiological situation in French Guiana.