Malaria Outbreak, Djibouti, 2019

International audienceno abstrac

Purpose of Review: Following Paraguay and Argentina, several countries from the Amazon region aim to eliminate malaria. To achieve this, all key affected and vulnerable populations by malaria, including people working on gold mining sites, must be considered. What is the situation of malaria in these particular settings and what are the challenges? This literature review aims to compile knowledge to answer these questions. Recent Findings: The contexts in which gold miners operate are very heterogeneous: size and localization of mines, links with crime, administrative status of the mines and of the miners, mobility of the workers or national regulations. The number of malaria cases has been correlated with deforestation (Brazil, Colombia), gold production (Colombia), gold prices (Guyana), or location of the mining region (Peru, Colombia, Venezuela, Guyana). The burden of malaria in gold mines differs between territories: significant in Guyana, French Guiana, or Venezuela; lower in Brazil. Although Plasmodiumvivax causes 75% of malaria cases in the Americas, P. falciparum is predominant in several gold mining regions, especially in the Guiana Shield. Because of the remoteness from health facilities, self-medication with under-the-counter antimalarials is frequent. This constitutes a significant risk for the emergence of new P. falciparum parasites resistant to antimalarial drugs. Summary: Because of the workers’ mobility, addressing malaria transmission in gold mines is essential, not only for miners, but also to prevent the (re-)emergence of malaria. Strategies among these populations should be tailored to the context because of the heterogeneity of situations in different territories. The transnational environment favoring malaria transmission also requires transborder and regional cooperation, where innovative solutions should be considered and evaluated.

In December 2010, a Plasmodium vivax malaria outbreak occurred among French forces involved in a mission to control illegal gold mining in French Guiana. The findings of epidemiological and entomological investigations conducted after this outbreak are presented here. Data related to malaria cases reported to the French armed forces epidemiological surveillance system were collected during the epidemic period from December 2010 to April 2011. A retrospective cohort study was conducted to identify presumed contamination sites. Anopheles mosquitoes were sampled at the identified sites using Mosquito Magnet and CDC light traps. Specimens were identified morphologically and confirmed using molecular methods (sequencing of ITS2 gene and/or barcoding). Anopheles infections with Plasmodium falciparum and P. vivax were tested by both enzyme-linked immunosorbent assay and real-time PCR. Seventy-two P. vivax malaria cases were reported (three were mixed P. falciparum/P. vivax infections), leading to a global attack rate of 26.5 % (72/272). Lack of compliance with vector control measures and doxycycline chemoprophylaxis was reported by patients. Two illegal gold mining sites located in remote areas in the primary forest were identified as places of contamination. In all, 595 Anopheles females were caught and 528 specimens were formally identified: 305 Anopheles darlingi, 145 Anopheles nuneztovari s.l., 63 Anopheles marajoara and 15 Anopheles triannulatus s.l. Three An. darlingi were infected by P. falciparum (infection rate: 1.1 %) and four An. marajoara by P. vivax (infection rate: 6.4 %). The main drivers of the outbreak were the lack of adherence by military personnel to malaria prevention measures and the high level of malaria transmission at illegal gold mining sites. Anopheles marajoara was clearly implicated in malaria transmission for the first time in French Guiana. The high infection rates observed confirm that illegal gold mining sites must be considered as high level malaria transmission areas in the territory. Illegal gold mining activities are challenging the control of malaria in French Guiana. Collaboration with neighbouring countries is necessary to take into account mobile populations such as gold miners. Malaria control strategies in the French armed forces must be adapted to P. vivax malaria and sylvatic Anopheles species.

Respiratory tract infections (RTIs) are common among Hajj pilgrims, but risk factors for RTIs and respiratory pathogen acquisition during the Hajj are not clearly identified. Based on previous studies, most frequent pathogens acquired by Hajj pilgrims were investigated: rhinovirus, human coronaviruses, influenza viruses, Streptococcus pneumoniae, Staphylococcus aureus, Klebsiella pneumoniae and Haemophilus influenzae. 485 pilgrims were included. 82.1% presented with RTIs. Respiratory chronic diseases were associated with cough, Influenza-like illness (ILI) and the acquisition of H. influenzae. Vaccination against invasive pneumococcal diseases (IPD) and influenza was associated with a decrease in the acquisition of S. pneumoniae and prevalence of ILI (aRR = 0.53, 95%CI [0.39–0.73] and aRR = 0.69, 95%CI [0.52–0.92] respectively). Individuals carrying rhinovirus and H. influenzae-S. pneumoniae together were respectively twice and five times more likely to have respiratory symptoms. Individual with H. influenzae-K. pneumoniae carriage were twice (p = 0.04) as likely to develop a cough. The use of disposable handkerchiefs was associated with a decrease in the acquisition of S. aureus (aRR = 0.75, 95%CI [0.57–0.97]). Results could be used to identify pilgrims at increased risk of RTIs and acquisition of respiratory pathogens. Results also confirm the effectiveness of influenza and IPD vaccinations in reducing ILI symptoms and acquisition of S. pneumoniae carriage respectively.