The Plasmodium falciparum-Specific Human Memory B Cell Compartment Expands Gradually with Repeated Malaria Infections

Immunity to Plasmodium falciparum (Pf) malaria is only acquired after years of repeated infections and wanes rapidly without ongoing parasite exposure. Antibodies are central to malaria immunity, yet little is known about the B-cell biology that underlies the inefficient acquisition of Pf-specific humoral immunity. This year-long prospective study in Mali of 185 individuals aged 2 to 25 years shows that Pf-specific memory B-cells and antibodies are acquired gradually in a stepwise fashion over years of repeated Pf exposure. Both Pf-specific memory B cells and antibody titers increased after acute malaria and then, after six months of decreased Pf exposure, contracted to a point slightly higher than pre-infection levels. This inefficient, stepwise expansion of both the Pf-specific memory B-cell and long-lived antibody compartments depends on Pf exposure rather than age, based on the comparator response to tetanus vaccination that was efficient and stable. These observations lend new insights into the cellular basis of the delayed acquisition of malaria immunity

Tuberculosis among transhumant pastoralist and settled communities of south-eastern Mauritania

Background: Transhumant pastoralists of Mauritania were assumed to have a high prevalence of tuberculosis (TB) because of reduced access to diagnostic testing. No population-based survey on TB has been published for Mauritania. Objective: The goal of this study was to estimate the prevalence of presumptive TB cases among mobile pastoralists and villagers in a remote zone of Mauritania. Design: In the south-eastern province of Hodh Ech Chargui, 250 adult pastoralists and 250 villagers were randomly enrolled using multistage cluster sampling in February 2012. A TB centre nurse examined participants using a standard clinical protocol, and a participant questionnaire was completed. Focus group discussions and interviews were conducted with community members and health personnel, respectively. Results: Fourteen new presumptive TB cases were identified, leading to an overall prevalence of 2.8%, (95% confidence interval (CI) 1.5–4.7%). The prevalence was non-significantly higher among villagers than pastoralists (3.6% vs. 2.0%). Assuming illness duration was 3 years and all presumptive cases started treatment, an overall crude incidence of 933 cases/100,000 was derived. Five of six presumptive cases in Djiguenni were confirmed by sputum smear microscopy, but none out of eight presumptive cases were confirmed in Néma, although the same nurse performed all clinical examinations in both departments. This result was attributed to the use of expired reagents in Néma. Communities mentioned distance rather than lack of information as the main constraint to seeking diagnosis, but poor diagnostic centre performance also delayed decision-making. Conclusions: TB prevalences were high among both pastoralists and villagers. None of the 14 presumptive cases sought prior diagnostic testing. TB diagnostic centres in the remote rural study zone were poorly equipped. These centres must remain in operation to reduce TB incidence in vulnerable communities in insecure remote rural zones and to reach national health goals

Acute acoustic trauma in the French armed forces during 2007–2014

International audienceCONTEXT:Despite existing preventive measures, the number of acute acoustic trauma (AAT) cases reported to the French Military Epidemiological Surveillance System (MESS) remains high.AIMS:The objective of this study was to describe AAT and the preventive measures already implemented.SUBJECTS AND METHODS:We conducted a descriptive cross-sectional analysis of AAT using data from the MESS for the period 2007-2014. In addition, we reviewed the current prevention measures that exist in the French armed forces.STATISTICAL ANALYSIS USED:Comparisons between different incidence rates were made by Poisson and quasi-Poisson regression.RESULTS:Between 2007 and 2014, 10,487 AAT cases were reported to the MESS, with a significant decrease in 2013 (P < 0.001). AAT incidence rates were the highest among those aged <25 years - 14.3 per 1000 person-years (PYs) (P < 0.001), and those in the army; with 8.1 per 1000 PYs (P < 0.001), and men had almost twice the risk of women (P < 0.001). AAT mainly occurred in training schools or at camps during exercises. The main prevention actions identified were the following: official regulations, education, making hearing protection devices (HPDs) available for all service members, and regular hearing monitoring. A working group has been set up and has proposed an informative chapter in the weapon handling instruction book, an AAT simulator, and a new HPD, the 3M® earplug, with an information brochure.CONCLUSIONS:AAT rates decreased from 2007 to 2014 in the French armed forces. Further analysis is needed to identify the underlying factors involved to improve the prevention actions proposed. The MESS and targeted surveys will assess the impact of the different prevention measures implemented

Emergence of Indian lineage of ECSA chikungunya virus in Djibouti, 2019

The chikungunya virus (CHIKV) originated from Africa and has spread worldwide. Since 2017, multiple chikungunya outbreaks have been reported in the Horn of Africa, without molecular characterization. In November 2019, an autochthonous acute chikungunya infection was diagnosed in a French patient living in Djibouti, marking the re-emergence of the virus in the country. The strain was isolated and fully sequenced. Phylogenetic analysis revealed that the Djiboutian strain belongs to the Indian lineage of the Eastern/Central/South African (ECSA) genotype. Two mutations highly increasing the virus’s fitness in Aedes aegypti, the sole vector present in Djibouti city, were identified

Monitoring of returnees from Ebola-affected areas: lessons learned based on the experience of French armed forces deployed in Guinea, 2015

Introduction During the 2014-15 Ebola virus disease (EVD) outbreak in West Africa, French armed forces were involved in the treatment and management of Ebola patients in Guinea. The constant flow of military personnel returning from their deployment posed a risk of secondary dissemination of the Ebola virus. Our objective was to describe the follow-up of returning service members that was implemented to prevent this risk of dissemination in France. Method For the French military, a specific complementary follow-up was added to the national monitoring to take into account the need for a detailed record for follow-up of returning military personnel and to keep the military chain of command informed. Results All the 410 service members deployed in Guinea underwent monitoring among whom 22 were suspected of EVD. Three of them were considered as possible EVD cases but none of them was tested positive for EVD. Conclusion The monitoring organized for French service members deployed in Guinea made it possible to follow all exposed military personnel after their return, know their health status on a near real-time basis and be aware of all alerts. To reach this goal the collaboration with French national health agencies was necessary and should be improved in the future

Epidemiological and entomological studies of a malaria outbreak among French armed forces deployed at illegal gold mining sites reveal new aspects of the disease's transmission in French Guiana

International audienceBackground: 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. Methods: 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. Results: 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 %). Discussion: 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. Conclusions: 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

Malaria in French Guiana Linked to Illegal Gold Mining

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Sharp decrease in malaria incidence among the French armed forces in French Guiana

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