Emilie Javelle

Background: Malaria elimination in Latin America (LATAM) is challenged by heterogeneous Plasmodium vivax transmission intensity, yet regional genomic evidence from malaria molecular surveillance (MMS) remains scarce. We aimed to generate regional genomic evidence to inform malaria control. Methods: We analyzed 578 P. vivax isolates collected in seven LATAM countries (2010–2024) using the Pv AmpliSeq Peru targeted sequencing assay. We investigated genetic diversity, complexity of infection, population structure, relatedness and connectivity, and candidate drug-resistance variants diversity. Findings: Genetic diversity (He: 0.15–0.39) and polyclonality (0–33%) varied across LATAM. Parasite populations showed country-level and subnational structure, including marked differentiation among Loreto, Amazonas and Tumbes in Peru (FST: 0.23–0.62). Country-level connectivity was limited but occurred across the Peru–Ecuador and Peru–Brazil borders. Highly related pairs (≥90% IBD) predominated in Amazonas (80.2%), Venezuela (75.4%) and Tumbes (56.9%). At lower thresholds, parasite connections among Venezuela, Colombia, Ecuador and Tumbes, geographically coincided with the regional migration corridor from Venezuela to Peru. Candidate pvmdr1 variants for reduced chloroquine susceptibility were uncommon (3.8–5.4%), whereas antifolate resistance mutations were widespread (42.8–80.6%). Interpretation: The geographic structure suggests that P. vivax transmission is mainly maintained locally, while connectivity in some border areas indicates parasite movement between countries by human mobility. Control strategies should be tailored to local transmission settings and supported by coordinated cross-border surveillance and longitudinal sentinel MMS, particularly in hotspots and border areas.

Background: Long-term follow-up data on the travel-associated burden of vector-borne diseases (VBDs) are scarce. A prospective multi-site observational study was conducted to delineate the longitudinal course, symptom patterns, physical and mental burden and factors associated with prolonged illness in travellers after four VBDs. Methods: Patients with confirmed travel-associated acute chikungunya, dengue, Zika or falciparum malaria were recruited at 15 GeoSentinel sites from 2016 to 2021. Persistent signs and symptoms were evaluated at 1, 3, 6, 12 and 18 months (M) post-diagnosis, using a multi-modular study questionnaire with quality of life (QOL) evaluated by 12-item short-form health survey (SF-12). Demographic, premorbid and acute disease characteristics were tested in multivariate analyses to determine factors associated with persistence of symptoms at M3. Missing data were imputed by rules and statistical methods. Results: Among 273 patients enrolled, 35 (13%) had chikungunya, 110 (40%) dengue, 19 (7%) Zika and 109 (40%) falciparum malaria. Median age was 38 years (interquartile range 30–49), 148/273 (54%) were men. At M3, 24/35 (69%) of chikungunya, 27/110 (25%) of dengue, 8/19 (42%) of Zika and 12/109 (11%) of malaria patients had persistent symptoms. The proportion of symptomatic chikungunya patients was 18/35 (51%) at M6, mainly due to musculoskeletal symptoms including arthritis and stiffness. In dengue patients, fatigue and musculoskeletal symptoms without arthritis persisted until 1 year. Zika patients reported persisting headaches, musculoskeletal symptoms including arthritis and fatigue. One month after malaria, fatigue was the main persisting symptom, which resolved almost completely at M3. At M12, 6/35 (17%) of chikungunya, 5/110 (5%) dengue, 3/19 (16%) Zika and only 1/109 (1%) of malaria patients were still symptomatic. Impaired QOL was noted at M3 by 23/35 (66%) of patients with chikungunya, 20/110 (18%) with dengue and 6/19 (32%) with Zika but only 4/109 (4%) with malaria. Female sex, Zika, chikungunya and musculoskeletal symptoms during acute infection were associated with persistent M3 symptoms. Conclusions: Post-arboviral symptoms and impaired QOL persisted beyond 6 months after chikungunya, dengue and Zika. In contrast, post-malaria fatigue syndrome resolved within 3 months.

Les maladies infectieuses lors des opérations militaires restent la première cause de morbi-mortalité non liée au combat, avec un potentiel épidémique. Le but de ce travail a été d’optimiser la prévention et la gestion des risques infectieux en opération, en améliorant les connaissances, en proposant de nouvelles stratégies (innovations), ou en réévaluant celles déjà existantes. Nous avons ciblé les principaux risques imposés par l’actualité, qu’ils soient endémiques connus, donc accessibles à une stratégie planifiée de prévention selon les définitions de l’OMS ; ou bien émergents peu anticipés et relevant d’une réponse pour leur gestion individuelle et collective. Concernant la prévention primaire, face à la résurgence mondiale de la rougeole en 2019, nous avons conduit un travail de revue de la littérature montrant que le seul rattrapage systématique de la deuxième dose vaccinale, pourrait être insuffisant à long terme pour maintenir une protection efficace contre la maladie et prévenir les épidémies. Dans le domaine de la prévention secondaire, nous avons complété l’évaluation de la balance bénéfice-risque de la doxycycline qui est la chimioprophylaxie du paludisme dans les Armées. Nous avons montré un impact métabolique négligeable qui peut être prévenu par des règles hygiéno-diététiques simples, et un bénéfice sur la survenue de diarrhée en mission, sans dysbiose intestinale majeure. Enfin, suite à des travaux de synthèse et des expériences de terrain en tant qu’infectiologue militaire, des stratégies ont été mises au point pour la gestion et le contrôle d’émergences épidémiques en opération, principalement arboviroses et zoonoses.

In the Indian Ocean Region (IOR), chikungunya virus (CHIKV) outbreaks have surged, driven by climate factors influencing vector ecology and transmission. We analyzed GeoSentinel traveler surveillance data from 2010 to 2024 alongside multiple climate indices representing dominant modes of regional variability, including the Mascarene Subtropical High (MSH), Indian Summer Monsoon, and El Niño Southern Oscillation. Here we identified region-specific associations: in South-Central Asia, chikungunya activity correlated strongly with intensified MSH area during El Niño; in sub-Saharan Africa, links were weaker and influenced by monsoon onset and cross-equatorial flow; in Southeast Asia, outbreaks followed moderate-to-large eastward MSH expansions with lagged effects. These findings suggest that large-scale climate variability modulates chikungunya transmission dynamics across the IOR. Incorporating such climate indicators into early warning systems may enhance outbreak forecasting and guide targeted public health interventions to mitigate chikungunya spread.

Highlight/Teaser: In the wake of a large outbreak in Reunion and Mayotte, the GeoSentinel network has been signalling chikungunya cases amongst returning travellers acquired in multiple African and Asian countries between 1 August 2024 and 10 June 2025. These surveillance data suggest a resurgence of chikungunya in the Indian Ocean Region.

Dihydroartemisinin (or artenimol)–piperaquine is one of the six artemisinin-based combination therapies recommended in uncomplicated malaria treatment. However, artemisinin partial resistance has been reported in Cambodia, Laos, Vietnam, India, and, recently, in Africa. Polymorphisms in the Pfk13 gene have been described as molecular markers of artemisinin resistance and the amplification of the plasmepsine II/III (Pfpmp2/Pfpmp3) gene has been associated with piperaquine resistance. However, some therapeutic failures with this combination remain unexplained by strains’ characterization. We provide an overview on the use of dihydroartemisinin–piperaquine in malaria treatment and discuss tools available to monitor its efficacy.

The 2024 Olympics and Paralympic Games will take place in Paris and could impact health risks in the capital of France this summer. The Paris region, also named Ile de France, includes eight French departments in the north-central part of France, centred on the capital, Paris. It represents roughly 2% of the metropolitan French territory and 20% of the national population. Based on reports from the French Observatory for Research on Mega Events published in January 2024, the Paris region expects a total of 15.3 million visitors, including 840 000 (5.5%) from outside Europe, between 26 July and 8 September, i.e. over 45 days. ¹ In comparison, there were 12.7 million tourists recorded in Paris region during the 3 summer months of 2022, i.e. over 92 days, 2.5 million (20%) coming from outside Europe, which was 6% less than during the summer 2019 before the period of travel restrictions. ² Thus, forecast figures do not appear to be very different from other years, but the population flows in France during this summer season could be a game changer.