Exploring fine-scale urban landscapes using satellite data to predict the distribution of Aedes mosquito breeding sites.

BACKGROUND: The spread of mosquito-transmitted diseases such as dengue is a major public health issue worldwide. The Aedes aegypti mosquito, a primary vector for dengue, thrives in urban environments and breeds mainly in artificial or natural water containers. While the relationship between urban landscapes and potential breeding sites remains poorly understood, such a knowledge could help mitigate the risks associated with these diseases. This study aimed to analyze the relationships between urban landscape characteristics and potential breeding site abundance and type in cities of French Guiana (South America), and to evaluate the potential of such variables to be used in predictive models. METHODS: We use Multifactorial Analysis to explore the relationship between urban landscape characteristics derived from very high resolution satellite imagery, and potential breeding sites recorded from in-situ surveys. We then applied Random Forest models with different sets of urban variables to predict the number of potential breeding sites where entomological data are not available. RESULTS: Landscape analyses applied to satellite images showed that urban types can be clearly identified using texture indices. The Multiple Factor Analysis helped identify variables related to the distribution of potential breeding sites, such as buildings class area, landscape shape index, building number, and the first component of texture indices. Models predicting the number of potential breeding sites using the entire dataset provided an R² of 0.90, possibly influenced by overfitting, but allowing the prediction over all the study sites. Predictions of potential breeding sites varied highly depending on their type, with better results on breeding sites types commonly found in urban landscapes, such as containers of less than 200 L, large volumes and barrels. The study also outlined the limitation offered by the entomological data, whose sampling was not specifically designed for this study. Model outputs could be used as input to a mosquito dynamics model when no accurate field data are available. CONCLUSION: This study offers a first use of routinely collected data on potential breeding sites in a research study. It highlights the potential benefits of including satellite-based characterizations of the urban environment to improve vector control strategies.

The role of health mediation in investigation of Hantavirus cases among informal settlements inhabitants of Cayenne area, French Guiana, 2022-2023.

Context: In 2022, four severe cases of Hantavirus pulmonary syndrome (HPS) were reported in patients from informal settlements around Cayenne, the main city in French Guiana. Regional Health Agency (RHA) was commissioned by the French Public Health Agency to estimate the seroprevalence of Hantavirus infections in the neighborhoods of confirmed cases of HPS. RHA then commissioned the French Red Cross (FRC) mobile public health team, providing support in environmental health issues to the population living in informal settlements by health mediators, to facilitate the investigation. The objective of this study was to describe the health mediators' activities set up to improve the efficiency of the investigation. Methods: The health mediators' team was specifically trained by virologist and infectiologist specialized in HPS. They helped the investigating team and health workers at various steps of the investigation. These interventions are then described in the results section. Results: The investigation took place between Nov. 2022 and March 2023 in three neighborhoods. During the pre-investigation activities, the mediators raised awareness about HPS of 343 people, among whom 319 (93%) planned to participate in the investigation. Altogether, 274 people finally participated in the investigation, including, i.e., 30.8% of the estimated population living in the three concerned settlements. The global proportion of patients with positive IgG anti-Hantavirus was 5.1%. The health mediators team supported the following steps: preliminary meetings and training modules, identification of resource persons, field visits and awareness and information campaigns (pre-investigation); on field data collection in informal settlements (per-investigation) and communication of individual results, public feedback meeting (post-investigation). Discussion/Conclusion: The involvement of mediators was probably a factor in the success of the public health response to socially vulnerable people living in the investigated neighborhoods. The preliminary prevention activities helped to raise awareness of the health risk and to enroll participants. Health mediation and outreach activities seem relevant tools of epidemiological field investigations in diseases affecting inhabitants of informal settlements.

Identifying suicidal risk factors in the French Overseas Territories with multimethod psychological autopsy (AUTOPSOM): a mixed-methods study protocol.

INTRODUCTION: Understanding suicide in more isolated territories is a challenge because of the entanglement of cultural identity with historical, geographical and sociocultural specificities. This knowledge is a necessary precondition for the implementation of targeted prevention strategies in regions such as the French overseas territories (FOT), where data concerning suicidal risk factors is still incomplete. We aim to untangle sociocultural and clinical suicide risk factors by integrating a novel anthropological and psycholinguistic approach into the psychological autopsy method. This article describes the protocol of the clinical study 'Contribution of Psychological Autopsy to the Understanding of Suicidal Behaviours in Overseas France' (AUTOPSOM study), designed to identify common or new specific suicide risk factors in four FOT. METHODS AND ANALYSIS: A multicentre epidemiological study will be carried out in four FOTs (French Polynesia, Martinique, La Reunion and French Guiana) and at a comparison site in mainland France (La Somme). The methodology will be based on a mixed-methods (quantitative and qualitative) approach using a psychological autopsy to collect clinical data and life events in the deceased's life. We implemented an exploratory multimethod strategy that combines a succession of epidemiological, anthropological, psycholinguistic and psychological methods with a semiautomated analysis of the discourse of relatives bereaved by suicide. ETHICS AND DISSEMINATION: The study protocol (first version) was approved by the French Ethics Committee (CPP OUEST II, approval #22.04267.000122) and the Ethics Committee of French Polynesia (JOPF of 5 April 2022; CEPF opinion n°91 of 29 March 2022). The overall results and the perspectives established at the end of the study will be communicated to the bereaved relatives according to their will and serve for local suicide prevention purposes. TRIAL REGISTRATION NUMBER: NCT05773898.

Research in an intercultural context: mediator-investigators of epidemiological health studies, bridges between two worlds.

Context: French Guiana is a French overseas department where very different linguistic, cultural and societal populations live together in a small area. Health issues and their specific epidemiological profiles call for research projects crossing several cultures. In this context, health mediators have a role to play in research. The aim of this study was to describe the perceptions, attitudes and opinions on research of mediators and researchers collaborating on research projects, and to describe the strengths and difficulties encountered during this cooperation. Methods: The Inter-med project was conducted in French Guiana between February 2022 and April 2023 on the base of semi-directive interviews with mediators, or researchers, all working in health research in the intercultural context of French Guiana. The socio-demographic characteristics of the participants were described. An inductive thematic analysis was carried out on all the interviews, and word occurrence analysis on certain themes. The information was triangulated with field coordination notebooks from two epidemiological surveys conducted in French Guiana between 2021 and 2022. Results: A total of 26 semi-structured interviews were conducted and 1,328 notebook pages analyzed. Mediation was described as an indispensable interface between the world of research and that of the population targeted by a survey. Mediators have a role to play at different stages of projects, in respect of good clinical practice, ethics and legislation. They act as interfaces between languages, concepts and representations. Their profession remains under-defined and under-dimensioned. The jobs offered are often precarious. Mediation work is emotionally costly, calls on soft skills and requires a combination of rigor and flexibility. All these aspects are implemented in the specific world of research, where there are common concepts and divergent perceptions. Researchers and mediators converge on a common goal: improving health. Conclusion: This study covers several aspects of the development and implementation of research projects. Respect for good clinical practice and people, transparency and data quality are redundant concerns, and this study touches on ethnocentrism, stigmatization and cultural representations. This study points out that the integration and recognition of mediators could be beneficial in research conducted in a cross-cultural context.

Clinical and parasitological features of Leishmania infection among gold miners in the Oiapoque basin, an international Brazil-French Guiana border.

Gold miners working illegally in mines live in poor health conditions related to their strenuous work and precarious housing. Therefore, they are at higher risk for infectious diseases. American tegumentary leishmaniasis (ATL) appears to be of great concern to the population living in the Guiana Shield region. Our aim was to describe their demographic characteristics, the clinical features of cutaneous leishmaniasis (CL), and the frequency of Leishmania infection in people working in illegal gold mines in French Guiana. A cross-sectional study was carried out from October to December 2019 in Oiapoque city, Amapá, Brazil. Indeed, many gold miners working in French Guiana are originally from Brazil, and from Oiapoque in particular. A total of 105 participants from 31 different mining sites in French Guiana were recruited. Suspected Leishmania infection was confirmed by the following: detection of kDNA in blood or the lesion site; detection of specific antibodies; or detection of IFN-γ release after blood incubation with leishmanial antigens (IGRA-Leish). Nine active CL cases, 38 healed ATL (hATL) and 58 cases with no history of ATL (noATL), were identified. Only half of the treated hATL (50.0%; n = 14) reported having been assisted by a health care unit and the others treated themselves. PCR-kDNA for Leishmania was positive in the blood of 100% of CL cases. Curiously, blood PCR-kDNA was positive in 13% of hATL patients and in 15.5% of noATL patients. The IGRA-Leish was positive in 60.5% of hATL and in 37.9% of noATL. In addition to scars suggestive of CL, 71% of hATL had laboratory evidence of Leishmania infection. Restriction fragment polymorphism (RFLP) of the hsp70 gene identified a sympatric circulation of L. (V.) guyanensis (n = 4), L. (V.) braziliensis (n = 1), L. (L.) amazonensis (n = 2), L. (V.) shawi (n = 1) and L. (V.) naiffi/shawi (n = 1). Taking the laboratory techniques and the clinical evaluations together, 76% (n = 80) of the 105 participants had evidence of Leishmania infection. These results suggests that illegal gold miners working in French Guiana are at high risk for infection with different species of Leishmania, but their illegal condition and remoteness make it difficult for them to access health services.

Core principles of Malakit intervention for transferability in other contexts.

To eliminate malaria, all populations must be included. For those who are not reached by the health care system, specific interventions must be tailor-made. An innovative Malakit strategy, based on the distribution of self-diagnosis and self-treatment kits, has been evaluated in the Suriname-French Guiana- Amapá (Brazil) region. The results showed effectiveness and good acceptability. The Malakit intervention is complex and has many components. Its transferability requires adaptation to other populations and regions, while retaining the main features of the intervention. This article provides the keys to adapting, implementing and evaluating it in other contexts facing residual malaria in hard-to-reach and/or mobile populations. The process of transferring this intervention includes: diagnosis of the situation (malaria epidemiology, characteristics of the population affected) to define the relevance of the strategy; determination of the stakeholders and the framework of the intervention (research project or public health intervention); adaptation modalities (adaptation of the kit, training, distribution strategy); the role of community health workers and their need for training and supervision. Finally, evaluation needs are specified in relation to prospects for geographical or temporal extension. Malaria elimination is likely to increasingly involve marginalized people due to climate change and displacement of populations. Evaluation of the transferability and effectiveness of the Malakit strategy in new contexts will be essential to increase and refine the evidence of its value, and to decide whether it could be an additional tool in the arsenal recommended in future WHO guidelines.

[Sickle cell disease in French Guiana: assessing 30 years of neonatal screening (1992-2021)]. / La drépanocytose en Guyane : bilan de 30 années de dépistage néonatal (1992-2021).

Background: Sickle cell disease is one of the most common genetic diseases in France. In French Guiana, neonatal screening was introduced in 1992, at the same time as other screening programs for childhood diseases. The aim of this study is to describe the organization of newborn screening for sickle cell disease in French Guiana. Materials and methods: We used several data sources: data collected from hospital records since 2005, activity reports from the national neonatal screening program and data from screening campaigns organized by the Drepaguyane association between 2010 and 2021 on 1,300 subjects. Blood samples from newborns are collected by capillary or venous sampling and absorbed on blotting paper (Guthrie) at the same time as those for other neonatal screenings. The dried papers are sent to the inter-regional laboratory in Lille, for further processing. In Saint-Laurent-du-Maroni, in order to reduce the proportion of people lost to follow-up, a double screening is carried out and the results are returned before discharge from the maternity hospital. All data were entered into an anonymous Excel file. The data were analyzed using STATA software. Results: Among the 175,593 screened neonates between 1992 and 2021, screening detected 823 infants with sickle cell disease and 17,950 heterozygotes. Sickle cell genotypes include 493 SS (60%), 302 SC (37%) and 28 S-Beta-thalassemia (3%). The incidence of sickle cell disease was 1/213, 95% CI [1/236-1/204], and that of heterozygotes 1/10, IC 95% [1/12-1/8]. The majority of these children (52%) were from the Maroni region. The delay between screening and test results was 7 days. Only pathological results (homozygous, heterozygous) were communicated to parents and/or the attending physician by post. These data confirm the upward trend in the number of children screened for sickle cell disease in French Guiana. Data from screening campaigns organized by the Drepaguyane association have enabled to describe the distribution of the various abnormal hemoglobin fractions, and to confirm that HbS is more frequent in Western French Guiana. In Cayenne, in 2021, the active file comprised 699 patients, including 266 children under 18 years old. Discussion and conclusion: This study provides valuable data on 30 years of neonatal screening for sickle cell disease in French Guiana, and on the evolution of sickle cell disease patients. It confirms that French Guiana is the French territory with the highest incidence of sickle cell disease. This incidence continues to rise over time. The study reveals the improvement in the organization of sickle cell disease management in French Guiana between 1992, when screening was introduced, and the present day. It highlights the role of patient associations in the fight against this disease, by organizing awareness and screening campaigns. These data will be used to guide public health policies in the pursuit of improved care and primary prevention.

Anthropology and ethnobotany in health mediation: an illustration of a clinical, personalized approach for Haitian migrants in a French Guianese hospital.

Introduction: In French Guiana, a European territory in Guiana shield in the Amazon area, close to 40% of the current population was born abroad. In this context, it is important to listen to the experiences of migrants to better understand the difficulties encountered within the healthcare pathways. This is the aim of ANRS Parcours d'Haïti project, an epidemiological, biographical and socio-anthropological study conducted on a representative sample of the Haitian community in French Guiana and focusing on the social determinants of health. Methodology: Within the framework of this study, the Infectious and Tropical Diseases clinical team of Cayenne Hospital has established close collaboration with health mediators and the ethnobotanist anthropologist of the study. To illustrate the contribution of a personalized approach to health mediation, we report the case of a migrant woman of Haitian origin admitted to the Infectious and Tropical Diseases Unit. We highlight the different socio-cultural aspects addressed and their place in the care process through a thematic discussion and socio-anthropological analysis of the care relationship, based on participatory ethnography and inductive analysis of an in-depth interview with the patient. Result: This example illustrates the need for a multidisciplinary approach to ensure culturally adapted care for patients. Personal interviews are important because they allow to better take into account the cultural specificities of patients' experiences and the socio-cultural environment in which they live (and especially, in the case of Haitian patients, their religious affiliation). By allowing them to speak and express themselves freely, they integrate not only their own cultural baggage, but also their own expectations and representations of the disease they suffer from and how it should be treated. Ultimately, this tripartite collaboration between patient, caregiver, and anthropologist or health mediator leads to a better therapeutic alliance. Conclusion: The analysis of this health care relationship is emblematic of the issue of cultural competence and pre-conceptualizes what intercultural mediation in health care could be, as close as possible to the caregiver and the individual.

[Oncology in French Guiana: A challenge to win]. / La cancérologie en Guyane : un défi à gagner.

French Guiana is an equatorial, multicultural, overseas territory in South America. The region is unique: a wealthy country with a universal healthcare system, but significant poverty, which bears little resemblance to its neighbors Brazil and Suriname. Cancer is the second leading cause of death. The incidence of cancer is lower than in France, stages are generally more advanced and the prognosis worse. To date, oncology has been organized through a joint venture between local institutions and healthcare professionals and a cancer center in mainland France, in line with the recommendations of the Institut National du Cancer. The implementation of a medical project and a complete medical studies curriculum in French Guiana is a tremendous opportunity for the development of oncology. The main challenges are consolidating medical care for patients, quality control, genetic oncology, molecular biology, implementation of radiotherapy and nuclear medicine, clinical and translational research, and teaching programs. Working in oncology in French Guiana is exciting because of the scientific interest (particular characteristics of cancers, notably the role of viral or micro-organism-induced carcinogenesis, genetic factors in these populations with African and Asian roots, and the importance of a public health policy) and human interest (patients from different cultures; all of them bring original approaches to health and illness that need to be deciphered in order to offer quality care). This requires the support of healthcare professionals who are enthusiastic about this unique adventure.

Inferred drought-induced plant allocation shifts and their impact on drought legacy at a tropical forest site.

While droughts predominantly induce immediate reductions in plant carbon uptake, they can also exert long-lasting effects on carbon fluxes through associated changes in leaf area, soil carbon, etc. Among other mechanisms, shifts in carbon allocation due to water stress can contribute to the legacy effects of drought on carbon fluxes. However, the magnitude and impact of these allocation shifts on carbon fluxes and pools remain poorly understood. Using data from a wet tropical flux tower site in French Guiana, we demonstrate that drought-induced carbon allocation shifts can be reliably inferred by assimilating Net Biosphere Exchange (NBE) and other observations within the CARbon DAta MOdel fraMework. This model-data fusion system allows inference of optimized carbon and water cycle parameters and states from multiple observational data streams. We then examined how these inferred shifts affected the duration and magnitude of drought's impact on NBE during and after the extreme event. Compared to a static allocation scheme analogous to those typically implemented in land surface models, dynamic allocation reduced average carbon uptake during drought recovery by a factor of 2.8. Additionally, the dynamic model extended the average recovery time by 5 months. The inferred allocation shifts influenced the post-drought period by altering foliage and fine root pools, which in turn modulated gross primary productivity and heterotrophic respiration for up to a decade. These changes can create a bust-boom cycle where carbon uptake is enhanced some years after a drought, compared to what would have occurred under drought-free conditions. Overall, allocation shifts accounted for 65% [45%-75%] of drought legacy effects in modeled NBE. In summary, drought-induced carbon allocation shifts can play a substantial role in the enduring influence of drought on cumulative land-atmosphere CO2 exchanges and should be accounted for in ecosystem models.

Kinetics of glucose-6-phosphate dehydrogenase (G6PD) activity during Plasmodium vivax infection: implications for early radical malaria treatment.

BACKGROUND: Plasmodium vivax relapses due to dormant liver hypnozoites can be prevented with primaquine. However, the dose must be adjusted in individuals with glucose-6-phosphate-dehydrogenase (G6PD) deficiency. In French Guiana, assessment of G6PD activity is typically delayed until day (D)14 to avoid the risk if misclassification. This study assessed the kinetics of G6PD activity throughout P. vivax infection to inform the timing of treatment. METHODS: For this retrospective monocentric study, data on G6PD activity between D1 and D28 after treatment initiation with chloroquine or artemisinin-based combination therapy were collected for patients followed at Cayenne Hospital, French Guiana, between January 2018 and December 2020. Patients were divided into three groups based on the number of available G6PD activity assessments: (i) at least two measurements during the P. vivax malaria infection; (ii) two measurements: one during the current infection and one previously; (iii) only one measurement during the malaria infection. RESULTS: In total, 210 patients were included (80, 20 and 110 in groups 1, 2 and 3, respectively). Data from group 1 showed that G6PD activity remained stable in each patient over time (D1, D3, D7, D14, D21, D28). None of the patients with normal G6PD activity during the initial phase (D1-D3) of the malaria episode (n = 44) was categorized as G6PD-deficient at D14. Patients with G6PD activity < 80% at D1 or D3 showed normal activity at D14. Sex and reticulocyte count were statistically associated with G6PD activity variation. In the whole sample (n = 210), no patient had severe G6PD deficiency (< 10%) and only three between 10 and 30%, giving a G6PD deficiency prevalence of 1.4%. Among the 100 patients from group 1 and 2, 30 patients (26.5%) were lost to follow-up before primaquine initiation. CONCLUSIONS: In patients treated for P. vivax infection, G6PD activity did not vary over time. Therefore, G6PD activity on D1 instead of D14 could be used for primaquine dose-adjustment. This could allow earlier radical treatment with primaquine, that could have a public health impact by decreasing early recurrences and patients lost to follow-up before primaquine initiation. This hypothesis needs to be confirmed in larger prospective studies.

Detection of Anaplasma and Ehrlichia bacteria in humans, wildlife, and ticks in the Amazon rainforest.

Tick-borne bacteria of the genera Ehrlichia and Anaplasma cause several emerging human infectious diseases worldwide. In this study, we conduct an extensive survey for Ehrlichia and Anaplasma infections in the rainforests of the Amazon biome of French Guiana. Through molecular genetics and metagenomics reconstruction, we observe a high indigenous biodiversity of infections circulating among humans, wildlife, and ticks inhabiting these ecosystems. Molecular typing identifies these infections as highly endemic, with a majority of new strains and putative species specific to French Guiana. They are detected in unusual rainforest wild animals, suggesting they have distinctive sylvatic transmission cycles. They also present potential health hazards, as revealed by the detection of Candidatus Anaplasma sparouinense in human red blood cells and that of a new close relative of the human pathogen Ehrlichia ewingii, Candidatus Ehrlichia cajennense, in the tick species that most frequently bite humans in South America. The genome assembly of three new putative species obtained from human, sloth, and tick metagenomes further reveals the presence of major homologs of Ehrlichia and Anaplasma virulence factors. These observations converge to classify health hazards associated with Ehrlichia and Anaplasma infections in the Amazon biome as distinct from those in the Northern Hemisphere.

Small for Gestational Age Newborns in French Guiana: The Importance of Health Insurance for Prevention.

Objectives: Small for gestational age (SGA) newborns have a higher risk of poor outcomes. French Guiana (FG) is a territory in South America with poor living conditions. The objectives of this study were to describe risk factors associated with SGA newborns in FG. Methods: We used the birth cohort that compiles data from all pregnancies that ended in FG from 2013 to 2021. We analysed data of newborns born after 22 weeks of gestation and/or weighing more than 500 g and their mothers. Results: 67,962 newborns were included. SGA newborns represented 11.7% of all newborns. Lack of health insurance was associated with SGA newborns (p < 0.001) whereas no difference was found between different types of health insurance and the proportion of SGA newborns (p = 0.86). Mothers aged less than 20 years (aOR = 1.65 [1.55-1.77]), from Haiti (aOR = 1.24 [1.11-1.39]) or Guyana (aOR = 1.30 [1.01-1.68]) and lack of health insurance (aOR = 1.24 [1.10-1.40]) were associated with SGA newborns. Conclusion: Immigration and precariousness appear to be determinants of SGA newborns in FG. Other studies are needed to refine these results.

Emerging and re-emerging infectious diseases in pregnant women in an amazonian region: a large retrospective study from French Guiana.

PURPOSE: Over the past decade, the Amazon basin has faced numerous infectious epidemics. Our comprehension of the actual extent of these infections during pregnancy remains limited. This study aimed to clarify the clinical and epidemiological features of emerging and re-emerging infectious diseases during pregnancy in western French Guiana and along the Maroni River over the previous nine years. METHODS: This retrospective cohort study enrolled pregnant women living in west French Guiana territory and giving birth in the only local referral center after 22 weeks of gestation between 2013 and 2021. Data on symptomatic or asymptomatic biologically confirmed emerging or re-emerging diseases during pregnancy was collected. RESULTS: Six epidemic waves were experienced during the study period, including 498 confirmed Zika virus infections (2016), 363 SARS-CoV-2 infections (2020-2021), 87 chikungunya virus infections (2014), 76 syphilis infections (2013-2021), and 60 dengue virus infections (2013-2021) at different gestational ages. Furthermore, 1.1% (n = 287) and 1.4% (n = 350) of pregnant women in west French Guiana were living with HIV and HTLV, respectively. During the study period, at least 5.5% (n = 1,371) faced an emerging or re-emerging infection during pregnancy. CONCLUSION: These results highlight the diversity, abundance, and dynamism of emerging and re-emerging infectious agents faced by pregnant women in the Amazon basin. Considering the maternal and neonatal adverse outcomes associated with these infections, increased efforts are required to enhance diagnosis, reporting, and treatment of these conditions.

Coverage of BCG Vaccination for children aged until 7 years old and its determinants in French Guiana.

INTRODUCTION: The overall incidence of tuberculosis (TB) in France is low; thus, BCG vaccination is no longer mandatory. In French Guiana - a French overseas territory - BCG vaccination is strongly recommended because the incidence of TB is high in the context of mass immigration from endemic countries with low BCG vaccination rates. Thus, it is important to assess Bacillus Calmette-Guérin (BCG) vaccination coverage and its predictors. METHODS: We used data from the 2014 French Guiana Yellow Fever survey, which was conducted by the Observatoire Régional de la Santé de Guyane. Demographic and immunization data from eligible children and their families were collected using a questionnaire. Children who had an immunization card and who were no older than 7 years of age at the time of the survey were eligible. The Coverage for BCG and other mandatory vaccines were estimated; the delay in BCG vaccination was also computed. Univariate and multivariate analyses identified predictors associated with BCG immunization and BCG delayed immunization (after 2 months of age). RESULTS AND CONCLUSION: Overall, 469 children were eligible for this study. The total BCG coverage was 79.5 %, and the proportion of children vaccinated with delay was 50.7 %. The multivariate analysis indicated that BCVA was significantly greater among children younger than 3 years of age, whose household head was employed and whose education level was greater. None of the predictors were associated with the delay of BCG vaccination.

Different profiles of soil phosphorous compounds depending on tree species and availability of soil phosphorus in a tropical rainforest in French Guiana.

BACKGROUND: The availability of soil phosphorus (P) often limits the productivities of wet tropical lowland forests. Little is known, however, about the metabolomic profile of different chemical P compounds with potentially different uses and about the cycling of P and their variability across space under different tree species in highly diverse tropical rainforests. RESULTS: We hypothesised that the different strategies of the competing tree species to retranslocate, mineralise, mobilise, and take up P from the soil would promote distinct soil 31P profiles. We tested this hypothesis by performing a metabolomic analysis of the soils in two rainforests in French Guiana using 31P nuclear magnetic resonance (NMR). We analysed 31P NMR chemical shifts in soil solutions of model P compounds, including inorganic phosphates, orthophosphate mono- and diesters, phosphonates, and organic polyphosphates. The identity of the tree species (growing above the soil samples) explained > 53% of the total variance of the 31P NMR metabolomic profiles of the soils, suggesting species-specific ecological niches and/or species-specific interactions with the soil microbiome and soil trophic web structure and functionality determining the use and production of P compounds. Differences at regional and topographic levels also explained some part of the the total variance of the 31P NMR profiles, although less than the influence of the tree species. Multivariate analyses of soil 31P NMR metabolomics data indicated higher soil concentrations of P biomolecules involved in the active use of P (nucleic acids and molecules involved with energy and anabolism) in soils with lower concentrations of total soil P and higher concentrations of P-storing biomolecules in soils with higher concentrations of total P. CONCLUSIONS: The results strongly suggest "niches" of soil P profiles associated with physical gradients, mostly topographic position, and with the specific distribution of species along this gradient, which is associated with species-specific strategies of soil P mineralisation, mobilisation, use, and uptake.

Molecular epidemiology identifies the expansion of the DENV2 epidemic lineage from the French Caribbean Islands to French Guiana and mainland France, 2023 to 2024.

In 2023, dengue virus serotype 2 (DENV2) affected most French overseas territories. In the French Caribbean Islands, viral circulation continues with > 30,000 suspected infections by March 2024. Genome sequence analysis reveals that the epidemic lineage in the French Caribbean islands has also become established in French Guiana but not Réunion. It has moreover seeded autochthonous circulation events in mainland France. To guide prevention of further inter-territorial spread and DENV introduction in non-endemic settings, continued molecular surveillance and mosquito control are essential.

Wastewater sequencing as a powerful tool to reveal SARS-CoV-2 variant introduction and spread in French Guiana, South America.

The origin of introduction of a new pathogen in a country, the evolutionary dynamics of an epidemic within a country, and the role of cross-border areas on pathogen dynamics remain complex to disentangle and are often poorly understood. For instance, cross-border areas represent the ideal location for the sharing of viral variants between countries, with international air travel, land travel and waterways playing an important role in the cross-border spread of infectious diseases. Unfortunately, monitoring the point of entry and the evolutionary dynamics of viruses in space and time within local populations remain challenging. Here we tested the efficiency of wastewater-based epidemiology and genotyping in monitoring Covid-19 epidemiology and SARS-CoV-2 variant dynamics in French Guiana, a tropical country located in South America. Our results suggest that wastewater-based epidemiology and genotyping are powerful tools to monitor variant introduction and disease evolution within a tropical country but the inclusion of both clinical and wastewater samples could still improve our understanding of genetic diversity co-circulating. Wastewater sequencing also revealed the cryptic transmission of SARS-CoV-2 variants within the country. Interestingly, we found some amino acid changes specific to the variants co-circulating in French Guiana, suggesting a local evolution of the SARS-CoV-2 variants after their introduction. More importantly, our results showed that the proximity to bordering countries was not the origin of the emergence of the French Guianese B.1.160.25 variant, but rather that this variant emerged from an ancestor B.1.160 variant introduced by European air plane travelers, suggesting thus that air travel remains a significant risk for cross-border spread of infectious diseases. Overall, we suggest that wastewater-based epidemiology and genotyping provides a cost effective and non-invasive approach for pathogen monitoring and an early-warning tool for disease emergence and spread within a tropical country.

Tuberculosis in prison: What about after release? The example of French Guiana.

INTRODUCTION: Tuberculosis is a major cause of mortality worldwide. Prisoners in Guiana have multiple risk factors. The primary objective of this study was to describe tuberculosis occurring in prison and after release in French Guiana between 2008 and 2020. Secondary objectives were to identify tuberculosis risk factors and determine annual incidences. METHODS: A retrospective cohort study of tuberculosis cases was carried out at the Guiana prison between 2008 and 2020. Data were collected from prison registers and cross-referenced with the list of tuberculosis notifications in French Guiana. RESULTS: A total of 36 cases of tuberculosis were studied. Incidence was high, at 263/100,000 per year, higher than elsewhere in France and comparable to that in Brazil. Despite visibly effective screening on entry, with little evidence of intra-prison circulation of tuberculosis, 39% of patients were diagnosed within two years of leaving prison (76% were symptomatic). This could be explained by the high prevalence of latent forms (LTI). DISCUSSION: Continued screening on entry, in combination with annual radiological and clinical screening, and reinforced follow-up on release seem indicated to improve patient management and the search for possible LTI.

Multi-locus sequence analysis unveils a novel genus of filarial nematodes associated with ticks in French Guiana.

Filarial nematodes of the Dipetalonema lineage include tick-borne filarioids that infect both domestic and wild vertebrate hosts, but they remain understudied in many cases. In this study, we conducted a molecular characterization of a Dipetalonema-like filarioid (DLF) recently identified in two tick species in French Guiana, South America. While the cox1 mitochondrial gene was the sole marker initially sequenced for describing DLF, its classification and phylogenetic relationship with other members of the Dipetalonema lineage were unclear. Therefore, we better characterized DLF through the sequencing of six additional gene markers and conducted phylogenetic analyses. Based on this multi-locus typing scheme, DLF exhibited significant divergence from known genera and species of filarioids, or other sequences available in public databases, suggesting its potential classification as a novel genus within the Dipetalonema lineage. Phylogenetic analyses further unveiled a close evolutionary relationship between DLF and all other filarioids associated with Acari (ticks and mites) within a robust monophyletic subclade in the Dipetalonema lineage. Overall, these findings confirm the existence of a specialized, Acari-borne group of filarioids and underscore the need for comprehensive investigations into their epidemiology and potential impact on animal health.

Title: Une analyse de séquences multi-locus dévoile un nouveau genre de nématodes filaires, associé aux tiques en Guyane française. Abstract: Les filaires de la lignée Dipetalonema comprennent des espèces transmises par les tiques qui infectent à la fois des hôtes vertébrés domestiques et sauvages, mais qui restent sous-étudiées dans de nombreux cas. Dans cette étude, nous avons réalisé une caractérisation moléculaire d'un filarioïde ressemblant à Dipetalonema (FRD) récemment identifié dans deux espèces de tiques en Guyane française. Alors que la séquence du gène mitochondrial cox1 était le seul marqueur génétique initialement séquencé pour décrire FRD, sa classification et sa relation phylogénétique avec d'autres membres de la lignée Dipetalonema étaient incertaines. Par conséquent, nous avons caractérisé plus précisément DLF en séquençant six gènes supplémentaires et en réalisant des analyses phylogénétiques. Sur la base de ce typage multi-locus, FRD présentait une divergence significative par rapport aux genres et espèces connus de filarioïdes, ou à d'autres séquences disponibles dans les bases de données publiques, suggérant sa classification potentielle en tant que nouveau genre au sein de la lignée Dipetalonema. Les analyses phylogénétiques ont en outre révélé une relation évolutive étroite entre FRD et tous les autres filarioïdes associés aux tiques et acariens au sein d'un sous-clade monophylétique dans la lignée Dipetalonema. Dans l'ensemble, ces résultats confirment l'existence d'un groupe spécialisé de filarioïdes transmis par les tiques et acariens et soulignent la nécessité d'études approfondies sur leur épidémiologie et leur impact potentiel sur la santé animale.