Vector competence of Aedes albopictus field populations from Reunion Island exposed to local epidemic dengue viruses.

Dengue virus (DENV) is the most prevalent mosquito-borne Flavivirus that affects humans worldwide. Aedes albopictus, which is naturally infected with the bacteria Wolbachia, is considered to be a secondary vector of DENV. However, it was responsible for a recent DENV outbreak of unprecedented magnitude in Reunion Island, a French island in the South West Indian Ocean. Moreover, the distribution of the cases during this epidemic showed a spatially heterogeneous pattern across the island, leading to questions about the differential vector competence of mosquito populations from different geographic areas. The aim of this study was to gain a better understanding of the vector competence of the Ae. albopictus populations from Reunion Island for local DENV epidemic strains, while considering their infection by Wolbachia. Experimental infections were conducted using ten populations of Ae. albopictus sampled across Reunion Island and exposed to three DENV strains: one strain of DENV serotype 1 (DENV-1) and two strains of DENV serotype 2 (DENV-2). We analyzed three vector competence parameters including infection rate, dissemination efficiency and transmission efficiency, at different days post-exposition (dpe). We also assessed whether there was a correlation between the density of Wolbachia and viral load/vector competence parameters. Our results show that the Ae. albopictus populations tested were not able to transmit the two DENV-2 strains, while transmission efficiencies up to 40.79% were observed for the DENV-1 strain, probably due to difference in viral titres. Statistical analyses showed that the parameters mosquito population, generation, dpe and area of sampling significantly affect the transmission efficiencies of DENV-1. Although the density of Wolbachia varied according to mosquito population, no significant correlation was found between Wolbachia density and either viral load or vector competence parameters for DENV-1. Our results highlight the importance of using natural mosquito populations for a better understanding of transmission patterns of dengue.

High risk human papillomavirus prevalence and genotype distribution in Reunion Island.

OBJECTIVE: The primary objective of this study was to assess the prevalence and genotypes of human papilloma virus (HPV) in Reunion Island. STUDY DESIGN: In this retrospective study, data were collected from the database of microbiology and anatomopathology laboratories from August 1st 2020 to July 31st 2021. RESULTS: The overall prevalence of human papillomavirus (HPV) in Reunion Island was 14.5 %. The most common HPV genotypes in Reunion Island, were as follows: cluster of HPV 56 + 59 + 66, representing 3.3 % of all samples, cluster of HPV 35 + 39 + 68 (3.2 %), HPV 16 (2.9 %), HPV 33 + 58 (2.3 %) and HPV 52 (2.2 %). HPV types contained in the vaccine accounted for 59.3 % of HPV-positive samples and significantly resulted in more severe cytological lesions compared to HPV types that were not included in the vaccine (p < 0.01). Cervical dysplasia were identified in 57.3 % of HPV-positive cases. Multiple infections were detected in 23.2 % of the cases and were more frequent among younger women (<30 years) and in pathological smears (p < 0.001). CONCLUSION: In this study, we highlighted that HPV genotypes contained in the vaccine are the most represented in Réunion Island and are the most likely to generate significant cytological abnormalities. Therefore, continuous efforts are necessary to increase HPV vaccination coverage, which is currently in the island among the lowest in developed countries, despite the high mortality rate associated with cervical cancer. Furthermore, considering the inequal offensive capacity of each HPV, identifying patients' HPV infection subtype, could allow customized management and follow-up.

Determinants of adult sedentary behavior and physical inactivity for the primary prevention of diabetes in historically disadvantaged communities: A representative cross-sectional population-based study from Reunion Island.

Populations undergoing extensive and rapid socio-economic transitions including historically disadvantaged communities face an increased risk of type-2 diabetes (T2D). In recent years, sedentary behavior and physical inactivity have been considered modifiable determinants when developing primary prevention programs to reduce T2D incidence. Reunion Island is a French overseas department with an increasing T2D population and a high level of socio-economic inequality. The objectives of our study were to identify the individual, social, and environmental factors associated with sedentary behavior and physical inactivity among the Reunion Island adult population, and to highlight these findings in order to propose T2D primary prevention strategies aiming at alleviating local social inequalities in health (SIH). In 2021, we conducted a population-based cross-sectional telephone survey using random sampling. Participants included adults over 15 years old living in ordinary accommodation on Reunion Island (n = 2,010). Using a sequential approach, multinomial logistic regression model (explaining 3 profiles of interest: sedentary/inactive, sedentary/active, non-sedentary/inactive), and sampling-design weighted estimates, we found that 53.9% [95% confidence interval: 51.1 to 56.7%] of participants had sedentary behavior and 20.1% [95% CI: 17.8 to 22.5%] were inactive. Abandoning physical activity due to the COVID-19 pandemic (p<0.001), final secondary school diploma or above (p = 0.005), student as professional status (p≤0.005) and living in fewer poor neighborhoods located far from city centers (p = 0.030) were four conditions independently associated with sedentary/inactive and/or sedentary/active profiles. Based on these findings, to help reduce SIH, we used a typology of actions based on the underlying theoretical interventions including four main action categories: strengthening individuals (using person-based strategies), strengthening communities, improving living and working conditions, and promoting health-based macro-policies. Our findings suggest several directions for reducing lifestyle risk factors and enhancing T2D primary prevention programs targeting psychosocial, behavioral, and structural exposures.

Mucocutaneous Manifestations in Patients with Dengue Fever: From the EPIDENGUE Cohort on Reunion Island.

Nearly 4 billion people live in a dengue risk area worldwide. The prevalence of dengue-related mucocutaneous manifestations and their association with severe dengue differ across studies. The aim of the study was to describe the characteristics of patients with dengue-related mucocutaneous manifestations and to investigate those were associated with severe dengue. A retrospective study was conducted in 2019 among patients with a positive RT-PCR for dengue at the University Hospital of Reunion, which has been experiencing a re-emergence of dengue since 2018. Of 847 patients with confirmed dengue, 283 (33.4%) developed mucocutaneous manifestations. Only manifestations of dehydration such as glossitis, dysgeusia, or conjunctivitis were associated with severe dengue, unlike pruritus and rash, in bivariate analysis but not in multivariate analysis. The rash and pruritus of dengue appear to be accompanied by a pronounced flu-like syndrome in younger people without comorbidity or severity, although careful examination of mucous membranes would better identify signs of dehydration and thus cases likely to worsen.

Characterization of Six Ampeloviruses Infecting Pineapple in Reunion Island Using a Combination of High-Throughput Sequencing Approaches.

The cultivation of pineapple (Ananas comosus) is threatened worldwide by mealybug wilt disease of pineapple (MWP), whose etiology is not yet fully elucidated. In this study, we characterized pineapple mealybug wilt-associated ampeloviruses (PMWaVs, family Closteroviridae) from a diseased pineapple plant collected from Reunion Island, using a high-throughput sequencing approach combining Illumina short reads and Nanopore long reads. Reads co-assembly resulted in complete or near-complete genomes for six distinct ampeloviruses, including the first complete genome of pineapple mealybug wilt-associated virus 5 (PMWaV5) and that of a new species tentatively named pineapple mealybug wilt-associated virus 7 (PMWaV7). Short reads data provided high genome coverage and sequencing depths for all six viral genomes, contrary to long reads data. The 5' and 3' ends of the genome for most of the six ampeloviruses could be recovered from long reads, providing an alternative to RACE-PCRs. Phylogenetic analyses did not unveil any geographic structuring of the diversity of PMWaV1, PMWaV2 and PMWaV3 isolates, supporting the current hypothesis that PMWaVs were mainly spread by human activity and vegetative propagation.

A Comparative Study of Human Leptospirosis between Mayotte and Reunion Islands Highlights Distinct Clinical and Microbial Features Arising from Distinct Inter-Island Bacterial Ecology.

Leptospirosis is a neglected zoonosis for which investigations assessing host-pathogen interaction are scarce. The aim of this study was to compare the severity and bacterial species involved in human cases of leptospirosis on Reunion and Mayotte islands, territories located in the southwest Indian Ocean that have recorded high human leptospirosis incidence but display fairly distinct epidemiological situations. A retrospective multicentric study including all patients over 18 years of age from Mayotte or Reunion with proven leptospirosis was conducted from January 2018 to April 2020. This study collected demographic, geographical, clinical, and biological data. Overall, 490 patients were included, 222 on Mayotte and 268 on Reunion. More patients were hospitalized on Reunion (n = 215, 80%) compared with Mayotte (n = 102, 46%). Severe disease was more common on Reunion (n = 75, 28%) than on Mayotte (n = 22, 10%). The dominant Leptospira species on Reunion was Leptospira interrogans (79%) followed by Leptospira borgpetersenii (21%), contrasting with the epidemiological situation on Mayotte where L. interrogans was found in only a minority of patients (10%). The high frequency of severe cases on Reunion could be explained not only by higher comorbidities but also by the higher occurrence of L. interrogans infections compared with Mayotte. Finally, the distribution of cases linked to L. borgpetersenii was found almost exclusively on the west coast of Reunion, raising the potential role of a ruminant reservoir.

Case Report: Severe Community-Acquired Pneumonia in Réunion Island due to Acinetobacter baumannii.

Acinetobacter baumannii (Ab) is a well-known nosocomial pathogen that has emerged as a cause of community-acquired pneumonia (CAP) in tropical regions. Few global epidemiological studies of CAP-Ab have been published to date, and no data are available on this disease in France. We conducted a retrospective chart review of severe cases of CAP-Ab admitted to intensive care units in Réunion University Hospital between October 2014 and October 2022. Eight severe CAP-Ab cases were reviewed. Median patient age was 56.5 years. Sex ratio (male-to-female) was 3:1. Six cases (75.0%) occurred during the rainy season. Chronic alcohol use and smoking were found in 75.0% and 87.5% of cases, respectively. All patients presented in septic shock and with severe acute respiratory distress syndrome. Seven patients (87.5%) presented in cardiogenic shock, and renal replacement therapy was required for six patients (75.0%). Five cases (62.5%) presented with bacteremic pneumonia. The mortality rate was 62.5%. The median time from hospital admission to death was 3 days. All patients received inappropriate initial antibiotic therapy. Acinetobacter baumannii isolates were all susceptible to ceftazidime, cefepime, piperacillin-tazobactam, ciprofloxacin, gentamicin, and imipenem. Six isolates (75%) were also susceptible to ticarcillin, piperacillin, and cotrimoxazole. Severe CAP-Ab has a fulminant course and high mortality. A typical case is a middle-aged man with smoking and chronic alcohol use living in a tropical region and developing severe CAP during the rainy season. This clinical presentation should prompt administration of antibiotic therapy targeting Ab.

Sexual health services for adolescents on Reunion Island: results from a descriptive interview-based study.

OBJECTIVES: To describe the experiences of sexual health services available for adolescents aged 15-19 years on Reunion Island. DESIGN: A qualitative descriptive study was conducted from 3 December 2022 to 24 October 2023. Data were analysed using the phenomenological interpretative method. SETTING: Centre Hospitalier Universitaire of Reunion Island. PARTICIPANTS: 15 participants were recruited through convenience sampling, but 3 of them did not attend the interviews. INTERVENTIONS: Face-to-face or videoconferencing open-ended individual interviews. PRIMARY AND SECONDARY OUTCOME MEASURES: Barriers and facilitators to access sexual health services, relationship between adolescents and healthcare professionals when using these services and suggestions made by adolescents for improving access to care and quality of care. RESULTS: In total, 12 adolescents were included with most being female (11 with a mean age of 18 years). Most interviewees were in a relationship, lived in urban areas and had sexual intercourse (nine, respectively). Participants attended high school, university and preparatory college (four, respectively). Most interviews were face to face (11). The mean duration of the interviews was 32 min. Two themes revealing the experiences of sexual health services emerged. Participants described maintaining sexual health as a difficult journey in their quest for information about sexual health and the available services provided. Participants demonstrated that they had the ability to cope with the consequences of unprotected sex. CONCLUSIONS: To date, sexual health services available on Reunion Island may not meet the needs of adolescents. Implementation of a strategy aimed at providing young people with skills, addressing their needs and working with them in a collaborative manner may be necessary. Appropriate teaching methods and the training of healthcare professionals should also be considered.

Quantifying climatic suitability for tourism in Southwest Indian Ocean Tropical Islands: Applying the Holiday Climate Index to Réunion Island.

Climate is a key resource for tourists and tourism providers. Varied approaches to quantifying climate resources for tourism have been developed in the last 40 years, computing indices from a range of meteorological variables to measure the comparative climatic suitability of different destinations through time. This study provides the first application of a tourism climate index in the tropical southwest Indian Ocean, applying the recently developed Holiday Climate Index (HCI) for Réunion Island. The suitability of this index is evaluated for the case of this French department, with a particular focus on air conditioning availability in tourism accommodation establishments as this index excludes night-time thermal comfort. Both iterations of the HCI (HCIBeach and HCIUrban) are computed with meteorological data from Roland Garros Airport for the period 1991-2020, exploring monthly, annual, and seasonal climatic suitability. Mean monthly HCI scores reveal considerable seasonality in climatic suitability for tourism on the island with scores ranging from 89.3 ('excellent') to 36.9 ('marginal') for the HCIBeach and 85.0 ('excellent') to 27.5 ('unacceptable') for the HCIUrban, with more favourable scores calculated for July and August, displaying a clear austral winter peak seasonal classification. Over the 30-year period, there is no statically significant change in mean annual climatic suitability, and at a monthly scale, only one month of the year for each index displays statistically significant trends. These results are important in informing tourism strategies for the island to maximise visitor satisfaction through targeting advertising more deliberately for peak touristic climate suitability during the winter months.

PRESOLRE: study protocol for a primary school-based, cluster randomised controlled trial of three sun exposure risk prevention strategies on Reunion Island.

INTRODUCTION: Reunion Island, a French overseas department, is located in the southern hemisphere, close to the Capricorn tropic. This island has a multicultural and multiethnic population of 860 000 inhabitants, a quarter of whom are at high risk of developing skin cancer due to intense ultraviolet radiation. Melanoma is responsible for the majority of skin cancer deaths. The early prevention of melanoma is based on sun protection in childhood, but French regulations are not adapted to the environmental conditions of this tropical region.The main objective of our study is to evaluate the effectiveness of three sun protection programs conducted in Reunionese primary schools through a pupil knowledge questionnaire. METHODS AND ANALYSIS: PRESOLRE is an interventional, open-label, cluster-randomised controlled trial, in four parallel arms, that is being conducted throughout 2022-2023 on Reunion Island. The trial design assumes an escalation interventional effect using: first, a control arm without proposed intervention (arm 1); second, an arm whose classes are encouraged to use the validated educational programme 'Living With the Sun' (LWS) (arm 2); third, an arm whose classes are encouraged to use both 'LWS' combined with 'Mission Soleil Réunion's sun protection awareness programme (arm 3); fourth, an arm benefiting from an intervention similar to arm 3, combined with the distribution of hats, sunglasses and sun creams (arm 4). In all, 1780 pupils from 18 classes of 20 pupils, on average, will be included. Randomisation applies to the classes of pupils (so defined as clusters). The primary outcome is based on the proportion of correct answers to the knowledge questions after the awareness programme, compared between the four arms using a linear mixed model with random intercept. ETHICS AND DISSEMINATION: The study obtained ethics approval in 2022 (ID: 2022-A00350-43). Results will be published in peer-reviewed journals. TRIAL REGISTRATION NUMBER: NCT05367180.

Dynamics of emergence and genetic diversity of dengue virus in Reunion Island from 2012 to 2022.

BACKGROUND: Dengue is a major public health concern in Reunion Island, marked by recurrent epidemics, including successive outbreaks of dengue virus serotypes 1 and 2 (DENV1 and DENV2) with over 70,000 cases confirmed since 2017. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we used Oxford Nanopore NGS technology for sequencing virologically-confirmed samples and clinical isolates collected between 2012 and 2022 to investigate the molecular epidemiology and evolution of DENV in Reunion Island. Here, we generated and analyzed a total of 499 DENV1, 360 DENV2, and 18 DENV3 sequences. By phylogenetic analysis, we show that different genotypes and variants of DENV have circulated in the past decade that likely originated from Seychelles, Mayotte and Southeast Asia and highly affected areas in Asia and Africa. CONCLUSIONS/SIGNIFICANCE: DENV sequences from Reunion Island exhibit a high genetic diversity which suggests regular introductions of new viral lineages from various Indian Ocean islands. The insights from our phylogenetic analysis may inform local health authorities about the endemicity of DENV variants circulating in Reunion Island and may improve dengue management and surveillance. This work emphasizes the importance of strong local coordination and collaboration to inform public health stakeholders in Reunion Island, neighboring areas, and mainland France.

Upscaling irradiation protocols of Aedes albopictus pupae within an SIT program in Reunion Island.

The implementation of the sterile insect technique against Aedes albopictus relies on many parameters, in particular on the success of the sterilization of males to be released into the target area in overflooding numbers to mate with wild females. Achieving consistent sterility levels requires efficient and standardized irradiation protocols. Here, we assessed the effects of exposure environment, density of pupae, irradiation dose, quantity of water and location in the canister on the induced sterility of male pupae. We found that the irradiation of 2000 pupae in 130 ml of water and with a dose of 40 Gy was the best combination of factors to reliably sterilize male pupae with the specific irradiator used in our control program, allowing the sterilization of 14000 pupae per exposure cycle. The location in the canister had no effect on induced sterility. The results reported here allowed the standardization and optimization of irradiation protocols for a Sterile Insect Technique program to control Ae. albopictus on Reunion Island, which required the production of more than 300,000 sterile males per week.

A Holistic Approach to Cardiometabolic and Infectious Health in the General Population of Reunion Island: The REUNION Study.

INTRODUCTION: Reunion Island is a French overseas department in the South West Indian Ocean with a unique multi-ethnic population. Cardiovascular diseases are the most common chronic conditions with higher prevalences of hypertension and diabetes compared to mainland France. Moreover, Reunion Island is particularly exposed to vector-borne diseases such as chikungunya and dengue. Our objective is to describe the prevalence of cardiometabolic and infectious diseases in Reunion Island and explore causal mechanisms linking these diseases. METHODS: The REUNION study is an ongoing French prospective study. From January 2022, 2,000 consenting participants (18-68 years old) are being recruited from the general population according to polling lists and random generation of cellphone number. Baseline examination consists of (i) general health examination, assessment of cardiovascular risk factors, markers of subclinical atherosclerosis, bronchial obstruction, neuropathic and autonomic dysfunction, (ii) questionnaires to determine sociodemographic characteristics, diet, exposure to vector-borne diseases, mental health and cognitive functions, social inequalities in health and ethnic origins, (iii) biological sampling for determination of cardiovascular risk factors, seroprevalence of infectious diseases, innovative lipid biomarkers, advanced omics, composition of intestinal, periodontal and skin microbiota, and biobanking. CONCLUSIONS: The REUNION study should provide new insights into the prevalence of cardiometabolic and infectious diseases, as well as their potential associations through the examination of various environmental pathways and a wide range of health aspects.

Socioeconomic and cultural factors associated with pap smear screening among French women living in Réunion Island.

BACKGROUND: Réunion Island is a French overseas territory located in the southern Indian Ocean, with a challenging socioeconomic and multicultural context. Compared to mainland France, Réunion has an overincidence and overmortality of cervical cancer. In order to investigate these two issues, it is important to evaluate the barriers and potential levers to Pap smear screening among female inhabitants of the island. We aimed to identify the specific socio-demographic factors, cultural factors, and living conditions associated with Pap smear screening in Réunion, with a view to increasing uptake. METHODS: We conducted a Knowledge Attitude Behavior and Practices (KABP) survey on cervical cancer screening practices among women aged between 25 and 65 years old living in Réunion Island, selected using random digit dialing sampling. Data were collected using Computer Assistant Telephone Interviews. Weighted chi-squared tests and Student's t-tests were used to compare women who had up-to-date Pap smear screening with women who did not. Weighted logistic models were used to identify the factors associated with not having up-to-date screening. RESULTS: A total of 1000 women were included in the study. Of these, 88.1% had a Pap smear test during the previous three years. Factors independently associated with not being up to date were as follows: aged over 55 (AOR 2.3 [1.2-4.3]), no children (AOR 2.5 [1.4-4.3]), having free universal health coverage (AOR 1.7 [1.1-2.7]), an income per unit consumption lower than 1500€ per month (AOR 2.0 [1.1-3.7]), low health literacy (AOR 2.7 [1.7-4.1]), not consulting a general practitioner in the prior 12 months (AOR 3.6 [2.0-6.5]), and a BMI > 30 (AOR 2.6 [1.5-4.4]). CONCLUSIONS: This is the first large-scale survey focusing on recommended Pap smear screening uptake in Réunion Island. Although self-reported screening incidence was higher than in mainland France, national screening policies must take into account the island's diverse social and cultural characteristics (e.g., an ageing population, low health literacy), while implementing actions to fight against poverty and increase general access to healthcare.

Severe leptospirosis in tropical and non-tropical areas: A comparison of two french, multicentre, retrospective cohorts.

BACKGROUND: Leptospirosis is an anthropozoonosis that occurs worldwide but is more common in tropical regions. Severe forms may require intensive care unit (ICU) admission. Whether the clinical patterns and outcomes differ between tropical and non-tropical regions with similar healthcare systems is unclear. Our objective here was to address this issue by comparing two cohorts of ICU patients with leptospirosis managed in mainland France and in the overseas French department of Réunion, respectively. METHODOLOGY/PRINCIPAL FINDINGS: We compared two retrospective cohorts of patients admitted to intensive care for severe leptospirosis, one from Reunion Island in the Indian Ocean (tropical climate) and the other from metropolitan France (temperate climate). Chi-square and Student's t tests were used for comparisons. After grouping the two cohorts, we also performed multiple correspondence analysis and hierarchical clustering to search for distinct clinical phenotypes. The Réunion and Metropolitan France cohorts comprised 128 and 160 patients respectively. Compared with the Réunion cohort, the metropolitan cohort had a higher mean age (42.5±14.1 vs. 51.4±16.5 years, p<0.001). Severity scores, length of stay and mortality did not differ between the two cohorts. Three phenotypes were identified: hepato-renal leptospirosis (54.5%) characterized by significant hepatic, renal and coagulation failure, with a mortality of 8.3%; moderately severe leptospirosis (38.5%) with less severe organ failure and the lowest mortality rate (1.8%); and very severe leptospirosis (7%) manifested by neurological, respiratory and cardiovascular failure, with a mortality of 30%. CONCLUSIONS/SIGNIFICANCE: The outcomes of severe leptospirosis requiring ICU admission did not differ between tropical and temperate regions with similar healthcare access, practices, and resources, despite some differences in patient characteristics. The identification of three different clinical phenotypes may assist in the early diagnosis and management of severe leptospirosis.

Analysis of endonasal sinus surgery in a private outpatient setting in a tropical environment: A STROBE analysis.

OBJECTIVES: To evaluate results and failure factors in endonasal surgery in a private outpatient setting in a tropical environment. MATERIAL AND METHOD: A single-center observational study included 337 patients consecutively undergoing endonasal surgery in a private hospital on Réunion Island, a French overseas administrative Département in the Indian Ocean between 2019 and 2021. The main objective was to assess the success rate of the outpatient pathway. Secondary objectives comprised analysis of complications and identification and management of factors for failure of outpatient management. The study was conducted according to the STROBE editorial guideline. RESULTS: The 337 surgeries notably comprised 112 septoplasties (37.5%), 104 meatotomies (30.3%), 15 unilateral total ethmoidectomies (4.6%), 48 bilateral total ethmoidectomies with sphenoidotomy (14.3%), and 18 Draf procedures (5.5%). Seventy-five percent of patients (252/337) were operated on as outpatients, with a success rate of 90% (227/252 patients). The rate of severe intraoperative complications was 1.5% (5/337). On multivariate analysis, 3 variables were identified as influencing risk of failure of the outpatient pathway: emergency analgesia in the operating room [odds ratio (OR): 91.61; 95% confidence interval (CI): 22.8-540.3], operating time (OR: 1.05; 95% CI: 1.01-1.09), and recovery room time (OR: 1.02; 95% CI: 1.01-1.03). CONCLUSION: Our study in a tropical environment found eligibility and success rates for outpatient endonasal surgery similar to those in metropolitan France. This makes surgical and anesthesiological training a key factor in the success of outpatient care, while the location of the care structure and the climate seem to have little impact.

Diagnostic performance of the WHO definition of probable dengue within the first 5 days of symptoms on Reunion Island.

The relevance of the World Health Organization (WHO) criteria for defining probable dengue had not yet been evaluated in the context of dengue endemicity on Reunion Island. The objective of this retrospective diagnostic study was to evaluate the diagnostic performance of the 2009 WHO definition of probable dengue and to propose an improvement thereof. From the medical database, we retrieved the data of subjects admitted to the emergency department of the University Hospital of Reunion Island in 2019 with suspected dengue fever (DF) within a maximum of 5 days post symptom onset, and whose diagnosis was confirmed by a Reverse Transcriptase Polymerase Chain Reaction (RT-PCR). The intrinsic characteristics of probable dengue definitions were reported in terms of sensitivity, specificity, positive and negative likelihood ratios (LR+ and LR-), using RT-PCR as the gold standard. Of the 1,181 subjects who exhibited a positive RT-PCR, 652 (55%) were classified as probable dengue. The WHO definition of probable dengue yielded a sensitivity of 64% (95%CI 60-67%), a specificity of 57% (95%CI 52-61%), a LR+ of 1.49 (95%CI 1.33-1.67), and a LR- of 0.63 (95%CI 0.56-0.72). The sensitivity and LR- for diagnosing and ruling out probable dengue could be improved by the addition of lymphopenia on admission (74% [95%CI: 71-78%] and 0.54 [95%CI: 0.46-0.63] respectively), at the cost of slight reductions of specificity and LR+ (48% [95%CI: 44-53%] and 1.42 [95%CI: 1.29-1.57], respectively). In the absence of, or when rapid diagnostic testing is unreliable, the use of the improved 2009 WHO definition of probable dengue could facilitate the identification of subjects who require further RT-PCR testing, which should encourage the development of patient management, while also optimizing the count and quarantine of cases, and guiding disease control.