Liver involvement in dengue: A systematic review.

Liver involvement is an unusual yet frequently overlooked dengue complication. Pivotal for an efficient clinical management, the early diagnosis of dengue-associated liver involvement relies on an accurate description of its clinical and biological characteristics, its prognosis factors, its association with severe dengue and its clinical management. We conducted a systematic review by searching PubMed and Web of Science databases for original case reports, cohort and cross-sectional studies reporting the clinical and/or biological features of dengue-associated liver involvement. The study was registered in PROSPERO (CRD42021262657). Of the 2552 articles identified, 167 were included. Dengue-associated liver involvement was characterised by clinical features including abdominal pain, hepatomegaly, jaundice, nausea/vomiting, and an echogenic liver exhibiting hepatocellular necrosis and minimal inflammation. Elevated Aspartate Aminotransferase and Alanine Aminotransferase but also elevated bilirubin, Alkaline Phosphatase, gamma-glutamyl transferase, increased International Normalised Ratio, creatinine and creatine kinase, lower albumin and prolonged prothrombin and activated partial thromboplastin time were prevalent in dengue-associated liver involvement. Cardiovascular and haematological systems were frequently affected, translating in a strong association with severe dengue. Liver involvement was more common in males and older adults. It was associated with dengue virus serotype-2 and secondary infections. Early paracetamol intake increased the risk of liver involvement, which clinical management was mostly conservative. In conclusion, this systematic review demonstrates that early monitoring of transaminases, clinical assessment, and ultrasound examination allow an efficient diagnosis of dengue-associated liver involvement, enabling the early identification and management of severe dengue.

Comparing the Performance of Three Models Incorporating Weather Data to Forecast Dengue Epidemics in Reunion Island, 2018-2019.

We developed mathematical models to analyze a large dengue virus (DENV) epidemic in Reunion Island in 2018-2019. Our models captured major drivers of uncertainty including the complex relationship between climate and DENV transmission, temperature trends, and underreporting. Early assessment correctly concluded that persistence of DENV transmission during the austral winter 2018 was likely and that the second epidemic wave would be larger than the first one. From November 2018, the detection probability was estimated at 10%-20% and, for this range of values, our projections were found to be remarkably accurate. Overall, we estimated that 8% and 18% of the population were infected during the first and second wave, respectively. Out of the 3 models considered, the best-fitting one was calibrated to laboratory entomological data, and accounted for temperature but not precipitation. This study showcases the contribution of modeling to strengthen risk assessments and planning of national and local authorities.

From dengue outbreaks to endemicity: Reunion Island, France, 2018 to 2021.

BackgroundAfter 40 years of limited viral circulation, Reunion Island has since 2018 experienced recurrent dengue outbreaks of increasing intensity and severity.AimWe aimed to report on the epidemiology and characteristics of dengue in Reunion Island between 2018 and 2021.MethodsBetween 2018 and August 2021, we systematically collected data on dengue cases via an automated transmission system between the health authorities and the medical laboratories. We set up additional surveillance systems for dengue-related activity in primary care, in emergency departments and in inpatient departments.ResultsUntil 2020, despite numerous cases, outbreaks had a limited public health impact because of few severe cases, low lethality and no heavy burden for the health care system. In 2021, however, the number of severe cases increased (from 0.4% of all cases in 2018 to 0.8% in 2021), as did the number of paediatric cases (from 8% in 2018 to 15% in 2021) and atypical clinical forms of dengue (108 cases of post-dengue maculopathy). Of note, haemorrhagic forms were rare and multi-organ failure was the most frequent severity throughout the study period. In parallel, the dominant serotype switched from DENV2 to DENV1 in 2020 and DENV1 became the only serotype detected in 2021.ConclusionThese findings indicate that dengue is becoming endemic in Reunion Island. Since comorbidities associated with severity of dengue are common in the population, health authorities should carefully consider the impact of dengue when addressing public health policies.

Investigation of Dengue Infection in Asymptomatic Individuals during a Recent Outbreak in La Réunion.

The number of dengue cases has increased dramatically over the past 20 years and is an important concern, particularly as the trends toward urbanization continue. While the majority of dengue cases are thought to be asymptomatic, it is unknown to what extent these contribute to transmission. A better understanding of their importance would help to guide control efforts. In 2019, a dengue outbreak in La Reunion resulted in more than 18,000 confirmed cases. Between October 2019 and August 2020, 19 clusters were investigated in the south, west, and east of the island, enabling the recruitment of 605 participants from 368 households within a 200 m radius of the home of the index cases (ICs). No active asymptomatic infections confirmed by RT-PCR were detected. Only 15% were possible asymptomatic dengue infections detected by the presence of anti-dengue IgM antibodies. Only 5.3% of the participants had a recent dengue infection confirmed by RT-PCR. Although the resurgence of dengue in La Réunion is very recent (2016), the rate of anti-dengue IgG positivity, a marker of past infections, was already high at 43% in this study. Dengue transmission was focal in time and space, as most cases were detected within a 100-m radius of the ICs, and within a time interval of less than 7 days between infections detected in a same cluster. No particular demographic or socio-cultural characteristics were associated with dengue infections. On the other hand, environmental risk factors such as type of housing or presence of rubbish in the streets were associated with dengue infections.

Genomic evolution of SARS-CoV-2 in Reunion Island.

Island communities are interesting study sites for microbial evolution during epidemics, as their insular nature reduces the complexity of the population's connectivity. This was particularly true on Reunion Island during the first half of 2021, when international travel was restricted in order to mitigate the risk for SARS-CoV-2 introductions. Concurrently, the SARS-CoV-2 Beta variant became dominant and started to circulate at high levels for several months before being completely replaced by the Delta variant as of October 2021. Here, we explore some of the particularities of SARS-CoV-2 genomic evolution within the insular context of Reunion Island. We show that island isolation allowed the amplification and expansion of unique genetic lineages that remained uncommon across the globe. Islands are therefore potential hotspots for the emergence of new genetic variants, meaning that they will play a key role in the continued evolution and propagation of COVID-19 as the pandemic persists.

Overview of dengue outbreaks in the southwestern Indian Ocean and analysis of factors involved in the shift toward endemicity in Reunion Island: A systematic review.

BACKGROUND: Dengue is the world's most prevalent mosquito-borne viral disease. It is endemic in many tropical and subtropical countries and represents a significant global health burden. The first reports of dengue virus (DENV) circulation in the South West Indian Ocean (SWIO) islands date back to the early 1940s; however, an increase in DENV circulation has been reported in the SWIO in recent years. The aim of this review is to trace the history of DENV in the SWIO islands using available records from the Comoros, Madagascar, Mauritius, Mayotte, Seychelles, and Reunion. We focus in particular on the most extensive data from Reunion Island, highlighting factors that may explain the observed increasing incidence, and the potential shift from one-off outbreaks to endemic dengue transmission. METHODS: Following the PRISMA guidelines, the literature review focused queried different databases using the keywords "dengue" or "Aedes albopictus" combined with each of the following SWIO islands the Comoros, Madagascar, Mauritius, Mayotte, Seychelles, and Reunion. We also compiled case report data for dengue in Mayotte and Reunion in collaboration with the regional public health agencies in these French territories. References and data were discarded when original sources were not identified. We examined reports of climatic, anthropogenic, and mosquito-related factors that may influence the maintenance of dengue transmission independently of case importation linked to travel. FINDINGS AND CONCLUSIONS: The first report of dengue circulation in the SWIO was documented in 1943 in the Comoros. Then not until an outbreak in 1976 to 1977 that affected approximately 80% of the population of the Seychelles. DENV was also reported in 1977 to 1978 in Reunion with an estimate of nearly 30% of the population infected. In the following 40-year period, DENV circulation was qualified as interepidemic with sporadic cases. However, in recent years, the region has experienced uninterrupted DENV transmission at elevated incidence. Since 2017, Reunion witnessed the cocirculation of 3 serotypes (DENV-1, DENV-2 and DENV-3) and an increased number of cases with severe forms and deaths. Reinforced molecular and serological identification of DENV serotypes and genotypes circulating in the SWIO as well as vector control strategies is necessary to protect exposed human populations and limit the spread of dengue.

Spread of SARS-CoV-2 Variants on Réunion Island, France, 2021.

In January 2021, after detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants, genomic surveillance was established on Réunion Island to track the introduction and spread of SARS-CoV-2 lineages and variants of concern. This system identified 22 SARS-CoV-2 lineages, 71% of which were attributed to the Beta variant.

From the threat to the large outbreak: dengue on Reunion Island, 2015 to 2018.

BackgroundWith more than 300 million infections estimated annually worldwide, dengue is the most prevalent arboviral infection. On Reunion Island, after a large outbreak in 1977-78, only limited episodes of viral circulation or sporadic cases were reported till 2015.AimOur objective was to document and report on the circulation of dengue virus after the occurrence of a small outbreak during austral summer 2015/16 and until the large outbreak of 2018.MethodsBeside the mandatory notification of biologically confirmed dengue cases, additional systems of surveillance were set up: estimation of dengue-like syndrome in people seeking care by their family doctor, surveillance of emergency department visits related to dengue, surveillance of hospitalised dengue patients and deaths classifications.ResultsAfter a moderate outbreak during summer 2015/16 with 231 cases, 2017 was characterised by limited viral circulation (97 cases) which, however, persisted during the austral winter. By February 2018, the number of cases had increased and led to a peak at the beginning of May 2018. More than 6,000 cases were reported this year (dengue virus type 2 only). In addition, six deaths of dengue patients were notified.ConclusionIn 2017, the persistence of transmission during winter created favourable conditions for the emergence of an epidemic during summer 2018. After this moderate epidemic wave, the viral circulation persisted during winter 2018 for the second year, opening the door for the second wave in 2019 and for potential endemisation of the disease on Reunion Island in the near future.