Factors Associated With Hospitalization and Severity of Arbovirosis in the Indian Ocean

Arboviroses, such as dengue, chikungunya and the Zika virus, represent a growing threat to public health in the Indian Ocean, but also in Europe and the rest of the world. Réunion has experienced several major epidemics, notably chikungunya in 2005-2006 and dengue since 2018, with a current resurgence of chikungunya. Mayotte was hit by a dengue epidemic in 2019, followed by a few cases of Rift Valley fever. The development of Zika could also affect this region.

Arboviruses, transmitted by hematophagous arthropods, require the coexistence of a reservoir and a vector. Dengue fever, transmitted by Aedes mosquitoes, is caused by four serotypes of dengue virus (DENV) from the orthoflavivirus family. Primary infection with one serotype confers lasting specific immunity, but only transient protection against the other serotypes. Chikungunya, caused by an alphavirus, now causes epidemics in major tropical areas. It is also transmitted by Aedes mosquitoes.

Arboviruses present four main clinical forms: algoeruptive, hemorrhagic, neurological and arthritic. Dengue fever is 75% asymptomatic, but can progress to a severe form, dengue hemorrhagic fever, characterized by increased vascular permeability and potentially fatal complications. Chikungunya causes a sudden onset of fever, polyarthralgia and maculopapular rash, with possible complications in newborns, the elderly and pregnant women.

Understanding the factors associated with hospitalization and the severity of these infections is crucial to improving patient management and optimizing medical resources. This cohort study aims to identify the clinical, demographic and environmental determinants influencing the severity of arbovirosis. By analyzing data from patients who have used a healthcare facility, we hope to establish risk profiles and severity criteria that may or may not be specific to each infection. The results will enable us to better understand the pathophysiology of these viruses, develop targeted prevention strategies and improve treatment protocols, thereby helping to reduce the morbidity and mortality associated with arboviroses in this region.

Due to the current chikungunya epidemic in La Réunion, this study will focus on the inclusion of patients affected by this arbovirosis as early as 2025. Its openness over the coming years will allow sufficient reactivity to include any arbovirosis on the territories of Mayotte and La Réunion.