Second most frequent arbovirosis in South America after dengue, oropouche virus infection (OROV) threatens directly between 2 and 5 million people. Since 2023-2024, a strong resurgence of cases has been observed.
Public health France (SPF) Alert on an increasing epidemic riskin particular in Guyana, Martinique and Guadeloupe. Its risk analysis is based on a report published in December 2024 which concluded a high epidemic threat in Guyana, Martinique and Guadeloupe, characterized by a strong uncertainty in Guyana and Martinique and weak in Martinique.
Despite its epidemic potential, OROV infection is still poorly known: the transmission cycle, the virus, the vectors, the hosts, the clinical presentations and the epidemiological data are not very documented.
What are the characteristics of the oropouche virus infection?
Oropouche disease is caused by a arbovirus called Oropouche virus (OROV). This virus belongs to the genus orthobunyavirus and has a segmented RNA genome, such as the influenza virus. It has the capacity to recombine itself by reassortment, thus facilitating the emergence of new viral strains.
In humans, Orov infection causes a sharp febrile syndrome evoking a flu: fever, headache, arthralgia, myalgia. In the majority of cases, the evolution is benign, but neurological forms (aseptic meningitis) can occur.
There is no specific treatment or vaccine against this disease.
What are the modes of transmission and the vectors?
Although little known, we know that Orov reaches animals and men and circulates according to two cycles:
- SELVATIC CYCLE: in forest environment via the transmission of arthropods;
- Urban cycle: interhuman transmission by anthropophilic flies, in particular Culicoids paraensis.
What are the challenges of the diagnosis of this infection?
The clinical diagnosis is not very specific and the virological tests (RT-PCR or serology) are little deployed.
In the absence of diagnosis, epidemics are underestimated, especially since OROV infections can go unnoticed or be confused with other arboviroses.
Why this risk analysis?
Risk analysis conducted by public health France is justified by several critical factors:
- An intense epidemic resurgence in South America since 2023-2024:
- Large diffusion affecting several countries such as Brazil, Peru, Colombia, Bolivia, Guyana and Venezuela, with extension to Panama and the Caribbean (Cuba, Barbados);
- Emergence of a viral sub-boarding resulting from a genetic restocking, detected for the first time in Guyana in 2020;
- Varying smaller, potentially more transmitted, and likely to escape the acquired immunity;
- Making-fetal transmission reports with congenital anomalies, Guillain-Barré syndromes, sexual or transfusion transmission.
- An extension of the circulation area subject to the alteration of the environment and biodiversity, demographic evolution and human mobility;
- A risk of high import in favor of travel and dissemination.
The estimated risk for the French departments of America (DFA) constitutes a worrying assessment.
The France’s Public Health Risk analysis of 2024 indicates that the epidemic risk is now deemed high in Guyana, Martinique and Guadeloupe.
However, uncertainties remain and the risks can evolve in particular according to the epidemiological context which justifies an updated international watch.
What are the recommendations for healthcare professionals?
The sensitive enhancement of the risk underlines the need for preparation, involving management measures, some of which are already in place.
The recommendations include:
- Strengthening of diagnostic capacities: effective provision in the hospital laboratories of the Antilles and in Guyana;
- Improvement of surveillance and alert devices: implementation in the Antilles and in Guyana of adapted surveillance with algorithms and access to diagnosis;
- Development of protection: the National Agency for Food, Environmental and Labor Safety (ANSES) has given an opinion on control measures Against type flies culicoids ;
- Continuation of epidemiological and entomological research.
