24/06/25
Oropouche: Where are we?
At the beginning of 2024, the Pan -American Organization of Health launched an alert to the circulation of the Oropouche virus in the Americas. This had proved to be particular compared to the previous episodes, as reported by Professor Loïc Epelboin, to the recent national days of infectiology. In August 2024, Public Santé France judged high the risk of emergence in Guyana, which was not done so far, while the reflux epidemic elsewhere on the continent. In May, during the annual seminar of the watch and health security club, Dr. Francky Mubenga stressed the importance of looking for other arboviruses than dengue, Chikungunya and Zika. For its part, the Pasteur Institute regularly searches for orthobunyavirus, of which Oropouche is part, as part of Sentinel surveillance.
Whether in the National Infectiology Days, mid-August in Tours (Indre-et-Loire) or at the annual seminar of the Housing and Health Safety Club, at the end of May in Paris, the Oropouche virus is regularly invited into the discussions. On June 12, Public Health France published an analysis of the risk of emergence of the Oropouche virus in Guyana and the Antilles. It was carried out in August 2024 and then updated in December, due to the epidemic raging on the continent.
This analysis had been initiated in 2020, after the detection by the Pasteur Institute of thirty cases with residents of Saul. This work had been paid due to the epidemic of COVID-19, but a first publication had taken place in the Revue Emerging Infectious Diseases in 2021. It was reactivated due to the epidemic of 2023-2024.
In August 2024, Public Health France then analyzed several risk factors:
- Human activities in the forest;
- The flow of travelers from other countries in Latin America;
- The flow of travelers between the interior of Guyana and the coast;
- The presence of animal species reservoirs in the forest;
- The presence of competent vectors, in particular the culicoid eyelash.
Public Health France then underlined: “The risk of epidemic depends on the combination of the risk of sporadic cases with the risk that sufficiently competent anthropophilic vectors are present. The agency then estimated “high” the risk of epidemic both inside and on the coast. However, she pointed out that “the analysis of this risk could be led to evolve, depending on the epidemic situation in Latin America, the occurrence of cases (in the inner zone) and the evolution of scientific knowledge. Finally, Guyana will not be affected. Since then, the epidemic has been in reflux elsewhere on the continent.
“Search for other viruses than dengue”
On May 22 and 23, the Center for Sanitary Crises (CCS) welcomed representatives of the ARS health and safety club for a work seminar. Beyond the daily link between the CSS and the ARS for the preparation and management of crises, this network meets regularly to promote exchanges. The meeting was opened by Professor Yazdan Yazdanpanah, Managing Director of the emerging infectious diseases, and Evan Malczyk, watch and health security advisor at the Ministry of Health.
Dr. Francky Mubenga, head of the watch and health security center at ARS Guyana, intervened with his counterpart in Guadeloupe, Patrick Saint-Martin, on the management of emerging arboviroses. They highlighted the specificities of our territories, in particular in terms of risk of emergence and re -emergence of arboviroses, and the interest of an association of the Antilles and Guyana in their management.
Apart from the Cyclical Epidemia of Dengue, which are known, they recalled the recent oropouche epidemic in the Americas, the detection of the first human case of West Nile in Guadeloupe last year, the return of chikungunya to the Indian Ocean, the detections of the Mayano virus in Guyana in the case of Stern Surveillance, a case of vaccine yellow fever and four cases of orthobunyavirus (oropouche) in 2024.
In 2025, in addition to the cases of dengue, the CNR arbovirus of the Institut Pasteur de Guyana reported to the ARS three cases of Chikungunya (all imported from the meeting), three cases of orthobunyavirus. “On a territory like Guyana where dengue is endemic, we know that other arboviruses circulate,” warns Dr. Mubenga. You have to look for them. The risk of emergence and re -emergence is important with us. This requires reinforced and specific watch, with the search for another virus than dengue, zika and chikungunya, each time the conditions are met. This alert surveillance will allow authorities to anticipate emergence and manage them effectively. We are currently working with laboratories, public health France and the territorial Umito to optimize and relaunch our arbovirus monitoring system in Guyana (Disarbo973). »»
A dozen Guyanese subjects, including Oropouche, presented to the JNI
The national infectiology days took place from June 11 to 13, in Tours (Indre-et-Loire). The Guyana University Hospital was very well represented, with several communications and posters, in particular on:
• The Curema project
• L’histoplasmose
• The leptospirose
• Fever Q
• Anticovid vaccination coverage
• T cell leukemia/T lymphoma
• only vih
• Rage
• Infections in kidney transplants
Professor Loïc Epelboin, infectious scientist at the CHU, returned to the “unexpected epidemic” of the Oropouche virus in Latin America in 2023 and 2024. Since the first case detected in Trinité-et-Tobago in 1955, several epidemics occurred in the territory. Brazil experienced ten until 2020, both in urban and rural areas, without reported death.
In February 2024, the Pan -American Health Organization (PAHO) launched an epidemic alert, noting “an increase in oropouche fever detections in recent months, in certain regions of the Americas”. Brazil will declare 13,785 cases confirmed last year, Peru 1,263. Further, Guyana will identify three.
For Professor Epelboin, the engines of this outbreak are multiple:
- Environmental pressure: with deforestation and intensive agriculture that modify the habitat of the vectors (monkeys then mosquitoes for transmission to humans);
- The explosion of vectors due to an prolonged rainy season;
- Virological factors with a more suitable and more transmitted virus;
- Immune factors due to the drop in collective immunity;
- Epidemiological factors due to late detection of the first cases;
- A context of viral hypercirculation with dengue, chikungunya and zika.
The epidemic started in 2023 is also distinguished by several particularities:
- Persistence in fluids, including sperm (up to 58 days);
- Unexpected clinical aspects such as Guillain-Barré syndrome;
- First five deaths listed in Brazil, including two women aged 21 and 24;
- First descriptions of fetopathies and maternity-fetal transmission which resulted in several deaths.
So many aspects that encourage monitoring of this virus.
At the Institut Pasteur, the orthobunyavirus continuously monitored
The Oropouche virus is one of the orthobunyavirus. We have known since the 1960s that they have been circulating in Guyana. The National Reference Center for Arboviruses, at the Pasteur Institute, has developed molecular diagnostic tools to be able to monitor. As part of sentry surveillance, samples of negative dengue serum in people by presenting dengue-like symptoms are therefore regularly tested for other arbovirus, including orthobunyavirus. Last year, during the Guyanese Assizes of Infectiology and Tropical Medicine (AGIT) then in an article in Medicine and Infectious Diseases, published in December, the CNR presents the results for the 944 samples taken between September 2022 and November 2023. Twelve samples proved to be positive for orthobunyavirus.
These results “testify to infections without epidemiological link between them and widely distributed over the department. However, a concept of night or evening exhibition, in the forest or peri -urban area, was found ”in the eleven cases informed. The Pasteur Institute also notes “significant genetic diversity”. The authors deem “urgent to continue the development of appropriate diagnostic tools in order to improve our knowledge that is still too limited about these viruses”.
Recommendations for travelers
In November, the High Council for Public Health issued recommendations to people going to zone at risk of transmission or seat of a proven epidemic, in particular for pregnant women or likely to become:
- In the event of a trip to an area at risk of exposure to the virus, to adopt anti -ferctorial personal protection measures (PPAV) integrating the wearing of covering clothing and the application of skin repellents, especially during the day;
- In the event of a trip to an area where an epidemic is proven, to postpone the trip to the extent possible;
- In the event of an imperative trip, to adopt the usual PPAV measures, ideally associated with the use of an impregnated mosquito net with fine mesh (phlebotomaire) at night or during nap hours (or in the absence of an impregnated mosquito net with usual mesh);
- In the event of a diagnosis of confirmed infection in a pregnant woman, to orient it towards a prenatal diagnostic center and to organize specialized pediatric monitoring for newborns of infected mothers.
The same anti -ferctoral personal protection recommendations in risk areas are issued for other travelers.
