On June 11, 2024, the Ministry of Public Health of Cuba reported the first-ever outbreak of Oropouche virus disease in the country, with confirmed cases emerging from the provinces of Santiago de Cuba and Cienfuegos. Oropouche virus disease is an arboviral infection transmitted to humans primarily through the bites of midges or mosquitoes. The detection of this disease in Cuba marks a significant public health event, given the high susceptibility of the population and the potential for further spread.
Description of the Situation
The outbreak was first reported on May 27, 2024, with a total of 74 confirmed cases: 54 from Santiago de Cuba and 20 from Cienfuegos. These cases were identified through enhanced surveillance following an increase in non-specific febrile illnesses. In Santiago de Cuba, the municipalities of Santiago de Cuba and Songo La Maya reported 29 and 25 cases, respectively. In Cienfuegos, cases were reported from Cienfuegos (8 cases), Rodas (5 cases), Abreu (5 cases), Aguada de Pasajeros (1 case), and Cumanayagua (1 case). The national reference laboratory at the Pedro Kourí Institute (IPK) confirmed Oropouche virus in 74 out of 89 samples tested.
Symptoms in the confirmed cases appeared between May 2 and May 23, peaking during the epidemic week ending May 24. Common symptoms included fever, lower back pain, headache, loss of appetite, vomiting, weakness, joint pain, and eye pain. The median age of the patients was 34 years, with ages ranging from 6 to 72 years. The most affected age group was 15 to 19 years old, with 12 cases. All patients showed signs of recovery within three to four days after symptom onset, and no severe or fatal cases were reported as of June 5.
Epidemiology of Oropouche Virus Disease
Oropouche virus (OROV) is a segmented single-stranded RNA virus belonging to the genus Orthobunyavirus of the Peribunyaviridae family. The virus circulates in Central and South America and the Caribbean. It is primarily transmitted to humans through the bite of the Culicoides paraensis midge, which is prevalent in forested areas and near water bodies, or certain Culex quinquefasciatus mosquitoes. There are two recognized cycles of viral transmission: the sylvatic cycle involving primates, sloths, and possibly birds, and the epidemic cycle where humans are the amplifying host.
The clinical symptoms of Oropouche virus disease are similar to those of dengue, with an incubation period of four to eight days after the infective bite. Symptoms include sudden onset of fever, headache, joint stiffness, pain, chills, nausea, and vomiting. Severe cases may result in aseptic meningitis, although this is rare. Most patients recover within seven days, but convalescence can be prolonged in some cases. There is no specific antiviral treatment or vaccine for Oropouche virus disease.
Public Health Response in Cuba
Cuban health authorities have implemented several public health measures to address the outbreak. These include:
- Activation of Temporary Working Groups: These groups analyze the epidemiological situation and conduct field operations.
- Case Definition Criteria: Establishing criteria for suspected and confirmed cases of Oropouche virus disease.
- Training of Health Personnel: All National Public Health System personnel are being trained on arboviruses, including OROV.
- Strengthening Medical Resources: Enhancing human resources for medical care in areas with transmission.
- Vector Control Actions: Implementing focal treatment in transmission and high-risk blocks, adulticidal treatment, and increased entomological surveillance.
- Environmental Sanitation Actions: Intensified efforts to clean up environments that could serve as breeding grounds for vectors.
- Public Information Campaigns: Issuing informative notes on the situation to keep the public informed.
WHO Risk Assessment
The first detection of Oropouche virus disease in Cuba suggests that the population is highly susceptible to the virus, posing a significant risk of additional cases. The virus has been endemic in several South American countries, with periodic outbreaks reported in Brazil, Bolivia, Colombia, Ecuador, French Guiana, Panama, Peru, and Trinidad and Tobago. Given Cuba’s status as an international tourist destination and the wide distribution of the vector in the Americas, there is a risk of international spread.
Potential Global Impact and New Outbreak Risks
The spread of Oropouche virus disease to new regions poses a considerable threat to global public health. The virus’s transmission dynamics, coupled with environmental factors and human activities, can lead to further outbreaks. The proximity of vector breeding sites to human habitations is a significant risk factor for infection. Effective prevention strategies include controlling or eradicating the vectors and implementing personal protection measures.
Control Measures and Personal Protection
Vector control measures aim to reduce midge populations by eliminating breeding sites. This involves reducing natural and artificial water-filled habitats that support midge larvae. Personal protection measures include using mosquito nets, insect repellent devices, repellent-treated clothing, and chemical insecticides like deltamethrin and DEET. These measures are crucial in preventing midge bites and controlling the spread of the virus.
Laboratory Diagnosis and Surveillance
Laboratory diagnosis is essential to confirm Oropouche virus cases, characterize outbreaks, and monitor disease trends. Accurate diagnosis helps distinguish Oropouche virus disease from other febrile illnesses like dengue, which is also prevalent in the region. The detection of OROV requires the use of Annex 2 of the International Health Regulations (IHR) and notification through established IHR channels.
Recent Outbreaks and Research Findings
Outbreaks of Oropouche virus disease have occurred primarily in the Amazon region over the past decade. The virus is endemic in many South American countries, and recent outbreaks have been reported in Bolivia, Brazil, Colombia, and Peru. Studies have indicated that landscape perturbation, such as deforestation and infrastructure development, can facilitate the emergence of Oropouche fever. For instance, the construction of a highway in Bélem, Brazil, was linked to an outbreak in 1962.
In Peru, research has shown that Oropouche-positive localities often experience vegetation loss before the beginning of an outbreak. Ecological niche models have identified suitable conditions for Oropouche fever transmission in neighboring departments, suggesting a risk of further disease translocation into unaffected areas. Studies in Brazil have found midges, including Culicoides paraensis, infected with Oropouche virus in outbreak localities, although a large number of midges were necessary for virus detection.
Reservoirs and Vectors
The understanding of Oropouche virus reservoirs and vectors is limited in some regions. Research in Brazil suggests that the virus’s reservoirs could include birds and various mammals such as sloths, rodents, and primates. Similar studies should be conducted in other regions, including Peru, to better understand the ecological dynamics of the virus. The detection of Oropouche virus in howler monkeys in Brazil indicates the importance of surveillance in non-human primates.
Ecological Impact and Disease Emergence
Landscape changes, such as deforestation and vegetation loss, have been proposed as drivers of Oropouche fever outbreaks. These environmental alterations can disrupt ecosystems and increase the risk of disease transmission. The dilution effect, an ecological theory suggesting that reduced biodiversity can facilitate the spread of diseases, may help explain the link between vegetation loss and Oropouche fever emergence.
Future Surveillance and Prevention Efforts
To mitigate the risk of future outbreaks, it is essential to prioritize economic and human resources for monitoring land cover changes and conducting active epidemiological surveillance. Retrospective serological surveys and ecological niche modeling can help identify areas at risk for Oropouche fever transmission. The recent findings of mixed infections of dengue and Oropouche fever in the Madre de Dios department of Peru underscore the need for accurate diagnosis and comprehensive surveillance.
The outbreak of Oropouche virus disease in Cuba highlights the importance of vigilant public health measures, effective vector control, and continuous surveillance. The global community must remain alert to the potential for new outbreaks, given the virus’s ability to spread through international travel and its presence in various vectors and reservoirs. Collaborative efforts and research are crucial to understanding the virus’s ecology and developing strategies to prevent its spread.
reference link : https://www.who.int/emergencies/disease-outbreak-news/item/2024-DON521
