Oropouche virus emerges as public health threat in Colombia

The Oropouche virus (OROV), a previously lesser-known mosquito-borne pathogen, is rapidly expanding its geographical reach across the Americas, prompting heightened concern among health authorities. Initially endemic to the Amazon region, the virus has now been detected in countries such as Bolivia, Cuba, and, most recently, Colombia, where cases had never been reported before. The situation over the last week has escalated, with Brazil recording two fatalities attributed to this obscure virus.

The Pan American Health Organization (PAHO) has issued an urgent epidemiological alert following the recent surge in OROV cases. As of July 30, 2024, a total of 8,078 confirmed cases have been reported across five countries in the Americas, including Bolivia (356 cases), Brazil (7,284 cases), Colombia (74 cases), Cuba (74 cases), and Peru (290 cases). Notably, Brazil, which has reported the highest number of cases, has also confirmed the first deaths linked to the virus. The fatalities involve two women under the age of 30, and have raised alarm as mortality had not previously been associated with severe OROV infections.

The Oropouche virus is transmitted primarily through the bites of infected mosquitoes and biting midges, particularly the species Culicoides paraensis, commonly known as maruim. The symptoms of OROV infection closely resemble those of dengue fever, another mosquito-borne illness, leading to potential misdiagnosis. Common symptoms include fever, headache, muscle and joint pain, and a rash. In severe cases, the virus can cause neurological disorders such as meningitis or encephalitis. Disorders also associated with Chikungunya and ZIKA.

The first identification of the Oropouche virus occurred in Trinidad and Tobago in 1955, and it has since been associated with sporadic outbreaks, mainly in tropical regions. The virus has shown a marked increase in activity in recent years, with new cases emerging in areas previously considered non-endemic. In Brazil, where the virus has predominantly circulated in the Amazon, the disease has now been documented in ten non-Amazonian states, suggesting a significant geographical expansion.

The current outbreak has led to heightened surveillance and diagnostic efforts across the region. PAHO has emphasized the need for countries to strengthen their prevention, detection, and response strategies to mitigate the spread of the virus. This includes enhanced vector control measures, public awareness campaigns, and increased laboratory capacity for accurate diagnosis.

One of the most concerning developments in the ongoing investigation is the potential for vertical transmission of the virus from pregnant women to their unborn children. This mode of transmission, reminiscent of the Zika virus outbreak, is under investigation by Brazilian health authorities in collaboration with PAHO. Although OROV is not known to be contagious between humans, the possibility of transmission during pregnancy raises significant public health concerns, particularly given the severe consequences observed with other arboviruses like Zika.

In response to the growing threat, countries across the Americas are urged to remain vigilant and to implement robust surveillance systems to track the spread of the virus. Public health officials are also advocating for increased research into the virus’s transmission dynamics, potential complications, and effective prevention strategies.

The emergence of the Oropouche virus as a public health threat follows the 2015 outbreak of the Chikungunya (CHKV) virus and the Zika epidemic across northern South America the following year. As the public health situation continues to evolve, Colombia’s Institute of Public Health (INS) remains on high alert to prevent further spread and to protect vulnerable populations in two departments – Meta and Amazonas – where cases have now been confirmed.