PAHO urges increased surveillance for Oropouche fever in the Americas

The Pan American Health Organisation (PAHO) has urged countries to strengthen surveillance against Oropouche fever (OROV).  PAHO said in 2024, the virus has been detected in areas where transmission had not been previously reported. Deaths associated with the infection were also reported, as were cases of vertical transmission.

Since the last PAHO epidemiological alert, issued on August 1, 2024, and up to September 6, 1,774 additional cases of Oropouche have been reported in six countries, increasing the total to 9,852 confirmed cases.  Countries are encouraged to report any unusual events, and reinforce vector prevention and control measures.

Brazil remains the most affected country with 7,931 cases and two deaths.

Other currently affected countries include Bolivia (356 cases), Colombia (74 cases), Cuba (506 cases), Peru (930 cases), and, more recently, the Dominican Republic (33 cases). Imported cases have also been recorded in the United States (21 cases) and Canada (1 case), following travel to endemic countries. Additionally, 30 imported cases have been documented in Europe.

Regarding mother-to-child transmission, a total of one fetal death and one case of congenital anomaly have been confirmed in Brazil.

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Currently, additional investigations are being conducted on other fetal deaths, miscarriages, and congenital anomalies.

Oropouche fever is a tropical viral infection which can infect humans. It is transmitted by biting midges and mosquitoes, from a natural reservoir which includes sloths, non-human primates, and bird. In some cases, it can cause more severe complications such as meningitis or encephalitis. Although most people recover completely, there is no specific treatment, and prevention is essential.

The virus is primarily transmitted through the bite of infected midges, small insects that usually bite during the day and inhabit humid areas with organic matter and in forested areas.

Given the increase in cases in 2024, PAHO reiterates the importance of implementing preventive measures, especially for pregnant women. These measures include:

• Using fine-mesh mosquito nets on doors and windows, with holes smaller than 1 millimeter, to prevent the entry of vectors.
• Wearing long-sleeved clothing and long pants, especially in homes with a sick person.
• Applying insect repellents containing DEET to exposed areas of skin.
• In outbreak situations, outdoor activities should be avoided during dawn and dusk, when vector activity is highest.
• Seek medical attention for any suspected symptoms.

PAHO said it is continuing to monitor the situation and is working closely with member countries to control the spread of the virus and minimize its impact on public health.