Oropouche virus outbreak in South America

What is Oropouche virus?

Oropouche virus (OROV) is a vector-borne disease transmitted among people primarily through bites of the midge (Culicoides paraensis). Mosquitoes, monkeys, birds, rodents, and sloths can also be involved in transmission. The midge species C. paraensis is not found in New Zealand but is widely distributed in the Americas. 

Symptoms

Symptoms usually start between four to eight days (but can be from three to 12 days) after the infective bite. Symptoms are usually self-limiting, and include sudden onset of fever, headache, stiff joints, aches, and pains and, in some cases photophobia (sensitivity to light), diplopia (double vision), nausea and persistent vomiting, and occasionally more severe symptoms, such as haemorrhage, neurological symptoms, and meningitis.

Symptoms can last from five to seven days. Direct human-to-human transmission of the virus has not yet been documented.  The overall prognosis is good, and deaths are extremely rare. The risk of transmission appears to be highest during the rainy season, during which the breeding of midges is increased.

There have been some reports that OROV infection in pregnant women may lead to miscarriage, abortion, developmental problems, and foetal deformities.

Vaccines and treatment

There are no vaccines to prevent OROV or specific treatment for OROV disease.

Oropouche outbreak in South America and imported cases in Europe

The virus is endemic in Brazil, Bolivia, Colombia, Ecuador, French Guiana, Panama, Peru, and Trinidad and Tobago.

In 2024, there has been a significant increase in cases in Brazil and cases have been reported for the first time in Cuba. Although the disease has historically described as mild, two deaths have been reported from Brazil in July 2024. These are the first ever reported deaths due to OROV.

Most at risk people and travel advice

Anyone travelling to, or within affected countries in the Americas, especially Cuba and Brazil should take precautions to prevent midge and mosquito bites. The European Centres for Disease Control (ECDC) assess the risk of infection for travellers or residents to affected areas in Americas as low, provided they adopt protection measures against midges and mosquito bites including using fine mesh mosquito nets in beds, wearing clothing that covers legs and arms, and applying repellents containing DEET, IR3535 or icaridin. As midges are much smaller than mosquitoes, traditional mosquito nets will not protect against their bites. 

People who are pregnant should be particularly careful to avoid being bitten given recent reports of potentially serious outcomes for the foetus/baby.

For further information about OROV transmission refer to the Pan American Health Organization website.