Brazil's Oropuche virus outbreak should be a 'wake-up call', say experts | Global Health

Deaths, miscarriages and birth defects in two young women Brazil A link has been suggested to the Oropouche virus, a little-known disease spread by midges and mosquitoes.

The number of infections in the country has been rising sharply this year, increasing by 7,284 cases compared to the same period last year. 832 in 2023Large numbers have been recorded in areas where the virus had not previously been seen.

A total of 8,078 cases have been confirmed in Brazil, Bolivia, Peru, Colombia and Cuba. By the end of July, doctors in the region were urging increased caution.

Experts warn that the climate emergency is likely driving virus-spreading insects to new areas, but genetic changes in the Oropouche itself may also be playing a role.

First known fatality On July 25, the Brazilian Ministry of Health announced that two women, ages 21 and 24, from the state of Bahia, had contracted acute myocardial infarction (MI), the most serious infectious disease in the world. Both women experienced sudden symptoms such as fever, body aches, and headaches, which led to fatal bleeding. The third related death is a 57-year-old man,under investigation.

One of the women who died had twice sought help from health facilities but had been discharged. “I think this has to do with people assuming that everything is dengue. Dengue is well known, so we give them fluids and send them home, but we need to understand that this is not the case. We are now in a different situation,” said Marcia San Pedro, head of epidemiological surveillance for the state of Bahia.

In June, authorities Pregnant woman reports miscarrying baby at 30 weeks pregnantA woman was found to be infected with Oropouché virus in the eighth week of pregnancy, and the virus was detected in umbilical cord and organ samples, and a woman who had a miscarriage in the eighth week of pregnancy was also linked to the virus.

Tests on four newborns with microcephaly, a condition in which the head is smaller than expected, also showed the presence of antibodies to the Oropouche virus, but these tests did not conclusively prove that the virus caused the birth defects.

The deaths and miscarriages are “really notable events that have little to do with the virus,” said Alan Cole, professor of virology at the Liverpool School of Tropical Medicine and an expert on Oropouche and other bunyaviruses. Cole stressed that it was “early stages” in assessing this outbreak and that many questions remained unanswered.

“The study is a step forward for the government and the health ministry,” said Felipe Naveca of the Oswaldo Cruz Foundation, a health research institute affiliated with Brazil's Ministry of Health. A study that discovered genetic changes in the form of Oropoush“There have been outbreaks of infection before, but not on the scale we are seeing now,” he said.

But severe outcomes such as deaths and miscarriages do not necessarily mean the virus is stronger, but may simply reflect that “when you have a very high number of cases, severe cases will inevitably occur,” Naveca said.

He said the increase in infections was largely due to increased surveillance and expanded testing, while climate change and deforestation were increasing the likelihood of contact between humans and virus-carrying insects.

The virus is typically found in primates and sloths and can be transmitted to humans through the bites of certain midges and mosquitoes. Published in The Lancet In January, he described Oropouche virus as “a classic neglected disease” and warned that there were significant gaps in the medical and scientific understanding of the virus, making it “a potentially major threat.”

First discovered in Trinidad and Tobago in 1955, the Oropouche virus tends to cause flu-like symptoms that last for about a week. In some cases, the virus can lead to more serious complications, such as meningitis.

Prof Jonathan Ball, deputy director of the LSTM, said while no link had been confirmed to miscarriages or microcephaly, it was possible the virus was spreading to new areas.

“Frequent exposure to the virus in endemic areas generates immunity before a woman reaches childbearing age and this immunity is thought to protect her and her unborn baby. But if the virus is newly introduced, this protection is not present,” he said.

There is no specific vaccine or treatment for oropouche, and the Pan American Health Organization says the focus should be on prevention, which includes covering arms and legs, using repellents containing DEET, IR3535, or Icaridin, and using fine-mesh mosquito nets over doors, windows, and beds. Because midges are much smaller than mosquitoes, traditional mosquito nets do not protect against bites.

Prof Andrew Pollard, from the University of Oxford, said the outbreak should serve as a “wake-up call”, adding: “As the climate continues to change, we can expect to see increased prevalence of insects that can transmit diseases to humans.”