The mysterious “sloth virus” with no cure

A mysterious virus once confined to the Amazon has now spread across the Americas after undergoing a potentially more potent genetic mutation.

Until recently, Oropouche virus was a relatively unknown disease largely confined to the Amazon basin in South America, but since late 2023, the virus has spread beyond its usual range.

There have already been more than 8,000 cases of the disease, commonly known as “sloth fever,” in five countries in the first seven months of 2024. The virus has also recently caused the deaths of two women and the possible deaths of two unborn babies in Brazil.

The US Centers for Disease Control and Prevention (CDC) has warned of a surge in cases of oropouche, which is spread by biting insects. Issue a health advisory Alert US doctors. First cases of the virus in Europe The virus was detected in infected travelers during visits to Brazil and Cuba in June and July 2024.

What is this mysterious virus, where did it come from, and why is it a concern?

The virus causes a fever in humans but is also found in many animals. Howler monkeys, marmosets There are also sloths and a variety of insects.

Oropouche is transmitted to humans and animals through the bite of an insect carrying the virus. Most commonly, A midge the size of a pinhead Curicoides paraensisIt is found in most of the Americas. However, Pentagonal Mosquito and Giant oyster mushroom mosquito.

The virus itself A single strand of genetic material Viruses are known as RNA wrapped in a protective protein shell and, once in the bloodstream, are thought to employ a “Trojan horse” approach, invading immune cells called phagocytes, then passing undetected through the body to reach target tissues and organs, where they infect cells and replicate.

The name of this virus is The first case was recorded. In 1955, the virus was isolated from the blood of a 24-year-old man with a fever. Forest Worker In the community of Vega de Orochi in Trinidad and Tobago.

Since then, the virus has caused sporadic infections across the Brazilian Amazon. It reached 100,000In total, the researchers 500,000 Although the number of diagnosed cases is high, this number may be an underestimate due to misdiagnosis, as many of the symptoms are similar to other febrile illnesses.

Reports of viral outbreaks began to appear in the late 1980s. Panama, Peru, EcuadorHowever, since 2000, the number of countries reporting the virus has increased to include Bolivia, Colombia, Ecuador and French Guiana.

In late 2023, large outbreaks began occurring in new areas of the Amazon basin and South America, where the virus was already endemic. In June 2024, cases of the virus were confirmed in Cuba.

Between January 1 and July 20, 2024, the World Health Organization Oropous 8,078 resultsThe majority of the cases – 7,284, including two deaths – are in Brazil, followed by 356 in Bolivia, 290 in Peru, 74 in Colombia and 74 in Cuba.

What's most worrying for public health officials is the current rise in cases. Occurs outside the Amazonand has also been recorded in 10 states outside the Brazilian Amazon region and in Cuba.

Unpublished analysis of the virus responsible for the recent outbreak suggests that its genetic code has somehow been shuffled, Replicate more efficiently It resides inside the infected person's cells, meaning that once the virus infects a cell and hijacks the cellular machinery, it can produce far more of itself.

This not only makes it possible for the virus to cause more severe illness in infected individuals, but also increases the chances that blood-sucking insects will pick up the virus and transmit it.

According to the CDC: Symptoms are usually Symptoms appear 3 to 10 days after the bite and last for 3 to 6 days. Recurs after a few days or weeks Up to 60% of patients subsequently experience relapses, and these recurrences tend to be similar. The cause of relapses is unclear, but it could be that the same infection is returning, or that people who live in areas with a high prevalence of insects that carry the virus are becoming reinfected.

On July 25, Brazilian authorities recorded the first deaths from Oropouche fever. The two women were aged 21 and 24, and neither had any pre-existing medical conditions.

However, the effects of oropouche on pregnancy and the fetus have not been proven. Under investigation.

However, many other wild animals are also thought to carry the virus, and the primary wild reservoir of the virus has yet to be identified.

Other researchers say:Urgent need for an effective vaccine“Vaccines against Oropauche have been tested in animal models but are not yet available or known to be effective in humans.”

“The patient needs to receive symptomatic treatment and rest while undergoing medical monitoring,” Brazil's Ministry of Health said.

Anyone who is infected should continue to use insect repellent to reduce the chance of being bitten by an insect and transmitting the virus to others.

Without a vaccine to control infection, the best way for people to protect themselves from Oropauche is to Preventing mosquito and midge bitesHealth officials recommend using fine-mesh mosquito nets on doors and windows because disease-carrying midges are smaller than mosquitoes and standard mosquito nets are considered less effective.

Wearing clothing that covers the arms and legs and using insect repellent can also help prevent bites.

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