International authorities are issuing warnings about "sloth fever" or Oropouche virus disease, after an increase in cases in South America, US and Europe.
The illness is primarily transmitted by blood-feeding insects, particularly biting midges.
Some outlets have used words as "concerning" and "terrifying" but the risk of the virus spreading to Australia is relatively quite low.
Around 60 per cent of people infected with the virus become ill and serious symptoms of the illness have only occasionally been reported.
No specific warnings have been issued by Australian authorities.
Let's unpack what the disease is and how serious it is around the world.
What is Oropouche virus disease?
The World Heatlh Organisation says Oropouche virus disease is a febrile disease caused by the Oropouche virus (OROV).
It is spread primarily through the bite of an insect known as a midge (Culicoides paraensis).
New South Wales Health Pathology says the virus is an orthobunyavirus.
This means it is from a different family of viruses to the flaviviruses (which includes dengue, Japanese encephalitis and Murray Valley encephalitis viruses) and alphaviruses (chikungunya, Ross River and Barmah Forest viruses).
The biting midges most important to the spread of the virus in the Americas are not present in Australia.
Why is it called sloth fever?
A three-toed sloth in Suriname. (Reuters: File)
It has sometimes been called sloth fever because scientists first investigating the virus found it in a three-toed sloth, and believed sloths were important in its spread between insects and animals.
WHO writes that primates, sloths and perhaps birds can host the disease.
It was first identified in 1955 in a 24-year-old forest worker on the island of Trinidad, and was named for a nearby village and wetlands.
What are symptoms?
Typically, the disease begins with the abrupt onset of a fever, a headache, chills, nausea, vomiting and a rash, says the Centers for Disease Control and Infection.
Less common symptoms can include sensitivity to light, dizziness, diarrhoea and severe abdominal pain.
Symptoms typically last less than seven days.
There have been very few deaths reported among people infected with Oropouche virus.
There are no vaccines to prevent infections and no medicines available to treat the symptoms.
How has it spread globally?
Humans have become infected while visiting forested areas.
They are believed to be responsible for helping the virus make its way to towns and cities.
However, person-to-person transmission hasn't been documented.
What is happening with the latest outbreak?
As of August 1, the World Health Organisation has reported 8078 confirmed Oropouche cases in the Americas and two deaths.
In July, the Pan American Health Organisation issued a warning after two women from north-eastern Brazil died following infection with Oropouche virus, the first fatalities linked to this virus.
There has also been one fetal death, one miscarriage and four cases of newborns with microcephaly, a condition characterised by an abnormally small head, where infection during pregnancy occurred.
Brazil has the highest number of cases.
There are reported cases in five other countries in the region.
| Country | Case |
|---|---|
| Brazil | 7284 |
| Peru | 290 |
| Colombia | 74 |
| Cuba | 74 |
| Bolivia | 356 |
Twenty-one people who returned to the US from Cuba have been infected by the virus in recent months.
None have died, and there is no evidence that it's spreading in the United States.
Officials are warning US doctors to be on the lookout for the infection in travellers coming from Cuba and South America.
On August 9, European health officials said they had found 19 cases, nearly all among travellers.
What is the advice to Australians travelling?
Mosquito repellent must be applied to all exposed skin to be effective. (Flickr: Miguel Garces)
No specific warnings have been issued by Australian authorities.
There are steps you can take to avoid mosquito and midge bites if travelling to South and Central America.
Mosquito repellents containing diethyltoluamide (DEET), picaridin and oil of lemon eucalyptus have been shown to be effective in reducing mosquito bites.
Protective clothing like long-sleeved shirts and pants and closed-in shoes will also help reduce the risk of being bitten.
Sleeping and resting under insecticide-treated mosquito bed nets will help, but much finer mesh nets are required as biting midges are much smaller than mosquitoes, New South Wales Pathology says.
Who is most at risk?
The CDC and European Centre for Disease Prevention and Control have warned that pregnant travellers should discuss travel plans and potential risks with a doctor.
In Brazil, officials are investigating reports that infections might be passed on from a pregnant woman to a fetus.
Why is it spreading?
WHO writes that the virus has historically been spread through the Amazon region.
Possible reasons for the spread beyond its historical range include:
- climate change
- deforestation
- unplanned urbanisation