Mpox: International health officials are issuing warnings about "sloth fever." How does "sloth fever" compare to other mosquito-borne diseases such as Zika?

Mpox: International health officials are issuing warnings about "sloth fever." How does "sloth fever" compare to other mosquito-borne diseases such as Zika?

Zika Virus: The World Health Organization (WHO) said last week that the recent increase in cases of Zika should be declared a matter of international concern and a public health emergency. According to the WHO, the Zika virus is spreading rapidly and is likely to have serious health effects. The last time this happened was in July 2022. Amidst this tension, international health officials are issuing warnings about "sloth fever". Although its name may make it seem like lazy fever, it actually has nothing to do with contact with sloths. Rather, to avoid it, you should avoid contact with mosquitoes and midges.

What is 'sloth fever'?

Sloth fever is caused by the Oropouche virus and is formally known as Oropouche virus disease or Oropouche fever. The virus is an Orthobunya virus. So it belongs to a different family of viruses to the flaviviruses (which include dengue, Japanese encephalitis, and Murray Valley encephalitis viruses) and the alphaviruses (chikungunya, Ross River, and Barmah Forest viruses).

The Oropouche virus was first identified in 1955. It takes its name from a village in Trinidad and Tobago where the person who first identified it lived.

Symptoms include fever, severe headache, chills, muscle aches, joint pains, nausea, vomiting, and rash. This makes it difficult to distinguish it from other viral infections. About 60% of people infected with this virus become ill.

There is no specific treatment and most people recover in less than a month.

However, serious symptoms, including encephalitis and meningitis (inflammation of the membranes surrounding the brain and spinal cord), have been occasionally reported.

What's going on with this latest outbreak?

In July, the Pan American Health Organization issued a warning after two women in northeastern Brazil died after being infected with the Oropouche virus, the first deaths linked to the virus.

There have also been cases of one fetal death, one miscarriage, and four newborns suffering from microcephaly, a condition in which the head is abnormally small, where the infection occurs during pregnancy. The situation is reminiscent of the Zika outbreak in 2015-16.

Oropouche has historically been a significant concern in the Americas. However, the disease's importance declined following the frequent outbreaks of chikungunya and Zika from 2013 to 2016, and more recently dengue.

How is the Oropouche virus spread?

Oropouche virus has not been well studied compared to other insect-borne pathogens. We still do not fully understand how the virus spreads. The virus is primarily spread by blood-feeding insects, particularly biting midges (especially Culicoides paraensis) and mosquitoes (possibly several Aedes, Coquillettidia, and Culex species).

We believe the virus spreads in wild areas, with non-human primates, sloths, and birds as the main suspected hosts. During urban outbreaks, humans may carry the virus and blood-sucking insects infect other people.

The involvement of biting midges (blood-sucking insects erroneously known as "sandflies" in Australia) makes the transmission cycle of the Oropouche virus slightly different from that of viruses spread solely by mosquitoes. The types of insects that transmit the virus may also differ between wild and urban areas.

Suddenly a severe cold came and it was found that the liver had failed, vitamins were given by inserting a tube in the nose, this is how the life of a 25-year-old woman was saved

Why is the Oropouche virus on the rise?

The United States Centers for Disease Control and Prevention (CDC) recently issued a warning about rising cases of Oropouche in the US. Cases are increasing outside of areas where it was previously found such as the Amazon Basin, which has officials concerned.

More than 8,000 cases of the disease have been reported in countries including Brazil, Bolivia, Peru, Colombia, and Cuba.

There have been cases of travelers acquiring the infection in Cuba and Brazil upon returning to Europe and North America, respectively.

Although changing climate, deforestation and increased movement of people may partly explain the virus's growth and geographic spread, there is something else that is also playing a role.

Oropouche virus appears to have a greater capacity for genomic reassortment. This means that the virus can evolve faster than other viruses, potentially leading to more severe disease or increased infectiousness.

It has been observed that other types of Orthobunya virus have genetic changes that result in more severe disease.

What can you do to protect yourself? There

is no vaccine or specific treatment available for the Oropouche virus. If you are traveling to countries in South and Central America, take steps to avoid mosquito and midge bites.

Mosquito repellents containing diethyltoluamide (DEET), picaridin, and oil of lemon eucalyptus have been shown to be effective in reducing mosquito bites and are expected to work against mosquito bites as well.

Wearing long-sleeved shirts, long pants, and covered shoes will further reduce the risk.

Sleeping and resting in an insecticide-treated mosquito net will help, but a very fine mesh net is needed as biting midges are much smaller than mosquitoes.

The CDC and the European Centre for Disease Prevention and Control warn that pregnant travelers should discuss travel plans and potential risks with their healthcare professional.

(Courtesy: The Conversation)

(Authors: Cameron Webb, University of Sydney, and Andrew van den Hurk, University of Queensland)