Experts racing to discover why monkeypox virus is spreading

Health authorities have been left scratching their heads over the monkeypox outbreak, but the spread of the virus may be linked to one long-eradicated illness.

A monkeypox virion. Picture: Cynthia S. Goldsmith/Centres for Disease Control and Prevention

The sudden emergence of the mysterious monkeypox virus has sent the internet into a spin, causing considerable concern among people still recovering from two years of Covid-19 lockdowns.

But the current increase in monkeypox cases may be partly due to a disease the world eradicated decades ago.

First seen in humans in The Congo in 1970, monkeypox is endemic in certain parts of Central and West Africa. But in recent weeks, it has spread to 15 countries around the globe, including two cases in Australia.

While the infection fatality ratio is around 1 per cent for the West African strain (which this current outbreak is), the spread of the disease in non-endemic countries has left health experts stumped.

There are some leading theories as to why though, chief among them that the discontinuation of the smallpox vaccine may have given monkeypox the platform needed to spread.

A patient suffering from monkeypox. Picture: AFP/Brian W.J. Mahy/Centres for Disease Control and Prevention

Waning immunity to devastating disease

One of history’s deadliest diseases, smallpox is estimated to have killed between 300 to 500 million people in the 20th century alone.

However, it was all but wiped out by 1977 after a staggering global immunisation campaign, making it the first disease to be eradicated by human hand.

A bonus of the smallpox vaccine was a considerably boosted immunity to other diseases – including monkeypox.

Professor Raina MacIntyre, head of the biosecurity program at the Kirby Institute, told the Medical Journal of Australia that, four decades on, the “waning of immunity from smallpox vaccination may be contributing to the increasing outbreaks of monkeypox”.

Researchers writing in the PLOS Neglected Tropical Diseases journal echoed Professor MacIntyre’s sentiments, noting that the discontinued vaccination campaign for smallpox “has established the landscape for the resurgence of monkeypox”.

Experts have also noted that vigilance around virus infections post-pandemic may have driven up detection numbers.

Cases of monkeypox have been re-emerging in Africa since 2010, and the increased awareness around the importance of early detection and symptom identification may have brought an already existing issue into the spotlight.

Low infection rates for close contacts

While the World Health Organisation (WHO) has warned we could see an increase in cases in the coming weeks, infection rates remain low with roughly 3 per cent of close contacts catching the disease.

A skin lesion caused by the monkeypox virus. Picture: Supplied

Doctors have also noted that many – but not all – patients in the current outbreak appear to be men who have sex with men (MSM).

However, officials have been quick to point out that the close contact that occurs during sex may be the cause of infection, as opposed to monkeypox itself being a sexually transmitted disease.

“We have seen messages stigmatising certain groups of people around this outbreak of monkeypox,” a WHO statement said.

“We want to make it very clear that this is not right.

“Anyone who has close physical contact of any kind with someone who has monkeypox is at risk, regardless of who they are, what they do, who they choose to have sex with or any other factor.”

WHO department of global HIV, hepatitis and STI strategies adviser Andy Seale added that MSM should be alert to symptoms – particularly any rashes that may appear on the face or genitalia.

“We know that MSM if they do spot an unusual rash, they’re likely to want to get it sorted out quite quickly,” Mr Seale said, according to Reuters reports.

Originally published as Experts racing to discover why monkeypox virus is spreading