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Explainer: What to Know About Monkeypox

The COVID-19 pandemic is still fresh in the minds of the people around the world, so it comes as no surprise that recent outbreaks of another virus are grabbing headlines.

Monkeypox outbreaks have now been reported in multiple countries, and it has scientists paying close attention. For everyone else, numerous questions come to the surface:

• How serious is this virus?
• How contagious is it?
• Could monkeypox develop into a new pandemic?

Below, we answer these questions and more.

What is Monkeypox?

Monkeypox is a virus in the Orthopoxvirus genus which also includes the variola virus (which causes smallpox) and the cowpox virus. The primary symptoms include fever, swollen lymph nodes, and a distinctive bumpy rash.

There are two major strains of the virus that pose very different risks:

• Congo Basin strain: 1 in 10 people infected with this strain have died
• West African strain: Approximately 1 in 100 people infected with this strain died

At the moment, health authorities in the UK have indicated they’re seeing the milder strain in patients there.

Where did Monkeypox Originate From?

The virus was originally discovered in the Democratic Republic of Congo in monkeys kept for research purposes (hence the name). Eventually, the virus made the jump to humans more than a decade after its discovery in 1958.

It is widely assumed that vaccination against another similar virus, smallpox, helped keep monkeypox outbreaks from occurring in human populations. Ironically, the successful eradication of smallpox, and eventual winding down of that vaccine program, has opened the door to a new viral threat. There is now a growing population of people who no longer have immunity against the virus.

Now that travel restrictions are lifting in many parts of the world, viruses are now able to hop between nations again. As of the publishing of this article, a handful of cases have now been reported in the U.S., Canada, the UK, and a number of European countries.

On the upside, contact tracing has helped authorities piece together the transmission of the virus. While cases are rare in Europe and North America, it is considered endemic in parts of West Africa. For example, the World Health Organization reports that Nigeria has experienced over 550 reported monkeypox cases from 2017 to today. The current UK outbreak originated from an individual who returned from a trip to Nigeria.

Could Monkeypox become a new pandemic?

Monkeypox, which primarily spreads through animal-to-human interaction, is not known to spread easily between humans. Most individuals infected with monkeypox pass the virus to between zero and one person, so outbreaks typically fizzle out. For this reason, the fact that outbreaks are occurring in several countries simultaneously is concerning for health authorities and organizations that monitor viral transmission. Experts are entertaining the possibility that the virus’ rate of transmission has increased.

Images of people covered in monkeypox lesions are shocking, and people are understandably concerned by this virus, but the good news is that members of the general public have little to fear at this stage.

I think the risk to the general public at this point, from the information we have, is very, very low.
–Tom Inglesby, Director, Johns Hopkins Center for Health Security

» For up-to-date information on monkeypox cases, check out Global.Health’s tracking spreadsheet

The Top 10 Largest Nuclear Explosions, Visualized

Just how powerful are nuclear explosions?

The U.S.’ Trinity test in 1945, the first-ever nuclear detonation, released around 19 kilotons of explosive energy. The explosion instantly vaporized the tower it stood on and turned the surrounding sand into green glass, before sending a powerful heatwave across the desert.

As the Cold War escalated in the years after WWII, the U.S. and the Soviet Union tested bombs that were at least 500 times greater in explosive power. This infographic visually compares the 10 largest nuclear explosions in history.

The Anatomy of a Nuclear Explosion

After exploding, nuclear bombs create giant fireballs that generate a blinding flash and a searing heatwave. The fireball engulfs the surrounding air, getting larger as it rises like a hot air balloon.

As the fireball and heated air rise, they are flattened by cooler, denser air high up in the atmosphere, creating the mushroom “cap” structure. At the base of the cloud, the fireball causes physical destruction by sending a shockwave moving outwards at thousands of miles an hour.

A strong updraft of air and dirt particles through the center of the cloud forms the “stem” of the mushroom cloud. In most atomic explosions, changing atmospheric pressure and water condensation create rings that surround the cloud, also known as Wilson clouds.

Over time, the mushroom cloud dissipates. However, it leaves behind radioactive fallout in the form of nuclear particles, debris, dust, and ash, causing lasting damage to the local environment. Because the particles are lightweight, global wind patterns often distribute them far beyond the place of detonation.

With this context in mind, here’s a look at the 10 largest nuclear explosions.

#10: Ivy Mike (1952)

In 1952, the U.S. detonated the Mike device—the first-ever hydrogen bomb—as part of Operation Ivy. Hydrogen bombs rely on nuclear fusion to amplify their explosions, producing much more explosive energy than atomic bombs that use nuclear fission.

Weighing 140,000 pounds (63,500kg), the Ivy Mike test generated a yield of 10,400 kilotons, equivalent to the explosive power of 10.4 million tons of TNT. The explosion was 700 times more powerful than Little Boy, the bomb dropped on Hiroshima in 1945.

#9: Castle Romeo (1954)

Castle Romeo was part of the Operation Castle series of U.S. nuclear tests taking place on the Marshall Islands. Shockingly, the U.S. was running out of islands to conduct tests, making Romeo the first-ever test conducted on a barge in the ocean.

At 11,000 kilotons, the test produced more than double its predicted explosive energy of 4,000 kilotons. Its fireball, as seen below, is one of the most iconic images ever captured of a nuclear explosion.

#8: Soviet Test #123 (1961)

Test #123 was one of the 57 tests conducted by the Soviet Union in 1961. Most of these tests were conducted on the Novaya Zemlya archipelago in Northwestern Russia. The bomb yielded 12,500 kilotons of explosive energy, enough to vaporize everything within a 2.1 mile (3.5km) radius.

#7: Castle Yankee (1954)

Castle Yankee was the fifth test in Operation Castle. The explosion marked the second-most powerful nuclear test by the U.S.

It yielded 13,500 kilotons, much higher than the predicted yield of up to 10,000 kilotons. Within four days of the blast, its fallout reached Mexico City, roughly 7,100 miles (11,400km) away.

#6: Castle Bravo (1954)

Castle Bravo, the first of the Castle Operation series, accidentally became the most powerful nuclear bomb tested by the U.S.

Due to a design error, the explosive energy from the bomb reached 15,000 kilotons, two and a half times what was expected. The mushroom cloud climbed up to roughly 25 miles (40km).

As a result of the test, an area of 7,000 square miles was contaminated, and inhabitants of nearby atolls were exposed to high levels of radioactive fallout. Traces of the blast were found in Australia, India, Japan, and Europe.

#5, #4, #3: Soviet Tests #173, #174, #147 (1962)

In 1962, the Soviet Union conducted 78 nuclear tests, three of which produced the fifth, fourth, and third-most powerful explosions in history. Tests #173, #174, and #147 each yielded around 20,000 kilotons. Due to the absolute secrecy of these tests, no photos or videos have been released.

#2: Soviet Test #219 (1962)

Test #219 was an atmospheric nuclear test carried out using an intercontinental ballistic missile (ICBM), with the bomb exploding at a height of 2.3 miles (3.8km) above sea level. It was the second-most powerful nuclear explosion, with a yield of 24,200 kilotons and a destructive radius of ~25 miles (41km).

#1: Tsar Bomba (1961)

Tsar Bomba, also called Big Ivan, needed a specially designed plane because it was too heavy to carry on conventional aircraft. The bomb was attached to a giant parachute to give the plane time to fly away.

The explosion, yielding 50,000 kilotons, obliterated an abandoned village 34 miles (55km) away and generated a 5.0-5.25 magnitude earthquake in the surrounding region. Initially, it was designed as a 100,000 kiloton bomb, but its yield was cut to half its potential by the Soviet Union. Tsar Bomba’s mushroom cloud breached through the stratosphere to reach a height of over 37 miles (60km), roughly six times the flying height of commercial aircraft.

The two bombs dropped on Hiroshima and Nagasaki had devastating consequences, and their explosive yields were only a fraction of the 10 largest explosions. The power of modern nuclear weapons makes their scale of destruction truly unfathomable, and as history suggests, the outcomes can be unpredictable.