The bubonic plague, affectionately known as the Black Death, was a pandemic responsible for the deaths of up to 200 million people in the 14th century. Considered to be one of the worst contagious diseases in history, the plague ravaged Europe and the Middle East, decimating the populations of entire continents.
While medical advancements in the centuries since the time of the Black Death have been staggering, there are still plenty of infectious diseases keeping the staff at the CDC up at night. As new viruses and dreaded "superbugs" show themselves to be immune to modern antibiotics, there is plenty of legitimate concern that another plague-like pandemic could be devastating on a global scale.
Hollywood films like Outbreak and Contagion have offered sensationalized looks at what the mass spread of deadly infectious disease looks like, but are they really that far off? What if there are several potential outbreaks just waiting to wipe us off the earth? Are you starting to feel a bit feverish? Let's take a look at some of the world's most dangerous infections that could bring humanity to its knees.
The inspiration behind the 2011 film Contagion, the deadly effects of the Nipah virus (NiV) are anything but fictional. As depicted in Steven Soderbergh's hit film, NiV is hosted by fruit bats, with pigs serving as an intermediary to human transmission. Contained generally to Southeast Asia, significant outbreaks have taken place in Malaysia, Singapore, and Bangladesh, claiming nearly 200 lives.
NiV moves quickly, with symptoms showing themselves within 14 days of incubation. Terrifyingly, this disease shows itself initially with severe mental confusion and disorientation caused by inflammation of the brain. Once you begin literally losing your mind, you can slip into a coma within 24-48 hours, with about a 40% chance of dying from respiratory failure or neural disease. And should you be fortunate enough to survive this horrifying ordeal? Well, you can look forward to personality changes and a lifetime of convulsions.
Could NiV have a devastating impact on the global population? It's possible. There are currently no vaccines or treatments for the disease, and person-to-person transmissions have occurred, though it has yet to cross the Atlantic, as we saw with Gwenyth Paltrow in Contagion. Still, it might be wise to watch your pork intake.
Generally located in sub-Saharan Africa, Rift Valley Fever (RVF) is a disease commonly observed in animals like camels, sheep, and goats (of which it claimed over 100,000 in an outbreak in Kenya in 1950-51). This infectious disease has the ability to spread to humans - again via those lovely pests, mosquitos - and in 1977, it showed up in Egypt, killing over 600 people.
For those unfortunate enough to contract RVF, the effects can be deadly and truly gruesome. With an incubation period of 2-6 days, typical symptoms are mild: fever, dizziness, and general weakness can occur. But for a subset of those infected, things can escalate quickly. RVF can result in ocular disease in the form of open lesions on your eyeballs, which after an extremely painful 10-12 months, will heal up, leaving you with a 50/50 shot at permanent blindness. Inflammation of the brain can also take place, causing severe headaches, coma, and seizures, but the most fatal risk from RVF is developing hemorrhagic fever. This starts out with jaundice as your liver slowly fails, and then you can look forward to vomiting blood, bloody stool, and bleeding from your nose and gums. Hemorrhagic fever is fatal in 50% of cases related to RVF, and with those sorts of symptoms, death might be a sweet relief.
As grim and painful as Rift Valley Fever is, transmission from human-to-human has yet to occur, so the chances of a global plague are relatively low. A vaccination for RVF does exist, though it's not licensed or commercially available and technically inactive. Should an outbreak occur, let's hope it doesn't spread too quickly.
In terms of current infectious diseases, the Ebola virus is probably the most infamous and vicious. Coming in at a 50% average fatality rate (though some outbreaks have reached as high as 90%), Ebola first appeared in the mid-70s in Central Africa, killing over 400 people in remote villages across Zaire and Uganda. After a slight period of dormancy before resurfacing in the mid-90s, outbreaks have increased in frequency over the past 20 years, resulting in over 10,000 deaths.
Though the natural reservoir host for Ebola is unknown, it is likely spread to humans via infected fruit bats. It can also be transmitted sexually, or through direct contact (open wounds, orifices) with blood and other bodily fluids. Once the human body becomes infected with Ebola, things get ugly very quickly. After an incubation period of 8 to 10 days, you can expect the standard fever, dizziness, and fatigue that comes with your average ailment... and then things take a turn. Soon comes painful vomiting and diarrhea (each containing a fair amount of blood), internal bleeding, severe weight loss, and just as you're near death, you can expect to bleed from literally every orifice in your body, including your eyes.
So, what sort of risk does Ebola pose as a global pandemic? According to experts, it's pretty minimal because the disease's transmission requires direct contact. Statistically, each person infected will only spread the disease to 1.5 other people, which is, I guess...comforting?
Primarily limited to tropical regions, the Zika virus began getting global attention during the 2016 Olympics in Rio de Janeiro, Brazil, when some Olympians and media personnel decided to forego the event due to risk of infection. While the World Health Organization would go on to declare the risk of an outbreak as small enough to recommend the Games go on, the effects of the Zika virus plainly justify anyone's travel hesitations.
While symptoms of Zika - which is transmitted via mosquito, as well as by sexual contact - typically appear as mild, including rash, headache, and pain behind the eyes, it can also cause internal bleeding, which was the cause of death for the first fatal American case of Zika. But the real devastating effects of Zika are brought on when it's contracted by women who are pregnant. Zika produces a horrifying effect on unborn children known as microcephaly, which is when a child's head develops to be abnormally small, affecting the brain and often leading to mental retardation, hearing loss, and blindness. These infected children also frequently perish during pregnancy, and there is not currently a way to detect when the disease strikes the child in the womb.
So, how likely is Zika to be a worldwide plague? Well, currently the risk is low, but there is reason enough to be alarmed. Zika transmission via mosquito has a range estimated as far north as New York City, and with no existing vaccinations or medicines, US experts have gone on record stating it is coming, and we are not prepared. With that in mind, bug spray and long sleeves are probably advisable.