With modern medicine, we often grow overly confident, assuming we can defeat any illness. Yet the resurgence of 10 deadly diseases proves that complacency is dangerous. Recent flare‑ups across the globe remind us that no one is immune.
10 Deadly Diseases on the Rise
1 Cholera
Cholera is a severe diarrheal illness. Before 2010, Haiti had gone a century without a cholera outbreak, but that peace shattered when the disease surged along the Meille River. Over 400 UN peacekeepers, fresh from a cholera‑stricken Nepal, were stationed nearby, and their waste contaminated the river.
The United Nations eventually apologized, but it was too late for the roughly 10,000 Haitians who died. Experts estimate that a simple $1‑per‑patient treatment could have cut the epidemic by 91 percent.
Cholera isn’t confined to distant, impoverished regions. South Korea reported its first homegrown case in 15 years. In the 19th century, cholera devastated the peninsula, claiming about 400,000 lives—nearly half the population. Officials there believe the recent incident may stay isolated, yet certainty remains elusive.
2 Dengue Fever
Dengue fever is ravaging tropical zones, transmitted by mosquitoes and causing fever, joint pain, and occasionally death. In late 2016, a 13‑year‑old girl in Karachi became the fourth fatality in Pakistan’s recent outbreak.
In 2015, Pakistan alone recorded 40 dengue deaths, while worldwide the disease claims roughly 20,000 lives each year. The United States isn’t immune either; Hawaii experienced its largest post‑statehood outbreak in 2015, with 261 confirmed cases.
The newly launched vaccine Dengvaxia, after two decades of development, carries a paradox: because dengue exploits a phenomenon called antibody‑dependent enhancement, the vaccine can sometimes worsen the disease if given to someone who has never been infected. It works best for those who have already survived dengue.
Thus, careful administration is crucial; otherwise, the vaccine could lead to more hospital visits rather than fewer.
3 Leprosy
Officially called Hansen’s disease, leprosy can cause disfigurement, blindness, and even death. Though often thought of as an ancient scourge, it still afflicts the United States, averaging about 150 cases per year.
Many assumed these infections arrived from distant, endemic regions, but recent research uncovered a surprising domestic source: armadillos. Studies revealed that the bacterial strain infecting humans in the southern states matches the one found in local armadillos.
Investigators examined 25 human patients and 28 armadillos, discovering a genetic overlap. Fortunately, when caught early, leprosy responds to antibiotic therapy.
4 Bubonic Plague
The bubonic plague, infamous for the Black Death that wiped out 60 percent of medieval Europe, still haunts humanity. Symptoms include fever, abdominal pain, swollen lymph nodes, and nausea.
A recent fatal case forced Chinese officials to quarantine the entire city of Yumen. In the previous year, Madagascar suffered an outbreak that claimed 39 lives. In the United States, Arizona, Colorado, and New Mexico serve as hot spots, with an average of seven cases annually, though 2015 saw more than double that number.
The culprit, Yersinia pestis, remains treatable with antibiotics, reducing mortality to roughly 16 percent when therapy starts promptly. Untreated, the fatality rate can soar to 93 percent. Alarmingly, antibiotic‑resistant strains have been identified, raising concerns among epidemiologists.
5 Polio
The World Health Organization has declared the Americas, Europe, the western Pacific, and Southeast Asia polio‑free, creating a false sense that the disease belongs only in history books. In reality, it persists.
Just as the WHO prepared to label Africa polio‑free, two cases erupted in Nigeria’s Borno State, a region dominated by Boko Haram. Health workers can only vaccinate residents when militants temporarily abandon an area. Similar “wild” polio outbreaks have surfaced in Afghanistan and Pakistan.
Ukraine also experienced a recent surge, but this time the virus originated from the weakened strain used in oral vaccines. With only about half of Ukraine’s population immunized, the situation could become dire.
6 Typhoid Fever
Typhoid fever, a deadly bacterial infection related to food‑borne salmonella, claims 600,000 lives annually out of 16–30 million cases worldwide. The disease thrives in densely populated regions with poor sanitation.
Transmission usually occurs through contaminated water or food, leading to high fever, abdominal pain, headaches, and nausea. Children are especially vulnerable, and infant mortality remains high. Improved sanitation, safe drinking water, and better hygiene can curb the spread.
Even in the United States, the disease is resurging. Oklahoma reported an outbreak north of its capital, traced to a single family that likely contracted the illness abroad. Florida has also seen a rapid increase in cases.
7 Diphtheria
In 2015, Spain recorded its first diphtheria case in 28 years—a young boy from Catalonia whose parents chose to forgo vaccination despite the country’s free, widely available program.
The disease has a grim history on the Iberian Peninsula, with devastating outbreaks in the 16th and 17th centuries, one famously dubbed the “year of strangulations.”
Diphtheria, caused by Cornynebacterium diphtheriae, primarily targets young children and adults over 60, killing roughly one in ten infected individuals.
The bacterium produces a toxin that creates a dead membrane coating the throat, making breathing and swallowing painful. If the toxin enters the bloodstream, it can damage internal organs.
8 Measles
In 2000, the United States declared measles eliminated, but a massive 2014 outbreak ignited at California’s Disneyland, eventually infecting 84 people across 14 states.
By late 2016, Arizona alone reported 22 confirmed cases, doubling the nation’s typical annual tally. Measles can cause encephalitis, blindness, and death.
The resurgence stems from two forces: importation of cases from abroad and the anti‑vaccine movement. Each year, 22 million people worldwide contract measles. Epidemiologists traced the latest U.S. flare‑up to the Eloy Detention Center in Arizona, suspecting the index patient arrived from outside the country.
From the 1960s onward, a robust vaccination campaign kept measles at bay, but growing vaccine refusal now threatens that progress. When unvaccinated individuals encounter the virus, the consequences can be severe.
9 Syphilis
What happens in Vegas stays in Vegas—unless it’s a sexually transmitted infection. A recent spike in syphilis cases in Sin City has exposed a fresh vulnerability to this age‑old bacterial disease.
During its early stage, syphilis is easily cured with penicillin. Left untreated, however, later stages can unleash a terrifying array of symptoms: loss of muscle control, dementia, rashes, blindness, and even death.
Researchers attribute the surge to shifting sexual habits. Smartphone hookup apps make anonymous encounters more common, and the success of HIV treatments has led some to forgo condoms.
Most reported infections involve gay men. Currently, Las Vegas holds the highest syphilis rate in the western United States, surpassed only by Washington, DC, on a national scale.
10 Leptospirosis
In 2009, the Philippines suffered a double blow: tropical storm Ketsana flooded the nation, followed by an outbreak of “rat fever,” or leptospirosis. This bacterial illness spreads through contact with animal urine, and the post‑storm floodwaters created a perfect breeding ground.
The outbreak claimed 157 lives, producing symptoms such as severe headaches, fever, kidney failure, and massive lung bleeding. Mortality rates typically hover between five and ten percent, but a 2015 surge in Mumbai saw a staggering 33 percent death rate.
Leptospirosis isn’t limited to tropical floods. In the United States, canine cases emerged in 2015 across California and Colorado, while sea lions on Oregon’s coast were devastated in 2009. Raccoons serve as major carriers, and up to 90 percent of urban rats harbor the bacteria.
How long before this pathogen jumps from animals to a broader human population in the United States?
Further Reading
These diseases aren’t the only things making a comeback! So are these lists from the archives:
10 Dreadful Symptoms Of Deadly Diseases
Top 10 Gruesome Disfiguring Diseases
Top 10 Odd Diseases With No Known Cause
10 Horrifying Diseases You Definitely Don’t Want To Catch
Abraham Rinquist is the Executive Director of the Winooski, Vermont, branch of the Helen Hartness Flanders Folklore Society. He is the coauthor of Codex Exotica and Song‑Catcher: The Adventures of Blackwater Jukebox.