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John Kucharski, USDA // Public Domain
John Kucharski, USDA // Public Domain

5 of the Worst Parasites You Can Get—And How to Avoid Them

John Kucharski, USDA // Public Domain
John Kucharski, USDA // Public Domain

No matter who you are, or where you live, you have, at some point in your life, served as the host to a parasite—“any organism that has a relationship with another organism where the first one gets a benefit and the other pays a cost,” Dan Riskin, biologist and expert on the Animal Planet series Monsters Inside Me, tells Mental Floss. “These relationships can be very short—like a mosquito [biting] you and then taking off—or they can last for decades, or your whole life.” 

Ahead of the new season of Monsters Inside Me, which premieres on October 15, we asked Riskin to come up with a list of five parasites you really don’t want to host. When making his picks, Riskin went for the most common and the least common, then filled in with different parasites in between. He wasn’t lacking for creatures to choose from; more than half of the animal kingdom, he says, consists of parasites, which have been “hugely influential in the history of humankind.” Read on to be terrified—and amazed.

1. NEW WORLD SCREWWORM (COCHLIOMYIA HOMINIVORAX)

This nasty little parasite (above) made news in the U.S. last year when it infected a herd of rare Key Deer in the Florida Keys. (That outbreak, thankfully, is over.) These creepy crawlies can infect humans, too—and one such case is featured on the new season of Monsters Inside Me. “This family went to Colombia to volunteer at an orphanage,” Riskin explains. Near the end of the trip, the daughter had gone to a water park and came back with a sore on the side of her head.

“The next day, when they were supposed to fly home, the feces hit the fan,” Riskin says. The sore became incredibly painful and started pussing, and the family had to decide: Should they stay in Colombia or go home? Ultimately, they got on the plane. Once back in the States, they took their daughter to the ER, where she was given a haircut that allowed doctors to see the “mobile larvae,” a.k.a. maggots, in her head.

A female Cochliomyia hominivorax fly had landed on the girl’s head and deposited its eggs in a lesion on her scalp; the eggs soon hatched into nearly 2-centimeter-long maggots that began chomping away. Unlike other parasitic maggots—like botflies, for example—the New World Screwworm does not stay put. These maggots were burrowing into the girl’s skull. “If they hadn’t gotten to it, these things would’ve migrated right down sort of towards her face and out her eyeballs or who knows what,” Riskin says. Thankfully, doctors were able to remove the maggots using a combination of petroleum jelly and bacon therapy (basically, luring the creepy critters out with the smell of bacon and the threat of suffocation).

How to Avoid It: Wearing long pants and long-sleeve shirts, applying DEET-based repellents, and sleeping under a mosquito net are your best methods of defense. If you suspect you might be hosting some screwworms, “seek medical attention immediately,” Riskin advises.

2. MALARIA

The malaria parasite.
iStock

According to the CDC, there were 212 million cases of malaria in 2015; 429,000 deaths were caused by the parasite. “You can get it almost anywhere tropical,” Riskin says. “All it takes is a mosquito bite.”

Mosquitos don’t hatch carrying malaria; the bugs pick it up from an infected person. Once inside the mosquito, the malaria parasite takes up residence in the insect’s salivary glands. “When the mosquito bites somebody else, it squirts a little bit of spit into them to help keep the blood flowing—that’s what causes an itching mosquito bite; it’s a reaction to that spit—but they can also be spitting these parasites into the next person,” Riskin says.

In humans, the parasites hang out in cells in the liver, then make their way to red blood cells, which they make explode, spreading more parasites that invade more blood cells. Anyone can get malaria, and people who contract it will experience fever and chills. “It just wreaks havoc on your body,” Riskin says.

The disease is potentially fatal; those who contract malaria and survive might relapse because some species of the parasite can lie dormant in the liver.

How to Avoid It: If you’re going to a country with malaria, consider taking preventative drugs. Otherwise, wear long pants and long sleeves, use DEET-based insect repellents, and sleep under a mosquito net when traveling in the tropics.

3. BRAIN-EATING AMOEBA (NAEGLERIA FOWLERI)

Technically, this amoeba—which can be found in warm, untreated fresh water—isn’t a parasite. “Normally, it’s totally harmless, doing its own thing in the mud, eating whatever it finds there, going about its business, not bugging anybody,” Riskin says. That all changes when a person goes water skiing and gets water harboring N. fowleri violently shoved up their nose.

Now in a new environment, the amoeba resumes eating whatever it can find in the nose. “It makes its way up that olfactory nerve, reproducing and eating, until it hits the brain,” Riskin says. “And once it’s in the brain, it’s game over for the kid that had it shoved up his nose.”

Typically, a victim will begin to show symptoms—which include fever, headache, and vomiting—around five days after infection (although symptoms can appear as early as one day after infection or as late as nine), and will usually die about five days after that. The death rate associated with infection by N. fowleri in the U.S. is 97.2 percent.

That said, getting a brain-eating amoeba is very, very rare: There were 40 infections reported in the U.S. from 2007 to 2016, a rate of four cases per year. (The CDC reports that “36 people were infected by recreational water, 3 people were infected after performing nasal irrigation using contaminated tap water, and 1 person was infected by contaminated tap water used on a backyard slip-n-slide.”) That gives you odds of about 1 in 70 million of contracting a brain-eating amoeba.

How to Avoid It: Basically, just keep water from slamming up your nose. If you plan on engaging in an activity like water skiing during the summer months, “you could wear a nose plug,” Riskin says. “But this is so rare, that might be overkill.”

4. LUNG FLUKES A.K.A. PARAGONIMUS

An adult Paragonimus westermani lung fluke.
CDC, Wikimedia Commons // Public Domain

Humans may find themselves hosting these coffee bean-sized parasites if they’ve eaten raw or undercooked shellfish. As the crab gets digested, the lung fluke larvae are released, and they “move through your body and go all over the place,” Riskin says. Typically, they tear through the abdominal wall and diaphragm to get into the lungs.

People infected with lung flukes may experience abdominal pain and a fever; eventually, they’ll begin to cough up blood laden with eggs. The blood is either spat out or swallowed, allowing eggs to pass in the stool (and, if a host is in water while defecating, the life cycle will continue).

“Our bodies are built to protect us from the environment,” Riskin says, but eating makes us vulnerable. “It’s like if you had a fortress with big stone walls all around it—you still have to get food to the people who live in the fortress. And so, every once in a while, you have to open the gate and let all these ox carts come in and then close the gate. And then, you’ve got to hope that there’s no Trojan horse.”

Untreated, lung flukes can live in the body for 20 years, according to the CDC. Thankfully, once an infection is identified, medication can wipe the infection out.

How to Avoid It: This one’s easy—just don’t eat raw or undercooked shellfish.

5. ELEPHANTIASIS A.K.A. LYMPHATIC FILARIASIS

An elderly man suffering from elephantiasis; one of his legs is much bigger than the other.
NOAH SEELAM/AFP/Getty Images

This condition is caused by several species of roundworms; like malaria, these roundworms thrive in the tropics and are transmitted by mosquito. Once in your body, the roundworms set up shop in your lymphatic vessels—small, one-way tubes in your body that drain liquid away from tissues—and can live there for decades. “They’re cloaked like a Klingon bird of prey,” Riskin says. “The immune system doesn’t even know they’re there.” At least, not until the worms die.

“Once they’re dead, the cloaking mechanism doesn’t work anymore,” Riskin explains. Then your body’s like, ‘Whoa, we’ve got an invader.’” Your body sends white blood cells to the site where the bodies of the roundworms have piled up. The problem is, their bodies have clogged the very vessels meant to drain the liquid away, causing limbs to swell. “It gets more swollen, and the body sends more fluid, and that area gets puffier,” Riskin says. “This just keeps happening, and there’s no way to drain. The draining system is busted.”

The parasite infected 120 million people in 2000, according to the World Health Organization; 40 million people were disfigured and incapacitated by it. While medications have little effect on adult roundworms, there are drugs to help and prevent transmissions to others: In 2015, the scientists who developed a treatment that could prevent infections for around a year won the Nobel Prize for Medicine (alongside another researcher who developed a novel malaria therapy).

How to Avoid It: This mainly affects people in Africa and Asia, so if you’re traveling there, wear long-sleeve shirts and pants, liberally apply insect repellent, and sleep under a mosquito net.

A new season of Monsters Inside Me begins October 15 at 9 p.m. EST on Animal Planet.

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Tony Karumba, AFP/Getty Images
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Animals
How a Pregnant Rhino Named Victoria Could Save an Entire Subspecies
Sudan, the last male member of the northern white rhino subspecies, while being shipped to Kenya in 2009
Sudan, the last male member of the northern white rhino subspecies, while being shipped to Kenya in 2009
Tony Karumba, AFP/Getty Images

The last male northern white rhino died at a conservancy in Kenya earlier this year, prompting fears that the subspecies was finally done for after decades of heavy poaching. Scientists say there's still hope, though, and they're banking on a pregnant rhino named Victoria at the San Diego Zoo, according to the Associated Press.

Victoria is actually a southern white rhino, but the two subspecies are related. Only two northern white rhinos survive, but neither of the females in Kenya are able to reproduce. Victoria was successfully impregnated through artificial insemination, and if she successfully carries her calf to term in 16 to 18 months, scientists say she might be able to serve as a surrogate mother and propagate the northern white rhino species.

But how would that work if no male northern rhinos survive? As the AP explains, scientists are working to recreate northern white rhino embryos using genetic technology. The San Diego Zoo Institute for Conservation Research has the frozen cell lines of 12 different northern white rhinos, which can be transformed into stem cells—and ultimately, sperm and eggs. The sperm of the last northern white male rhino, Sudan, was also saved before he died.

Scientists have been monitoring six female southern white rhinos at the San Diego Zoo to see if any emerge as likely candidates for surrogacy. However, it's not easy to artificially inseminate a rhino, and there have been few successful births in the past. There's still a fighting chance, though, and scientists ultimately hope they'll be able to build up a herd of five to 15 northern white rhinos over the next few decades.

[h/t Time Magazine]

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(c) Field Museum, CSZ5974c, photographer Carl Akeley, used with permission.
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The Time Carl Akeley Killed a Leopard With His Bare Hands
(c) Field Museum, CSZ5974c, photographer Carl Akeley, used with permission.
(c) Field Museum, CSZ5974c, photographer Carl Akeley, used with permission.

Carl Akeley had plenty of close encounters with animals in his long career as a naturalist and taxidermist. There was the time a bull elephant had charged him on Mount Kenya, nearly crushing him; the time he was unarmed and charged by three rhinos who missed him, he said later, only because the animals had such poor vision; and the time the tumbling body of a silverback gorilla he'd just shot almost knocked him off a cliff. This dangerous tradition began on his very first trip to Africa, where, on an otherwise routine hunting trip, the naturalist became the prey.

It was 1896. Following stints at Ward’s Natural Science Establishment and the Milwaukee Public Museum, Akeley, 32, had just been appointed chief taxidermist for Chicago’s Field Museum of Natural History, and he was tasked with gathering new specimens to bolster the 3-year-old museum's fledgling collections. After more than four months of travel and numerous delays, the expedition had reached the plains of Ogaden, a region of Ethiopia, where Akeley hunted for specimens for days without success.

Then, one morning, Akeley managed to shoot a hyena shortly after he left camp. Unfortunately, “one look at his dead carcass was enough to satisfy me that he was not as desirable as I had thought, for his skin was badly diseased,” he later wrote in his autobiography, In Brightest Africa. He shot a warthog, a fine specimen, but what he really wanted was an ostrich—so he left the carcass behind, climbed a termite hill to look for the birds, then took off after a pair he saw in the tall grass.

But the ostriches eluded him at every turn, so he returned to camp and grabbed the necessary tools to cut off the head of his warthog. However, when he and a “pony boy” got to the spot where he’d left the carcass, all that remained was a bloodstain. “A crash in the bushes at one side led me in a hurry in that direction and a little later I saw my pig's head in the mouth of a hyena travelling up the slope of a ridge out of range,” Akeley wrote. “That meant that my warthog specimen was lost, and, having got no ostriches, I felt it was a pretty poor day.”

As the sun began to set, Akeley and the boy turned back to camp. “As we came near to the place where I had shot the diseased hyena in the morning, it occurred to me that perhaps there might be another hyena about the carcass, and feeling a bit ‘sore’ at the tribe for stealing my warthog, I thought I might pay off the score by getting a good specimen of a hyena for the collections,” he wrote. But that carcass was gone, too, with a drag trail in the sand leading into the bush.

Akeley heard a sound, and, irritated, “did a very foolish thing,” firing into the bush without seeing what he was shooting at. He knew, almost immediately, that he'd made a mistake: The answering snarl told him that what he’d fired at was not a hyena at all, but a leopard.

The taxidermist began thinking of all the things he knew about the big cats. A leopard, he wrote,

“... has all the qualities that gave rise to the ‘nine lives’ legend: To kill him you have got to kill him clear to the tip of his tail. Added to that, a leopard, unlike a lion, is vindictive. A wounded leopard will fight to a finish practically every time, no matter how many chances it has to escape. Once aroused, its determination is fixed on fight, and if a leopard ever gets hold, it claws and bites until its victim is in shreds. All this was in my mind, and I began looking about for the best way out of it, for I had no desire to try conclusions with a possibly wounded leopard when it was so late in the day that I could not see the sights of my rifle.”

Akeley beat a hasty retreat. He’d return the next morning, he figured, when he could see better; if he’d wounded the leopard, he could find it again then. But the leopard had other ideas. It pursued him, and Akeley fired again, even though he couldn’t see enough to aim. “I could see where the bullets struck as the sand spurted up beyond the leopard. The first two shots went above her, but the third scored. The leopard stopped and I thought she was killed.”

The leopard had not been killed. Instead, she charged—and Akeley’s magazine was empty. He reloaded the rifle, but as he spun to face the leopard, she leapt on him, knocking it out of his hands. The 80-pound cat landed on him. “Her intention was to sink her teeth into my throat and with this grip and her forepaws hang to me while with her hind claws she dug out my stomach, for this pleasant practice is the way of leopards,” Akeley wrote. “However, happily for me, she missed her aim.” The wounded cat had landed to one side; instead of Akeley’s throat in her mouth, she had his upper right arm, which had the fortuitous effect of keeping her hind legs off his stomach.

It was good luck, but the fight of Akeley’s life had just begun.

Using his left hand, he attempted to loosen the leopard’s hold. “I couldn't do it except little by little,” he wrote. “When I got grip enough on her throat to loosen her hold just a little she would catch my arm again an inch or two lower down. In this way I drew the full length of the arm through her mouth inch by inch.”

He felt no pain, he wrote, “only of the sound of the crushing of tense muscles and the choking, snarling grunts of the beast.” When his arm was nearly free, Akeley fell on the leopard. His right hand was still in her mouth, but his left hand was still on her throat. His knees were on her chest and his elbows in her armpits, “spreading her front legs apart so that the frantic clawing did nothing more than tear my shirt.”

It was a scramble. The leopard tried to twist around and gain the advantage, but couldn’t get purchase on the sand. “For the first time,” Akeley wrote, “I began to think and hope I had a chance to win this curious fight.”

He called for the boy, hoping he’d bring a knife, but received no response. So he held on to the animal and “continued to shove the hand down her throat so hard she could not close her mouth and with the other I gripped her throat in a stranglehold.” He bore down with his full weight on her chest, and felt a rib crack. He did it again—another crack. “I felt her relax, a sort of letting go, although she was still struggling. At the same time I felt myself weakening similarly, and then it became a question as to which would give up first.”

Slowly, her struggle ceased. Akeley had won. He lay there for a long time, keeping the leopard in his death grip. “After what seemed an interminable passage of time I let go and tried to stand, calling to the pony boy that it was finished.” The leopard, he later told Popular Science Monthly, had then shown signs of life; Akeley used the boy’s knife to make sure it was really, truly dead.

Akeley’s arm was shredded, and he was weak—so weak that he couldn’t carry the leopard back to camp. “And then a thought struck me that made me waste no time,” he told Popular Science. “That leopard has been eating the horrible diseased hyena I had killed. Any leopard bite is liable to give one blood poison, but this particular leopard’s mouth must have been exceptionally foul.”

He and the boy must have been quite the sight when they finally made it back to camp. His companions had heard the shots, and figured Akeley had either faced off with a lion or the natives; whatever the scenario, they figured Akeley would prevail or be defeated before they could get to him, so they kept on eating dinner. But when Akeley appeared, with “my clothes ... all ripped, my arm ... chewed into an unpleasant sight, [with] blood and dirt all over me,” he wrote in In Brightest Africa, “my appearance was quite sufficient to arrest attention.”

He demanded all the antiseptics the camp had to offer. After he'd been washed with cold water, “the antiseptic was pumped into every one of the innumerable tooth wounds until my arm was so full of the liquid that an injection in one drove it out of another,” he wrote. “During the process I nearly regretted that the leopard had not won.”

When that was done, Akeley was taken to his tent, and the dead leopard was brought in and laid out next to his cot. Her right hind leg was wounded—which, he surmised, had come from his first shot into the brush, and was what had thrown off her pounce—and she had a flesh wound in the back of her neck where his last shot had hit her, “from the shock of which she had instantly recovered.”

Not long after his close encounter with the leopard, the African expedition was cut short when its leader contracted malaria, and Akeley returned to Chicago. The whole experience, he wrote to a friend later, transported him back to a particular moment at the 1893 World’s Columbian Exposition, which he’d visited after creating taxidermy mounts for the event. “As I struggled to wrest my arm from the mouth of the leopard I recalled vividly a bronze at the World’s Columbian Exposition in Chicago, depicting the struggle between a man and bear, the man’s arm in the mouth of the bear,” he wrote. “I had stood in front of this bronze one afternoon with a doctor friend and we discussed the probable sensations of a man in this predicament, wondering whether or not the man would be sensible to the pain of the chewing and the rending of his flesh by the bear. I was thinking as the leopard tore at me that now I knew exactly what the sensations were, but that unfortunately I would not live to tell my doctor friend.”

In the moment, though, there had been no pain, “just the joy of a good fight,” Akeley wrote, “and I did live to tell my [doctor] friend all about it.”

Additional source: Kingdom Under Glass: A Tale of Obsession, Adventure, and One Man's Quest to Preserve the World's Great Animals

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