As The Toast searches for its one true Gal Scientist, we will be running a ton of wonderful one-off pieces by female scientists of all shapes and sizes and fields and education levels, which we are sure you will enjoy. They’ll live here, so you can always find them. Most recently: Mansplaining Physics. Today’s column is sponsored by the lovely Sarah Redmond, so blame her for your nightmares.
Parasites make for great conversation starters at any social occasion. Tales of parasitic diseases are like ghost stories: people are creeped out, but they can’t help asking what happens next. Sometimes they say things more along the lines of “ew, that’s disgusting” or “please, I just want to eat my sandwich in peace,” but trust me, they really do want you to keep talking. Even if they don’t show genuine curiosity, comfort yourself in the fact that you are helping people protect themselves against the scourges of mankind.
To help you choose the right story for the right occasion, I have listed a few examples of situations where it might be particularly appreciated. It’s safe to say that any of these are perfectly appropriate for preschool graduations, gender reveal parties, or your ex-boyfriend’s wedding.
Plasmodium — Malaria
The next time you get together with your friends for a night out, pour yourselves a gin and tonic and toast to the British Empire for popularizing the drink. Your hangover the next morning will remind you that you were protected from malaria, if not alcohol-induced dehydration.
Malaria is one of the most notorious parasitic diseases and it definitely deserves its bad reputation. Over 200 million people suffer from malaria, and more than 500,000 die each year. Malaria is caused by protozoans of the genus Plasmodium that are carried by mosquitoes and cause flu-like symptoms. Untreated, the disease can progress to the brain, lungs, kidneys, and liver. Fatality rates can reach as high as 20%.
There are several anti-malarial medicines in use now, but the oldest and best known is quinine. Unfortunately, quinine, an alkaloid from the bark of the cinchona tree, tastes awful. It is terribly bitter and must be consumed daily to ensure Plasmodium is killed. The soldiers of the British Empire who went conquer India, understandably, did not want to take their daily quinine. However, it is difficult to conquer if your soldiers keep dropping dead of disease. Adding soda and a hint of sugar to quinine to masks the bitter taste and makes a refreshing drink: tonic water. Even now, if you buy a can of Schweppes to make your G&Ts at home, you’ll see a label in small font: “Contains Quinine.” British officers found it was more pleasant to add gin to make it a medicinal afternoon drink. It’s like an adult version of Mary Poppins’ “A Spoonful of Sugar.” Just a shot (or two) or gin makes the quinine go down.
The perfect story for: bachelorette parties in tropical locales, trying out a fake British accent, telling your spouse “it’s medicinal” if they question the number of G&Ts you are consuming.
Chances are you’ve never even heard of schistosomiasis before, but it actually affects 200 million people worldwide. It’s the second most prevalent parasitic disease after malaria, and has plagued humans for thousands of years. The ancient Egyptians actually had a hieroglyphic symbol for it. Technically the symbol meant “blood in urine,” but the point stands: schistosomiasis is one of the deadliest diseases you’ve never heard of.
Schistosoma worms spend half their life in fresh water and infect snails. They grow and mature inside the snail until light causes the larva to swim out of the snail and into the surrounding water. If you are the unlucky human nearby, they will pass directly through your skin and into your blood vessels. You won’t notice their entry; they are less than a millimeter in size and have special enzymatic secretions that break down your skin. Are you scared yet?
Once inside your body, the worms settle down inside blood vessels to eat red blood cells and mate. As with most parasites, the females are significantly larger. The smaller male sits enveloped by the female, which produces between 300 and 3,000 eggs per day. The eggs find their way into your bowels or bladder, depending on the species of worm. As you contaminate other fresh water sources with your urine or stool, the Schistosoma life cycle continues. The worms, meanwhile, stay inside you as long as they please. There have been documented cases where the worms have lived for several decades inside their hosts.
So what do these worms do inside you besides constantly eat and mate? Not a whole lot, actually, but it’s the eating and mating that makes you sick. For one thing, you need all those red blood cells they’re devouring. Anemia is always the first sign that something bad is happening inside you. Iron is a very limited resource; parasites, bacteria, and even tumor cells do everything they can to get more of it. Anemia leads to muscle weakness, poor cognitive function in children, and stunted growth.
Most of the long-term problems are not caused by the worms but by their eggs. The worms are able to slip past your immune system through a number of tricks, but the eggs cannot. Your body, understandably, tries to fight, but only makes things worse by causing inflammation. Long-term inflammation leads to severe damage in the liver, kidneys, or bowels and a predisposition to cancer in these areas. Inflammation can even cause sores, in the case of Schistosoma haematobium, in the female uro-genital region. Sores facilitate the entrance of HIV, so in parts of the world where both diseases are endemic the parasite unwittingly helps a virus that will eventually kill its host.
This is the part that most people overlook when they think of parasites: most parasites don’t want to kill you, but they make it a lot easier for you to die.
The perfect story for: romantic dinners featuring escargot, winning a point at pub trivia, justifying your hatred of snails
If you have donated blood recently, you may have noticed a question near the end of the form that asks “have you ever been diagnosed with Chagas disease?” Chagas disease, caused by the protozoan Trypanasoma cruzi, infects over ten million people, mostly the poor in Latin America, South America, and the Caribbean. Some researchers are actually calling it “the new HIV/AIDS.”
Trypanosomes spend part of their lives inside blood sucking insects called “kissing bugs” that like to bite humans near their lips. After sucking out some of your blood, the beetle turns around and defecates next to its bite. You wake up, itchy, and scratch your face, inadvertently introducing T. cruzi into your blood stream. Like the HIV virus, T. cruzi can be spread through blood transfusions and organ donations (hence the question on the blood donation form), and from mother to fetus. Unlike HIV, it can be transmitted in food. If you are making yourself some delicious sugarcane juice and there happen to be kissing bugs hiding on the stalks, you end up with a glass full of trypanosomes once you’ve crushed everything to a pulp. A bunch of Brazilian children were infected with very high parasite loads this way.
Now that you’re terrified to itch your face or drink juice, you should know why T. cruzi is so dangerous. While there is a treatment for the “acute phase” of infection (the first few weeks after the parasite enters you), there is no treatment for the chronic phase, which ultimately kills 20-40% of those infected. In the chronic stage, trypanosomes settle down to make their home inside of you, especially in your heart. Chagas can affect the digestive and nervous systems, but usually it’s the damage to the circulatory system that kills. Over time, trypanosomes slowly devour your heart, causing inflammation that enlarges and weakens the muscle. Chagas disease is the leading cause of heart failure in Latin America.
If you remember nothing else about these parasites, remember that they will make an excellent metaphor for your ex-boyfriend in any terrible poetry you will write. You were my trypanosome/ living inside me/ consuming my heart.
The perfect story for: connecting with sullen teenagers, Valentine’s Day, getting people on juice cleanses to stop talking to you
If you lack a paranoid coworker to send you terrible news stories on Facebook, perhaps you did not hear about the two high-profile cases of a brain-eating amoeba that infected two children in the United States last summer. Naegleria fowleria is a deadly protozoan: it kills more than 99% of the people it infects.
Parasites do not usually kill their hosts quickly. Why bite the hand that feeds you when you can slowly nibble on it for years? N. fowleria is an accidental parasite. It can live out its entire life cycle in freshwater, dividing and propagating in warm ponds and poorly chlorinated pools. They don’t need a human host to live, but if they go up your nose when you jump into the pool, they will keep going about their business. Only now their business is inside your nose, and the amoebas go into attack mode.
Your nose is the first victim. N. fowleria kills your olfactory bulbs and eats them; one of the major early symptoms of the disease is losing the ability to smell. After dining on your nasal cavity, N. fowleria travels along the neurons connected to your brain. It takes between three to seven days for the amoebas to make the journey, but once they’ve reached the brain you are pretty much screwed. Amoebas feast on your brain in earnest, causing you to suffer from hallucinations and seizures. Soon, the rest of the brain will begin swell until you fall into a coma. Within two weeks, amoebas are eating your brain stem, and the brain can no longer tell the lungs to breathe; respiratory failure is the ultimate cause of death.
If you were ever teased as a child for being a wimp and plugging your nose when you jumped off the diving board, take comfort in the fact that you were protecting yourself from N. fowleria. Then impress everyone by doing a cannonball in the pool (just make sure it’s full of chlorine first).
The perfect story for: children’s birthday parties, visiting water parks, skinny-dipping during camping trips
Guinea worms are some of the least prevalent human parasites, but they are definitely one of the most disgusting. Guinea worms are only found in four countries with 96% of all cases found in South Sudan. Reported cases have dropped 99.98% since 1989, with only 97 infected in 2013 as of August. If you know what guinea worms are, that’s 97 cases too many.
Guinea worm larvae live inside water fleas. When you drink contaminated water, the water fleas die in your stomach, but the worm larvae escape into your body and mature into adults. After the adults mate, the male worms die while the females burrow into connective tissue. They particularly like the space next to leg bones, which allows them to grow unperturbed. While adult males are only an inch long, female worms will grow up to two to three feet in length. That’s right, there’s a worm two to three feet long inside of you, and it’s as thick as a cooked spaghetti noodle.
A year passes before the female worm makes its move. A blister forms on your leg or foot, and within three days the blister pops, revealing the end of the worm. The blister is extremely painful and, seeking relief, you soak your foot in cold water. The worm uses this chance to release her eggs, contaminating the water. All the while, there is a three-foot worm sticking out of your foot.
Extracting the guinea worm is as horrifying as you might imagine. The main method has been used since the time of the ancient Egyptians: slowly and gently wrapping the worm around a stick. The blistered area stings like crazy and you must take great care not to break the worm. If the worm snaps in two, the part left in the body with either rot or, worse, petrify. Some worms like to wrap around joints, and having a petrified worm in your knee is obviously a problem. The slow extraction can take anywhere from hours to months. As you can imagine, this is pretty disruptive to people’s daily lives. It’s hard to be a productive member of society if you have a giant worm slowly coming out of you for months at a time.
The good news is Guinea worms, while painful, do not kill their hosts. The downside is there’s a giant worm coming out of your leg.
The perfect story for: spaghetti dinners, adorning the Christmas tree with tinsel, inducing vomiting after eating too much on Thanksgiving
Louise Goupil is a chemical biology graduate student at the University of California, San Francisco. She enjoys cutting up flatworms and making fun of the weird stuff Anthropologie sells.