The amazonian vampire fish likes more than just blood

Animals, Humans

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Vandellia cirrhosa is the scientific name for the Candiru, a parasitic catfish inhabiting the murky waters of the Amazon River. They are known as the ‘vampire fish’ by the locals as they feed on the blood of larger fish. The Candiru detect the urea and ammonia expelled by fish as they breathe through their gills. Following this trail, they actually swim inside the gills of the fish, lodge themselves in using a sharp dorsal spine, make an incision with their sharp teeth, and begin feeding.

Candiru parasitizing hostCandiru parasitizing host: Retrieved from the Aquarium Society

They only stay latched on for two-three minutes, at which time they are so engorged with blood that the meal contents are actually visible through the swollen belly. The parasitized fish will probably survive the actual attack, but is weaker due to tissue damage and loss of blood. This obviously also makes the victim a target for other predators.

However, what is truly disturbing is that the Candiru are a known accidental parasite of humans. Not just like a leech - having a blood-sucking fish latch onto you is freaky enough, but these guys take it a step further. You remember that these fish are able to detect urea? When humans urinate, urea is also given off. The Candiru are thought to mistaken this for the same urea given off from fish gills, and will thus follow the trail and swim towards the source. To spell it out: this means that the fish will swim up the urinary tract, into the urethra.

This is obviously quite painful for the human host.

Once inside, the Candiru proceeds to jab its dorsal fin into the flesh, lodging itself into urogenitals of the human. This would include the penis on a male, and most frequently the vagina of a female. They then make the incision as normal, and start taking a blood meal.

Unfortunately, the Candiru cannot survive inside a human, and thus will die inside the urinary tract. Because of this, they will not dislodge themselves and surgery is generally the only way to remove the parasite. Amputation of the penis may be necessary, although there has been a case of a successful removal by a urologist that did not have to involve the removal of that particular limb.

An urban myth surrounding the Candiru states that these catfish are able to leap out of the water and enter the urogenitals of a person urinating while standing on the shore or on a boat. Logically, this can’t be true, since the fish neither has the thrust capacity to leap that high or to combat the downward stream of urine. However there has been one documented, anecdotal case of a Candiru leaving the water - at least a short distance - to enter the penis of an unfortunate human. Stephen Spotte, a fish physiologist, recounts a case where he observed Dr. Samad extract the parasite from a human host:

Candiru removed from penisCandiru removed from penis: Retrieved from Dr. Samad
By the fourth day the patient presented with fever, intense pain, scrotal edema [swelling of the scrotum], and extreme abdomen distention from urine retention. Surgical removal of the fish was considered, but rejected in favor of endoscopy [insertion of a TV-equipped tube into the urethra]. The patient was anesthetized with 5% lidocain and the procedure was performed. The fish was grasped using an alligator-clip attachment on the endoscope and removed in one piece. Fortunately the fish was dead, and decay was beginning to soften its tissues. Tension on the spines had relaxed in death, and they no longer gripped. Had the candirú been alive, its removal would have been more difficult and resulted in greater trauma to the patient. The fish penetrated the victim’s urethra while he was standing in the river urinating, actually emerging from the water and entering his penis, filling the entire anterior urethra. He reported trying to grab hold of the fish, but it was very slippery, and it forced its way inside with alarming speed.

- Spotte, Straight Dope

I don’t know what would be worse - having a living, squirming fish living inside you, or a rotting, decaying one.

I suppose there’s a reason not a lot is known of these parasitic fish!

I would like to call the Maggot to the stand

Animals, Humans

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A stomach of steel is required for a lot of jobs in science. Pathologists regularly explore the inner recesses of deceased beings, prodding, shifting, removing, cutting organs, peeling back skin and drilling into skulls, to help discover how death came about. Entomologists study the earth’s creepy crawlies, researching pests and raising bees, observing bugs and collecting beetles.

There is a unique job that combines the ‘best of both worlds’. A blending of the study of death with too many legs.

Enter, the Forensic Entomologist.

Imagine you are called in to view the scene of a crime. A young girl lays at the side of the road, a gunshot wound adorning her head. Upon close inspection, you see movement around the body - a mass of squirming insects have invaded the hole. Maggots.

Far from being disgusted, you are excited at the sight of these creatures! Taking environmental factors into account, and tying that into your immense knowledge of the maggot life cycle, you conclude that the body has been dead for about five days.

And that, is the job of a Forensic Entomologist.

MaggotsMaggots feeding on decomposed Opossum: Retrieved from OakleyOriginals

This was actually a true Case Study. When police knew the date of disappearance, they were able to identify both her and her killer. The work of the Forensic Entomologist is frequently used as evidence in court, and has helped in solving a variety of cases.

There is a particularly cool (and gruesome!) collection of photos taken by the Science Museum which shows the progression of a recently deceased pig to a putrid mass of bones and insects. If you think your stomach can handle it, onwards! Studies such as these help us understand more about the stages of decay and the associated life cycles of corpse-chewing insects.

When Your Uterus Turns Inside Out

Humans

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When giving birth, something other than the baby may pop out.

In rare cases (stats range from 1 in 2000 births to 1 in 15,000), the placenta lining the uterine wall doesn’t separate fully. As a result, delivery of the baby pulls the top of the uterus (the fundus) outside the body of the mother, essentially turning the uterus inside out. This is known as a Uterine Inversion.

Excessive bleeding caused by hemorrhaging soon follows, as well as extreme pain and shock. Uterine Inversion is an emergency, which needs to be corrected manually and immediately by the attending obstetrician. Local anesthesia is first administered to the site to help control the pain. Attempts to physically push the uterus back inside the body follows - failing that, a cocktail of drugs are used to help relax the uterus and dilate the cervix. In some cases, surgery is required for correction.

Correction of Uterine Inversion
Correction of a Uterine Inversion.
Retrieved from WHO

A Uterine Inversion is life-threatening, but if handled quickly and swiftly the prognosis is good. It almost never happens with non-pregnant women (and when it does, it’s usually because of a tumor pushing down on the uterus). It has been linked to certain classes of pregnancies - those that give birth vaginally after a previous cesarean section, have given birth vaginally several times, experience either very long or very rapid labours, and who have had a previous Uterine Inversion are more at risk.

A gynecologic oncologist recalls a harrowing case of this:

When I reached the delivery room, all was chaos. There were three residents, an obstetrical attending physician, two anesthesiologists, and four nurses. All of them seemed to be shouting. The patient, with no family in sight, was under a mask, her face invisible. Someone was working to start an intravenous line in one arm, another in her neck. The paper drapes were crumpled. Bloody gauze littered the floor; clots seemed to be everywhere. The senior obstetrician explained the situation.

“She’s only 26,” he said, “but she’s been in labor for two days. The baby’s fine, just big. I was doing a cesarean in another room when this happened, but the residents tell me that the delivery was unremarkable—at least till the uterus everted.”

The obstetrics team had tried all the usual measures. After making sure that the bleeding wasn’t compounded by tears in the vagina or from retained bits of placenta stuck on the uterine wall, they had succeeded in replacing the uterus in the abdomen—no small success. Sometimes the cervix continues to contract after eversion, trapping the body of the uterus inside it. When this happens, blood cannot return to the heart because of the cervix’s tightening pressure on uterine veins. Yet blood continues to pour into the uterus through the arteries. Blood is being pumped into the trapped uterus, but it can’t flow back out. If that goes on for more than half an hour, the patient will bleed to death.

- Stewart Massad, Discover

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