Buzz
[WARNING: The following content may be unsettling for most readers.] Thankfully, many of us will never have to endure the experience of dealing with these parasites. However, there are individuals who are exposed to these risks daily, facing both severe symptoms and the potential threat of death if they become infected—or worse, infested.
10. Taeniasis (Tapeworm)
Taeniasis is an infection caused by tapeworms. Typically, tapeworm infestations do not exhibit noticeable symptoms. It's usually detected when the infected person notices segments of proglottids in their stool, especially if the segments are still moving. Sounds delightful, right? Definitely not. Tapeworms are contracted by consuming undercooked meat or freshwater fish contaminated with tapeworm cysts. In most cases, tapeworms in the intestine cause no noticeable symptoms, but they may lead to discomfort, diarrhea, and loss of appetite. However, if the tapeworms migrate to the brain, they can cause a range of issues, including headaches, seizures, and confusion. [JFrater: Given the choice between a picture of the worm itself and the image above, it was an easy decision.]
9. Bot Fly Larva
The Dermatobia hominis, a single species of bot fly, is the only one that targets humans. It deposits its eggs directly onto animal skin, or the larvae fall from the egg, with the heat of the animal causing the larvae to hatch. These parasites do not kill their host, and some rodent-infesting bot flies even consume the host's reproductive organs. To remove them, smoke can be used to force them to the surface, or tape can be applied to the wound to encourage the larvae to surface, allowing extraction. A gruesome video demonstrates an extraction from a human head.
8. Ascaris Infection
Ascariasis is the most prevalent worm infection in humans. It is found globally, particularly in tropical and subtropical regions with poor sanitation and hygiene. Children are more frequently infected than adults, though it is rare in the United States, mostly occurring in rural southern areas. Anesthesia seems to disturb the worms, and when adults infect the lungs, they may exit through the mouth or nose. The ascaris life cycle involves migration to the lungs during the larval stage, then developing into adults in the intestines. In some cases, the adult worms remain in the lungs. Ascaris eggs are present in human feces, and after contamination of the soil, the eggs become infectious after a few weeks. Infection occurs when a person unknowingly ingests these eggs. In the stomach, the eggs hatch into larvae, which travel to the lungs and then the throat to be swallowed. Upon reaching the intestines, they mature into adult worms. Female adult worms lay eggs that are passed in feces, completing the cycle in 2-3 months. The thought of these creatures wriggling out of the body is unimaginable! If you don't believe they can emerge from the nose and mouth, take a look at this picture [warning: don’t – it is revolting].
7. Onchocerciasis
Known as river blindness, Onchocerciasis is the second most common infectious cause of blindness in the world. This disease is triggered by the Onchocerca volvulus, a type of nematode that can live inside the human body for up to 15 years. The infection is transmitted through the bite of a black fly. Once inside the body, the worms spread, and their death leads to severe itching and a robust immune response that can damage nearby tissues, including the eyes, causing blindness.
6. Lymphatic Filariasis
A tropical disease caused by parasitic, thread-like filarial nematodes. These worms infest the lymphatic system, including the lymph nodes, and in chronic cases, lead to the condition known as Elephantiasis, as depicted above.
5. Guinea Worms
The Guinea worm begins its life inside a water flea, which is consumed by a human. Once ingested, the flea is broken down by the stomach's digestive acids, releasing the larvae of the Guinea worm. These larvae remain in the stomach for up to three months. After mating, the male worm dies, and the female begins her journey through the body, typically heading towards the lower legs or feet, although she can travel to any body part. Settling just beneath the skin, she starts to grow by feeding on the host's tissue, eventually reaching lengths of three to five feet. This process causes excruciating pain and severely cripples the host, making movement difficult. As the worm matures, a painful blister forms on the skin. When the affected area is submerged in water, the blister ruptures, releasing hundreds of thousands of tiny first-stage larvae into the water. The adult female worm slowly exits the host's body through the wound made by the blister, a process that can take several weeks to complete.
4. Cutaneous leishmaniasis
Cutaneous leishmaniasis is a skin infection caused by a single-celled parasite, transmitted through the bites of sand flies. These tiny, 2-mm long, hairy flies are capable of passing through the netting typically used to protect against mosquitoes. Sand flies thrive near human settlements, often breeding in organic waste like feces, manure, rodent burrows, and leaf litter. The disease manifests as painful sores that, if left untreated or infected, could be fatal.
3. Naegleria brain-eating amoeba
Avoid drinking the water, and for safety’s sake, don’t put your head in it either. Naegleria fowleri, a dangerous amoeba, lives in warm fresh water, particularly in the American Southwest. While it usually resides harmlessly in the water, it sometimes finds its way into the human brain. This infection causes primary amebic meningoencephalitis (PAM), a condition marked by brain inflammation that ultimately destroys brain tissue. Symptoms of PAM begin 1 to 14 days after infection, including headache, fever, nausea, vomiting, and neck stiffness. As the amoeba wreaks havoc on brain cells, it leads to confusion, disorientation, loss of balance, seizures, and hallucinations. The disease progresses quickly, often resulting in death within 3 to 7 days after symptoms appear.
2. African trypanosomiasis sleeping sickness
Sleeping sickness is a vector-borne parasitic disease transmitted by the bite of an infected tsetse fly. Initially, the parasites multiply in the subcutaneous tissues, blood, and lymph. Over time, they cross the blood-brain barrier, invading the central nervous system. Tsetse flies, which are found in Sub-Saharan Africa, are the primary vectors, but only certain species are responsible for transmission. These flies are commonly found in vegetation near rivers and lakes, in gallery forests, and in large areas of wooded savannah. By the time symptoms appear, the disease is often already in an advanced stage. The first phase, known as the haemolymphatic phase, is characterized by fever, headaches, joint pain, and itching. The second phase, or neurological phase, begins when the parasite crosses into the central nervous system. It is at this stage that confusion, sensory disturbances, and poor coordination appear. A hallmark of this phase is a disruption of the sleep cycle, which gives the disease its name. Without treatment, sleeping sickness is fatal.
1. Screw-worm fly
The screw-worm fly is a parasitic insect that targets warm-blooded animals. It is identifiable by its red eyes and shiny blue-green body, resembling Australian blowflies. These flies lay their eggs on the edges of open wounds caused by injuries, scratches, branding, dehorning, or castration. Once the larvae hatch, they begin feeding on the flesh beneath the wound, causing severe tissue damage. If left untreated, the animal may die from infection or the loss of bodily fluids. Notably, the larvae are known for eating their host from the inside out!
+ Candiru
This bonus entry comes from Top 10 Worst Things in Nature. The Candiru is a tiny parasitic catfish found primarily in the Amazon River, where it is considered even more dangerous than piranhas. Growing up to about six inches in length, the Candiru feeds on the blood of its host by swimming into the gills and using sharp spines on its head to latch onto the host. It then gnaws its way through the body until it reaches a major artery, where it drinks blood until full. The fish locates its prey by scent, and this is where things get particularly disturbing: the smell of human urine attracts the Candiru, which can then find its way into human genitalia under the water, attaching itself and causing immense pain. Removal generally requires surgery. So a word of warning: avoid peeing in the Amazon River.
