- Diseases, Disorders & Conditions
Human Parasites! Three Of The Most Repulsive!
The beasts that like to invade the human body!
For the most part parasites that infect humans are not of plague proportions. However, they can been found just about anywhere. None of these minuscule monsters are pleasant, but some more than others can cause stomach-churning repulsion. I've chosen three but these are merely the tip of an incredibly shocking ice-berg!
Human parasites are generally divided into two categories:
- Endoparasites - found inside the body
- Ectoparasites - found outside the body, for example on the skin
These groups will include numerous kinds of protozoa and worms. When infesting the human body they cause parasitic diseases. For the most part, having good, regular hygiene usually protects us from them.
Lastly, these parasites are not a modern phenomena. Archaeologists have found traces of both parasites and their eggs in human faeces dating to before 5000BCE. They have identified lung flukes, round worms, hook worms and tape worms among others.
Today most parasite infections can be treated successfully. However, there are some that can be fatal.
Scary human parasites
Here are my top three most disgusting parasites that can invade the human body:
1. Dermatobia hominis - botfly
According to the US National Library of Medicine the botfly - normally found in South and Central America - mainly targets horses and cows to lay it's eggs. The species of botfly known to infest humans is dermatobia hominis, but thankfully, these infections are still rare. However, when it does happen, it's nasty.
Botflies - the word 'bot' means 'maggot'- all belong to the family 'Oestridae' and their life cycles can vary depending on the species. Other names for the botflies are:
- warble flies
- heel flies
The botfly basically kidnaps another insect such as a house fly or mosquito and lays it's eggs on them. With the human botfly, the female usually uses either a mosquito or foliage. When the mosquito lands or people rub against foliage then the eggs can land on them. The eggs will then hatch and the larvae burrow into the skin. There is no pain at this stage all that can be seen is a small, red raised area. This is called in medical terms a myiasis. Normally with the botfly, a human will develop cutaneous myiasis, which means a larval infestation under the skin.
The larvae will stay in the host for about 5 to 10 weeks where it continues to grow and buries deeper into the skin. This causes the small bump to become larger and more like a boil with a hole in the middle that allows the parasite to breath. On occasion it's even possible to see the tail of the larva sticking out. Due to this burrowing, the area becomes painful, itchy and people often report that they can feel movement inside. These sensations are often experienced at night.
When development has finished, the larvae burrow back out of the skin and drop to the ground. When this happens they develop into adult flies. For most people the wounds do heal and normally there is little if any scarring. However, in rare cases some people develop a bacterial infection or other medical disease such as tetanus.
Treatment is usually by either cutting the larvae out or enticing them out by blocking up the hole that they breath through. When the larvae's air supply is cut off the come out onto the skin. The patient is also given a course of anti-biotics to help the wound to heal.
2. Dracunculus - guinea worm
Number two on the list is a horrible parasite known dracunculus or the guinea worm normally found in Africa and Asia. This parasite is caught by drinking stagnant water harbouring fleas. These tiny little insects can carry the guinea worm larvae. It's the larvae that infect people, eventually turning into worms. When people drink water that has a water flea in it, the flea is killed by the hydrochloric acid in the person's stomach. However, the guinea worm larvae are freed and burrow into the gut wall. The larvae then move through the body and make their way to the lower limbs.
According to the World Health Organisation (WHO), humans:
"are the only known reservoirs for this disease."
When the larvae first infect a person there is no indication that anything has happened. However, about a year after infestation a blister develops that is extremely painful and the sore usually appears on the lower leg. At this stage one or more worms start to emerge from the blistered area causing a burning sensation. One of the ways that the burning pain is relieved is when the area is immersed in water. When this happens the worm releases thousands of larvae into the water. The cycle begins again when the larvae infect the water fleas.
There is no actual preventative vaccine or cure for guinea worm. It can be removed via surgery by a doctor, but since the worms are found in some of the poorest countries and in remote areas, it's not an option open to many. Therefore, other means have to be used.
Traditionally the worm has to be removed only a few inches at a time by winding it around a stick. The worms can grow up to a meter long and so this process is not only painful, but can take weeks to get the worm out. The technique of removing the worm this way has to be slow and careful to prevent the worm from breaking and slipping back inside the body.
These parasites don't kill anyone. However, people infected become ill and unable to function normally for a considerable time. There are now a number of preventative measures being put in place in countries such as Mali, including providing safe water, education and treatment of natural water sources.
3. Filarial worm - causing Elephantitis (Lymphatic filariasis)
Lymphatic filariasi, (LF), is caused by microscopic worms that invade the lymphatic system of the body. The lymphatic system not only drains fluids from our tissues but has an infection-fighting role as well. There are three types of worm that may infect humans, all are carrried by the mosquito. The species are:
- Wuchereria bancrofti - responsible for about 90% of cases
- Brugia malayi - causes most of the remaining cases
- B. Timori - can also cause LF.
Mosquitoes pick up the larvae of the worm from people who are already infected. When they bite another person, they inject the larvae into the their blood stream. The larvae then find their way to the lymphatic system.
This system - which helps to maintain the fluid balance between the blood and tissues - becomes severely disrupted. It's unclear whether this chaos is caused by the worms or by the reaction of the lymphatic system to them. What is certain is that once tissue damage has occurred the person becomes vulnerable to infection from bacteria or fungi. It is these secondary infections that cause many of the symptoms of LF. The adult worms live in the human body for up to eight years while millions of their larvae are dispersed in the blood.
Many people are infested as children but since the symptoms can take years to develop, they are often into adulthood before anything is noticed. One of the main symptoms is the grotesque swellings of the legs and torso, along with thickened, blistering skin that is darker in colour. This is where the other name for the disease - elephantitis - comes from, as the limbs can resemble those of an elephant.
In some areas of the world - the disease is now mainly found in tropical areas - people who are disfigured by the disease are sometimes shunned by their family and community and many never get the chance to marry. It is obviously a very disabling condition and numerous sufferers are unable to work. The saddest point about the disease is that it is treatable, however, the medications necessary are not always available to the people who need it.
Which of the three parasites do you find the most repulsive?
Parasites are here to stay
Although the parasites described here are largely found in African/Asian areas or other tropical regions, there can be threats to Western people travelling for work or going on holiday. In addition, due to the ever increasing traffic of goods and people around the world, it's much easier for parasites and other infection dangers to hitchhike to different countries. Add to this the global changes in weather and the environment, who knows what repulsive little critters we might find outside our own doorstep in the not too distant future?