Why Do Parasites Live In The Brain?
Different parasites choose to make their home in different places in the body. Some parasitic worms prefer the environment of the digestive system, while certain flukes thrive in the tissues of the lungs. Other parasites, like the pig tapeworm, Taenia solium, make their way to the brain to live and multiply.
The brain is filled with oxygen and nutrients, and it also has structures in place that prevent the immune system from attacking parasites in the initial stages of infection. This makes for an inviting home for brain parasites!
How Do Parasites Get Into The Brain?
Most brain parasites must make a rather long journey in order to make their home in the brain. In addition, the brain can be a difficult place to invade due the protective barrier between the bloodstream and brain fluid, called the blood-brain barrier. This barrier between the blood and the fluid in the brain is comprised of cells that form a tight seal around the blood vessels that bring nutrients to and from the brain. This makes it difficult (but not impossible) for parasites and other toxins to enter the brain.
When parasite numbers become overwhelmingly large, or when a deficiency exists in the systems of the brain, parasites can make the leap from the bloodstream to the fluids of the brain.
So scientists have speculated that the parasites in the brain may release an enzyme that dissolves a portion of the blood brain barrier which allows the organism to enter. However, this is just a theory.
Which Parasites Can Infect The Brain?
There are two known brain parasites:
- 1) The pork tapeworm, Taenia solium
- 2) The amoeba, Naegleria fowleri
The pig tapeworm, Taenia solium, is responsible for the condition known as neurocysticercosis, the most common parasitic infection of the brain. Neurocysticercosis affects more than fifty million people all over the world, and it is the leading cause of brain seizures. This disease develops when larvae from Taenia solium enter the body via the ingestion of diseased pork meat. Once inside the body, the tapeworm migrates to the small intestine and remains there until it reaches maturity. From here the parasite makes its way to the brain where it attaches either to the brain tissues or to the cavities within the brain.
The parasite will then form cystic lesions that can also affect the eyes, muscles and spinal cord. The exact location of the cysts will determine the symptoms of the disease. Parasites in the brain can interrupt the normal neurological activity and cause brain seizures. On the other hand, parasites that attach to the brain-fluid cavities will cause symptoms such as headaches, migraines, nausea, and dizziness, as well as brain seizures. These additional symptoms may occur because the parasite is interrupting the normal flow of brain fluid within the brain. Over time, this blockage of fluid may cause pressure to build up that can lead to permanent brain damage.
Unlike the pork tapeworm, Naegleria fowleri, another common parasite in the brain, have only infected about 175 people in the world. Therefore this organism is not as easily known or understood. It is rare to become infected with this parasite, but extremely dangerous if you do.
Naegleria fowleri is an dangerous brain parasite that causes a condition called primary amoebic meningo-cephalitis. Out of the 175 cases of this disease that have been reported, only six patients have survived. For this reason, scientists are eagerly searching for more answers as to these particular kinds of parasites in the brain and how they can be treated.
Naegleria fowleri is an amoeba that is commonly found in the wild, especially in warm freshwater lakes and ponds. It can also survive in heated swimming pools. This parasite can infect a human host that is swimming in contaminated waters by attaching to the inside of its host’s nose and then traveling up the nose and into the brain. Once in the area of the brain, the amoeba releases an enzyme that allows it to dissolve the host’s tissues, and enter the tissues of the brain. Naegleria fowleri can then into feast on the valuable nutrients with the neurons of the brain. This is why this particular parasite causes such rapid death.
In addition to the brain damage caused by destroying the brain’s neurons, the presence this parasite can also cause inflammation of the tissues within the brain. This inflammation can lead to additional brain damage and even death.
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