The most known parasite infection of the brain is Neurocysticercosis or Cysticercosis Cellulosae which is caused by the flatworm (Cestode), Taenia solium.
It is transmitted to humans through fecal-oral contamination or the consumption of pig meat infected with taenia cysts .
Neurocysticercosis can also result in encephalitis when affecting other parts of the brain.
However, there are types of worms that can infect the brain including flatworms (cestodes) and roundworms (nematodes) causing diseases such as echinococcosis, or Schistosomiasis .
1. What Parasites Infect the Brain?
There are 2 types of parasites that can infect the brain: Protozoa and Metazoa parasites .
Protozoa parasites are single-cell parasites (made of 1 cell) that cause the following diseases:
- Cerebral Malaria
- American Trypanosomiasis (Chagas Disease)
- African Trypanosomiasis (Sleeping Sickness)
Metazoa parasites are multi-cellular parasites (worms) that cause the following diseases:
1.1. Which Protozoan Parasites Infect the Brain?
1.1.1. What Is Cerebral Malaria?
Malaria of the brain is caused by Plasmodium falciparum which is transmitted to humans by insect bite (Anopheles mosquito) resulting in encephalitis (inflammation of the brain).
These symptoms are due to the presence of schizonts (mature malaria parasites) in the brain venules which causes their damage.
1.1.2. What Is American Trypanosomiasis (Chagas Disease) of the Brain?
American Trypanosomiasis or Chagas disease is caused by Trypanosoma cruzi which is transmitted to humans by insect bite (Triatomine bug) resulting in meningoencephalitis particularly in immunoexpressed individuals such as individuals with HIV. It is mostly found in Latin America .
1.1.3. What Is African Trypanosomiasis (Sleeping Sickness) of the Brain?
African trypanosomiasis or sleeping sickness is caused by Trypanosoma brucei which is transmitted to humans by the Tsetse fly resulting in an infection of the brain parenchyma which if untreated early on leads to meningitis or meningoencephalitis with edema .
1.1.4. What Is Toxoplasmosis of the Brain?
Toxoplasmosis is caused by Toxoplasma gondii which is transmitted to humans through contaminated food with feces from cats, birds, or rodents.
Toxoplasmosis infection results in cysts within the brain, but also in cardiac muscle, and skeleton muscle, resulting in headaches, fever, confusion, and seizures .
1.1.5. What Is Leishmaniasis of the Brain?
Leishmaniasis of the brain is caused by Leishmania donovani which is transmitted to humans by dogs, resulting in seizures, paresis, meningoencephalitis, and cranial nerves dysfunction, and hemorrhagic stroke .
1.1.6. What Is Amoebiasis of the Brain?
Amoebiasis of the brain is caused by several species of amoeba, including Naegleria fowleri, Acanthamoeba species, and Balamuthia mandrillaris .
Naegleria fowleri is found in freshwater and is transmitted to humans while swimming in freshwater. It causes meningoencephalitis that manifests with headache, fever, nausea, and vomiting.
Acanthamoeba is found in water and can cause encephalitis in individuals with a weak immune system which manifests with headache, dizziness, nausea, vomiting, double vision, confusion, ataxia, and seizures.
Balamuthia mandrillaris is found in soil and its infection of the brain results in similar symptoms to those of acanthamoeba encephalitis.
1.1.7. What Is Cerebral Microsporidiosis?
Cerebral microsporidiosis is mainly caused Enterocytozoon bieneusi resulting in encephalitis and seizures .
1.2. Which Metazoan Parasites Infect the Brain?
Metazoan parasite infections involve flatworms (Trematoda and Cestodes) and roundworms (nematodes).
1.2.1. What Is Schistosomiasis?
Schistosomiasis is caused by the flatworms (Trematoda), Schistosoma mansoni, and Schistosoma haematobium that infect the spinal cord, and Schistosoma japonicum that mostly infects the brain.
1.2.2. What is Paragonimiasis of the Brain?
Paragonimiasis is caused by the flatworm, Paragonimus westermani, which is transmitted to humans through fecal-oral contamination, or the consumption of uncooked contaminated crustaceans (e.g., crabs, shrimps, lobster).
Paragonimiasis infection causes an inflammation associated with a reaction to the parasite or its eggs and results in cerebral hemorrhage .
1.2.3. What is Cysticercosis Cellulosae?
Neurocysticercosis or Cysticercosis Cellulosae is caused by the flatworm (Cestode), Taenia solium, which is transmitted to humans through fecal-oral contamination, or the consumption of pig meat infected with taenia cysts .
Neurocysticercosis results in the production of cysts in the brain parenchyma leading to headaches, seizures, cognitive abnormalities, and local nerve tissue damage.
Neurocysticercosis can also result in encephalitis when affecting other parts of the brain.
Coernurosis is caused by different Taenia species, including Taenia multiceps, T. serialis, T. brauni, and T. glomeratus .
These parasites infect humans through the consumption of contaminated food (by dogs or sheep feces) resulting in symptoms like those of neurocysticercosis, including headache, seizures, cognitive abnormalities, local nerve tissue damage, and encephalitis.
1.2.5. What is Hydatidosis or Echinococcosis?
Hydatidosis or echinococcosis is caused by Echinococcus granulosus and Echinococcus multilocularis which result in the formation of cysts in the brain.
The rupture of the cysts results in cerebral lesions and seizures .
1.2.6. What Is Sparganosis of the Brain?
Sparganosis is caused by the flatworms (cestodes), Spirometra mansoni, Spirometra ranarum, Spirometra mansonoides, Spirometra erinacei, and Sparganum proliferum, which infect humans through drinking water .
Brain sparganosis results in headaches, seizures, weakness, and abnormal skin sensations.
1.2.7. What Is Gnathostomiasis of the Brain?
Gnathostomiasis is caused by the roundworm (Nematode), Gnathostoma spinigerum, which is transmitted to humans through the consumption of undercooked birds’ meat and freshwater fish, eels, and frogs.
Although the gnasthostoma mainly infects the skin (under the skin), it can also infect the brain resulting in nerve pain, paralysis, coma, and death .
1.2.8. What Is Angiostrongyliasis of the Brain?
Angiostrongyliasis is caused by the roundworm (Nematode), Angiostrongylus cantonensis, which is transmitted to humans through the consumption of undercooked food such as shrimps, crabs, snails, and slugs .
Angiostrongyliasis results in meningitis (eosinophil meningitis) that manifests with headaches, neck stiffness, nausea, and vomiting.
1.2.9. What Is Toxocariasis of the Brain?
Toxocariasis is caused by the roundworms (Nematodes), Toxocara canis and Toxocara cati, transmitted to humans by dogs and cats, respectively.
Although infection of the brain is rare, toxocariasis can result in meningitis (eosinophil meningitis), seizures, meningomyelitis (inflammation of the myelin sheath), and optic neuritis (inflammation of the optic nerve) .
1.2.10. What Is Strongyloidiasis of the Brain?
Strongyloidiasis is caused by the roundworm (Nematode), Strongyloides stercoralis, which is transmitted to humans through contaminated soil.
Strongyloidiasis is often associated with sepsis due to the infiltration of bowel bacteria into the bloodstream following the parasite perforation of the bowel, resulting in bacterial meningitis and meningoencephalitis .
1.2.12. What Is Baylisarcariasis?
Baylisarcariasis is caused by the roundworm (Nematode), Baylisascaris procyonis, which is transmitted to humans by raccoons, resulting in meningoencephalitis and vision loss .
1.2.15. What Is Lagochilasarcariasis of the Brain?
Lagochilasarcariasis is caused by the roundworm (Nematode), Lagochilascaris minor Leiper, resulting in purulent abscesses in the different organs of the body, including the brain. It was mainly reported in Brazil.
1.2.16. What Is Onchocerciasis?
Onchocerciasis is caused by the roundworm (Nematode), Onchocerca volvulus, which is transmitted to humans through repeated bites by blackflies of the genus Simulium.
Onchocerciasis can cause nodding syndrome and epileptic encephalopathy .
2. How Common Are Brain Parasites?
Although parasitic brain infections are less common in the United States, they are more common in developing countries . The worldwide prevalence of parasitic diseases that can affect the brain is as follows:
- Malaria: 214 million
- Schistosomiasis: 207 million
- Cysticercosis: 50 million
- Onchocerciasis: 42 million
- American Trypanosomiasis: 10 million
- Echinococcosis: 1 million
- African Trypanosomiasis: 50,000 to 70,000
3. What Parasites Cause Neurological Symptoms?
There are many parasites that can infect the brain and cause neurological symptoms, including flatworms (cestodes) and roundworms (nematodes), causing diseases such as neurocysticercosis (Cysticercosis Cellulosae), echinococcosis, or Schistosomiasis .
4. Do Parasites Show Up on an MRI?
Parasites are usually detected by MRI and CT scans which allow visualizing their localization within the body of the infected individual .
5. Can You Have Worms in Your Brain?
There are several worms that can infect your brain including flatworms (cestodes) and roundworms (nematodes) causing diseases such as neurocysticercosis (Cysticercosis Cellulosae), echinococcosis, or Schistosomiasis .
6. Can Parasites Cause Mental Health?
Parasites can cause mental health issues, particularly by causing behavioral changes in the infected individual . Parasites do this through the following actions:
- Interference with the immune-neuronal communication of the affected individual
- Secretion of substances that interfere with the brain activity of the affected individual
- Induction of changes in the brain gene and protein expression
7. How Do You Get Rid of Parasites in the Brain?
Some parasitic infections require surgery such as echinococcosis, or Coernurosis to remove the cysts; however, other parasitic infections require the use of drugs :
- Neurocysticercosis is treated with Albendazole with corticosteroids, praziquantel with corticosteroids or a combination of the 2 drugs with corticosteroids.
- Schistosomiasis is treated with praziquantel
- Cerebral malaria is treated with artesunate and quinine dihydrochloride or quinine gluconate
- Onchocerciasis is treated with ivermectin and doxycycline
- American Trypanosomiasis is treated with benznidazole and nifurtimox
- African Trypanosomiasis is treated with different drugs depending on the species of Trypanosoma, including drugs such as pentamidine, suramin, eflornithine, nifurtimox, and melarsopol
Parasitic infections of the brain are less common in the United States but are more common in developing countries where they have significant health and economic burden.
These diseases have a neurological impact on the organs, mobility, and cognitive functions of the affected individuals resulting in lifelong disabilities, social shame, and a reduction in economic productivity.