What is a Parasite?

Parasites are defined as organisms that live off other organisms, or hosts, to survive. The effects of parasites can vary from mild to severe. Often, when patients only experience mild, nonspecific symptoms, the parasitic infection may go undetected for an extended period of time.

Parasitologist Dr. Omar Amin estimates that up to one-third of the population is infected with some type of parasite. This estimate is higher than the Centers for Disease Control and Prevention numbers, which Dr. Amin says is due to the use of less sensitive testing. His own improved detection techniques revealed that parasites are more common than we think. In addition, he has found that several types of parasites previously thought to be non-pathogenic can indeed cause symptoms in some patients. Parasites can also be transmitted through exposure to contaminated water, juice, food, pets, and soil. A common misconception surrounding parasites is that they cause digestive issues only, but they are also capable of causing systemic illness and symptoms as well.

Types of Parasites and Their Respective Symptoms


Trichomoniasis (“trich”) is a common sexually transmitted infection. According to the CDC’s conservative estimation, approximately 3.7 million Americans suffer from trich. Symptoms typically begin anywhere from five to 28 days after this parasite is contracted and consist of discharge, itching, burning, and pain during urination. However, some people with this infection only experience mild to no symptoms. Luckily tric is easily treated with antibiotics.

Giardia lamblia

Giardiasis is an infection in your small intestine and is caused by the microscopic parasite, Giardia lamblia. Symptoms of giardiasis generally show up one to two weeks after exposure and greatly vary, making it difficult to notice or diagnose like many parasitic infections. Symptoms include: fatigue, nausea, loss of appetite, and abdominal pain. Once diagnosed, Giardiasis is treated with antibiotics or other medications. Occasionally, Giardiasis will clear up on its own as well.

Moreover, Giardia lamblia has been shown to be related to the development of celiac disease (autoimmune response to the ingestion of the dietary proteins, gluten, and gliadin) since as early as the 1940s. And yet curiously, this rarely gets attention in the media or amongst gastroenterologists who are treating celiac patients. A private medical practice in Los Angeles, California conducted a study between the years 2000 and 2013 to investigate this link further.

The researchers took stool and saliva samples from 1,336 patients complaining of nonspecific gastrointestinal symptoms and tested them for various types of gut pathogens as well as blood markers for celiac disease. Almost half of the subjects tested positive for at least one infection, while 13% tested positive for four or more! The most common infections were T. gondii and E. histolytica/dispar (parasites) and also H. pylori (gram-negative bacteria). A high percentage of subjects who tested positive for gliadin (one of the diagnostic markers for celiac disease) also tested positive for enteropathogens.

Toxoplasma gondii

Toxoplasmosis is an infection caused by the parasite, Toxoplasma gondii. The CDC reports that over 60 million people in the United States are infected with this parasite, but few notice its effects. People who do develop symptoms may experience a fever, swollen lymph nodes, headaches, muscle pains, and a sore throat. Occasionally, this infection resolves on its own, but patients who are immunocompromised are at a greater risk of toxoplasmosis’s symptoms worsening. If left untreated, those with a weakened immune system can experience brain inflammation, seizures, lung infections, and more. Thankfully, toxoplasmosis is treatable with medications.

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Systematic Dysfunction

In addition to the parasite-induced symptoms parasites that are listed above, parasites can also significantly impact vital organ systems such as the gut, heart, and brain.

Gut Health

The journal Genome Biology features a study where scientists from the University of Pennsylvania investigated the connection between parasites and the microbiome in people from Cameroon. They found that the presence of a parasitic infection strongly correlated to the composition of the participants’ gut microbiomes. In fact, in some cases, given the state of the microbiome, the scientists could predict the presence of gut parasites with 80% accuracy.

Parasite infections particularly affect the presence of a group of gut bacteria in the microbiome called Bacteroidales, which are critical for digestive and immune system functions. There is also evidence that parasitic infections can activate gut bacteria involved with immune system function, leading to inflammation.

Although the full extent of how parasites impact gut health is still unclear, any effect it has on the microbiome is cause for concern as the gut microbiome plays critical roles in the functioning of the heart, immune system, brain, and more.

Heart Health

Parasites such as Toxoplasma gondii can impair heart health if left unaddressed. According to research reported in the Journal of Clinical Medicine Research, T. gondii can persist in heart muscle. This can lead to the development of tissue cysts that can remain throughout the host’s lifetime. In fact, there is evidence to suggest that a chronic parasitic infection such as T. gondii is linked to heart disease.

Brain Health

Parasitic infections impacting the brain and its central nervous system are a frequent cause of mortality worldwide, particularly in low- and middle-income countries. However, cases are occurring at an increased rate in nonendemic areas because of an increase in both international travel and immunocompromising conditions.

Parasites that can affect the brain such as Toxoplasma, are often associated with seizures and epilepsy. In fact, in a recent study of people with active epilepsy, exposure to multiple pathogens such as parasites was a common occurrence.

Because the gut is physically connected to the brain through millions of nerves, the gut microbiome has the ability to significantly impact brain function as it helps control the messages that are sent to the brain. Studies have even shown that people with various psychological disorders have different species of bacteria in their guts, compared to the control group. Consequently, when a parasite disturbs the gut microbiome, brain signaling and function can be negatively impacted.

Who’s at Risk?

Anyone can get a parasitic infection as it is commonly contracted through contaminated food and water. However, some people are at a higher risk of contracting a parasite or developing a more severe infection such as:

  • People who are immunocompromised
  • People who live in a tropical region
  • People who lack access to clean drinking water
  • People who swim in bodies of water where Giardia and other parasites are known to be found
  • People who own outdoor cats that come into contact with infected animals

Final Thought

There is a wide variety of parasitic infections that can affect a patient’s quality of life. Holtorf Medical Group physicians are trained to recognize these types of infections and implement effective treatments, which may include dietary changes, supplements, or other forms of treatment. If you believe you have a parasitic infection, contact a Holtorf Medical Group team member today.

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