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Blastocystis - Diagnosis and Trearment

Published on Mar 30, 2023   -  5 min read


Blastocystis hominis is a unicellular parasite that lives in the intestine and can cause gastrointestinal symptoms. Read the article to know more.


Blastocystis is a genetically varied unicellular parasite with unknown pathogenic potential that colonizes the intestines of humans and a wide variety of non-human animals. The organism has been labeled a stramenopile based on molecular information. Other stramenopile examples include diatoms, chrysophytes, water molds, and slime nets. There are at least 22 different subtypes of blastocystis, and nine of them can infect people. Blastocystosis is widespread throughout the world. However, because many individuals are unaware they have it, healthcare professionals are unsure how widespread it is. It is more prevalent generally in developing nations.

Most often, blastocystis organisms exist harmlessly in a person's digestive system. However, food, water, contact with human or animal feces, and other sources of contamination can all spread blastocystis. People who work with animals and those who reside in or travel to developing nations tend to be more susceptible to blastocystis infection.

What Are the Symptoms of Blastocystis Infection?

  • Many people infected with blastocystis hominis exhibit no symptoms. Blastocystosis is associated with digestive tract inflammation (enteritis). However, it is unknown whether blastocystis is the cause of gastrointestinal disorders or if its presence in the digestive system is merely coincidental.

  • Among those who report symptoms, vomiting, diarrhea, and abdominal pain are most frequently experienced. Other symptoms include weight loss, constipation, an itchy anal area, and excessive gas.

  • Even if blastocystis is discovered in the stools, other illnesses could still bring these symptoms. The intestine can harbor blastocystis species for weeks, months, or even years.

  • Hives and skin rashes are additional symptoms of blastocystosis (urticaria). Hives are welts of red, itchy, and frequently swollen skin.

How Does Blastocystis hominis Spread?

The method of transmission of blastocystis is unknown, since the organism is found in the gastrointestinal tract, fecal-oral transmission is the most likely method of transmission. An individual could become infected through the consumption of food or water tainted with blastocystis or though a contact with someone who has the infection. Poor handwashing practices can cause infection in people, especially those who work with animals or attend daycare facilities.

Who Is at Risk?

Many individuals carry the bacterium blastocystis in their intestines, some of whom never exhibit any symptoms. According to some studies, blastocystis can be found in stools at higher rates in individuals with weakened immune systems. Travelers to unsanitary regions are also more likely to be diagnosed with blastocystis. People who work closely with animals and people who get in contact with human feces, like in a child day care or nursing home, are also at increased risk of contracting the illness.

How Is Blastocystis Diagnosed?

Diagnosing the root cause of diarrhea and associated symptoms may be challenging. Even if blastocystis is discovered in the stool, the symptoms might not be because of it. Instead, another food or water-borne organism may be frequently the most likely culprit behind the illness.

In addition to performing a physical examination, the doctor may ask about recent activities, such as travel. Several laboratory procedures are available to identify parasitic illnesses and other non-infectious causes of gastrointestinal symptoms:

  • Examination of the Stool: This examination looks for parasites. The doctor may provide a container filled with preservative liquid for the stool sample. The sample is then examined under microscope.

  • Endoscopy: The doctor might advise this test if the patient has symptoms, but the fecal exam does not identify the underlying cause. A special camera mounted on a tube examines the digestive tract while the patient is sedated.

  • Blood Test: A blood test can identify blastocystis, but it is not frequently used. However, the doctor might recommend blood tests to rule out other potential causes of the signs and symptoms.

How Is Blastocystosis Treated?

The exact cause of blastocystosis is unknown, it is unclear whether it should be treated.

The therapies that medical professionals use include:

  • Antibiotics that contain both Trimethoprim and Sulfamethoxazole, such as Metronidazole or Cotrimoxazole.

  • Antiparasitic drugs, like Nitazoxanide.

Although they frequently relieve symptoms, these drugs aren't always reliable. Antibiotic resistance or variation in the different strains of Blastocystis may cause variable treatment outcomes. As an alternative, another organism might be to blame for the symptoms.

How to Prevent Blastocystosis?

Good hygiene is the most effective method of preventing blastocystis infection:

  • Before consumption, fruits and vegetables must be thoroughly washed.

  • Cooking surfaces must be cleaned.

  • Frequent hand washing.

Handwashing Tips

Washing the hands frequently for at least 20 seconds with soap and water. Use a hand sanitizer with at least 60 % alcohol when soap and water are unavailable.

Washing hands often, especially:

  • The preparation of a meal before, during, and after.

  • After using the restroom.

  • After assisting a child in using the restroom or changing a diaper.

  • After assisting someone who is ill and experiencing vomiting or diarrhea.

  • After interacting with animals and handling their feces or food.

  • After working with garbage.

  • Before and after cleaning a cut or an wound.

Travel Advice

Taking precautions to reduce the risk of blastocystis exposure while traveling. It is generally advised not to eat anything that can not be boiled, cooked, or peeled. Avoid, more specifically:

  • Food sold by street peddlers.

  • Unpasteurized dairy products, such as ice cream.

  • Uncooked or raw meat, fish, shellfish, or eggs.

  • Food is served at room temperature, including sauces and buffet selections.

  • Foods that can not be peeled, like berries, fresh greens, fruits, and vegetables.

  • Flavored ice and frozen pops.

  • Condiments or meals made with raw fruits or vegetables.

Safe Drinking-Water Tips

The following tips can be followed if a person is traveling to a country with poor sanitation or potentially unsafe drinking water:

  • Avoid drinking unclean water from the tap, a well, or a stream.

  • Boiled and cooled water must be used for drinking and cooking.

  • A chemical water purifier, typically a mixture of bleach and iodine can be used.

  • Drinking tap water, including ice cubes must be avoided.

  • Clean water must be used for brushing teeth, bathing, etc.

  • Hot drinks such as coffee or tea must be boiling hot.

  • Drinking bottled beverages only from unopened bottles.


Blastocystis is a genetically varied unicellular parasite with unknown pathogenic potential that colonizes the intestines of humans and a wide variety of non-human animals. Many people with Blastocystis hominis infection may not exhibit any symptoms. However, this infection is associated with digestive tract inflammation (enteritis). Digestive illnesses can be prevented by frequently washing the hands and avoiding contaminated food and water. If symptoms such as chronic diarrhea or other gastrointestinal changes are observed, a healthcare provider must be consulted. The best way to get better is to discuss the potential causes of illness and seeking appropriate treatment.

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30 Mar 2023  -  5 min read




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