Diagnosis

The cause of your diarrhea may be difficult to diagnose. Even if blastocystis is present on a fecal exam, it may not be causing your symptoms.

Your doctor likely will take your medical history, ask you about recent activities, such as traveling, and perform a physical exam. A number of lab tests help diagnose parasitic diseases and other noninfectious causes of gastrointestinal symptoms:

  • Stool (fecal) exam. This test looks for parasites or their eggs (ova). Your doctor may give you a special container with preservative fluid for your stool samples. Refrigerate — don't freeze — your samples until you take them to your doctor's office or lab.
  • Endoscopy. If you have symptoms, but the fecal exam doesn't reveal the cause, your doctor may request this test. After you're sedated, a doctor, usually a gastroenterologist, inserts a tube into your mouth or rectum to look for the cause of your symptoms. You'll need to fast beginning the night before the test.
  • Blood tests. A blood test that can detect blastocystis is now available, but it isn't commonly used. However, your doctor may order blood tests to look for other causes of your signs and symptoms.

Treatment

If you have blastocystis without signs or symptoms, then you don't need treatment. Mild signs and symptoms may improve on their own within a few days.

Potential medications for treating blastocystis infection include:

  • Antibiotics, such as metronidazole (Flagyl) or tinidazole (Tindamax)
  • Combination medications, such as sulfamethoxazole and trimethoprim (Bactrim, Septra, others)
  • Antiprotozoal medications, such as paromomycin, or nitazoxanide (Alinia)

However, keep in mind that response to medication for blastocystis infection varies greatly from person to person. And, because the symptoms you're having might be unrelated to blastocystis, it's also possible that any improvement may be due to the medication's effect on another organism.

Preparing for your appointment

You'll probably first see your primary care doctor. However, in some cases when you call to set up an appointment, you may be referred to an infectious disease specialist or someone who specializes in digestive system disorders (gastroenterologist).

Because appointments can be brief, it's a good idea to be well-prepared for your appointment. Here's some information to help you get ready for your appointment, and what to expect from your doctor.

What you can do

  • Be aware of any pre-appointment restrictions. At the time you make the appointment, be sure to ask if there's anything you need to do in advance, such as restrict your diet.
  • Write down any symptoms you're experiencing, including any that may seem unrelated to the reason for which you scheduled the appointment.
  • Write down key personal information, including any major stresses or recent life changes. Let your doctor know if you've recently traveled out of the country, especially if you traveled to a developing country.
  • Make a list of all medications, vitamins or supplements you're taking.
  • Write down questions to ask your doctor.

Preparing a list of questions can help you make the most of your time with your doctor. Some basic questions to ask your doctor include:

  • What's the most likely cause of my symptoms?
  • Are there other possible causes?
  • Do I need any tests?
  • What treatments are available, and which one do you recommend for me?
  • Is there a generic alternative to the medicine you're prescribing me?
  • Are there any brochures or other printed material that I can take home with me? What websites do you recommend?

In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask additional questions during your appointment.

What to expect from your doctor

Your doctor is likely to ask you a number of questions. Being ready to answer them may reserve time to go over any points you want to spend more time on. Your doctor may ask:

  • When did you first begin experiencing symptoms?
  • Do you have symptoms all the time or do they come and go?
  • How severe are your symptoms?
  • Does anything seem to improve your symptoms?
  • What, if anything, appears to worsen your symptoms?
  • Have you traveled out of the country recently?
  • Do you have any other health conditions?

What you can do in the meantime

If your symptoms are related to blastocystis, they may go away on their own before you even see your doctor. Be sure to stay well-hydrated in the meantime. Oral rehydration solutions — available through drugstores and health agencies worldwide — can effectively replace lost fluids and electrolytes.

If oral rehydration solution isn't available, you can make your own by combining 5 cups (about 1 liter) of bottled or boiled water with 6 level teaspoons (about 34 grams) of table sugar and 1/2 level teaspoon (about 3 grams) of table salt.

Anti-diarrheal medications aren't generally recommended, because they can make some diarrheal illnesses worse.