Cyclospora infection (cyclosporiasis) causes watery, and sometimes explosive, diarrhea. The one-celled parasite that causes cyclospora infection can enter your body when you ingest contaminated food or water. Fresh produce is the culprit in many cases of cyclospora infection.

Because diarrhea can be caused by many things, it can be difficult to diagnose cyclospora infection unless a specialized stool test is done. Treatment for cyclospora infection is antibiotics. Food safety precautions may help prevent the disease.

Some people infected with the microscopic parasite that causes cyclospora infection develop no signs or symptoms. For others, signs and symptoms — which usually begin within two to 11 days of eating contaminated food or drinking contaminated water — may include:

• Frequent, watery diarrhea
• Bouts of diarrhea alternating with bouts of constipation
• Loss of appetite and weight loss
• Bloating, flatulence and burping
• Stomach cramps
• Nausea and vomiting
• Muscle aches
• Fever
• Fatigue — this symptom may last long after the active infection has gotten better
• General feeling of unwellness (malaise)

The diarrhea may end by itself within a few days, or it may last for weeks. If you have HIV or another condition that compromises your immune system, the infection can last for months if not treated.

When to see a doctor

Many conditions can cause diarrhea and other gastrointestinal signs and symptoms. If you develop persistent diarrhea that lasts several days or recurs, contact your doctor so that he or she can identify the cause and recommend treatment. If you've eaten a food that's been recalled because of a cyclospora outbreak or traveled in an area where parasites such as cyclospora are common, be sure to tell your doctor.

If you experience dehydration due to diarrhea, see your doctor. Warning signs of dehydration include:

• Sunken eyes
• Dry mouth and tongue
• Reduced production of tears
• Decreased urine output

A one-celled parasite, Cyclospora cayetanensis, causes cyclospora infection. You get it by drinking water or eating food that's been contaminated by a person infected with the parasite.

A person infected with cyclospora passes the parasite in stool. However, unlike some other foodborne parasites, cyclospora doesn't become infectious until days or weeks after it's passed in a bowel movement. So it's unlikely that you can get the infection directly from a person infected with cyclospora, such as a restaurant worker who doesn't wash his or her hands adequately after using the toilet.

Before the 1990s, sporadic cases of cyclospora infection turned up only in people who traveled in developing countries and in those with HIV or another condition that caused a weakened immune system. However, since the 1990s, lettuce, fresh basil and imported raspberries have been implicated in cyclospora outbreaks in the United States and Canada.

In the past, people who traveled in developing countries were more likely to get cyclospora infection. These days, the infection is found worldwide, and anyone who ingests contaminated food or water can get it.

The prolonged diarrhea of untreated cyclospora infection can cause dehydration. If you're an otherwise healthy adult, you can treat dehydration by drinking more fluids. Some people may need to be hospitalized to receive intravenous fluids because they're at higher risk of severe dehydration. Examples include:

• People with other serious illnesses
• Infants and young children
• Older adults

When traveling to developing nations, it's essential to be careful about what you eat and drink. However, recent cyclospora infection outbreaks have been linked to foods imported to or grown in the United States and Canada. Unfortunately, even careful washing of foods isn't enough to eliminate the parasite that causes the infection.

To keep track of what foods have been linked to recent outbreaks of cyclospora infection, you may want to periodically check the food safety alert section of the Food and Drug Administration's website.

Because there are so many possible causes of diarrhea and other gastrointestinal symptoms, diagnosis of cyclospora infection requires a laboratory test to identify the parasite in your stool. There are no blood tests to diagnose a cyclospora infection.

Treatment for cyclospora infection is a combination antibiotic known as trimethoprim-sulfamethoxazole (Bactrim, Septra). If you're unable to take trimethoprim-sulfamethoxazole, your doctor may prescribe ciprofloxacin or nitazoxanide (Alinia).

To prevent or treat mild to moderate fluid loss from the severe diarrhea associated with cyclospora infection, it's generally adequate for healthy adults to drink water.

For children and infants, you may want to use an oral rehydration solution, such as Pedialyte. Sports drinks and carbonated beverages don't offer the right balance of nutrients that children need.

If you have a mild case of cyclospora infection, you may not need to seek medical treatment because it will clear up by itself. However, call your doctor if the illness lasts more than a few days or if it appears to be causing dehydration.

What you can do

• Symptom history. Write down any symptoms you've been experiencing and for how long.
• Recent exposure to possible sources of infection. Be sure to describe any international trips or any exposure to potentially contaminated foods.
• Medical history. Make a list of your key medical information, including other conditions for which you're being treated and any medications, vitamins or supplements you're currently taking.
• Questions to ask your doctor. Write down your questions in advance so that you can make the most of your time with your doctor.

For cyclospora infection, some basic questions to ask your doctor include:

• What's the most likely cause of my symptoms?
• Will I need any tests?
• What's the best treatment approach? Are there any alternatives?
• Will I need to take medicine?
• Is there a generic alternative to the medicine you're prescribing me?
• What can I do at home to help ease my symptoms?

What to expect from your doctor

Your doctor will need to know certain details about your illness to make a diagnosis. Be prepared to answer questions such as:

• When did the illness begin?
• Are your symptoms continuous, or do they come and go?
• How often do you experience vomiting or diarrhea?
• Can you tell whether the vomit or diarrhea contains bile, mucus or blood?
• Do you have a fever?
• Does anything seem to improve your symptoms?
• What, if anything, appears to worsen your symptoms?