Cyclospora infection

Definition

Cyclospora infection is an intestinal infection caused by a one-celled parasite.

The symptoms of cyclospora infection, including diarrhea, make it difficult to distinguish this infectious diarrhea from many other causes. Diagnosis requires a specialized test to identify the cyclospora parasite in stool samples.

Although uncommon, cyclospora infection has a widespread worldwide distribution. Sources of infection have included contaminated water and produce.

Treatment for cyclospora infection is with antibiotics. Food-safety precautions may help to prevent the disease.

Symptoms

Some people infected with the parasite that causes cyclospora infection develop no signs or symptoms. For other people, the main indications of the infection are:

• Watery diarrhea
• Frequent and sometimes explosive bowel movements

If you're otherwise healthy, the diarrhea may end by itself within a few days, or it may become chronic, lasting for weeks. If you have a compromised immune system, such as from HIV or other chronic illness, the infection can last for months if not treated.

For some people, bouts of diarrhea may alternate with bouts of constipation. Signs and symptoms usually begin within two to 11 days of eating contaminated food or drinking contaminated water.

Other signs and symptoms include:

• Loss of appetite
• Weight loss
• Bloating
• Flatulence
• Burping
• Stomach cramps
• Nausea
• Vomiting
• Muscle aches
• Low-grade fever
• Fatigue
• General feeling of unwellness (malaise)

Causes

Cyclospora infection was first described fewer than three decades ago, with the first human cases reported in the medical literature in 1979. A tiny, one-celled parasite, Cyclospora cayetanensis, causes the infection. You get it by drinking water or eating food that's been contaminated by an infected person.

Exactly how cyclospora is transmitted is not understood. A person infected with cyclospora passes the parasite in stool. Unlike some other food-borne 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 an infected person, such as a restaurant worker who hasn't adequately washed hands after using the toilet.

Reports of infection have been linked to inadequately filtered or untreated water or stagnant water in storage tanks and to some produce. Because cyclospora infection is an emerging illness, it's not yet known whether animals can become infected and pass the infection to people.

Before 1996, sporadic cases of cyclospora infection turned up only in people who traveled in developing countries and in people with compromised immune systems, such as from HIV. Since 1996, imported raspberries, mesclun lettuce and fresh basil have been implicated in cyclospora outbreaks in the United States and Canada.

Risk factors

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.

Despite outbreaks around the world, the risk of getting cyclospora infection is still low compared with other intestinal food-borne and water-borne illnesses.

When to seek medical advice

There are many possible causes of 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, be sure to tell your doctor.

Tests and diagnosis

Because there are so many possible causes of diarrhea and other gastrointestinal symptoms, diagnosis of cyclospora infection requires special laboratory tests to identify the parasite in your stool. Cyclospora infection diagnosis commonly uses a method called an acid-fast staining test, which uses a stool sample to identify the parasite under a microscope.

Complications

The prolonged diarrhea of untreated cyclospora infection can cause dehydration. If you're an otherwise healthy adult, you usually can treat dehydration by drinking more fluids. Severely dehydrated people; those with compromised immune systems; older adults; and infants and young children, who become dehydrated more easily than adults, may need to be hospitalized to receive salts and fluids through a vein (intravenously).

Treatments and drugs

In many cases, cyclospora infection is self-limiting, although it can recur. Treatment of cyclospora infection focuses on:

• Shortening the duration of the illness by ridding your body of the parasite
• Preventing excessive fluid loss

The only effective treatment is a combination antibiotic known as trimethoprim-sulfamethoxazole (Bactrim, Septra). For people who can't take sulfa, ciprofloxacin (Cipro) or nitazoxanide (Alinia) may be effective.

To prevent or treat mild to moderate fluid loss, it's generally adequate for healthy adults to drink water. Avoid coffee, tea and other drinks that contain caffeine and alcohol because they can increase dehydration. Fruit juice and soda can make diarrhea worse.

Treating fluid loss in children
Your doctor can advise you on treating fluid loss in infants and children. Generally, however, unless your doctor advises otherwise, use an oral rehydration solution, such as Pedialyte, for infants and children who have diarrhea, vomiting or fever.

These solutions contain water and salts in specific proportions to replenish both fluids and electrolytes. They also contain glucose or another carbohydrate, such as rice powder, to enhance absorption in the intestinal tract. Begin giving fluids early in the course of an illness instead of waiting until the situation becomes urgent.

Oral rehydration products are readily available in most drugstores, and many pharmacies carry their own brands.

For emergency rehydration
In an emergency situation where a preformulated solution is unavailable, you can make your own oral rehydration solution by mixing the following:

• 1/2 teaspoon salt
• 1/2 teaspoon baking soda
• 3 tablespoons sugar
• 1 liter (about 1 quart) of safe drinking water

Be sure to measure accurately. Incorrect amounts can make the solution less effective or even harmful. If possible, have someone else check your measurements for accuracy.

Be sure to give enough solution. Your doctor may suggest specific amounts, depending on your child's age and degree of dehydration, but, in general, keep giving liquids slowly until your child's urine becomes clear in color. When your child is vomiting, try giving small amounts of solution at frequent intervals — 1 teaspoon every minute, for instance. If your child can't keep this down, wait 30 to 60 minutes and try again. Room temperature fluids are best.

Don't take antidiarrheal medications
Taking antidiarrheal medication could interfere with your body's efforts to rid itself of the parasite, prolonging or worsening your signs and symptoms.

Prevention

When traveling to developing nations, 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. Even careful washing of these imported foods isn't enough to eliminate the parasite that causes the infection.