Blastocystis Hominis Infection

The parasite Blastocystis hominis appears in the stools of many healthy and sick people. According to the Centers for Disease Control and Prevention, doctors are engaged in an ongoing debate over whether B. hominis causes health problems and how it gets transmitted. When patients do experience symptoms that may result from a B. hominis infection such as diarrhea, they can usually find relief by taking antibiotics or antiprotozoal medications.

Transmission

• The Centers for Disease Control and Prevention says how Blastocystis is transmitted is unknown. According to the Mayo Clinic, the leading theory of how B. hominis travels from person to person is that the parasite passes in microscopic amounts of feces on people's hands, on food and in water.

Possible Symptoms

• The Mayo Clinic lists diarrhea as the most common problem reported by people whose stool contains B. hominis. Other symptoms of B. hominis infection may include abdominal cramps and bloating, anal itching, fatigue, flatulence and nausea. The Mayo Clinic advises patients to seek medical care when these problems last for three or more days.

Treatments

• Both the CDC and the Mayo Clinic stress that people who have asymptomatic B. hominis infections do not need treatment. When doctors determine that a patient's infection does require treatment, the patient will usually receive a prescription for an antibiotic. Antibiotics that have proven effective against B. hominis include metronidazole (Flagyl) and sulfamethoxazole-trimethoprim (Bactrim). Some patients may also benefit from taking the medication iodoquinol (Yodoxin), which kills amoebas and protozoas.

Prognosis

• The Mayo Clinic describes diarrhea in people whose stool contains B. hominis as "self-limiting." This means that the symptom will usually resolve within a few days even without treatment. The CDC does note, however, that B. hominis infections can persist in people for years. If the parasite does indeed cause health problems, those problems can occur at any time during which B. hominis lives inside a person's body.

Prevention

• Despite questions over how B. hominis enters the body, the CDC offers several tips for how people can prevent infections. According the agency, people should wash their hands with soap and water every time after using the bathroom or changing a baby's diaper, drink only boiled or bottled water when traveling in developing countries and wash and peel raw vegetables and fruits before eating them.