Key points
- Dientamobea fragilis infections are often asymptomatic and require no treatment.
- If symptoms occur and the parasite is the only organism found on a stool specimen, some medications might be effective in reducing symptoms.
Treatment options
Oral paromomycin, metronidazole, and tetracycline antibiotics have been used to treat symptoms associated with D. fragilis infections.
Drug
Dosage and regimen for adults
Paromomycin
25–35 mg per kg per day orally, in three divided doses, for 7 days
Metronidazole*
500–750 mg orally, three times daily for 10 days
Tetracycline (adult)
500 mg (10 mg/kg) orally, twice daily for 10 days
Doxycycline (adult)
100 mg (2 mg/kg) orally, twice daily for 10 days
* Metronidazole is a nitroimidazole drug and patients should be cautioned not to use alcohol. Other nitroimidazole drugs that have been used for treatment of D. fragilis infection include secnidazole, ornidazole, and tinidazole. Iodoquinol (650 mg orally three times daily for 20 days) has also been effective in treating symptomatic D. fragilis infection but is not FDA-approved for this use.
Benzimidazoles (albendazole, mebendazole) are not effective in treating symptomatic D. fragilis infection.
Treatment precautions
Treatment in Pregnancy
The Food and Drug Administration has not assigned oral paromomycin a pregnancy category. Data on the use of oral paromomycin in pregnant women are limited. Generally, the gastrointestinal tract poorly absorbs oral paromomycin, with minimal, if any, systemic availability. Paromomycin in pregnant women might be warranted if the benefits clearly outweigh any potential risks.
Treatment During Lactation
Oral paromomycin is poorly absorbed and is unlikely to be excreted in breast milk. Available information suggests that it may be used in nursing women with normal renal function, if infant renal function is also normal.
Treatment in Pediatric Patients
There has been no formal evaluation on the safety of oral paromomycin in children. However, the safety profiles likely are comparable in children and adults.
Treatment in Pregnancy
Mebendazole is a pregnancy category C drug. Data on the use of mebendazole in pregnant women are limited. The available evidence suggests no difference in congenital anomalies in the children of women treated with mebendazole during mass drug administration (MDA) campaigns compared with those who were not. In MDA campaigns in countries where soil-transmitted helminths are common, World Health Organization (WHO) has determined that the benefits of treatment outweigh the risks and WHO allows use of mebendazole in the 2nd and 3rd trimesters of pregnancy. However, in a pregnant woman infected with a soil-transmitted helminth, balance the risks of treatment for the fetus with the risks of disease progression in the woman in the absence of treatment.
Pregnancy Category B: Either animal-reproduction studies have not demonstrated a fetal risk but there are no controlled studies in pregnant women or animal-reproduction studies have shown an adverse effect (other than a decrease in fertility) that was not confirmed in controlled studies in women in the first trimester (and there is no evidence of a risk in later trimesters).
Treatment During Lactation
Metronidazole is excreted in breast milk. The American Academy of Pediatrics classifies metronidazole as a drug for which the effect on nursing infants is unknown but may be of concern. The World Health Organization (WHO) advises to avoid metronidazole treatment in lactating women. Use metronidazole in lactating women only if the potential benefit of therapy to the mother justifies the potential risk to the infant.
Treatment in Pediatric Patients
The safety of metronidazole in children is unclear. The WHO Model List of Essential Medicines for Children lists metronidazole as an antiamebic and antigiardiasis medicine that can be used in children. The recommended pediatric dosage for oral use in infants, children, and adolescents is Oral: 15 to 50 mg/kg/day in divided doses every 8 hours; maximum daily dose: 250 mg.
Treatment in Pregnancy
Tetracycline antibiotics are assigned to FDA pregnancy category D. Animal studies have shown evidence of toxic effects to the embryo and on skeletal formation. There are no controlled data in human pregnancy; however, congenital defects and maternal liver damage are reported. When used during tooth development (second half of pregnancy) tetracyclines may cause permanent yellow-gray-brown discoloration of the teeth and affect enamel development. The use of tetracycline during pregnancy is generally not recommended, especially during the last half of pregnancy.
Treatment During Lactation
Tetracycline antibiotics are excreted in breast milk. The American Academy of Pediatrics reports that in neonates, tetracycline should be used with caution due to risk to skeletal development and bone growth (particularly in premature infants), as well as tooth discoloration and effects on enamel development. Use tetracycline with caution in lactating women.
Treatment in Pediatric Patients
Tetracycline use in neonates, infants, and children <8 years of age is identified on the Key Potentially Inappropriate Drugs in Pediatrics (KIDs) list by the American Academy of Pediatrics. In neonates, tetracycline is associated with retardation of skeletal development and bone growth in premature neonates. In older infants and children <8 years of age, it should be used with caution due to risk of tooth discoloration and enamel hypoplasia.