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Taeniasis in humans is a parasitic infection caused by the tapeworm species Taenia saginata (beef tapeworm), Taenia solium (pork tapeworm), and Taenia asiatica (Asian tapeworm). Humans can become infected with these tapeworms by eating raw or undercooked beef (T. saginata) or pork (T. solium and T. asiatica). People with taeniasis typically have mild gastrointestinal symptoms or may be asymptomatic.
Humans become infected by eating raw or undercooked infected beef or pork. Once ingested, cysticerci attach to the small intestine and develop into adult tapeworms over the course of 2 months. The adult tapeworms produce proglottids that mature, detach, and migrate to the anus and are then passed in the feces.
T. saginata tapeworms are usually 4-12 m in length, but can grow to be 25 m; the adult tapeworms produce 1,000 to 2,000 proglottids/ worm and may produce up to 100,000 eggs per worm.
T. solium (pork) tapeworms are smaller, 2-8 m in length, produce an average of 1,000 proglottids/worm, and may produce 50,000 eggs per worm.
T. asiatica tapeworms range in size from 4-8 m, produce 700 proglottids/worm and may produce 80,000 eggs per proglottid.
More on: DPDx: Taeniasis
Disease
Because of the large size of T. saginata tapeworms, T. saginata taeniasis is more frequently symptomatic compared to T. solium or T. asiatica taeniasis. Typical symptoms of taeniasis include mild epigastric discomfort, nausea, flatulence, diarrhea, or hunger pains. In some instances, passage of tapeworm segments is perceptible.
The most visible symptom of taeniasis is the active passing of proglottids through the anus and in the feces. In rare cases, proglottids may become lodged in the appendiceal lumen, or bile or pancreatic ducts.
Diagnosis
Microscopic identification of eggs and proglottids in feces is diagnostic for taeniasis; however, eggs and proglottids are not released into the feces until approximately 2 to 3 months after the adult tapeworm is established in the upper jejunum. Repeated examination and concentration techniques will increase the likelihood of detecting light infections. Examination of 3 stool samples collected on different days is recommended to increase the sensitivity of microscopic methods. Eggs of Taenia spp. cannot be differentiated; a species determination may be possible if mature, gravid proglottids (or, more rarely, examination of the scolex) are present.
Recently developed coproantigen and molecular assays are more sensitive than stool examination, but these assays are not yet available outside of the research laboratory. Serologic methods, which are available only in research settings, may be used to identify T. solium tapeworm carriers.
Household contacts of neurocysticercosis cases should be evaluated for taeniasis to reduce the risk of cysticercosis.
More on: Cysticercosis
Treatment
Praziquantel is the medication most often used to treat active taeniasis, given at 5-10 mg/kg orally once for adults and 5-10 mg/kg orally once for children. If the patient has cysticercosis in addition to taeniasis, praziquantel should be used with caution. Praziquantel is cysticidal and can cause inflammation around dying cysts in those with cysticercosis, which may lead to seizures or other symptoms. Niclosamide is an alternative, given at 2 g orally once for adults and 50 mg/kg orally once for children. After treatment, stools should be collected for 3 days to search for tapeworm proglottids for species identification. Stools should be re-examined for Taenia eggs 1 and 3 months after treatment to be sure the infection is cleared.
Oral praziquantel is available for human use in the United States.
Niclosamide is NOT available for human use in the United States.
Praziquantel
Note on Treatment in Pregnancy
Praziquantel is pregnancy category B. There are no adequate and well-controlled studies in pregnant women. However, the available evidence suggests no difference in adverse birth outcomes in the children of women who were accidentally treated with praziquantel during mass prevention campaigns compared with those who were not. In mass prevention campaigns for which the World Health Organization (WHO) has determined that the benefit of treatment outweighs the risk, WHO encourages the use of praziquantel in any stage of pregnancy. For individual patients in clinical settings, the risk of treatment in pregnant women who are known to have an infection needs to be balanced with the risk of disease progression 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).
Note on Treatment During Lactation
Praziquantel is excreted in low concentrations in human milk. According to WHO guidelines for mass prevention campaigns, the use of praziquantel during lactation is encouraged. For individual patients in clinical settings, praziquantel should be used in breast-feeding women only when the risk to the infant is outweighed by the risk of disease progress in the mother in the absence of treatment.
Note on Treatment in Pediatric Patients
The safety of praziquantel in children aged less than 4 years has not been established. Many children younger than 4 years old have been treated without reported adverse effects in mass prevention campaigns and in studies of schistosomiasis. For individual patients in clinical settings, the risk of treatment of children younger than 4 years old who are known to have an infection needs to be balanced with the risk of disease progression in the absence of treatment.
Niclosamide
Note on Treatment in Pregnancy
Niclosamide is in pregnancy category B. Data on the use of niclosamide in pregnant women are limited. Niclosamide is not thought to be systemically absorbed. Niclosamide should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.
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).
Note on Treatment During Lactation
It is not known whether niclosamide is excreted in breast milk, although niclosamide is not thought to be systemically absorbed. The World Health Organization (WHO) classifies niclosamide as compatible with breastfeeding, although data on the use of niclosamide during lactation are limited.
Note on Treatment in Pediatric Patients
The safety of niclosamide in children has not been established, although niclosamide is not thought to be systemically absorbed. Available evidence suggests that the safety profiles are comparable in children 2 years or older and adults.
- Page last reviewed: January 10, 2013
- Page last updated: January 10, 2013
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