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. 2007 Apr 17;9(1):60–68. doi: 10.1007/s11908-007-0024-1

Parasites of the small intestine

Theodore W Schafer 1,✉, Amer Skopic
PMCID: PMC7101920  PMID: 17254506

Abstract

This paper discusses the most important parasites that inhabit the human small intestine. Beginning with the protozoa and proceeding through the various species of cestodes, nematodes, and trematodes that inhabit the human small bowel, the most important organisms are presented. Possible future developments are discussed along with pathophysiology and treatment in this phylogenic approach. Zoonotic illnesses, those diseases that by their rarity are of little import, and diseases without significant clinical or social implications are beyond the scope of this article and are not discussed.

Keywords: Adult Worm, Albendazole, Praziquantel, Giardiasis, Cryptosporidiosis

References and Recommended Reading

  • 1.Hanson K.L., Cartwright C.P. Use of an enzyme immunoassay does not eliminate the need to analyze multiple stool specimens for sensitive detection of Giardia lamblia. J Clin Microbiol. 2001;39:474–477. doi: 10.1128/JCM.39.2.474-477.2001. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 2.Centers for Disease Control and Prevention: Cryptosporidiosis Surveillance — United States 1999–2002 and Giardiasis Surveillance — United States, 1998–2002. In Surveillance Summaries, January 28, 2005. MMWR 2005:54(No. SS-1). [PubMed]
  • 3.Thompson R.C. Giardiasis as a re-emerging infectious disease and its zoonotic potential. Int J Parasitol. 2000;30:1259–1267. doi: 10.1016/S0020-7519(00)00127-2. [DOI] [PubMed] [Google Scholar]
  • 4.Kappus K.D., Lundgren R.G., Juranek D.D., et al. Intestinal parasitism in the United States: update on a continuing problem. Am J Trop Med Hyg. 1994;50:705–713. doi: 10.4269/ajtmh.1994.50.705. [DOI] [PubMed] [Google Scholar]
  • 5.Aldeen W.E., Carroll K., Robison A., et al. Comparison of nine commercially available enzyme-linked immunosorbent assays for detection of Giardia lamblia in fecal specimens. J Clin Microbiol. 1998;36:1338–1340. doi: 10.1128/jcm.36.5.1338-1340.1998. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 6.Bingham A.K., Meyer E.A. Giardia excystation can be induced in vitro in acidic solutions. Nature. 1979;277:301–302. doi: 10.1038/277301a0. [DOI] [PubMed] [Google Scholar]
  • 7.Boucher S.E.M., Gillin F.D. Excystation of in vitro-derived Giardia lamblia cysts. Infect Immun. 1990;58:3516–3522. doi: 10.1128/iai.58.11.3516-3522.1990. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 8.Mastropasqua E., Rolandi R., Farruggio A., Lirussi F. Giardia duodenalis: a confounding factor for the diagnosis of celiac disease. J Clin Gastroenterol. 2003;36:185–186. doi: 10.1097/00004836-200302000-00023. [DOI] [PubMed] [Google Scholar]
  • 9.Hartong W.A., Gourley W.K., Arvanitakis C. Giardiasis: clinical spectrum and functional-structural abnormalities of the small intestinal mucosa. Gastroenterology. 1979;77:61–69. [PubMed] [Google Scholar]
  • 10.Farthing M.J. The molecular pathogenesis of giardiasis. J Pediatr Gastroenterol Nutr. 1997;24:79–88. doi: 10.1097/00005176-199701000-00018. [DOI] [PubMed] [Google Scholar]
  • 11.Rossignol J.A., Ayoub A., Ayers M.S. Treatment of diarrhea caused by Cryptosporidium parvum: a prospective randomized, double-blind, placebo-controlled study of nitazoxanide. J Infect Dis. 2001;184:103–106. doi: 10.1086/321008. [DOI] [PubMed] [Google Scholar]
  • 12.Roy S.L., DeLong S.M., Stenzel S.A., et al. Emerging Infections Program FoodNet Working Group. Risk factors for sporadic cryptosporidiosis among immunocompetent persons in the United States from 1999 to 2001. J Clin Microbiol. 2004;42:2944–2951. doi: 10.1128/JCM.42.7.2944-2951.2004. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 13.Colford J.M., Jr, Tager I.B., Hirozawa A.M., et al. Cryptosporidosis among patients infected with human immunodeficiency virus. Factors related to symptomatic infection and survival. Am J Epidemiol. 1996;144:807–816. doi: 10.1093/oxfordjournals.aje.a009015. [DOI] [PubMed] [Google Scholar]
  • 14.Goldin R.D., Hunt J. Biliary tract pathology in patients with AIDS. J Clin Pathol. 1993;46(8):691–693. doi: 10.1136/jcp.46.8.691. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 15.Tumwine J.K., Kekitiinwa A., Nabukeera N., et al. Cryptosporidium parvum in children with diarrhea in Mulago Hospital, Kampala, Uganda. Am J Trop Med Hyg. 2003;68(6):710–715. [PubMed] [Google Scholar]
  • 16.Smerdon W.J., Nichols T., Chalmers R.M., et al. Foot and mouth disease in livestock and reduced cryptosporidiosis in humans, England and Wales. Emerg Infect Dis. 2003;9:22–28. doi: 10.3201/eid0901.020512. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 17.Chen X.M., Keithly J.S., Paya C.V., LaRusso N.F. Cryptosporidiosis. N Engl J Med. 2002;346:1723–1731. doi: 10.1056/NEJMra013170. [DOI] [PubMed] [Google Scholar]
  • 18.Mehta P. Laboratory diagnosis of cryptosporidiosis. J Postgrad Med. 2002;48:217–221. [PubMed] [Google Scholar]
  • 19.Rossignol J.F., Ayoub A., Ayers M.S. Treatment of diarrhea caused by Cryptosporidium parvum: a prospective randomized, double-blind, placebo-controlled study of nitazoxanide. J Infect Dis. 2001;184:103–106. doi: 10.1086/321008. [DOI] [PubMed] [Google Scholar]
  • 20.Miao Y.M., Awad-El-Kariem F.M., Franzen C., et al. Eradication of cryptosporidia and microsporidia following successful antiretroviral therapy. J Acquir Immune Defic Syndr. 2000;25:124–129. doi: 10.1097/00042560-200010010-00006. [DOI] [PubMed] [Google Scholar]
  • 21.Ramos J.T., Saavedra J., Ruiz-Contreras J. Cryptosporidium in patients infected with human immunodeficiency virus: azithromycin revisited. J Pediatr. 1997;130:1009–1010. doi: 10.1016/S0022-3476(97)70296-8. [DOI] [PubMed] [Google Scholar]
  • 22.Dionisio D., Orsi A., Sterrantino G., et al. Chronic cryptosporidiosis in patients with AIDS: stable remission and possible eradication after long-term, low dose azithromycin. J Clin Pathol. 1998;51:138–142. doi: 10.1136/jcp.51.2.138. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 23.Centers for Disease Control and Prevention: Recommendations of the International Task Force for Disease Eradication. MMWR 1993, 42(No. RR-16). [PubMed]
  • 24.Garcia H.H., Gilman R.H., Gonzalez A.E., et al. Cysticercosis Working Group in Peru. Hyperendemic human and porcine Taenia solium infection in Peru. Am J Trop Med Hyg. 2003;68:268–275. [PubMed] [Google Scholar]
  • 25.Vazquez-Flores S., Ballesteros-Rodea G., Flisser A., Schantz P.M. Hygiene and restraint of pigs is associated with absence of Taenia solium cysticercosis in a rural community of Mexico. Salud Publica Mex. 2001;43:574–576. doi: 10.1590/s0036-36342001000600009. [DOI] [PubMed] [Google Scholar]
  • 26.Carpio A., Hauser W.A. Prognosis for seizure recurrence in patients with newly diagnosed neurocysticercosis. Neurology. 2002;59:1730–1734. doi: 10.1212/01.wnl.0000036320.69823.ea. [DOI] [PubMed] [Google Scholar]
  • 27.Bragazza L.M., Vaz A.J., Passos A.D., et al. Frequency of serum anti-cysticercus antibodies in the population of a rural Brazilian community (Cassia dos coqueiros, SP) determined by ELISA and immunoblotting using Taenia crassiceps antigens. Rev Inst Med Trop Sao Paulo. 2002;44:7–12. doi: 10.1590/s0036-46652002000100002. [DOI] [PubMed] [Google Scholar]
  • 28.Garcia H.H., Gonzalez A.E., Gilman R.H., et al. Cysticercosis Working Group in Peru. Short report: transient antibody response in Taenia solium infection in field conditions-a major contributor to high seroprevalence. Am J Trop Med Hyg. 2001;65:31–32. doi: 10.4269/ajtmh.2001.65.31. [DOI] [PubMed] [Google Scholar]
  • 29.DeGiorgio C., Pietsch-Escueta S., Tsang V., et al. Seroprevalence of Taenia solium cysticercosis and Taenia solium taeniasis in California, USA. Acta Neurol Scand. 2005;111:84–88. doi: 10.1111/j.1600-0404.2005.00373.x. [DOI] [PubMed] [Google Scholar]
  • 30.Proano-Narvaez J.V., Meza-Lucas A., Mata-Ruiz O., et al. Laboratory diagnosis of human neurocysticercosis: double-blind comparison of enzyme-linked immunosorbent assay and electroimmunotransfer blot assay. J Clin Microbiol. 2002;40:2115–2118. doi: 10.1128/JCM.40.6.2115-2118.2002. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 31.Suss R.A., Maravilla K.R., Thompson J. MR imaging of intracranial cysticercosis: comparison with CT and anatomopathologic features. Am J Neuroradiol. 1986;7:235–242. [PMC free article] [PubMed] [Google Scholar]
  • 32.Mehta S.S., Hatfield S., Jessen L., Vogel D. Albendazole versus praziquantel for neurocysticercosis. Am J Health Syst Pharm. 1998;55:598–600. doi: 10.1093/ajhp/55.6.598. [DOI] [PubMed] [Google Scholar]
  • 33.Garcia H.H., Gilman R.H., Horton J., et al. Albendazole therapy for neurocysticercosis: a prospective double-blind trial comparing 7 versus 14 days of treatment. Cysticercosis Working Group in Peru. Neurology. 1997;48:1421–1427. doi: 10.1212/wnl.48.5.1421. [DOI] [PubMed] [Google Scholar]
  • 34.Hachinski V. Medical treatment of cysticercosis. Arch Neurol. 1995;52:104. doi: 10.1001/archneur.1995.00540250112022. [DOI] [PubMed] [Google Scholar]
  • 35.del Brutto O.H. Medical treatment of cysticercosis—effective. Arch Neurol. 1995;52:102–104. doi: 10.1001/archneur.1995.00540250110021. [DOI] [PubMed] [Google Scholar]
  • 36.Kramer L.D. Medical treatment of cysticercosis—ineffective. Arch Neurol. 1995;52:101–102. doi: 10.1001/archneur.1995.00540250109020. [DOI] [PubMed] [Google Scholar]
  • 37.von Bonsdorff B., Gordin R. Castle’s test (with vitamin B12 and normal gastric juice) in the ileum in patients with genuine and patients with tapeworm pernicious anaemia. Acta Med Scand. 1980;208:193–197. doi: 10.1111/j.0954-6820.1980.tb01176.x. [DOI] [PubMed] [Google Scholar]
  • 38.Khuroo M.S. Asciriasis. Gastroenterol Clin North Am. 1996;25:553–577. doi: 10.1016/S0889-8553(05)70263-6. [DOI] [PubMed] [Google Scholar]
  • 39.Seltzer E. Ascariasis. In: Guerrant R.L., Weller P.F., editors. Tropical Infectious Diseases: Principles, Pathogens and Practice. edn. 1. Philadelphia: Churchill Livingstone; 1999. pp. 553–577. [Google Scholar]
  • 40.Mahmoud A.A.F. Intestinal nematodes (roundworms) In: Mandell G.L., Douglas R.G., Benett J.E., editors. Principles and Practice of Infectious Diseases. edn 5. New York: Churchhill Livingstone; 2000. pp. 2938–2943. [Google Scholar]
  • 41.Chu W.G., Chen P.M., Huag C.C., et al. Neonatal ascariasis. J Pedriatr. 1972;81:783–785. doi: 10.1016/S0022-3476(72)80103-3. [DOI] [PubMed] [Google Scholar]
  • 42.Lindo J.F., Dubon J.M., Ager A.L., et al. Intestinal parasitic infections in human immunodeficiency virus (HIV)-positive and HIV-negative individuals in San Pedro Sula, Honduras. Am J Trop Med Hyg. 1998;58:431–435. doi: 10.4269/ajtmh.1998.58.431. [DOI] [PubMed] [Google Scholar]
  • 43.Swartzman J. Ascariasis. In: Strickland G.T., editor. Hunter’s Tropical Medicine and Emerging Infectious Disease. edn 8. Philadelphia: WB Saunders Co.; 2000. pp. 726–729. [Google Scholar]
  • 44.Oberhelmon R.A., Guerrero E.S., Fernandez M.L., et al. Correlation between intestinal parasitosis, physical growth, and psychomotor development among infants and children from rural Nicaragua. Am J Trop Med Hyg. 1998;58:470–475. doi: 10.4269/ajtmh.1998.58.470. [DOI] [PubMed] [Google Scholar]
  • 45.Hlaing T. Ascariasis and childhood malnutrition. Parasitology. 1993;107(Suppl):S125–S136. doi: 10.1017/S0031182000075557. [DOI] [PubMed] [Google Scholar]
  • 46.Hall A. Intestinal parasitic worms and the growth of children. Trans R Soc Trop Med Hyg. 1993;87:241–242. doi: 10.1016/0035-9203(93)90108-3. [DOI] [PubMed] [Google Scholar]
  • 47.Weller P.F. Parasitic pneumonias. In: Pennington J.E., editor. Respiratory Infections: Diagnosis and Management. edn 3. New York: Raven Press; 1994. p. 695. [Google Scholar]
  • 48.Shad J.A., Lee Y.R. Pancreatits due to Ascaris lumbricoides: second occurance after 2 years. South Med J. 2001;94(1):78–80. [PubMed] [Google Scholar]
  • 49.Hall A., Anwar K.S., Tomkins A.M. Intensity of reinfection with Ascaris lumbricoides and its implications for parasite control. Lancet. 1992;339:1253–1257. doi: 10.1016/0140-6736(92)91593-W. [DOI] [PubMed] [Google Scholar]
  • 50.Igra-Siegman Y., Kapila R., Sen P., et al. Syndrome of hyperinfection with Strongyloides stercoralis. Rev Infect Dis. 1981;3:397–407. doi: 10.1093/clinids/3.3.397. [DOI] [PubMed] [Google Scholar]
  • 51.Beal C.B., Viens P., Grant R.G., Hughes J.M. A new technique for sampling duodenal contents. Demonstration of upper small-bowel pathogens. Am J Trop Med Hyg. 1970;19:349–252. doi: 10.4269/ajtmh.1970.19.349. [DOI] [PubMed] [Google Scholar]
  • 52.Savage D., Foadi M., Haworth C., Grant A. Marked eosinophiliain an immunosuppresed patient with stronglyoidiasis. J Intern Med. 1994;236:473–475. doi: 10.1111/j.1365-2796.1994.tb00828.x. [DOI] [PubMed] [Google Scholar]
  • 53.Kalg R.E., Grossman M.E. Periumbilical purpura in disseminated strongyloidiasis. JAMA. 1986;256:1170–1171. doi: 10.1001/jama.256.9.1170. [DOI] [PubMed] [Google Scholar]
  • 54.Scowden E.B., Schaffner W., Stone W.J. Overwhelming strongyloidiasis: an unappreciated opportunistic infection. Medicine (Baltimore) 1978;57:527–544. [PubMed] [Google Scholar]
  • 55.Genta R.M. Global prevalence of strongyloides: critical review with epidemiological insights into the prevention of disseminated disease. Rev Infect Dis. 1989;11:755–767. doi: 10.1093/clinids/11.5.755. [DOI] [PubMed] [Google Scholar]
  • 56.Linder J.D., Monkemuller K.E., Lazenby A.J., Wilcox C.M. Streptococcus bovis bacteremia associated with Strongyloides stercoralis colitis. Gasrointest Endosc. 2000;52:796–798. doi: 10.1067/mge.2000.109717. [DOI] [PubMed] [Google Scholar]
  • 57.Lee M.G., Terry S.I. Arteriomesenteric duodenal occlusion associated with strongyloidiasis. J Trop Med Hyg. 1989;92:41–45. [PubMed] [Google Scholar]
  • 58.Sato Y., Kobayashi J., Toma H., Shiroma Y. Efficacy of stool examination for detection of Strongyloides infection. Am J Trop Med Hyg. 1995;539:248–250. doi: 10.4269/ajtmh.1995.53.248. [DOI] [PubMed] [Google Scholar]
  • 59.Maxwell C., Hussain R., Nutman T.B., et al. The clinical and immunologic responses of normal human volunteers to low dose hookworm (Necator americanus) infection. Am J Trop Med Hyg. 1987;37:126–134. doi: 10.4269/ajtmh.1987.37.126. [DOI] [PubMed] [Google Scholar]
  • 60.Hotez P.J., Pritchard D.I. Hookworm infection. Sci Am. 1995;272:68–74. doi: 10.1038/scientificamerican0695-68. [DOI] [PubMed] [Google Scholar]
  • 61.Stanssens P., Bergum P.W., Gansemans Y., et al. Anticoagulant repertoire of the hookworm Ancylostoma caninum. Proc Natl Acad Sci USA. 1996;93:2149–2154. doi: 10.1073/pnas.93.5.2149. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 62.Anyaeze C.M. Reducing burden of hookworm disease in the management of upper abdominal pain in the tropics. Trop Doct. 2003;33:174–175. doi: 10.1177/004947550303300321. [DOI] [PubMed] [Google Scholar]
  • 63.de Silva N.R., Brooker S., Hotez P.J., et al. Soil-transmitted helminth infections: updating the global picture. Trends Parasitol. 2003;19:547–551. doi: 10.1016/j.pt.2003.10.002. [DOI] [PubMed] [Google Scholar]
  • 64.Kato T., Kamoi R., Iida M., et al. Endoscopic diagnosis of hookworm disease of the duodenum. J Clin Gastroenterol. 1997;24:100–102. doi: 10.1097/00004836-199703000-00012. [DOI] [PubMed] [Google Scholar]
  • 65.Stephenson L.S., Latham M.C., Kurz K.M., et al. Treatment with a single dose of albendazole improves growth of Kenyan schoolchildren with hookworm, Trichuris trichiura, and Ascaris lumbricoides infection. Am J Trop Med Hyg. 1989;41:78–87. [PubMed] [Google Scholar]
  • 66.Sakti H., Nokes C., Hertanto W.S., et al. Evidence for an association between hookworm infection and cognitive function in Indonesian school children. Trop Med Int Health. 1999;4:322–334. doi: 10.1046/j.1365-3156.1999.00410.x. [DOI] [PubMed] [Google Scholar]
  • 67.Bethony J., Chen J., Lin S., et al. Emerging patterns of hookworm infection: influence of aging on the intensity of Necator infection in Hainan Province, People’s Republic of China. Clin Infect Dis. 2002;35:1336–1344. doi: 10.1086/344268. [DOI] [PubMed] [Google Scholar]
  • 68.Olatunde B.O., Onyemelukwe G.C., et al. Immunosuppression in Nigerians with hookworm infection. Afr J Med Sci. 1994;23:221–225. [PubMed] [Google Scholar]
  • 69.Loukas A., Prociv P. Immune responses in hookworm infections. Clin Microbiol Rev. 2001;14:689–703. doi: 10.1128/CMR.14.4.689-703.2001. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 70.Brooker S., Bethony J., Hotez P.J. Human hookworm infection in the 21st century. Adv Parasitol. 2004;58:197–288. doi: 10.1016/S0065-308X(04)58004-1. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 71.Fincham J.E., Markus M.B., Adams V.J. Could control of soil-transmitted heminthic infection influence the HIV/AIDS pandemic? Acta Trop. 2003;86:315–333. doi: 10.1016/S0001-706X(03)00063-9. [DOI] [PubMed] [Google Scholar]
  • 72.Nacher M., Singhasivanon P., Yimsamran S., et al. Intestinal helminth infections are associated with increased incidence of Plasmodium falciparum malaria in Thailand. J Parasitol. 2002;88:55–58. doi: 10.1645/0022-3395(2002)088[0055:IHIAAW]2.0.CO;2. [DOI] [PubMed] [Google Scholar]
  • 73.Shapiro A.E., Tukahebwa E.M., Kasten J., et al. Epidemiology of helminth infections and their relationship to clinical malaria in southwest Uganda. Trans R Soc Trop Med Hyg. 2005;99:18–24. doi: 10.1016/j.trstmh.2004.02.006. [DOI] [PubMed] [Google Scholar]
  • 74.Modjarrad K., Zulu I., Redden D.T., et al. Treatment of intestinal helminths does not reduce plasma concentrations of HIV-1 RNA in coinfected Zambian adults. J Infect Dis. 2005;192:1277–1283. doi: 10.1086/444543. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 75.Prevention and control schistosomiasis and soil-transmitted helminthiasis. World Health Organ Tech Rep Ser 2002, 912:1–57. [PubMed]
  • 76.Sabine Vaccine Institute: Human hookworm vaccine initiative (HHVI). Available at: http://www.sabin.org/hookworm.htm. Accessed 2/26/05.
  • 77.Chai J.Y., Lee S.H. Food-borne intestinal trematode infections in the Republic of Korea. Parasitol Int. 2002;51:129–154. doi: 10.1016/S1383-5769(02)00008-9. [DOI] [PubMed] [Google Scholar]
  • 78.Liu L.X., Harinasuta K.T. Liver and intestinal flukes. Gastroenterol Clin North Am. 1996;25:627–636. doi: 10.1016/S0889-8553(05)70266-1. [DOI] [PubMed] [Google Scholar]
  • 79.Belizario V.Y., Jr, Bersabe M.J., de Leon W.U., et al. Intestinal heterophyidiasis: an emerging food-borne parasitic zoonosis in southern Philippines. Southeast Asian J Trop Med Public Health. 2001;32(Suppl2):36–42. [PubMed] [Google Scholar]

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