Learn about the various types of parasites, symptoms, and the sources of infection and spread.
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Protozoa
Protozoa, microscopic single-celled organisms, are the most common type of parasite in the United States. Unlike other kinds of parasites, they reproduce very rapidly. They do this in the intestines, and can travel to other organs such as the liver, lungs, pancreas, and heart. Protozoa have an indefinite life span. These organisms include:
Roundworms and Hookworms
These are unsegmented worms. They produce eggs that require incubation in soil or in another host before parasitizing humans. Below are examples of some of the many types of roundworms and hookworms that cause infection in humans:
Tapeworms
Flukes or Flatworms
Also read aboutpargonimus,schistosomiasis, andcryptosporidium.
21 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.National Organization for Rare Disorders.Babesiosis.Centers for Disease Control and Prevention.CDC yellow book: health information for international travel.van Woerden HC, Martínez-Girón R, Martínez-Torre C.Protozoan cysts in faecal pellets of German cockroaches (Blattella germanica), with particular emphasis onLophomonas blattarum.Acta Parasit. 2020;65(4):831-836. doi:10.2478/s11686-020-00213-2Centers for Disease Control and Prevention.Trichomoniasis.Centers for Disease Control and Prevention.Ascariasis.Centers for Disease Control and Prevention.DPDx - laboratory identification of parasites of public health concern: ascariasis.Garcia LS, Arrowood M, Kokoskin E, et al.Practical guidance for clinical microbiology laboratories: laboratory diagnosis of parasites from the gastrointestinal tract.Clin Microbiol Rev. 2018;31(1):e00025-17. doi:10.1128/CMR.00025-17Khanna V, Tilak K, Mukhopadhyay C, Khanna R.Significance of diagnosing parasitic infestation in evaluation of unexplained eosinophilia.J Clin Diagn Res. 2015;9(7):DC22-DC24. doi:10.7860/JCDR/2015/12222.6259Centers for Disease Control and Prevention.Hookworm (intestinal).Centers for Disease Control and Prevention.Enterobiasis.Centers for Disease Control and Prevention.Trichuriasis.Centers for Disease Control and Prevention.Trichinellosis (trichinosis).Centers for Disease Control and Prevention.Taeniasis.Centers for Disease Control and Prevention.Cysticercosis.Centers for Disease Control and Prevention.DPDx - laboratory identification of parasites of public health concern: taeniasis.Centers for Disease Control and Prevention.DPDx - laboratory identification of parasites of public health concern: diphyllobothriasis.Centers for Disease Control and Prevention.Diphyllobothrium.Centers for Disease Control and Prevention.DPDx - laboratory identification of parasites of public health concern: fasciolopsiasis.Centers for Disease Control and Prevention.Paragonimus.Centers for Disease Control and Prevention.DPDx - laboratory identification of parasites of public health concern: fascioliasis.Centers for Disease Control and Prevention.Clinical overview of fasciola.
21 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.National Organization for Rare Disorders.Babesiosis.Centers for Disease Control and Prevention.CDC yellow book: health information for international travel.van Woerden HC, Martínez-Girón R, Martínez-Torre C.Protozoan cysts in faecal pellets of German cockroaches (Blattella germanica), with particular emphasis onLophomonas blattarum.Acta Parasit. 2020;65(4):831-836. doi:10.2478/s11686-020-00213-2Centers for Disease Control and Prevention.Trichomoniasis.Centers for Disease Control and Prevention.Ascariasis.Centers for Disease Control and Prevention.DPDx - laboratory identification of parasites of public health concern: ascariasis.Garcia LS, Arrowood M, Kokoskin E, et al.Practical guidance for clinical microbiology laboratories: laboratory diagnosis of parasites from the gastrointestinal tract.Clin Microbiol Rev. 2018;31(1):e00025-17. doi:10.1128/CMR.00025-17Khanna V, Tilak K, Mukhopadhyay C, Khanna R.Significance of diagnosing parasitic infestation in evaluation of unexplained eosinophilia.J Clin Diagn Res. 2015;9(7):DC22-DC24. doi:10.7860/JCDR/2015/12222.6259Centers for Disease Control and Prevention.Hookworm (intestinal).Centers for Disease Control and Prevention.Enterobiasis.Centers for Disease Control and Prevention.Trichuriasis.Centers for Disease Control and Prevention.Trichinellosis (trichinosis).Centers for Disease Control and Prevention.Taeniasis.Centers for Disease Control and Prevention.Cysticercosis.Centers for Disease Control and Prevention.DPDx - laboratory identification of parasites of public health concern: taeniasis.Centers for Disease Control and Prevention.DPDx - laboratory identification of parasites of public health concern: diphyllobothriasis.Centers for Disease Control and Prevention.Diphyllobothrium.Centers for Disease Control and Prevention.DPDx - laboratory identification of parasites of public health concern: fasciolopsiasis.Centers for Disease Control and Prevention.Paragonimus.Centers for Disease Control and Prevention.DPDx - laboratory identification of parasites of public health concern: fascioliasis.Centers for Disease Control and Prevention.Clinical overview of fasciola.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
National Organization for Rare Disorders.Babesiosis.Centers for Disease Control and Prevention.CDC yellow book: health information for international travel.van Woerden HC, Martínez-Girón R, Martínez-Torre C.Protozoan cysts in faecal pellets of German cockroaches (Blattella germanica), with particular emphasis onLophomonas blattarum.Acta Parasit. 2020;65(4):831-836. doi:10.2478/s11686-020-00213-2Centers for Disease Control and Prevention.Trichomoniasis.Centers for Disease Control and Prevention.Ascariasis.Centers for Disease Control and Prevention.DPDx - laboratory identification of parasites of public health concern: ascariasis.Garcia LS, Arrowood M, Kokoskin E, et al.Practical guidance for clinical microbiology laboratories: laboratory diagnosis of parasites from the gastrointestinal tract.Clin Microbiol Rev. 2018;31(1):e00025-17. doi:10.1128/CMR.00025-17Khanna V, Tilak K, Mukhopadhyay C, Khanna R.Significance of diagnosing parasitic infestation in evaluation of unexplained eosinophilia.J Clin Diagn Res. 2015;9(7):DC22-DC24. doi:10.7860/JCDR/2015/12222.6259Centers for Disease Control and Prevention.Hookworm (intestinal).Centers for Disease Control and Prevention.Enterobiasis.Centers for Disease Control and Prevention.Trichuriasis.Centers for Disease Control and Prevention.Trichinellosis (trichinosis).Centers for Disease Control and Prevention.Taeniasis.Centers for Disease Control and Prevention.Cysticercosis.Centers for Disease Control and Prevention.DPDx - laboratory identification of parasites of public health concern: taeniasis.Centers for Disease Control and Prevention.DPDx - laboratory identification of parasites of public health concern: diphyllobothriasis.Centers for Disease Control and Prevention.Diphyllobothrium.Centers for Disease Control and Prevention.DPDx - laboratory identification of parasites of public health concern: fasciolopsiasis.Centers for Disease Control and Prevention.Paragonimus.Centers for Disease Control and Prevention.DPDx - laboratory identification of parasites of public health concern: fascioliasis.Centers for Disease Control and Prevention.Clinical overview of fasciola.
National Organization for Rare Disorders.Babesiosis.
Centers for Disease Control and Prevention.CDC yellow book: health information for international travel.
van Woerden HC, Martínez-Girón R, Martínez-Torre C.Protozoan cysts in faecal pellets of German cockroaches (Blattella germanica), with particular emphasis onLophomonas blattarum.Acta Parasit. 2020;65(4):831-836. doi:10.2478/s11686-020-00213-2
Centers for Disease Control and Prevention.Trichomoniasis.
Centers for Disease Control and Prevention.Ascariasis.
Centers for Disease Control and Prevention.DPDx - laboratory identification of parasites of public health concern: ascariasis.
Garcia LS, Arrowood M, Kokoskin E, et al.Practical guidance for clinical microbiology laboratories: laboratory diagnosis of parasites from the gastrointestinal tract.Clin Microbiol Rev. 2018;31(1):e00025-17. doi:10.1128/CMR.00025-17
Khanna V, Tilak K, Mukhopadhyay C, Khanna R.Significance of diagnosing parasitic infestation in evaluation of unexplained eosinophilia.J Clin Diagn Res. 2015;9(7):DC22-DC24. doi:10.7860/JCDR/2015/12222.6259
Centers for Disease Control and Prevention.Hookworm (intestinal).
Centers for Disease Control and Prevention.Enterobiasis.
Centers for Disease Control and Prevention.Trichuriasis.
Centers for Disease Control and Prevention.Trichinellosis (trichinosis).
Centers for Disease Control and Prevention.Taeniasis.
Centers for Disease Control and Prevention.Cysticercosis.
Centers for Disease Control and Prevention.DPDx - laboratory identification of parasites of public health concern: taeniasis.
Centers for Disease Control and Prevention.DPDx - laboratory identification of parasites of public health concern: diphyllobothriasis.
Centers for Disease Control and Prevention.Diphyllobothrium.
Centers for Disease Control and Prevention.DPDx - laboratory identification of parasites of public health concern: fasciolopsiasis.
Centers for Disease Control and Prevention.Paragonimus.
Centers for Disease Control and Prevention.DPDx - laboratory identification of parasites of public health concern: fascioliasis.
Centers for Disease Control and Prevention.Clinical overview of fasciola.
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