CDC - DPDx - Artifacts (2022)

CDC - DPDx - Artifacts (1)

[Blood] [Stool] [Tissue]

Epithelial and white blood cells in stool.

Epithelial and white blood cells are often seen in trichrome-stained stool smears and may be mistaken for amebae.

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Figure A: White blood cells in a trichrome-stained stool smear.

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Figure B: Macrophages in a trichrome-stained stool smear.

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Figure C: Epithelial cell in a trichrome-stained stool smear.

Yeast and other fungal elements in stool.

Yeast and other fungal elements are common in stool. Depending on the size and shape, they may be confused for a variety of helminth and protozoan species.

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Figure A: Yeast in an iodine-stained concentrated wet mount of stool. Yeast in wet mounts may be confused for Giardia.

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Figure E: Fungal spore in a wet mount of stool. Such spores may be confused for the cysts of Entamoeba spp.

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Figure B: Spore of a morel mushroom. Such spores may be confused for helminth eggs, especially hookworm.

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Figure C: Fungal spore in concentrated wet mounts of stool. Such spores may be confused for protozoa such as Giardia or Chilomastix.

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Figure D: Fungal spore in concentrated wet mounts of stool. Such spores may be confused for protozoa such as Giardia or Chilomastix.

Pollen grains in stool.

Pollen spores are very common in stool and may be confused for a variety of helminth eggs.

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Figure A: Pollen grain in a concentrated wet mount of stool. This grain looks very similar to the fertile egg of Ascaris lumbricoides, although the spine-like structures on the outer layer should separate the two.

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Figure E: Possible pollen grain or algal or fungal spore, similar to the one in Figure B, but in a trichrome-stained stool specimen. Image courtesy of the Washington State Public Health Laboratories.

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Figure B: Possible pollen grain or algal or fungal spore in a concentrated wet mount of stool. Grains like this one resemble the operculated eggs of Clonorchis, Metagonimus and related. These grains are usually smaller than the trematode eggs, however. Image courtesy of the Washington State Public Health Laboratories.

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Figure C: Pollen grain in a concentrated wet mount of stool.

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Figure D: Pollen grain in a trichrome-stained stool specimen. In this focal plane, the grain looks like the striated egg of Taenia sp. However, notice the lack of refractile hooks.

Plant material and plant hairs in stool.

Plant material is very common in stool and may be confused for a variety of helminth eggs and larvae.

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Figure A: Plant cell in a concentrated wet mount of stool. Such material can be common in stool and may be confused for helminth eggs, although they are usually much larger than the eggs of most helminth species.

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Figure B: Plant material in an iodine-stained concentrated wet mount of stool. This material can be confused for a hookworm egg. Image courtesy of the Alaska State Public Health Laboratory.

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Figure C: Plant hair in a concentrated wet mount of stool. Plant hairs can be common in stool and may be confused for the larvae of hookworm or Strongyloides stercoralis. However, they are often broken at one end, have a refractile center and lack the strictures seem in helminth larvae (esophagus, genital primordium, etc).

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Figure D: Plant hair in a concentrated wet mount of stool. Plant hairs can be common in stool and may be confused for the larvae of hookworm or Strongyloides stercoralis. However, they are often broken at one end, have a refractile center and lack the strictures seem in helminth larvae (esophagus, genital primordium, etc).

Artifacts in acid-fast stained stool specimens.

Several objects may be seen in acid-fast stained stool specimens that may be confused for the oocysts of Cryptosporidium and Cyclospora.

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Figure A: Yeast in an acid-fast stained stool specimen. These may be confused for the oocysts of Cryptosporidium sp. Images courtesy of the Arizona State Public Health Laboratory.

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Figure E: Object, probably fungal, in an acid-fast stained stool specimen. Such objects may be confused for the oocysts of Cyclospora spp.

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Figure B: Yeast in an acid-fast stained stool specimen. These may be confused for the oocysts of Cryptosporidium sp. Images courtesy of the Arizona State Public Health Laboratory.

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Figure F: Object, probably fungal, in an acid-fast stained stool specimen. Such objects may be confused for the oocysts of Cyclospora spp.

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Figure C: Fungal element in an acid-fast stained stool specimen. Such objects may be confused for the oocysts of Cryptosporidium spp. Images courtesy of the Georgia State Public Health Laboratory.

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Figure D: Fungal element in an acid-fast stained stool specimen. Such objects may be confused for the oocysts of Cryptosporidium spp. Images courtesy of the Georgia State Public Health Laboratory.

Miscellaneous artifacts in stool.

Miscellaneous artifacts in stool.

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Figure A: Unknown object in a concentrated stool specimen. This object looks like the egg of Hymenolepis but lacks refractile hooks and the polar filaments seen in H. nana.

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Figure E: Diatoms in stool. Diatoms do not specifically resemble any parasites of humans, but their size and shape and apparent structure may cause the microscopist to take notice.

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Figure B: Unknown objects in a formalin-concentrated stool specimen. Although these objects do not specifically resemble any parasites of humans, their unique appearance may cause the microscopist to take notice.

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Figure F: Mite egg in a formalin-concentrated stool specimen. Mite eggs are similar to hookworm eggs but are usually larger (but not always). In this specimen, leg buds can be seen in the lower right area of the egg.

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Figure C: Charcot-Leyden crystals. These crystals are the breakdown products of eosinophils and maybe found in the feces and sputum of people with tissue-invading parasitic infections or various allergic reactions.

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Figure D: Charcot-Leyden crystals. These crystals are the breakdown products of eosinophils and maybe found in the feces and sputum of people with tissue-invading parasitic infections or various allergic reactions.

Platelets.

Elongated and degenerating platelets in blood may be confused for Trypanosoma spp. or malaria elements.

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Figure A: Platelet in a thick blood smear. The nature of the platelet gives it the appearance of a trypomastigote of Trypanosoma sp.

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Figure B: Platelet in a thin blood smear. The nature of the platelet gives it the appearance of a trypomastigote of Trypanosoma sp.

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Figure C: Platelets in thin blood smears. The nature of the platelets gives them the appearance of trypomastigotes of Trypanosoma cruzi.

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Figure D: Platelets in thin blood smears. The nature of the platelets gives them the appearance of trypomastigotes of Trypanosoma cruzi.

White blood cells.

Normal white blood cells.

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Figure E: Small lymphocyte (left) and neutrophil in a thin blood smear, stained with Giemsa.

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Figure B: Neutrophils in a thin blood smear, stained with Giemsa.

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Figure F: Neutrophil (lower) and lymphocyte (upper) in a thin blood smear, stained with Giemsa.

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Figure C: Neutrophil in a thin blood smear, stained with Giemsa.

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Figure D: Small lymphocyte in a thin blood smear, stained with Giemsa.

Miscellaneous blood elements.

Miscellaneous blood elements.

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Figure A: Unidentified objects (probably fungal) in a thin blood smear, stained with Giemsa. Such objects may be confused for amastigotes of Leishmania or Trypanosoma cruzi, but the lack of a distinct nucleus and kinetoplast should rule-out these parasites.

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Figure E: Howell-Jolly bodies in a thin blood smear, stained with Giemsa. Howell-Jolly bodies are inclusion that may be seen in splenectomized patients or patients with an otherwise non-functioning or atrophic spleen, and in patients with severe anemia or leukemia.

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Figure B: Fungal spore of Helicosporium (or related). Such objects are air-borne contaminants in laboratories and may be mistaken for microfilariae in stained blood smears.

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Figure C: Nucleated red blood cell in a thin blood smear, stained with Giemsa. There are several conditions which can cause a premature release of nucleated red blood cells into circulation. Such objects may be confused for schizonts of Plasmodium spp.

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Figure D: Nucleated red blood cell in a thin blood smear, stained with Giemsa. There are several conditions which can cause a premature release of nucleated red blood cells into circulation. Such objects may be confused for schizonts of Plasmodium spp.

Miscellaneous artifacts in tissue.

Miscellaneous blood and tissue elements.

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Figure A: Yeast in a Giemsa-stained tissue biopsy. Such objects may be confused for amastigotes of Leishmania or Trypanosoma cruzi, but the lack of a distinct nucleus and kinetoplast should rule-out these parasites.

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Figure B: Seed in an intestinal biopsy specimen. Such object may be confused with parasites, such as intestinal trematodes or Balantidium coli. The boxy, compartmentalized cells are characteristic of plant tissue. Image courtesy of the Children's Hospital of Eastern Ontario, Canada.

Earthworms, horsehair worms and aquatic fly larvae.

Occasionally, non-parasitic worms and insects are brought to the laboratory for identification. They need to be distinguished from true parasites and vectors.

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Figure A: Earthworms (Lumbricus and related) are commonly sent to the public health laboratories for identification. The presence of setae, segmentation, and a clitellum (red arrow, Figure B) should distinguish them from parasitic helminths. Images courtesy of the Kentucky Department of Health.

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Figure E: Aquatic larvae of flies. The free-living aquatic larvae of various flies breed in standing water, including toilets, leading to the misconception they came from stool or urine. The presence of prolegs, a head capsule, breathing tubes (arrow), segmentation and/or setae will usually distinguish them from true parasitic worms.

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Figure B: Earthworms (Lumbricus and related) are commonly sent to the public health laboratories for identification. The presence of setae, segmentation, and a clitellum (red arrow) should distinguish them from parasitic helminths. Images courtesy of the Kentucky Department of Health.

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Figure F: Aquatic larvae of flies. The free-living aquatic larvae of various flies breed in standing water, including toilets, leading to the misconception they came from stool or urine. The presence of prolegs, a head capsule, breathing tubes (arrow, Figure E), segmentation and/or setae will usually distinguish them from true parasitic worms.

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Figure C: Horsehair worms (Gordius and related). Horsehair worms are parasites of insects and may be found in households and end up in toilets. As a result, they are often sent to the public health laboratories for identification. Images courtesy of the Wisconsin State Laboratory of Hygiene.

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Figure D: Horsehair worms (Gordius and related). Horsehair worms are parasites of insects and may be found in households and end up in toilets. As a result, they are often sent to the public health laboratories for identification. Images courtesy of the Wisconsin State Laboratory of Hygiene.

DPDx is an educational resource designed for health professionals and laboratory scientists. For an overview including prevention, control, and treatment visit www.cdc.gov/parasites/.

Page last reviewed: May 3, 2016

Content source: Global Health, Division of Parasitic Diseases and Malaria

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FAQs

What are artifacts in parasitology? ›

Artifacts mean pseudoparasites, supposed parasites and parasitic delusions. Pseudoparasites include undigested leftovers or coincidentally or purposely ingested nonparasitic organisms or their parts. Supposed parasites are wild organisms which were incorrectly identified as the components of faeces.

What is the importance of distinguishing artifacts from actual parasites? ›

Artifacts are an integral part of the diagnosis process and they are cause of common misdiagnosis in the laboratory. Their differentiation from pathogenic parasitic agents is done by proper diagnosis, which leads to proper treatment of parasitic infections.

Do all parasites show up in stool sample? ›

No, it will only detect those that live in the digestive tract and whose eggs are passed through the stool. There are other tests specific for other parasites, such as pinworms, or blood parasites that cause malaria.

What can be mistaken for parasites? ›

Mimicking Protozoa

The most common structures misidentified as protozoan parasites are human cells, yeasts, and starch grains. 4,5 [T2] provides a comparison of these cells with the more common protozoa with which they are confused.

Which techniques can be used for parasite identification? ›

Current laboratory diagnostic methods for the identification of parasites include: polymerase chain reaction (PCR), random amplified polymorphic DNA (RAPD), amplified fragment length polymorphism (AFLP), restriction fragment length polymorphism (RFLP), microsatellite marker method, Luminex xMAP-based technology (areas ...

What is the most common intestinal parasite? ›

Giardia is arguably the most common parasite infection of humans worldwide, and the second most common in the United States after pin-worm. Between 1992 and 1997, the Centers for Disease Control and Prevention (CDC) estimated that more than 2.5 million cases of giardiasis occur annually.

How do you calculate Kato Katz? ›

A Kato-Katz smear consists of 41.7 mg of stool. To calculate the number of eggs per 1 g of stool (EPG) multiply the egg count from the slide by a factor of 24 (24 x 41.7 mg ≈ 1 g).

What does RBC in stool mean? ›

Bright red blood or maroon-colored stools usually indicate a problem in the lower part of the digestive tract such as hemorrhoids or diverticulitis. After getting a medical history and doing a physical exam, the health care provider may order tests to determine the cause of bleeding.

What is accidental parasite? ›

Accidental parasites - Also known as incidental parasites, accidental parasites are those that attack or establish themselves in unusual hosts (hosts that they do not normally parasitize). Here, the host is referred to as an unnatural host.

What is an O&P test? ›

In an ova and parasites (O&P) exam, a technician views a sample of stool under a microscope to look for parasites and their ova (eggs) or cysts, which are hard shells that protect some parasites at a certain stage in their lifecycle.

What are some examples of pseudo parasites? ›

Common pseudoparasites include pollen, plant cells, grain mites, and psocids (book lice). Pollen may be found in feces and can resemble protozoal cysts or even helminth eggs, although pollen is usually several-fold smaller than even the smallest of helminth eggs. Pollen is usually ingested with feed.

What type of doctor should I see for parasites? ›

On This Page
Kind of doctorA doctor who specializes in:
Infectious Disease SpecialistIllnesses caused by infections with bacteria, viruses, or parasites
Internal Medicine SpecialistDiseases of adults, similar to a general practitioner, but with additional specialized training
3 more rows

What does a parasite look like in poop? ›

For roundworms, you may find pieces of worms or large, live worms in your feces. For pinworms, you may see thin, white worms that appear like pieces of thread. Pinworms, which are about the length of a staple , are sometimes visible around the anal region at night, when females lay their eggs on the surrounding skin.

What does it feel like when you have parasites? ›

Stomach pain or tenderness. Feeling tired. Weight loss. Passing a worm in your stool.

What kills parasitic worms in humans? ›

Today, only one drug, praziquantel, is widely used to treat schistosomiasis. It works primarily by killing the adult stages of the parasite in the human body.

What are the 5 most common parasites? ›

In the United States, the most common foodborne parasites are protozoa such as Cryptosporidium spp., Giardia intestinalis, Cyclospora cayetanensis, and Toxoplasma gondii; roundworms such as Trichinella spp. and Anisakis spp.; and tapeworms such as Diphyllobothrium spp. and Taenia spp.

What are the 3 types of parasitic infection? ›

There are three main classes of parasites that can cause disease in humans: protozoa, helminths, and ectoparasites.

What diagnostic method is the gold standard in parasite diagnosis? ›

Microscopic Examination. Microscopic examination is a basic and gold standard method for the diagnosis of parasitic infections. It has been used for parasitological diagnosis for several hundred years (Figure 1) [12].

Will an MRI show parasites? ›

MRI is superior to CT scan in the evaluation of most CNS parasitic infections and is nearly diagnostic, particularly in endemic areas. Contrast-enhanced study is essential not only for specific diagnosis of the disease, but also for assessment of the inflammatory activity.

Are stool tests for parasites accurate? ›

These findings indicate that at least three stool specimens should be examined to confirm the presence of intestinal parasites. Even with such practice, it is not possible to guarantee that there is no infestation, but examination of fewer specimens would run a definite risk of false negative results.

Will a colonoscopy prep get rid of parasites? ›

First, the clean-out process for the colonoscopy is very thorough (if you've had one you know what I mean) and it wipes out any obvious parasites. Even more important, is the fact that parasites actually live INSIDE the colonic wall which will not be seen with the camera.

Do all humans have parasites? ›

Not restricted to underdeveloped countries, parasites exist around the world and can afflict anyone of any race, gender or socioeconomic status. They can cause a myriad of symptoms, only a few of which affect the digestive tract, but the good news is that yes, they are treatable.

What is a parasite cleanse? ›

A parasite cleanse is a dietary or supplement regimen meant to detoxify the human body and rid it of parasitic infections. The goal of the cleanse is to do this without prescription medications. However, there's little research suggesting that this is an effective way to treat a parasitic infection.

Which is more accurate Kato Katz or Kato thick? ›

Garcia et al2 observed that the Kato-Katz method was more sensitive than the thick smear technique for diagnosing helminths2, while Martin & Beaver5 concluded that the Kato thick-smear technique is reliable and practical for the quantitative diagnosis of hookworm, Trichuris Trichiura and Schistosome infections5.

What is Kato thick or Kato Katz? ›

The Kato-Katz technique facilitates the detection and quantification of helminth eggs that infected subjects pass in their faeces. A thick smear is prepared on a microscopic slide and helminth eggs are enumerated under a light microscope and recorded for each helminth species separately.

What is the purpose of glycerine in Kato Katz? ›

The glycerin, in the malachite green in Kato Katz's technique, functions as a clearing agent while the malachite green besides being a dye, is bactericidal 2,3.

When should you worry about blood in your stool? ›

When to see the doctor for blood in the stool. Continuous rectal bleeding, large quantities of blood in the stool, or black or tarry stool can all be symptoms of serious diseases. In addition, the presence of a fever or excessive weakness combined with bloody stool requires a visit to the doctor.

Is red blood in stool serious? ›

It's usually a good idea to reach out to your healthcare provider whenever you have rectal bleeding. It can be a sign of another health condition that might need treatment. If you have heavy bleeding or are seeing blood in multiple bowel movements, it's urgent that you see your provider.

Is occult blood in stool serious? ›

Occult blood in the stool may indicate colon cancer or polyps in the colon or rectum — though not all cancers or polyps bleed. Typically, occult blood is passed in such small amounts that it can be detected only through the chemicals used in a fecal occult blood test.

What are permanent parasites? ›

A parasite, such as a fluke or an itch mite, that lives on its host until maturity or spends its entire life on its host.

What are the examples of temporary parasites? ›

Known Temporary Parasites
Temporary ParasiteHost
Formica caucasicolaFormica picea
Formica dakotensisFormica fusca
Formica dakotensisFormica glacialis
Formica dakotensisFormica lepida
112 more rows
Aug 19, 2020

What are temporary parasites? ›

(1) Facultative parasite, see there. (2) A parasite that survives for a time after ingestion by a host species other than its customary host. (3) A parasite that is free-living during part of its life cycle.

What is included in an ova and parasite test? ›

What is an ova and parasite test? An ova and parasite test looks for parasites and their eggs (ova) in a sample of your stool. A parasite is a tiny plant or animal that gets nutrients by living off another creature. Parasites can live in your digestive system and cause illness.

What can be detected in a stool sample? ›

A stool analysis is a series of tests done on a stool (feces) sample to help diagnose certain conditions affecting the digestive tract. These conditions can include infection (such as from parasites, viruses, or bacteria), poor nutrient absorption, or cancer.

Can the O&P be completed in the office Why or why not? ›

The test may be done in the doctor's office or a laboratory. The patient collects a stool sample in one or more sterile containers containing special chemical fixatives. The feces should be collected directly into the container. It must not be contaminated with urine, water, or other materials.

What is a pseudo parasite? ›

: an object or organism that resembles or is mistaken for a parasite.

What is Coprozoic parasite? ›

Parasite living permanently in a host and cannot live without a host, e.g. Trichomonos species, most human parasites. 3-Coprozoic (spurious) parasites: Foreign organisms which have been swallowed, merely pass along alimentary canal of man (without establishment) to be recovered in faeces (without affect). Page 7. Host.

What procedure is used to detect G lamblia? ›

Direct microscopy method has been considered economical and rapid for the diagnosis in the medical diagnostic laboratory. Fecal concentration is a recommended and routine procedure that allows the detection of a small number of Giardia cysts may be missed by using wet mounts direct smear.

Which of the following is a key characteristic of the thick blood film? ›

Which of the following is a key characteristic of the thick blood film? RBCs must be laked during or before Giemsa staining.

What is helminth egg? ›

Helminth eggs are the infective agents for the types of worm diseases known globally as helminthiases. Although helminths are pluricellular animals their eggs are microscopic (around 20 to 80 μm for those that are important in the sanitary field) and are contained in variable amounts in wastewater, sludge and excreta.

What is ova of Ascaris lumbricoides? ›

Ascaris lumbricoides, along with whipworm and hookworm, is a type of parasite known as a soil-transmitted helminth (STH). The roundworm lays eggs, which then pass in the person's stool, or poop. It can spread when an infected person defecates near farmland or crops.

1. VET PARA 1 | Intro to the Basic Concepts of Vet Parasitology | Chapter 1
(Pinoy Vet Acadz)

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