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Ascaris lumbricoides (Roundworms) – Overview, Testing & Treatment

Ascaris lumbricoides (Roundworms) – Overview, Testing & Treatment
By Med Support News December 8, 2025

Ascaris lumbricoides (Roundworm) - Overview, Testing & Treatment Ascariasis Best Parasite TestAscaris lumbricoides (Roundworms) – Overview, Testing & Treatment

Are you or your patients planning to travel for the holidays? Are you concerned about what might be lurking in the food and environment during travel? Currently, Ascaris lumbricoides is the most common helminthic (parasitic worm) infection worldwide. Ascaris lumbricoides infects more than a billion people, and it is more common in areas with poor sanitation.1

Ascaris lumbricoides is the Latin name for a parasitic roundworm. While the eggs are microscopic, the mature, adult roundworm is large enough to be seen with the naked eye. The adult female worm can grow up to 20-35 cm in length, which is over 13 inches long. The adult male worm can grow up to 15-30 cm in length, or nearly a foot long.1

Ascaris lumbricoides (Roundworm) - Overview, Testing & Treatment Ascariasis Best Parasite TestHow Common Are Infections with Ascaris lumbricoides in the United States?

Populations in the United States have not been thoroughly tested for Ascaris lumbricoides infections in recent years. A systematic review published in 2011 noted that high-quality studies performed between 1942 and 1982 concluded parasitic infection was highly prevalent throughout the southern US.2

One of the most recent studies included in the review was performed in the Southeastern United States in the 1980s. The study determined that over 55% of participants were infected with whipworm, almost 20% had a hookworm infection, and nearly 50% were infected with Ascaris lumbricoides. Therefore, as recently as the 1980s, there is evidence that over half of people living in the southern US had a parasitic infection. Even with improvements in sanitation and agriculture methods, it is possible those living in the US could be infected with a parasite.2,3

A case study published last year, in 2024, describes the case of a 2-year-old girl in Mississippi who expelled a large adult Ascaris lumbricoides worm into her diaper. She never traveled outside the United States but did live on a farm.4

Ascaris lumbricoides (Roundworm) - Overview, Testing & Treatment Ascariasis Best Parasite TestThe Unusual Life Cycle of the Parasite Ascaris lumbricoides

The life cycle of Ascaris lumbricoides begins in the intestines, where an adult female worm can lay approximately 200,000 eggs per day. The sticky eggs are then excreted in the stool and can cause infections. The eggs can survive on surfaces in the home environment, on hands after using the restroom, and in the soil. Eggs in the soil can contaminate fruits, vegetables, herbs, and animals.1

Once eggs are swallowed via food contamination, exposure to fecal matter, or hand-to-mouth contact with a contaminated substance or surface, the eggs hatch in the intestine. After hatching, the larvae migrate to the liver and the lungs within the first week of infection. The larvae then mature in the lungs and climb into the throat, where they are swallowed to travel back into the GI tract. The larvae then become adult worms in the intestine and begin producing more eggs.1

An adult worm can live in the intestines for up to two years, while its eggs can remain viable and infectious in soil for up to 10 years, despite freezing temperatures and extreme heat.4,5

Ascaris lumbricoides (Roundworm) - Overview, Testing & Treatment Ascariasis Best Parasite Test

What are the Signs & Symptoms of an Infection with Ascaris lumbricoides (Ascariasis)?

An infection with the parasite Ascaris lumbricoides is known as ascariasis. Those with ascariasis often have no symptoms. But, since the larvae travel throughout the body, from the intestines to the liver, to the lungs, and then back to the intestines, several symptoms are possible.1

Signs & symptoms of ascariasis can include:

  • Abdominal pain
  • Anorexia
  • Appendicitis
  • Asthma
  • Atopic Dermatitis
  • Bloating
  • Cholangitis
  • Cholecystitis
  • Cough
  • Diarrhea
  • Eosinophilia
  • Fever
  • Hemoptysis
  • Hives
  • Intestinal obstruction
  • Intestinal perforation
  • Liver abscess
  • Nausea
  • Nutrient deficiencies
  • Pancreatitis
  • Pneumonia
  • Pneumonitis
  • Shortness of breath
  • Vomiting
  • Wheezing1,6-9

Ascaris lumbricoides (Roundworm) - Overview, Testing & Treatment Ascariasis Best Parasite TestWhat is the Best Test for Ascaris lumbricoides?

The gold standard method of diagnosing an Ascaris lumbricoides infection is stool microscopy.1 For a stool microscopy test, a preserved stool sample is collected in a B-vial and sent to DiagnosTechs for analysis. In the laboratory, the stool sample will be centrifuged and then thoroughly inspected under a microscope for Ascaris lumbricoides eggs (ova) and worms. When ova or worms are present in the stool, an active Ascaris lumbricoides infection is confirmed.10

Ascaris lumbricoides (Roundworm) - Overview, Testing & Treatment Ascariasis Best Parasite TestOva and worms are not expelled with every bowel movement. Therefore, the Centers for Disease Control (CDC) in the US recommends that patients collect three or more stool samples on different days for analysis.10 The Infectious Diseases Society of America and the American Society for Microbiology recommend collecting up to three stool samples if the first two microscopic examinations are negative despite ongoing symptoms.11

Stool microscopy is the preferred diagnostic test because mature adult females lay many eggs, approximately 200,000 per day. Please note that the stool microscopy test will be negative during the migration and maturation of Ascaris lumbricoides, which lasts 30 – 70 days.12,13 Due to this phenomenon, in rare cases, the collection of multiple sets of stool samples monthly for up to three months might be required to confirm an active infection via stool microscopy.

Ascaris lumbricoides (Roundworm) - Overview, Testing & Treatment Ascariasis Best Parasite TestThe Best Test Panels to Diagnose a Parasitic Infection

The following test panels include stool microscopy:

To place a test order, click here. DiagnosTechs will drop ship test kits directly to your patients. You may select this option at the top of the order form.

Please visit our Provider Tools page for more information about Ascaris (Roundworm) Treatment Protocols.

Ascaris lumbricoides (Roundworm) - Overview, Testing & Treatment Ascariasis Best Parasite TestReferences:

  1. Ahmed M. Intestinal Parasitic Infections in 2023. Gastroenterology Res. 2023;16(3):127-140. doi:10.14740/gr1622
  2. Starr MC, Montgomery SP. Soil-transmitted Helminthiasis in the United States: a systematic review–1940-2010. Am J Trop Med Hyg. 2011;85(4):680-684. doi:10.4269/ajtmh.2011.11-0214
  3. Miswan N, Singham GV, Othman N. Advantages and Limitations of Microscopy and Molecular Detections for Diagnosis of Soil-transmitted Helminths: An Overview. Helminthologia. 2022;59(4):321-340. doi:10.2478/helm-2022-0034
  4. Hobbs CV, Rhinewalt JM, Arguello I, et al. Autochthonous Ascariasis, Mississippi, USA. Emerg Infect Dis. 2024;30(4):821-823. doi:10.3201/eid3004.240176
  5. CDC – Ascariasis – Prevention & Control. Centers for Disease Control and Prevention. February 15, 2018. Accessed May 13, 2024. https://www.cdc.gov/parasites/ascariasis/prevent.html.
  6. Bethony J, Brooker S, Albonico M, et al. Soil-transmitted helminth infections: ascariasis, trichuriasis, and hookworm. Lancet. 2006;367(9521):1521-1532. doi:10.1016/S0140-6736(06)68653-4
  7. Cheema HA, Waheed N, Saeed A. Rare presentation of haemobilia and Loeffler’s pneumonia in a child by ascaris lumbricoides. BMJ Case Rep. 2019;12(8):e230198. doi:10.1136/bcr-2019-230198
  8. Buendía E, Zakzuk J, Mercado D, et al. The IgE response to Ascaris molecular components is associated with clinical indicators of asthma severity. World Allergy Organ J. 2015;8(1):8. doi:10.1186/s40413-015-0058-z
  9. Qualizza R, Losappio LM, Furci F. A case of atopic dermatitis caused by Ascaris lumbricoides infection. Clin Mol Allergy. 2018;16:10. doi:10.1186/s12948-018-0088-5
  10. CDC – Parasites – resources – diagnosis. Centers for Disease Control and Prevention. October 5, 2023. Accessed May 13, 2024. https://www.cdc.gov/parasites/references_resources/diagnosis.html.
  11. Miller JM, Binnicker MJ, Campbell S, et al. A Guide to Utilization of the Microbiology Laboratory for Diagnosis of Infectious Diseases: 2018 Update by the Infectious Diseases Society of America and the American Society for Microbiology. Clin Infect Dis. 2018;67(6):e1-e94. doi:10.1093/cid/ciy381
  12. de Lima Corvino DF, Horrall S. Ascariasis. In: StatPearls. Treasure Island (FL): StatPearls Publishing; July 17, 2023.
  13. Braseth AL, Elliott DE, Ince MN. Parasitic Infections of the Gastrointestinal Track and Liver. Gastroenterol Clin North Am. 2021;50(2):361-381. doi:10.1016/j.gtc.2021.02.011