Ascaris lumbricoides



Ascaris lumbricoides


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Ascaris lumbricoides

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A 23-year-old man presents to a rural clinic in South Asia for evaluation of abdominal pain. The pain began 5 hours ago and is rated as 10 out of 10 in severity. The patient has had several episodes of non-bloody emesis. The patient has also experienced episodes of wheezing and non-productive coughing for the past 3 months. Temperature is 38.3°C (100.9°F), blood pressure is 130/89 mmHg, and pulse is 115/min. Physical examination reveals a diffusely distended abdomen. The heart and lungs are clear of auscultation. An abdominal radiograph is obtained and shown below. Which of the following pathogens is most likely responsible for this patient’s symptoms?

Image reproduced from Radiopedia

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Ascaris lumbricoides p. , 156


Ascaris lumbricoides, also known as the giant intestinal roundworm, is a parasitic nematode (roundworm) that causes human ascariasis, which is an infection caused by this roundworm in humans. The adult worm can grow up to 40 cm (16 in) in length and 2 cm (0.8 in) in width, making it one of the largest parasites that infect humans.

Humans contract ascariasis by ingesting food or soil contaminated by its eggs. When eggs reach into the intestines, they hatch into larvae. Next, larva migrate to the lungs through blood circulation, where they mature into adult worms, get expectorated and swallowed, eventually returning into the intestines. In the intestines, adult worms mate and produce more eggs, and the cycle starts again. Symptoms depend on whether the worm is in its intestinal or pulmonary phase. They may include dry cough, difficulty in breathing, abdominal pain, diarrhea, and vomiting. Ascaris lumbricoides is diagnosed through a stool sample analysis.


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