Ascariasis
Updates to Article Attributes
Ascariasis is due to infection with the Ascaris lumbricoides adult worm, and typically presents with gastrointestinal or pulmonary symptoms, depending on the stage of development.
Epidemiology
Ascaris lumbricoides is widely distributed in tropical and subtropical regions and in other humid areas. Approximately one-fourth quarter of the world's population is infected at any given time. It is much less common in developed countries and relatively rare in the United States.
Clinical presentation
Clinical presentations vary according to the stage of the life cycle of infection (see parasitology below).
Gastrointestinal manifestations
Gastrointestinal manifestations are due to adult worms.
MostThe most common complication of ascariasis is mechanical small bowel obstruction caused by a large number of worms. A large worm bolus can also cause volvulus or intussusception.
Infestation with Ascaris lumbricoides can also cause a variety of other complications as well, including pancreatitis, acute cholecystitis, and liver abscess.
Rare complications include cardiac tamponade and airway obstruction.
Adult worms may be passed through the anus or through the mouth while vomiting.
Pulmonary manifestions
Pulmonary manifestations occur 5-26 days following ingestion of viable eggs.
Ascaris pneumonia may develop and consists of migratory, transient, localized intraalveolarlocalised intra-alveolar inflammatory reactions.
Pulmonary ascariasis is the most common cause of Loeffler syndrome, which is characterizedcharacterised by fever, cough, sputum, asthma, eosinophilia, and infiltrates seen at chest radiography.
Parasitology
The Ascaris lumbricoides adult worm is typically 15-30 cm long and 3-6 mm thick. Humans are permanent hosts.
The life cycle begins when embryonated eggs, shed by the adult worm, are passed in the fecesfaeces of an infected individual. Eggs can then contaminate soil, water, or even food.
Humans become infected after ingesting contaminated material. Gastric secretions then cause the eggs to hatch in the small bowel. The larvae penetrate the intestinal mucosa and are hematogenouslyhaematogenously transported to the lung.
Pulmonary manifestations vary widely. The worms grow whilewhilst in the alveoli, eventually traveltravelling up the airway to the epiglottis, and are swallowed againthen re-swallowed.
Once they are back in the small bowel, the worms grow to lengths of up to 35 cm. The life span of an adult female worm is 6six months to 1one year.
Radiographic features
For a discussion of the pulmonary appearances of ascariasis please refer to simple pulmonary eosinophilia.
Plain radiograph
Worms can often be seen on conventional abdominal radiographs as curvilinear soft-tissue density cords. If bowel obstruction is present, the typical pattern of airgas-filled, dilated loops of small bowel with multiple airgas-fluid levels can be seen on an upright radiograph.
Fluoroscopy
Barium studies
Intestinal ascariasis appears as individual worms, each seen as a longitudinal tubular structuresstructure on bariuma contrast enema. If the alimentary tract of the worm is empty, the worm may appear as a filling defect. If its alimentary tract is distended, the worm appears as parallel bands. On transverse sections, the worm appears as a target sign with body wall and a central dot representing its gut 1.
Ultrasound
Ultrasound will depict the adult worm as a hypoechoic tubular structure with well-defined echogenic walls. During real-time evaluation, the worms can be seen making curling movements.
CT
The worms can usually be visualizedvisualised within the bowel lumen at CT with soft-tissue windowing.
Treatment and prognosis
Treatment with oral administration of a single 400 mg dose of albendazole is usually successful.
In the presence of bowel obstruction, surgery is usually indicated.
-<p><strong>Ascariasis</strong> is due to infection with the<em> Ascaris lumbricoides</em> adult worm, and typically presents with gastrointestinal or pulmonary symptoms, depending on the stage of development. </p><h4>Epidemiology</h4><p><em>Ascaris lumbricoides</em> is widely distributed in tropical and subtropical regions and in other humid areas. Approximately one-fourth of the world population infected at any given time. It is much less common in developed countries and relatively rare in the United States.</p><h4>Clinical presentation</h4><p>Clinical presentations vary according to the stage of the life cycle of infection (see parasitology below). </p><h5>Gastrointestinal manifestations</h5><p>Gastrointestinal manifestations are due to adult worms. </p><p>Most common complication of ascariasis is mechanical <a href="/articles/small-bowel-obstruction">small bowel obstruction</a> caused by a large number of worms. A large worm bolus can also cause <a href="/articles/volvulus">volvulus</a> or <a href="/articles/intussusception">intussusception</a>.</p><p>Infestation with <em>Ascaris lumbricoides</em> can cause a variety of other complications as well, including <a href="/articles/acute-pancreatitis">pancreatitis</a>, <a href="/articles/acute-cholecystitis">acute cholecystitis</a>, and <a href="/articles/hepatic-abscess-1">liver abscess</a>.</p><p>Rare complications include <a href="/articles/cardiac-tamponade">cardiac tamponade</a> and airway obstruction.</p><p>Adult worms may be passed through the anus or through the mouth while vomiting.</p><h5>Pulmonary manifestions</h5><p>Pulmonary manifestations occur 5-26 days following ingestion of viable eggs.</p><p>Ascaris pneumonia may develop and consists of migratory, transient, localized intraalveolar inflammatory reactions.</p><p>Pulmonary ascariasis is the most common cause of <a href="/articles/loeffler-syndrome">Loeffler syndrome</a>, which is characterized by fever, cough, sputum, asthma, eosinophilia, and infiltrates seen at chest radiography.</p><h4>Parasitology</h4><p>Ascaris lumbricoides adult worm is typically 15-30 cm long and 3-6 mm thick. Humans are permanent hosts. </p><p>The life cycle begins when embryonated eggs, shed by the adult worm, are passed in the feces of an infected individual. Eggs can then contaminate soil, water, or even food. </p><p>Humans become infected after ingesting contaminated material. Gastric secretions then cause the eggs to hatch in the small bowel. The larvae penetrate the intestinal mucosa and are hematogenously transported to the lung.</p><p>Pulmonary manifestations vary widely. The worms grow while in the alveoli, eventually travel up the airway to the epiglottis, and are swallowed again. </p><p>Once they are back in the small bowel, the worms grow to lengths of up to 35 cm. The life span of an adult female worm is 6 months to 1 year.</p><h4>Radiographic features</h4><p>For a discussion of the pulmonary appearances of ascariasis please refer to <a href="/articles/loeffler-syndrome">simple pulmonary eosinophilia</a>. </p><h5>Plain radiograph</h5><p>Worms can often be seen on conventional abdominal radiographs as curvilinear soft-tissue density cords. If bowel obstruction is present, the typical pattern of air-filled, dilated loops of small bowel with multiple air-fluid levels can be seen on an upright radiograph.</p><h5>Fluoroscopy</h5><h6>Barium studies</h6><p>Intestinal ascariasis appears as individual worms seen as longitudinal tubular structures on barium enema. If the alimentary tract of the worm is empty, the worm may appear as a filling defect. If its alimentary tract is distended, the worm appears as parallel bands. On transverse sections, the worm appears as a target sign with body wall and a central dot representing its gut <sup>1</sup>.</p><h5>Ultrasound</h5><p>Ultrasound will depict the adult worm as a hypoechoic tubular structure with well-defined echogenic walls. During real-time evaluation, the worms can be seen making curling movements.</p><h5>CT</h5><p>The worms can usually be visualized within the bowel lumen at CT with soft-tissue windowing.</p><h4>Treatment and prognosis</h4><p>Treatment with oral administration of a single 400 mg dose of albendazole is usually successful.</p><p>In the presence of bowel obstruction, surgery is usually indicated.</p>- +<p><strong>Ascariasis</strong> is due to infection with the<em> Ascaris lumbricoides</em> adult worm, and typically presents with gastrointestinal or pulmonary symptoms, depending on the stage of development. </p><h4>Epidemiology</h4><p><em>Ascaris lumbricoides</em> is widely distributed in tropical and subtropical regions and in other humid areas. Approximately one quarter of the world's population is infected at any given time. It is much less common in developed countries and relatively rare in the United States.</p><h4>Clinical presentation</h4><p>Clinical presentations vary according to the stage of the life cycle of infection (see parasitology below). </p><h5>Gastrointestinal manifestations</h5><p>Gastrointestinal manifestations are due to adult worms. </p><p>The most common complication of ascariasis is mechanical <a href="/articles/small-bowel-obstruction">small bowel obstruction</a> caused by a large number of worms. A large worm bolus can also cause <a href="/articles/volvulus">volvulus</a> or <a href="/articles/intussusception">intussusception</a>.</p><p>Infestation with <em>Ascaris lumbricoides</em> can also cause other complications, including <a href="/articles/acute-pancreatitis">pancreatitis</a>, <a href="/articles/acute-cholecystitis">acute cholecystitis</a>, and <a href="/articles/hepatic-abscess-1">liver abscess</a>.</p><p>Rare complications include <a href="/articles/cardiac-tamponade">cardiac tamponade</a> and airway obstruction.</p><p>Adult worms may be passed through the anus or through the mouth while vomiting.</p><h5>Pulmonary manifestions</h5><p>Pulmonary manifestations occur 5-26 days following ingestion of viable eggs.</p><p>Ascaris pneumonia may develop and consists of migratory, transient, localised intra-alveolar inflammatory reactions.</p><p>Pulmonary ascariasis is the most common cause of <a href="/articles/loeffler-syndrome">Loeffler syndrome</a>, which is characterised by fever, cough, sputum, asthma, eosinophilia, and infiltrates seen at chest radiography.</p><h4>Parasitology</h4><p>The <em>Ascaris lumbricoides</em> adult worm is typically 15-30 cm long and 3-6 mm thick. Humans are permanent hosts. </p><p>The life cycle begins when embryonated eggs, shed by the adult worm, are passed in the faeces of an infected individual. Eggs can then contaminate soil, water, or even food. </p><p>Humans become infected after ingesting contaminated material. Gastric secretions then cause the eggs to hatch in the small bowel. The larvae penetrate the intestinal mucosa and are haematogenously transported to the lung.</p><p>Pulmonary manifestations vary widely. The worms grow whilst in the alveoli, eventually travelling up the airway to the epiglottis, and then re-swallowed. </p><p>Once they are back in the small bowel, the worms grow to lengths of up to 35 cm. The life span of an adult female worm is six months to one year.</p><h4>Radiographic features</h4><p>For a discussion of the pulmonary appearances of ascariasis please refer to <a href="/articles/loeffler-syndrome">simple pulmonary eosinophilia</a>. </p><h5>Plain radiograph</h5><p>Worms can often be seen on conventional abdominal radiographs as curvilinear soft-tissue density cords. If bowel obstruction is present, the typical pattern of gas-filled, dilated loops of small bowel with multiple gas-fluid levels can be seen on an upright radiograph.</p><h5>Fluoroscopy</h5><h6>Barium studies</h6><p>Intestinal ascariasis appears as individual worms, each seen as a longitudinal tubular structure on a contrast enema. If the alimentary tract of the worm is empty, the worm may appear as a filling defect. If its alimentary tract is distended, the worm appears as parallel bands. On transverse sections, the worm appears as a target sign with body wall and a central dot representing its gut <sup>1</sup>.</p><h5>Ultrasound</h5><p>Ultrasound will depict the adult worm as a hypoechoic tubular structure with well-defined echogenic walls. During real-time evaluation, the worms can be seen making curling movements.</p><h5>CT</h5><p>The worms can usually be visualised within the bowel lumen at CT with soft-tissue windowing.</p><h4>Treatment and prognosis</h4><p>Treatment with oral administration of a single 400 mg dose of albendazole is usually successful.</p><p>In the presence of bowel obstruction, surgery is usually indicated.</p>
Systems changed:
- Paediatrics
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