Ascariasis

Ascariasis

1. Ascariasis is an infection caused by a soil-transmitted intestinal parasitic nematode
2. An initial pulmonary migration phase (that may cause an asthmalike episode associated with Löffler pneumonia) is followed by intestinal infection, which may be asymptomatic or may be complicated by intestinal obstruction, biliary tract disease, pancreatic disease, malnutrition, and (in children) restricted growth and cognitive function
3. Diagnosed mainly by microscopic identification of eggs in stool
   • Imaging is used to diagnose complications due to intestinal, hepatobiliary, and pancreatic duct obstructions
4. Usually overlaps with infection caused by other soil-transmitted intestinal parasites and other helminths
5. Single-dose treatment with anthelmintic drugs (albendazole, mebendazole, or ivermectin) is safe, effective, and the mainstay of treatment; used for diagnosed infections and for periodic large-scale deworming programs in endemic areas
6. Surgical or endoscopic therapy is necessary in some cases of intestinal or ductal obstruction
7. Infection can be prevented by employing proper sanitation and waste management and by health education, largely on circumstances and techniques for handwashing

Pitfalls

• Coinfection with other intestinal helminths is common
  • Some are not as readily diagnosed as ascariasis and may be missed
  • May not respond to the agents used to treat ascariasis

• Ascariasis is infection with Ascaris lumbricoides (roundworm), a parasitic nematode transmitted by the ingestion of infective larvae from contaminated soil, water, or food 
  • Also caused (rarely) by Ascaris suum, a closely related organism that is native to pigs and capable of infecting humans
• Endemic in Asia, sub-Saharan Africa, South America, and Central America
• Ascariasis has 2 phases, which are reflected in the manifestations of disease 
  • Pulmonary (larval migration stage)
    • Larvae migrate from intestines through portal circulation to lungs and trachea, triggering an immune-mediated type I hypersensitivity reaction
    • Results in eosinophilic pneumonia that may be clinically evident (Löffler syndrome)
    • Larvae then ascend the tracheobronchial tree, cross the epiglottis, are swallowed, and move back to the intestines
  • Gastrointestinal (adult stage)
    • Worms mature to adults in the gastrointestinal tract. They may reach 15 to 35 cm and can obstruct intestinal lumen, biliary tract, or pancreatic duct
    • Nutrient depletion (eg, vitamin A), restricted growth, and restricted cognitive function have been associated with high worm burdens
  • Rarely, aberrant migration occurs, with appearance of adult worms at unusual sites (eg, peritoneum, pleural cavity, surgical wounds)

Classification

• By parasite load, as measured by fecal egg count 
  • Light: 1 to 4999 eggs/g feces
  • Moderate: 5000 to 49,999 eggs/g feces
  • Heavy: 50,000 eggs/g feces or more

Clinical Presentation

History

• Most patients with light infection (approximately 85% of infected persons) are asymptomatic 
• Some patients report worms in stool or vomitus
• Symptoms may occur in previously sensitized patients or in those with higher parasite load during larval migration through the lungs (ie, early in the course of infection). Symptoms include: 
  • Mild fever
  • Nonproductive cough
  • Dyspnea and wheezing resembling asthma
• Symptoms due to adult worm infection of the intestine include:
  • Malaise and weakness
  • Anorexia
  • Nausea and vomiting
  • Abdominal discomfort
  • Diarrhea (uncommon)
  • Impaired weight gain in children
• Complications due to luminal or ductal obstruction may cause symptoms characteristic of the clinical syndrome
  • Intestinal obstruction
    • Generalized abdominal pain, vomiting, and constipation
  • Biliary obstruction
    • Right upper quadrant abdominal pain (may be colicky or constant), vomiting, and jaundice
  • Pancreatitis
    • Epigastric pain and vomiting
  • Appendicitis
    • Right lower quadrant pain
• Patients who do not live in an endemic area may have a history of travel to such an area or may have been exposed to live pigs

Physical examination

• Many patients, especially those in good health and those who acquire infection through travel, appear normal and have no significant physical findings
• Physical findings associated with the larval migration phase may include wheezing, crackles, hepatomegaly (including tenderness), and urticaria
• With established infection (adult worms), mild abdominal tenderness may be elicited
  • Children with high worm burdens may appear malnourished and listless
• Severe or localizing symptoms may suggest complications:
  • Findings suggestive of intestinal obstruction include abdominal distention, tympany, and diffuse tenderness
  • In some cases, a mass of worms may be palpated (most commonly in the right lower quadrant)
  • Right upper quadrant tenderness with or without jaundice raises the possibility of biliary obstruction
  • Pancreatitis is characterized by severe epigastric tenderness (often with rebound) and decreased bowel sounds (uncommon)
  • Right lower quadrant tenderness, with or without rebound, and decreased bowel sounds suggest appendicitis (rare)

Causes and Risk Factors

Causes

• Ingestion of Ascaris lumbricoides (or Ascaris suum) eggs from contaminated soil, water, or food 
  • Eggs are shed in the feces of infected humans (or pigs, in the case of Ascaris suum) but require maturation in soil to be infectious; therefore, direct human-to-human infection does not occur
  • Eggs remain viable in soil for up to 15 years

Risk factors and/or associations

Age 

• Children generally have a greater parasite burden than adults
  • Reflects a slow buildup of specific immunity in older cohorts
  • Suggests changing susceptibility to infection over time
  • Correlates with age-related behaviors (eg, poor hand hygiene, sucking on objects)
• Intestinal obstruction occurs in children more often than in adults owing to combination of high worm burden and smaller intestinal lumen diameter 
• Obstruction of hepatobiliary and pancreatic ducts occurs more often in middle-aged adults 

Sex

• Females may have greater predisposition to infection than males, but the difference is not consistently reported 
• Women have a significantly greater frequency of hepatobiliary/pancreatic duct invasion than men 
  • Pregnant patients develop hepatobiliary ascariasis more often than nonpregnant patients 

Genetics

• Individual predisposition to infection appears to be heritable (OMIM 604291) 
• Several quantitative trait loci have been associated with intensity of and susceptibility to ascariasis infection 

Other risk factors/associations

• Ascaris lumbricoides infection is associated with ecological, socioeconomic, and behavioral factors 
  • Infection is endemic in tropical and subtropical areas with warm and moist climates 
    • Warm and wet climate throughout the year favors embryonation and transmission of eggs
    • Prevalence of Ascaris lumbricoides infection in endemic areas 
      • Oceania: 18.2%
      • Asia: 15.9%
      • Latin America and the Caribbean: 14.7 %
      • Sub-Saharan Africa: 13.8%
      • North Africa and the Middle East: 5.6%
      • Ascariasis was prevalent in the southeastern United States and Appalachia through the mid-20th century; recent data are not available 
  • Lower education status and poverty contribute to unhygienic practices 
    • Children of mothers with lower education level have highest level of infection 
    • Communities with poor sanitation and inadequate sewage disposal have high fecal contamination of the environment 
  • Behavioral factors at individual, family, and community levels
    • Lacking private and public latrines for individual families and the community
    • Using human feces, raw sewage, and untreated wastewater as fertilizer to grow crops for human consumption 
    • Eating unwashed fruits and vegetables contaminated with soil
    • Not washing hands after defecating and before eating
• Ascaris suum infection is associated with pig farming or using pig manure to fertilize crops 
• Fever and anesthetic agents increase movement of the worms and may precipitate a complication (eg, ductal or intestinal obstruction) 

Diagnostic Procedures

Primary diagnostic tools

• May be suspected in patients with abdominal complaints in endemic areas or in travelers or immigrants from those areas
• May be considered in children with a bout of asthmatic symptoms or eosinophilic pneumonia
• Generally based on microscopic identification of eggs in feces 
• Sometimes based on patient observation of adult worm in stool or vomitus; collection and preservation of the worm allow for definitive diagnosis 
• Adult worms or larvae may be an unexpected finding in studies or treatment of clinical illness
  • Chest radiography and high-resolution CT to evaluate pulmonary symptoms 
  • Plain radiography, ultrasonography, abdominal CT, and endoscopy may reveal adult worms in the intestinal lumen or ducts 
  • Ascaris species have been recovered from the appendix of children who did not have preoperative diagnosis of worm infection; conversely, Ascaris species have been found incidentally in uninflamed appendix in children undergoing surgery for intestinal obstruction due to ascariasis 
  • Endoscopic retrograde cholangiopancreatography to evaluate biliary obstruction may be both diagnostic and therapeutic 
• Molecular diagnosis (polymerase chain reaction methodology) has been developed but is not widely clinically used 
  • Where available, provides diagnostic advantage over microscopy, particularly in light infections or infection with multiple pathogens
• Blood testing is not diagnostic; however, tests done in the course of a symptomatic workup may reveal eosinophilia or high levels of IgE during the larval migration phase
  • Patients with pancreatitis or cholecystitis due to ascariasis will have laboratory abnormalities typical of those conditions

Laboratory

• Macroscopic fecal analysis
  • Identification of adult worms is based on macroscopic morphologic features 
    • Large roundworms (15-35 cm) with 3 liplike features at the anterior end
    • Males are smaller and often have curved tails
• Microscopic fecal analysis of eggs
  • Adult female Ascaris species produce large numbers of eggs and a single specimen is often diagnostic; however, examination of several specimens from different days is often recommended because: 
    • Day-to-day variability exists in shedding of eggs, especially in light infections
    • Eggs are not evenly spread within stool
    • Coinfection with multiple species is common, and some species do not produce high numbers of eggs
  • Lower concentrations occur in the liquid stools of breastfed infants, reducing sensitivity 
• Sputum or bronchoalveolar lavage fluid analysis
  • Reveals larval forms and Charcot-Leyden crystals 

Imaging

• Plain radiography
  • Chest radiography during larval migration may show ground-glass attenuation and patchy alveolar infiltrates 
  • Adult worms in the intestine typically produce a whirlpool effect on radiograph or are seen as tangled group of thick cords against bowel gas 
    • Signs of obstruction might be seen (eg, dilated small bowel proximal to the worm mass)
• High-resolution CT and ultrasonography
  • High-resolution CT to evaluate pulmonary symptoms triggered by larval migration may show alveolar infiltrates and hemorrhage
  • In intestinal ascariasis, CT scan of the abdomen depicts worms as elongated or rounded filling defects in the intestine lumen
  • Ultrasonography can typically detect biliary ascariasis; however, it often cannot detect worms in the intestinal lumen or the ampullary orifice and may miss up to 50% of cases of hepatobiliary ascariasis 
    • On real-time ultrasonography using low-frequency transducer, an adult worm may be seen as 2 parallel echogenic lines with an anechoic fluid-filled gut of the worm 
    • Cross-sectional view of the worm shows target sign 
    • In hepatobiliary and pancreatic duct involvement, ultrasonography may show echogenic worm in dilated duct with edema of gallbladder and pancreas 

Procedures

• Endoscopic examination of the duodenal lumen and ampulla of Vater, with instillation of radiopaque dye for radiographic visualization of ducts
  • High accuracy in detecting hepatobiliary ascariasis
  • Shows worms as smooth, linear, filling defects, which may or may not be motile
• In some cases, endoscope can function therapeutically to remove worm
• Suspected obstruction of pancreatic or common bile duct

Differential Diagnosis

Most common

• Differential diagnosis is broad and depends upon presentation (eg, eosinophilic pneumonia, intestinal obstruction, cholecystitis, pancreatitis)
• Worm infections with fecal passage of macroscopic worms and/or worm infections with a symptomatic pulmonary phase, with caveat that coinfection by multiple species is common
• Infections by soil-transmitted helminths
  • Hookworm (Ancylostoma duodenale, Necator americanus)
    • Infective larvae in soil penetrate human skin by chance contact and enter subcutaneous venules and lymphatic vessels, then pass through the lung and migrate into the gastrointestinal tract
    • Ancylostoma duodenale can also infect the gastrointestinal tract directly via ingestion of larvae
    • Hookworm disease features that are common with ascariasis infection are cough and wheezing during larval migration and abdominal pain due to adult worms in the small bowel. Malnutrition and delayed cognitive development may occur
    • Unlike ascariasis, hookworms cause blood loss and significant anemia through both blood sucking and production of anticoagulants and platelet inhibitors; this leads to symptoms of iron-deficiency anemia, hypoproteinemia, and anasarca
    • Hookworm infections occur in both children and adults (including elderly people) with high frequency and intensity, whereas most intense Ascaris infections are in children aged 5 to 14 years 
    • Definitive diagnosis is made by identifying hookworm eggs and adult worms and by assessing disease symptoms
      • Hookworm eggs passed in the feces are oval or elliptical, thin, and transparent, with 4 to 8 blastomeres; Ascaris eggs have a thick mammillated shell 
      • Adult hookworms are small (0.7-1.3 cm) and have a hook-shaped head, whereas Ascaris adult worms are as large as 15 to 40 cm 
  • Whipworm (Trichuris trichiura)
    • After ingestion, eggs develop into larvae and move into the colon where they burrow into the epithelium and further develop into adult whipworms
    • Symptoms common to trichuriasis and ascariasis are abdominal pain, diarrhea, and impaired growth
    • Acute trichuriasis can be differentiated from ascariasis clinically by the presence of dysentery (passage of blood and mucus in the stools) and rectal prolapse; longstanding infection may cause a syndrome similar to noninfectious inflammatory bowel disease (eg, Crohn disease, ulcerative colitis) 
    • Definitive diagnosis
      • Microscopic identification of lemon-shaped eggs with thick light yellow shells and of adult worms shaped like whips
      • Adult whipworm measures 3 to 5 cm as compared with 15 to 40 cm for Ascaris worm 
  • Strongyloides stercorales 
    • Infection occurs through penetration of skin by larvae, which migrate through lymphatic and venous circulations to lungs and upper airways. They are then swallowed and pass to the small intestine
    • Under some conditions (eg, immunocompromise), infective larvae in the intestine can penetrate the mucosa or perianal skin and repeat the pulmonary cycle indefinitely (autoinfection)
    • Like ascariasis, the pulmonary phase may be symptomatic, with cough, wheezing, and dyspnea
    • Abdominal infection may cause variable symptoms (eg, abdominal pain and diarrhea alternating with constipation) that are similar to irritable bowel syndrome
    • In children, diarrhea and systemic symptoms may be more prominent and significant malabsorption may occur
    • Definitive diagnosis is made by microscopic identification of the larval form in stool or other sites or by polymerase chain reaction 
• Toxocariasis (Toxocara canis, Toxocara cati)
  • Primary hosts are dogs and cats; humans acquire infection through ingestion of embryonated eggs
  • Like ascariasis, toxocariasis may include pulmonary infection, resulting in an eosinophilic pneumonia with wheezing
  • Unlike Ascaris, these organisms have a greater propensity for widespread organ invasion
    • Classically cause a syndrome of visceral larva migrans, with:
      • Hepatosplenomegaly (sometimes massive)
      • Eosinophilia
      • Symptoms related to involved organs (eg, ocular larva migrans, myocarditis, nephritis, encephalopathy)
  • Diagnosis can be made serologically or by tissue biopsy; humans are dead-end hosts and eggs are not produced
• Tapeworm (cestode) 
  • Infection caused by the ingestion of food contaminated by feces containing parasite eggs or by eating raw or undercooked meat harboring immature larvae (cysts)
    • Infections present in 2 forms: mature tapeworms in the gastrointestinal tract or invasive larval cysts in liver, lung, muscle, brain, eye, or other tissues
    • Certain species (eg, Diphyllobothrium latum, Taenia saginata, Taenia solium) may cause clinical features similar to Ascaris, including abdominal discomfort and passage of adult worms or proglottids (tapeworm body segments containing eggs), which are easily seen and may be motile
    • Eosinophilia and elevation of IgE may be noted
  • Definitive diagnosis is by microscopic identification of eggs and proglottids in fecal samples

Treatment Goals

• In nonendemic settings (eg, travel related) and in symptomatic patients in any setting, goal is elimination of infection
• In endemic settings with high prevalence of infection and continuous risk for reinfection, periodic targeted treatment of high-risk populations is provided with goal of decreasing worm burden, mitigating nutritional and developmental consequences, and reducing transmission

Admission criteria

Acute intestinal obstruction and, in rare cases, airway obstruction by adult worms

Hepatobiliary/pancreatic disease

Appendicitis

Criteria for ICU admission

• Rare cases of intestinal perforation, airway obstruction, or laryngospasm

Recommendations for specialist referral

• Consult a gastroenterologist for patients with pancreatitis or biliary tract disease for possible endoscopic intervention
• Consult a general surgeon for management of bowel obstruction

Treatment Options

Anthelmintic treatment is recommended for all patients diagnosed with ascariasis 

• CDC recommends albendazole, mebendazole, or ivermectin
  • Other effective drugs are levamisole (not available in the United States) and pyrantel pamoate 
  • A 2017 meta-analysis found the following cure rates for treatment of ascariasis: 
    • Albendazole: 95.7%
    • Mebendazole: 96.2%
    • Levamisole: 97.3%
    • Pyrantel pamoate: 92.6%
  • A 2020 Cochrane review concluded that treating ascariasis with a single dose of albendazole, mebendazole, or ivermectin was safe and effective (93% overall cure rate) in both children and adults, with little difference between drugs in terms of efficacy or adverse effects 
• In patients with severe disease and a surgical abdomen, administer anthelmintics only if patient is able to pass flatus or feces 
• Coinfection with multiple helminth species and other parasites is common, and some require different therapeutic regimens

Targeted deworming using anthelmintic drugs active against soil-transmitted helminths (ie, roundworms, including Ascaris; hookworms; whipworms) 

• WHO recommends large-scale deworming programs in endemic areas with a prevalence of 20% or more; may be administered to the entire population (mass deworming) or to a target risk group
  • Group deworming: targeted administration of anthelmintic medication to groups at risk for soil-transmitted helminth infection but without documented diagnosis of individuals
    • Preschool-aged (12-59 months) and school-aged (6-12 years) children
    • Nonpregnant adolescent patients (10-19 years)
    • Nonpregnant patients of childbearing age (15-49 years)
  • Recommended frequency of administration depends on the prevalence of soil-transmitted helminth infection
    • Once per year for 20% to 50% infection prevalence in the target population
    • Twice per year for greater than 50% infection prevalence in the target population
  • Routine deworming of pregnant patients after the first trimester is recommended based on presence of 2 criteria pertaining to hookworm and whipworm (but not ascariasis):
    • Prevalence rate of hookworm and/or whipworm in pregnant patients is 20% or more
    • Prevalence rate of anemia in pregnant patients is 40% or more
• Benzimidazoles (albendazole and mebendazole) are the first line drugs in helminth control programs
  • Efficacy rates differ among the various soil-transmitted helminth species but exceed 95% for Ascaris, according to a meta-analysis done in the preparation of the 2017 WHO guideline 
  • Use of combination anthelmintic therapy in mass deworming efforts to achieve higher efficacy against whipworm without sacrificing Ascaris coverage is an area of active investigation 

Mechanical interventions may be necessary (in addition to anthelmintic medication) for patients with hepatobiliary/pancreatic duct ascariasis or intestinal obstruction 

• For hepatobiliary/pancreatic duct obstruction
  • Consider the following interventions when there is no response to conservative treatment within a few days after hospitalization or when the worm is not expelled from the biliary tree after 3 weeks 
    • Bile duct ascariasis may require percutaneous biliary drainage under ultrasonographic guidance or worm extraction by endoscopic retrograde cholangiopancreatography
    • Cholecystectomy is recommended in rare cases of gallbladder ascariasis
    • Broad-spectrum antibacterial antibiotics are recommended in cases of cholecystitis and cholangitis
• For intestinal obstruction 
  • Nasogastric suction and supportive therapy are recommended initially
  • Instillation of piperazine citrate (if available) paralyzes the worms and may aid in their expulsion
  • Surgery is required if conservative measures fail and in case of complications (eg, intestinal gangrene)
• For appendicitis 
  • Appendectomy may be performed based on the usual indications; preoperative recognition of ascariasis as cause is often absent

Hydration is essential for patents who are dehydrated or unable to ingest fluids 

Drug therapy

• Benzimidazoles
  • Albendazole
    • Administer with food (preferably a high-fat meal) to increase oral bioavailablity; tablets may be chewed or crushed
    • Albendazole Oral tablet; Children and Adolescents: 400 mg PO as a single dose.
    • Albendazole Oral tablet; Adults: 400 mg PO as a single dose.
  • Mebendazole
    • Mebendazole Chewable tablet; Children and Adolescents 2 to 17 years: 100 mg PO twice daily for 3 days. If not cured 3 weeks after treatment, a second course of therapy is recommended.
    • Mebendazole Chewable tablet; Adults: 100 mg PO twice daily for 3 days. If not cured 3 weeks after treatment, a second course of therapy is recommended.
    • Most recommendations, including those from WHO, refer to a single 500 mg dose as the more conventional course of treatment
• Anthelmintic agents
  • Ivermectin
    • Safety not established for children weighing less than 15 kg
    • Ivermectin Oral tablet; Children and Adolescents weighing 15 kg or more: 150 to 200 mcg/kg/dose PO as a single dose.
    • Ivermectin Oral tablet; Adults: 150 to 200 mcg/kg/dose PO as a single dose.
  • Pyrantel pamoate
    • Safety not established for children younger than 2 years
    • Pyrantel pamoate Oral suspension; Children and Adolescents: 11 mg/kg base/dose (Max: 1 g/dose) PO once daily for 3 days.
    • Pyrantel pamoate Oral suspension; Adults: 11 mg/kg base/dose (Max: 1 g/dose) PO once daily for 3 days.

Nondrug and supportive care

Procedures

Endoscopic worm extraction 

General explanation

• Endoscopic worm extraction from the ampullary orifice and from the bile ducts
• May be performed using snares, Dormia basket, or biopsy forceps
• Successful in more than 90% of cases 
• Has become the treatment of choice in biliary ascariasis

Indication

• Biliary ascariasis
• Acute pyogenic cholangitis (urgent)

Contraindications

• Acute pancreatitis
• Hemodynamic instability (eg, sepsis)
• Severe cardiopulmonary disease
• Uncorrected coagulopathy

Complications

• Pancreatitis
• Cholangitis

Percutaneous biliary drainage 

General explanation

• Placement of percutaneous biliary catheters for drainage

Indication

• Bile duct ascariasis
• Cholangitis with biliary strictures or with worms in the gallbladder
• Large hepatic abscesses

Contraindications

• Multiple intrahepatic obstructions
• Massive ascites
• Bleeding diathesis

Cholecystectomy 

General explanation

• Gallbladder resection
• May be performed laparoscopically or as an open procedure

Indication

• Gallbladder ascariasis

Contraindications

• Inability to tolerate general anesthesia
• Uncontrolled coagulopathy
• Gallbladder cancer

Laparotomy

General explanation

• Open abdominal surgery for exploration and intervention
  • Worms may be “milked” through the intestine to reduce bolus size or extracted through an enterotomy site
  • Resection of necrotic bowel is performed as needed

Indication

• Intestinal obstruction
• Peritonitis

Comorbidities

• Coinfection with other soil transmitted helminths is common
  • Hookworm (Ancylostoma duodenale and Necator americanus)
  • Whipworm (Trichuris trichiura)
  • All soil-transmitted helminth infections can be treated together with albendazole or mebendazole 
    • However, unlike single-dose treatment of ascariasis, several doses of these agents are needed for hookworm and whipworm treatment 
• Numerous other parasitic infections are common in some regions endemic for ascariasis, and these require different antiparasitic agents for treatment. Coinfection may contribute to malnutrition and stunted growth and development, undermining effective treatment of ascariasis 
  • Studies looking at nutritional supplementation have not demonstrated benefit in the treatment of children with soil-transmitted helminth infections 

Special populations

• Adolescent girls, women of reproductive age, and pregnant patients
  • Anthelmintic drugs recommended by WHO are not licensed for use in pregnancy 
  • However, risk-benefit analysis showed treating women of reproductive age and pregnant patients provided health advantages that outweighed risks to mothers and babies 
    • Proven benefits in the absence of any evidence of drug teratogenicity or embryotoxicity support the treatment with albendazole or mebendazole after the first trimester of pregnancy 
  • Pyrantel pamoate may be used at any stage of pregnancy if prompt treatment is deemed necessary 

Monitoring

• Some authorities recommend follow-up microscopic analysis of 3 stool samples 2 weeks after definitive therapy 

Complications

• Complications relate primarily to worm burden and propensity of the worms to travel and to enter small orifices
  • Intestinal obstruction occurs primarily in children owing to high worm burden and small intestinal luminal diameter, and it can lead to intestinal perforation and peritonitis
  • Volvulus and intestinal gangrene may occur
  • Intussusception has been associated with ascariasis, although causality and mechanism are unclear
  • Rarely, worms obstruct the appendix, causing appendicitis
  • Obstruction of bile ducts may cause cholecystitis, cholangitis, and liver abscess
    • Chronically recurring pyogenic cholangitis has been described as a result of irreversible mechanical damage to the sphincter of Oddi in patients who have had biliary ascariasis 
  • Pancreatic duct obstruction is uncommon but may cause pancreatitis
  • Ascariasis has been associated with nutritional deficiency, stunted growth, and impaired cognitive performance; however, most children with ascariasis also harbor other parasites so the magnitude of effect is difficult to attribute

Prognosis

• Uncomplicated ascariasis is effectively treated by current anthelmintics; however, in endemic areas, reinfection is likely without other interventions (eg, hygiene, safe water)
• Adult worms may live for a year or more, but most are expelled earlier; in the absence of reinfection, infection is self-limited 
• Untreated, about 20% children and 4% of adults with ascariasis die from complications 
• In a prospective study of 360 children with intestinal ascariasis complications: 
  • Conservative management was successful in 78% of patients
  • Surgical intervention was successful in 22% of patients
  • Postoperative complications occurred in 42% of patients
  • Mortality occurred in 1% of patients
• In a prospective study of 61 children with hepatobiliary ascariasis complications: 
  • Conservative management with broad-spectrum antibiotics, antispasmodics, and anthelmintics was successful in 72.1% of patients
  • Endoscopic retrograde cholangiopancreatography was successful in 13.1% of patients
  • Surgical intervention was successful in 14.7% of patients

Screening

At-risk populations

• In highly endemic areas, limited screening of high-risk populations is done to determine whether threshold for mass deworming program is met 
  • Preschool-aged (1-5 years) and school-aged (6-15 years) children and women of childbearing age

Screening tests

• Stool microscopy 

Prevention 

• Prevented by proper sanitation and waste management practices
• Provide education on the following topics, especially to children and women of childbearing age in endemic areas
  • Handwashing before handling food
  • Handwashing after touching or handling pigs, cleaning pig pens, or handling pig manure
  • Vigilance with cooking practices
    • Wash, peel, or cook all raw vegetables and fruits before eating 
  • Avoid ingesting soil that may be contaminated with human or pig feces, including where human fecal matter, wastewater, or pig manure is used to fertilize crops 

References

Dold C et al: Ascaris and ascariasis. Microbes Infect. 13(7):632-7, 2011 Reference