Ascariasis Treatment & Management

Specific patient and community-wide public health approaches to ascariasis should be coordinated. Individual patient deworming can prevent surgical and nutritional complications and can serve as an opportunity to investigate, educate, and treat other family members and neighbors. Community- and school-based epidemiological deworming programs should be administered under WHO guidelines and would be subject to diagnostic methods used to determine pretherapy and posttherapy prevalence. Newer highly sensitive diagnostic methods instead of classic stool sampling would be most useful for communities with moderate (30%-70%) prevalence, rather than very high or low prevalence, ^[46] whereas they may be more useful for screening in adults, who have lower worm burden and lower prevalence than children. ^[4]

In an area with high prevalence of soil-transmitted helminth infection, intestinal ascariasis should be suspected in patients with nonspecific abdominal discomfort, anorexia, nausea, or vomiting with or without the intestinal, biliary or pancreatic complications. The diagnosis is established via stool microscopy for ova or parasites. If the patient has suspected intestinal obstruction, radiographic imaging can reveal the etiology.

 

Early phase:

Management of pulmonary manifestations in the early phase of Ascaris infection consists of supportive care with inhaled bronchodilators for wheeze and cough or systemic corticosteroids for severe pneumonitis. However, it is imperative to rule out Strongyloides by examination of sputum and stool for Strongyloides larvae and serologic testing due to concern of Strongyloides hyperinfection syndrome-associated multiorgan system dysfunction and septic shock secondary to steroid administration.

Anthelminthic therapy is generally not administered during the pulmonary phase and is delayed to 2 months after resolution of pulmonary symptoms, because the efficacy of drugs against larvae in the lungs is uncertain.

Late phase:

Management of intestinal manifestations in the late phase of Ascaris infection include management of the individual presentation or complications such as intestinal obstruction, malnutrition, hepatobiliary involvement, and pancreatitis.

Malnutrition

Due to high parasitic burden, ascariasis results in malnutrition secondary to poor intestinal absorption of lactose, proteins and vitamins A and C. This is seen as growth retardation and poor cognitive development in young children, with improvement seen after treatment. However, due to the demographics of the disease in areas with poor housing and sanitation, there are socioeconomic factors that confound the nutritional deficiencies as well. ^[47]

Hepatobiliary and pancreatic involvement

Ascariasis can cause obstructive jaundice, ascending cholangitis, biliary colic, biliary strictures, liver abscesses, and bile duct perforation with peritonitis during the migration phase of the adult worms. It can also cause acalculous cholecystitis due to parts of dead worms serving as a nidus for biliary stones; this results in recurrent pyogenic cholangitis if present in the bile duct or pancreatitis if obstructing the pancreatic duct. This accounts for about a third of the biliary and pancreatic disease. ^[48]

Other manifestations

Migration of worms outside the gastrointestinal tract may produce atypical presentation including ectopic sites such as the mouth, nose, esophagus, lungs, lacrimal ducts, umbilicus, inguinal canal, or skin. This is unusual and is seen in physiological stress associated with febrile illness, anthelmintic medications, starvation, or other acute serious illness.

 

Because of the risk for complications, patients with ascariasis who have other concomitant helminthic infections should always undergo treatment for ascariasis first. Medical therapy is usually not indicated during active pulmonary infection, because dying larvae are considered a higher risk for significant pneumonitis. Pulmonary symptoms may be ameliorated with inhaled bronchodilator therapy or corticosteroids, if necessary. Initial treatment for uncomplicated disease is anthelminthic therapy. If other parasitic coinfections are detected, they will have to be treated as well. It is important to note that treatment does not prevent reinfection and if eggs or worms are detected after treatment, the patient should repeat the course. These anthelminthic agents are active against adult worms but not against larvae and may not be effective until all the worms are mature.

Albendazole  400 mg one dose orally is the drug of choice for ascariasis in stable patients older than 12 months with uncomplicated infection. ^[2] A 2012 study from Indonesia showed that albendazole provided statistically significant better sterilization of Ascaris eggs than mebendazole but equivalent cure rates and egg reduction rates. ^[49] A 2017 systematic review and meta-analysis of 34 studies demonstrated a 95.7% cure rate with single-dose albendazole. ^[50] Ascariasis commonly coexists with whipworm infection, which appears to be most susceptible to triple-dose mebendazole. ^[51] Albendazole is not recommended during pregnancy; pyrantel pamoate is the drug of choice in these cases. Adverse effects include transient gastrointestinal discomfort, headache, and, rarely, leukopenia.

Mebendazole  (100 mg bid for 3 days or 500 mg orally single dose) is alternative therapy. Mebendazole is not recommended during pregnancy; pyrantel pamoate is the drug of choice in these cases. Randomized clinical trials indicate high cure rates with single doses of albendazole and mebendazole, but this is insufficient for treatment of concomitant hookworm or Trichuris infection.

Ivermectin  can be given as an alternative in a dose of 150-200 micrograms/kg bodyweight. ^[2]

Paralyzing vermifuges (eg, pyrantel pamoate, ivermectin)  should be avoided in patients with complete or partial intestinal obstruction, because the paralyzed worms may necessitate or further complicate surgery. Pregnant women can be safely treated with a single dose of pyrantel pamoate (11 mg/kg up to 1g). Adverse effects include gastrointestinal disturbances, headaches, rash, and fever.

In the setting of mass treatment, the WHO allows use of albendazole for pregnant women in the second and third trimesters.  ^[52]  Ivermectin (200 mcg/kg single dose) causes paralysis of adult worms.

Vitamin A supplementation  improved growth development of children in Zaire; deworming did not improve growth development in this study. ^[53]

Retreatment: Drug therapy affects only adult worms. If the patient lives in an endemic area or has recently relocated, he or she may still be carrying larvae that are not yet susceptible. Such patients should be re-evaluated in 3 months and retreated if stool ova persist. In endemic areas, reinfection rates approach 80% within 6 months.

Nitazoxanide , a drug used primarily for protozoal infection, was shown to have 89% clinical efficacy for the treatment of ascariasis in rural Mexico, and may offer a future alternative to other medications. ^[54]

Compliance with antiparasitic drugs, especially at the community level, has emerged as a concern, particularly for the effectiveness of community-wide therapy. ^{[29, 55]}

Newer agents are being developed because of concern for emergence of resistance potentially associated with mass deworming campaigns. ^[56]

Intestinal obstruction:

Ascaris infection with a high worm burden can cause acute intestinal obstruction by obstructing the bowel lumen; this is most commonly seen at the ileocecal valve, but migrating worms can also cause appendicitis. In endemic regions, it is the most common cause of acute abdominal surgical emergencies accounting for about 35 percent of all bowel obstructions. Out of these obstructions, approximately 85 percent of are seen in children younger than 5 years with an overall incidence of approximately one in 500. Symptoms include melena, anemia, colicky abdominal pain, vomiting, and constipation. Emesis or stool may contain worms. In some cases, an abdominal mass that changes in size and location may be appreciated on serial physical examinations. Other complications associated with A. lumbricoides intestinal obstruction include volvulus, ileocecal intussusception, gangrene, and intestinal perforation. ^{[57, 16, 23]}

Conservative (nothing by mouth, nasogastric suction and repletion of fluids and electrolytes) management of partial intestinal obstruction and biliary ascariasis is usually effective but might be more quickly accomplished with orally administered contrast medium. ^[2] A controlled trial from Pakistan found that, in patients without peritonitis, hypertonic saline enemas relieved obstruction more quickly (1.6 d vs 3.4 d) and resulted in shorter hospital stays (4 d vs 6 d) than intravenous fluids alone. A recent study from India demonstrated that conservative therapy was successful in 19 of 22 (89%) children with intestinal obstruction. The regimen used consisted of no oral intake, intravenous fluids, antibiotics, piperazine salt per nasogastric tube, and glycerine plus liquid paraffin emulsion enemas. ^[35]  Anthelminthic therapy should be administered when the acute obstruction is relieved.

Recommended criteria for surgical exploration include the following:

• Passage of blood per rectum

• Multiple air fluid levels on abdominal radiographs

• An ill child with abdominal distension and rebound tenderness

• Unsatisfactory response to conservative therapy

• Appendicitis and primary peritonitis

• Hepatobiliary disease

• Pancreatic pseudocyst

Patients with biliary ascariasis usually respond with conservative management. Antibiotics may be needed for cholangitis or bacterial peritonitis. Indications for endoscopic or surgical worm removal include presence of worm(s) trapped in the biliary tree or invasion of the liver by one or more worms. ^{[40, 58]}

Biliary tract obstruction:

Most (49-90%) worms eventually migrate from the biliary system spontaneously. Drug therapy should be delayed in patients with right upper quadrant or pancreatic pain, as no evidence has shown that drugs are active against worms located in the biliary tree. Regardless, death of the worm in the duct may provoke both inflammation and obstruction. Patients with ascariasis who have only minor symptoms can undergo observation for 3 days. If the minor symptoms persist after 3 days or the patient develops frank cholangitis or pancreatitis, removal of the worms with ERCP should be attempted, if available. Although technically challenging at times, ERCP extraction rates have exceeded 90%. ^[41]

Invasion of the gall bladder necessitates cholecystectomy, common duct exploration, and T-tube drainage until the patient is stabilized and dewormed.

Intestinal gangrene usually occurs at the terminal ileum, more often after the use of pyrantel pamoate, which tetanically paralyzes worms and thereby enhances the risk for obstruction. Recently, two cases of delayed distal intestinal disease have been reported, which were thought to be secondary to toxins from the worms. Therefore, patients should probably be monitored for some time after the surgical removal of worms.

Milking of worms to the large bowel, resection of gangrenous bowel, ileostomy, and enterotomy are the most common surgical procedures used to manage bowel obstruction. Intestinal or biliary surgery may be necessary for complications of ascariasis.

Any patients from highly endemic areas should be screened, and if positive, treated for ascariasis and malnutrion prior to elective surgery because of possible provocation of worm migration with anesthesia agents. ^[59] In particular, patients who live in endemic areas should be dewormed before and after elective cholecystectomy.

Community control of ascariasis has been difficult to achieve. The most successful control programs, such as those in Japan, have consisted of combined approaches, including improved sanitation, night soil disposal, and mass community treatment. Concern has increased for the emergence of drug resistance among heavily retreated populations.

The prevalence of ascariasis in Japan in 1949 was 63%; the disease was essentially eliminated by 1973. Hand washing may be a neglected means of prevention, even in endemic areas, as shown by a recent study from Sri Lanka.

A program of latrine construction, health education, and twice-annual anthelmintics decreased the prevalence of ascariasis in Korea from 80% in 1949 to 55% by 1971. After a 4-year educational campaign and latrine construction program in northern Bangladesh, 36% of children aged 5 to 13 remained infected. Rates of infection were lower among children who used latrines and who had been educated concerning the risks of ascariasis. ^[60]  As rates of ascariasis lessen, specific infected families should be targeted. A recent systematic review and meta-analysis of preventive water and sanitation measures concluded that the risk of ascariasis was lowered 60% by piped water, 38% by access to sanitarian latrines, and 62% by handwashing before eating and 55% after defecating. ^[61]  Each, in combination with the use of soap, has the potential for significant control, especially if applied in schools together with thrice yearly deworming. ^[62]

Current ascariasis treatment strategies recommend repeated mass treatment of communities to reduce intensity of worm burden until socioeconomic progress allows improved sanitation. Although such targeted therapy programs may control the morbidity of ascariasis by decreasing the number of worms per patient, they do not seem to decrease transmission rates. The ascariasis reinfection rate after a single community campaign in South Africa was 40% at 29 weeks. Children have been targeted in school campaigns, but continued worm burden and shedding by adults have blunted impact, especially if campaigns are less than thrice yearly. A 6-month educational program directed at behavioral remediation of school children and their parents in Java has shown promise when combined with a deworming campaign.

A 2012 Cochrane review ^[63]  was rather discouraging in its assessment of the benefit of community deworming programs, suggesting only the possibility of slight benefit in weight gain and hemoglobin, but not cognitive improvement as measured by school attendance and performance.

Avoiding pigs and pig manure prevents A suum infection in developed countries.

Work continues on a vaccine. A recombinant, nasally administered 16-kd secretory protein, As16, was shown to result in a 56% decrease in worm burden in mice challenged with A suum larvae. ^[64]  The Sabin Vaccine Institute is developing a "Pan-anthelminthic" vaccine against hookworm, trichuriasis, and ascariasis using at least two of six candidate A suum antigens. It appears that at least 5 years will be required to field such a candidate vaccine. ^[65]

Follow-up 

 Routine repeat stool testing is not essential due to the high cure rate with anthelminthic therapy, however, in endemic areas, repeat stool testing may be done 2 to 3 months after treatment to ensure resolution of infection. Detection of eggs at follow-up stool examination suggests inadequate elimination of adult worms or reinfection. In such cases, retreatment with the same regimen is warranted. It takes about 10 days for the complete expulsion of adult Ascaris worms after albendazole treatment; therefore, it is pertinent to  wait at least 2 weeks after treatment before performing follow-up egg count or stool testing. In endemic areas or case clusters with persistent or repeated infections despite prior therapy it is important to test all family members and concurrent treatment  with albendazole or mebendazole. Reinfection occurs frequently in these cases, sometimes more than 80 percent of individuals become reinfected within 6 months. Intermittent mass drug therapy for such circumstances is discussed separately. ^[66]

Patients with ascariasis who have partial or complete obstruction should be treated at facilities with surgical support.