Human Ascariasis: An Updated Review

Background: Ascaris lumbricoides is the most common helminthic infection. More than 1.2 billion people have ascariasis worldwide.

Objective: This article aimed to provide an update on the evaluation, diagnosis, and treatment of ascariasis.

Methods: A PubMed search was conducted in February 2020 in Clinical Queries using the key terms "ascariasis" OR 'Ascaris lumbricoides'. The search strategy included meta-analyses, randomized controlled trials, clinical trials, observational studies, and reviews published within the past 10 years. The search was restricted to the English literature. The information retrieved from the above search was used in the compilation of the present article. Patents were searched using the key term "ascariasis" OR 'Ascaris lumbricoides' in www.freepatentsonline.com.

Results: Ascaris lumbricoides is transmitted through ingestion of embryonated eggs from fecal-contaminated material. Ascariasis has high endemicity in tropical and subtropical areas. Predisposing factors include poverty, poor sanitation, inadequate sewage disposal, and poor personal hygiene. The prevalence is greatest in children younger than 5 years of age. The majority of patients with intestinal ascariasis are asymptomatic. For those with symptoms, anorexia, nausea, bloating, abdominal discomfort, recurrent abdominal pain, abdominal distension, and intermittent diarrhea are not uncommon. Other clinical manifestations vary widely, depending on the underlying complications. Complications include Löeffler syndrome, intestinal obstruction, biliary colic, recurrent pyogenic cholangitis, cholecystitis, acalculous cholecystitis, obstructive jaundice, cholelithiasis, pancreatitis, and malnutrition. The diagnosis is best established by microscopic examination of fecal smears or following concentration techniques for the characteristic ova. Patients with A. lumbricoides infection warrant anthelminthic treatment, even if they are asymptomatic, to prevent complications from migration of the parasite. Albendazole and mebendazole are the drugs of choice for children and nonpregnant individuals with ascariasis. Pregnant women with ascariasis should be treated with pyrantel pamoate. Recent patents related to the management of ascariasis are also discussed.

Conclusion: The average cure rate with anthelminthic treatment is over 95%. Unfortunately, most treated patients in endemic areas become re-infected within months. Health education, personal hygiene, improved sanitary conditions, proper disposal of human excreta, and discontinuing the use of human fecal matter as a fertilizer are effective long-term preventive measures. Targeting deworming treatment and mass anthelminthic treatment should be considered in regions where A. lumbricoides is prevalent.

Keywords: Albendazole; Ascaris lumbricoides; Löeffler syndrome; biliary obstruction; intestinal obstruction; mebendazole; pancreatitis; pyrantel pamoate..