Enterobiasis Overview and Epidemiology

Enterobiasis

• Also known as oxyuriasis or pinworm infection
• Caused by the parasite Enterobius vermicularis
• Infection usually asymptomatic
• Common cause of perianal itching and itching of the vagina

Epidemiology

• Cosmopolitan distribution
• More prevalent in temperate countries than tropical countries
• Higher rate of infection in children aged 5-7 years
• Nail biting and thumb sucking contribute to fecal-oral transmission
• Common in nurseries and boarding schools

Habitat

• Adults typically inhabit the lumen of the large intestine, specifically the cecum, appendix, and ascending colon
• Occasionally found in the rectum and lower colon

Morphology and Life Cycle

• Adult female worm: 8-13 mm long, 0.3-0.5 mm wide; pointed posterior end with vulva located one-third from the anterior end
• Adult male worm: 2.5-5 mm long, 0.2 mm wide with a curved tail and spicule
• The worm has a cuticular alar expansion (cervical alae) at the anterior end
• Gravid females migrate to the perianal region at night to lay 11,000-15,000 eggs
• Eggs mature and become infectious within several hours after passage
• Adult females die after oviposition
• Eggs are plano-convex, flattened ventrally, 50-60 μ by 20-30 μ, hyaline, and albuminous
• Eggs are viable for 2-3 weeks outside the host and easily attach to fingers and clothing
• Sometimes eggs hatch in the perianal region and then crawl back into the anus and colon, resulting in autoinfection
• Ingested eggs hatch in the duodenum
• Liberated rhabditiform larvae molt twice before reaching adolescence in the jejunum and upper ileum; copulation occurs in the cecum
• Life cycle duration from egg ingestion to perianal migration of gravid females: 4-6 weeks
• Adult females live 30-45 days

Pathology and Symptomemology

• Symptoms include perianal itching, irritation of the vagina
• Both adult worms and eggs cause itchiness
• Additional symptoms may include poor appetite, loss of sleep, weight loss, hyperactivity, enuresis, insomnia, irritability, teeth grinding, abdominal pain, nausea, and vomiting
• Ectogenic migration can cause appendicitis, vaginal, uterine, fallopian tubule, peritoneal cavity, and urinary bladder involvement
• Can cause urinary tract infections (UTIs)

Diagnosis

• Scotch tape test is used to identify eggs
• Cellophane tape is used to collect eggs from the perianal area, preferably in the early morning before bathing

This quiz covers the essential aspects of Enterobiasis, including its causative agent, Enterobius vermicularis, and its clinical implications. You will learn about the epidemiology, life cycle, and morphology of this common parasitic infection, particularly in children. Test your knowledge on how this infection spreads and its impact.