Enterobiasis Past Paper PDF

ENTEROBIASIS ENTEROBIASIS DISEASES: Enterobiasis, oxyuriasis, pinworm, seatworm Cause of Disease: Enterobius vermicularis -infection usually asymptomatic -causing perianal pruritus and pruritus of the vagina  Epi...

ENTEROBIASIS ENTEROBIASIS DISEASES: Enterobiasis, oxyuriasis, pinworm, seatworm Cause of Disease: Enterobius vermicularis -infection usually asymptomatic -causing perianal pruritus and pruritus of the vagina  Epidemiology Cosmopolitan in distribution Higher prevalence in temperate countries compared to tropical rate of infection was higher in older children (5-7 years) nail biting and thumb sucking are significant factors facilitating fecal-oral transmission. Also prevalent at nursery, boarding schools HABITAT: The usual habitat of adults - in lumen of the large intestine especially in the caecum , appendix & ascending colon. Occasionally adults are found in the rectum and lower part of colon MORPHOLOGY AND LIFE CYCLE: -the worm has a cuticular alar expansion at the anterior end (cervical alae) -adult ♀worm:8-13 mm in length and diameter 0.3-0.5mm.Posterior end is pointed and vulva located 1/3 from the anterior. -adult ♂worm:2.5-5mm in length and diameter 0.2mm with curved tail and a spicule. E. Vermicularis adult (female) Female Enterobius vermicularis Morphology and life cycle(cont) -The gravid females migrate at night to the perianal region and lay 11,000 to 15,000 eggs. - eggs mature and infectious several hours after passage. -The adult females die after oviposition. Morphology and life cycle (cont) - the eggs are plano-convex, flattened on the ventral side and measure 50-60 µ by 20 to 30µ. - egg shell hyaline, albuminous, easily attached to fingers and clothing. - eggs are viable for 2-3 weeks outside host. - the adult worm and eggs cause pruritus and discomfort. - Sometimes eggs laid at perianal region hatch and crawl back into the anus and colon to develop as adults – retrofection a type of autoinfection - ingested eggs hatch in duodenum. The liberated rhabditiform larvae molt twice before reaching adolescence in the jejunum and upper ileum. Copulation takes place in cecum. - duration of life cycle from ingestion of eggs to perianal migration of gravid females 4-6 weeks. - the adult females live 30-45 days - eggs attached to dust particles may be inhaled and ingested PATHOLOGY & SYMPTOMATOLOGY - causing perianal itching/irritation(pruritus ani), irritation of vagina (pruritus vulvae) due to migrating ♀adults. - Both adult worm and the eggs responsible for itchiness - signs and symptoms: poor appetite, loss of sleep, weight loss, hyperactivity, enuresis, insomnia, irritability and grinding of teeth, abdominal pain, nausea and vomiting.  Signs & Symptoms Adult worm and ova causing Adult worms at perianal region itchiness - May be asymptomatic also. - ectopic migration to appendix causing appendicitis. - Adult♀may migrate to vagina, uterus and fallopian tubules, peritoneal cavity and urinary bladder. - Can cause urinary tract infection (UTI) DIAGNOSIS: - identification using Scotch tape technique. It gives greatest number of eggs. - It is made of cellophane tape. - Scotch tape is applied to perianal area preferably in the early morning before taking a bath. Scotch tape swab for perianal eggs  Scotch Tape Technique Performing the Scotch Tape Technique TREATMENT: - individual treatment unsatisfactory if members of household are untreated and remain source of infection. - Mebendazole(Vermox) or Albendazole PREVENTION: - Personal cleanliness is essential. - Finger nails should be cut short. - Hands washed thoroughly with soap after using toilet. - Group treatment - Difficulty in preventing dust-borne and retroinfection may account in failure of strict hygienic measures.