Enterobius vermicularis infestation of urinary tract leading to recurrent urinary tract infection.

Sir,

Enterobius infestation is endemic in tropical countries with the prevalence of up to 46% in some areas.[1] Most common site of infestation is gastrointestinal tract. Uncommon sites for infestation include vulva, vagina, uterus, fallopian tubes, ovary, and even peritoneum through fallopian tube in females. Other rare reported site includes lung, liver, breast, and spleen.[2] Transmigration of intestinal flora to urinary tract with Enterobius has been cited as one of the reasons for recurrent urinary tract infection (UTI) in areas with high prevalence of enterobiasis.[3]

A 58-year-old female presented to our outdoor clinic with a history of recurrent dysuria and increased frequency of urination for the past 9 months. There was no history of associated fever or hematuria. However, the patient complained of occasional pruritus in perianal and periurethral region. The patient was known diabetic and was on oral hypoglycemic medications. She denies any history of urethral instrumentation in the past. She was treated previously with prophylactic antibiotics, but symptoms did not resolve. Repeated urine culture came out to be sterile; however, there were increased pus cells in urine. One week before outdoor visit, the patient noticed small, white worms in urine. She carried one such urine sample to outdoor [Figure 1]. On low power microscope, it was identified as Enterobius vermicularis. Ultrasound screening of kidney ureter bladder region revealed some echogenic floating materials in urinary bladder. She underwent cystoscopic examination, which failed to reveal any worm-like structure in bladder or any other abnormality. Planoconvex ova of the E. vermicularis were identified in the urine sample; however, wet mount examination of stool does not reveal any eggs. The patient was treated by a single dose of 400 mg of oral albendazole which was repeated after 2 weeks to eradicate any emerging parasites. The patient completely resolved of symptoms and there was no recurrence of symptoms at 6-month follow-up. Urine examination at 6 months does not reveal any abnormality.

Figure 1

Adult pinworm isolated from urine.

E. vermicularis is one of the most common parasites inhabiting human gastrointestinal tract. It is ubiquitous in geographical distribution and affects both genders equally. The majority of infections are attributed to shared infective source and low socioeconomic status. The gravid female is a nocturnal migrator, which either die on the excursion or return safely to anal canal. Most frequent symptom of enterobiasis is itching in perianal region; however, the majority of pinworm infections are asymptomatic. An abnormal route is taken at times, involving vagina in females, through which it can ascend to uterus to fallopian tube to ovary or drop into peritoneum. Migration in urethra is rare and only a few cases have been reported in literature so far.[45] Urinary tract infestation generally occurs by ectopic movement of pinworms which may also carry Escherichia coli and other bacteria from rectum to urinary tract.[6] In children, Enterobius infection was also found to be related to introital bacteriology and recurrent UTI.[7] As the life span of pinworm is only for few months, such an infection usually resolves spontaneously. Diagnosis of Enterobius infestation is made by either scotch-tape test or finding worms or typical planoconvex ova in stool or rarely in urine sample. Routine examination of stool sample gives positive diagnosis in only 5%–15% of patients.[8] Best time to identify ova is in the morning, so scotch-tape test should be done in the morning. A single examination detects 50% infection whereas three consecutive tests detect 90% of infestation.[9] Effective medical therapy is available. However, due to its frequent recurrence and shorter life span, a community-based approach is preferred by regular inspection and improvement in personal hygiene in high-prevalent areas. Treatment of enterobiasis is done using mebendazole, albendazole, or pyrantel pamoate, usually single dose followed by repetition after 2 weeks to eradicate emerging parasite.

E. vermicularis is a well-adapted parasite of humans with ubiquitous distribution. Ectopic migration and involvement of urinary tract may lead to recurrent UTI. Recurrent UTI is a rare presentation of Enterobius, and diagnosis is challenging in terms of rarity of the disease and thus low clinical suspicion.