Human Pinworms

Human Pinworms

Human pinworms

     Enterobius vermicularis is the etiologic agent of enterobiosis. Patient is infected by eating embryonated eggs by infected food or water or by dirty hands. The digestive path and the autoinfection are the most frequent modes of contamination of the patient.

     Adult worms usually populate the terminal ileum, check, vermiform appendix and proximal ascending colon. They are found in the intestinal lumen, they have a non invasive character (unless the host is immune compromised). After copulation, the female migrates to the rectum and if it is not eliminated with the faeces outside, it leaves the perineum where it laid the eggs. They become infective in 6-8 hours and they maintain viable (in good conditions of environment) even in 3 weeks.

     Another method of infection is the endogenous autoinfection infection - if the eggs stay for a very long time in the anal region, especially in the anal mucosal folds, in conditions of poor hygiene, larvae enters the colon and reach the check, where they will form adult worm, incorporating the infection cycle.

     Infection with pinworms may take between 30-50 days (this is often the time of survival of the worm) and is maintained by recurrent auto infections. They are also the main reason for therapeutic failures.

     The most frequent risk factors associated with this infection (and its perpetuation) are mainly: - the age: the more the patient is very young, the more is exposed to infection. Mostly the affected children have 5-9 years

  • Local: the infection is transmitted even in the same family. If a member is diagnosed with pinworm is most likely that other people will be found as testing positive. Human pinworms treatment should be addressed to all members to prevent recurrence. The risk of transmitting the infection and to take the infection is also increased in kindergartens, schools and various other institutions (over 50% of people who spend a lot of time in such institutions are at risk)
  • Environmental factors: it seems that the warm environment, wet, favors the prolonged survival of eggs outside the body.
  • Poor hygiene: is a factor that participates in transmitting the human pinworms infection, but is not the decisive one.


     Human pinworms often cause intense itching around the anus. Most patients are asymptomatic and are unaware that they are infected. Sometimes the infection can transmit in the absence of treatment.

     The most common symptoms include:

  • Anal or vulvae itching
  • Restless sleep (which can interfere in the day, causing a permanent state of fatigue and inattention)
  • Burning or pain when urinating
  • Hives (it is common to all parasitosis)
  • Loss of appetite and weight loss
  • Abdominal pain accompanied by changes in bowel habits: mucous stools, diarrhea
  • Vaginitis, cervicitis, salpingitis (especially in severe cases, disseminated)
  • Permanent anxiety.

     These symptoms must achieve a very wide differential diagnosis. This includes: ascaridiosis, giardiasis, appendicitis, contact dermatitis, inflammatory bowel disease, perianal dermatitis secondary to poor hygiene, cervicitis.

     Common complications of the disease are remote infection structures such as urethra, prostate. This occurs if the parasite migrates aberrantly.

     Perianal abscesses may also occur (by invading glands located at this level) or even block the intestinal lumen with parasites (especially the Appendix). The association of the ulceration of the small and thick bowel infection, the transient synovitis and enuresis seems to be more coincidental than causal.