Parasitic Infection of the Children Digestive Tract (Enterobiasis)

Parasitic Infection of the Children Digestive Tract (Enterobiasis)

  Autor dr. Molfea Camelia Data: 12.01.2006

Parasitic Infection of the Children Digestive Tract (Enterobiasis)
Enterobius vermicularius is more frequent in temperate countries than at tropics. Over 40 millions of American people especially children, are considered to be infected with pinworms. 

Enterobiasis (infection with pinworms) is caused by a round visible worm, which measures 4 mm, called ENTEROBIUS VERMICULARIS. The human is the only known host. The adult parasite settles in the caecum and in the colon. From here, the adult female get out especially during the night and deposits thousands of eggs on the skin near the anus, causing intense itching. By scratching the anal area, the eggs get under the nails and stick to the fingertips, thus reaching the mouth and infecting the human. By contaminating the night-clothing and the bed linen, the infections transmits to other hosts too (most frequently to the members of the same family). 

The most common symptoms are the pruritus ani and the perineal pruritus, more intense during the night, and when associated with pruritus vulvae in girls (vulvovaginitis caused by the migration of worms to these parts) suggest the presence of pinworms. The pruritus is quite intense and leads to insomnia, anxiety and agitation. The acute appendicitis occurs very rarely as the result of parasite migration to the appendix. The scratching leads to tearing of the skin in the anal area, sometimes to enuresis, and to vulvovaginitis in girls. Besides these symptoms of the enterobiasis, there also occur chronic abdominal pains located around the umbilical cord, vomiting, stools modification and some nervous disorders, nasal pruritus, headaches determined by the toxic and allergic action of the parasite. The adult Enterobius worm is about 1 cm long and lives in the intestine. The gravid female migrates to the perianal region (the skin around the anus) during the night and deposits about 10000 immature eggs. The eggs become infectious in a few hours and are transmitted to the mouth, bu hand.
The larvae hatch and mature completely in the gastrointestinal tract. This life cycle lasts for about a month, and the adult worm live for 2 month. The autoinfection occurs by anal scratching (around the anus) and transmits the infected eggs from hand or from under nails to the mouth. As the human- to-human transmission is very easy, the enterobiasis is common among family members or institutionalized people. 
Most infections with pinworms are asymptomatic. The pruritus ani (itching) is the main symptom. The scratching is often intense especially during the night - because of the night migration of the female worm - and might cause excoriations (scratches) and secondary bacterial infection. The massive infections could cause abdominal pain and weight loss. Rarely, the pinworm might invade the women genital apparatus, leading to vulvovaginitis and pelvic and peritoneal granulomas. 

The positive diagnosis is based on the clinical signs and symptoms, and also on the observation of the adult worms in the perianal region or the surface of the stools especially early in the morning. The specific eggs, oval with a flat surface are detected on a miscroscopic examination of the stool (they are collected with a transparent adhesive tape applied on the anal area, which is then fixed on a glass tape and examined with the microscope). The collection is made in the morning and it is repeated on the next days if necessary (3 samples make the diagnosis about 90% exact). At 30% of the sick people, the eggs may be found under the nails. If the lab tests fail, there will be applied a test therapy.
As the pinworms eggs are not released in the intestine, the diagnosis cannot be established by detecting the eggs in the feces. Instead of this, the eggs deposits in the anal region are observed by applying - in the morning - a clean tape of cellulose acetate on the anal region. The tape is then fixed on a miscroscope slide and it is examined with a low magnitude objective to detect the oval eggs specific to the pinworms (55 per 25 micrometers). 

All people infected with enterobiasis must be treated with a dose of mebendazole or Pyrantel parmoate which repeated after 10-14 days. People who live in the same house with infected ones should be treated also, in order to eliminate the asymptomatic reservoirs of infection. 
The drugs treatment includes: 
  • Piperazine (Nematocton or Vermicid 10 % ) in a dose of 65 mg /kg /per day for 7 days. This drug is used less in the last period of treatment. 
  • Mebendazole (Vermox or Thelmox) is considered to be an effective drug, by some authors. Mebendazole is not used during pregnancy, while the Pyrantel is allowed. 
  • Albendazole (Zentel -suspension or tablets, depending on the age) has been used lately with a good therapeutic effect, in only one dose eventually repeated at 3 weeks. 
The Prevention of the contamination and of autoinfection is done as follows: 
  • a strict hygiene of alimentation, body and clothes; 
  • in case you got infected, you must treat the entire family, the bed linen and the clothes must be washed, boiled and ironed very well. 
It it not allowed to shake the bed lined outside because it spreads the infection. The night clothes of your child must be made so that it prevents the contact of fingers with anal region (he must wear pants when sleeping). Wash the hands with lots of water and soap after using the toilet, before eating, and cut the nails short. In order to prevent the infection with pinworms it is recommended to educate your child properly regarding the hygiene after using the toilet and even more. He must wash the hands with soap each time after using the toilet. However, if there is any case of enterobiasis in your home, it is recommended that all the family members take the proper treatment prescribed by the doctor, have an adequate hygiene, their own soap and towel and more than this, wash their hands after each stool. 

Read the English version of this article: Parasitic Infection of the Children Digestive Tract (Enterobiasis)