Introduction
Enterobius vermicularis (pinworm) is the most common among all helminths in the world with a prevalence rate of 20-40 million in the United States. Treatment of pinworm infection is fairly easy and medication can be provided at all public health facilities. This paper seeks to provide an analysis of the pinworm as a parasite as well as demonstrate effective methods of treatment and prevention.
Taxonomy
Enterobius Vermicularis (pinworm) belongs to the kingdom Animalia, phylum Nematoda, order Oxyuroidea and family Oxyuridae (Gutiérrez, 2000)
History
The first incidence of the pinworm was recorded in Egypt between 30BC and AD395. The pinworm has been described as an inherited parasite in the sense that it is a host-specific parasite and has over the years evolved alongside man.
Morphology
The pinworms are generally small with females being larger than the males. The female’s measure between 8 and 13mm with an average 0.5mm thickness while the males measure between 2 and 5mm with 0.2mm thickness. The females have a pointed posterior while the males have a rounded one. (Markell, John, and Krotoski, 1999).
Habitat
Humans are the only confirmed reservoir for pinworms. Adult pinworms live in the lumen of the caecum (Gutiérrez, 2000). Extra-intestinal infections have been reported with pinworms being found in the lungs, liver, breast, and spleen (Burkhat, and Burkhat, 2005).
Presentation
Generally, pinworm infestation is asymptomatic, and when clinical features do present the most common symptom is perianal itching (Michelle, Kalyana, 2005). The itching is more severe during the night because this is the time when the female pinworms migrate to the anus to lay eggs.
Eggs
Pinworm eggs measure 20-33mm and are translucent with a sticky surface. The shell is flattened on one side (Caldwell, 1982).
Transmission
The transmission of pinworms is usually from one human to another (Cook, 1994). Once the eggs have been deposited at the anus, the female pinworm usually dies. The eggs are then picked up in fingernails or stuck onto bed linen from which other people can collect them. The eggs are then ingested during meals or through nail-biting. If an individual picks eggs from his perianal region and proceeds to take them, autoinfection is said to occur. Sometimes the eggs are picked up in dust when shaking bed linen. The dust containing the eggs is inhaled and then swallowed into the gastrointestinal tract where hatching takes place (Cook, 1994).
Diagnosis
Pinworm diagnosis is done by scotch/cellophane tape test where a transparent and adhesive cellulose tape is placed directly in the perianal area first thing in the morning-i.e. before bathing (Cook, 1994). The tape containing the eggs is then placed directly on a slide and studied under a microscope. If necessary, Lactophenol cotton blue may be used to stain the eggs for easy identification (Cook, 1994). For extra-intestinal infection, a more specialized investigation is required including colonoscopy, cervical smears, and vaginal wet mounts.
Treatment/therapy
The most common medications for pinworms are Mebendazole and Albendazole (Michelle, and Kalvana, 2005). Mebendazole is administered in a single dose of 100mg orally. The dose should be repeated after 14days in order to avoid reinfection. The drug has a 95% effectiveness and works by blocking the uptake of glucose by adult worms hence causing death. Albendazole should be given in a single dose of 400mg for adults and 100mg for children under two years (Michelle, and Kalvana, 2005). This dosage should ideally be repeated after 14days as well. Albendazole works by blocking the energy-producing molecule ATP hence causing depletion of energy and eventually death of the adult worms.
Alternative medication
Phenothiazine has been proposed as an alternative medication for children (Miller, and Allen, 1942). A study was carried out to analyze the effectiveness of phenothiazine and its side effects were carried out by Max J. Miller and Della Allen (1942). 23 children between the ages of 4 to 12 years all infected with pinworms were treated with Phenothiazine. The drug was administered in chocolate tablets as other tablets were found to pass through the intestines without disintegration, while tablets that could disintegrate were found to be too bulky for the children to swallow. Seven grams of Phenothiazine were in three successive doses of 2.5, 2.5, and 2 grams respectively. After treatment, all 23 children were found to be entirely free of infection. In other words, the drug was 100% effective in the treatment of pinworm infection (Miller, and Allen, 1942).
The effect of Phenothiazine on hemoglobin was also analyzed during the three days of treatment as well as some days after the treatment was over. 20 c.mm of blood was diluted in 5 c.c. N/10 HCl. A Klett-Summerson photoelectric colorimeter was used to read the solution against the green filter (Miller, and Allen 1942). Hemoglobin determinations on the first day of treatment and on the 2nd, 7th, 11th, and 21st day after treatment was started. It was noted that hemoglobin levels dropped rapidly to reach the lowest level on the 7th day after which they began to rise reaching the normal levels after 21 days. The average hemoglobin levels were plotted graphically as shown below (Miller, and Allen, 1942).
The conclusion made was that Phenothiazine was very effective in the treatment of pinworm infection. The side effect noted was slight anemia but this was transient in nature in the sense that it easily resolved without intervention after a certain period of time (Miller, and Allen, 1942).
Prevention
Proper personal hygiene is the key prevention against pinworm infection (Caldwell, 1982). Basic hygienic procedures include washing the hands with soap and water, clipping the fingernails, changing beddings on a daily basis, and keeping the bedroom floor clean. Food should also be covered to avoid contamination through the air (Caldwell, 1982).
Complications
Pinworm infection especially when it occurs in the extraintestinal regions may result in varied complications (Burkhat, and Burkhat, 2005). These include appendicitis, intestinal obstruction, sialadenitis, intestinal perforation, enterocolitis, hepatic infection, urinary tract infections, salpingitis, and epididymitis (Burkhat, and Burkhat, 2005).
Summary
- The pinworm is the most common helminth in the world and was first discovered in Egypt.
- The females are bigger than the males and have a pointed end. The males have a rounded posterior.
- Adult pinworms live in the caecumthroughh extra-intestinal infections have been reported.
- The females move to the perianal region to lay eggs after which they die. The eggs have a sticky surface.
- Transmission is from one human to another majorly through contaminated finger nails.
- Diagnosis is carried out first thing in the morning by scotch tape test.
- Treatment is done by Mebendazole and Albendazole. Phenothiazine has been found to be 100% in treating infected children.
- Personal hygiene is the key control measure against pinworms.
Conclusion
The pinworm is very common around the world but at the same time very easy to treat and prevent. This report has provided an in-detail analysis of the pinworm and laid emphasis on treatment. With the prevalence rates being highest in children, a study on phenothiazine, a drug with 100% effectiveness in handling pinworms in children has been summarized. In conclusion, it is worth noting that pinworm infection if left untreated could result in complications. It is therefore imperative that proper prevention and treatment procedures be practiced in all infected households.
References
Burkhart , C.N., Burkhart, C.G. 2004. Assessment of frequency, transmission, and genitourinary complications of enterobiasis (pinworms). International journal of dermatology, 44, 837–840.
Caldwell, J. P. 1982. Pinworms (Enterobius Vermicularis). Can Fam Physician, 28: 306–309.
Cook, G.C. 1994. Enterobius vermicularis infection. Hospital for Tropical Diseases, London, 35, 1159–1162.
Gutiérrez, Y. 2000. Diagnostic pathology of parasitic infections with clinical correlations (2nd ed.). Oxford University Press
Markell, E., John, D., Krotoski., W. 1999. Markell and Voge’s Medical Parasitology (8th ed.). Saunders.
Michelle, P., Kalyana, I. 2005. Unusual Endoscopic and Microscopic View of Enterobius vermicularis: A Case Report with a Review of the Literature. Southern Medical Journal, 98, 9, 926-928.
Miller, J.M., Allen, D. 1942. Studies on pinworm Infections: Tests with Phenothiazine in the treatment of pinworm infections. Can Med Assoc J, 46, 2, 111-115.