| disease | Enterobiasis (Surgery) |
| alias | Enterobiasis |
Enterobiasis is a type of intestinal parasitic disease characterized by perianal and perineal cutaneous pruritus. It is prevalent worldwide, with an estimated 300–500 million people infected. The condition is widespread in both southern and northern regions of China, with higher infection rates among children compared to adults, particularly in group settings such as childcare institutions. Domestic survey data indicate that the infection rate among children ranges from 40% to 70%, with urban children in communal living environments showing higher rates than those in rural areas. In households with poor sanitation, multiple family members are often infected simultaneously, making enterobiasis a significant public health concern.
bubble_chart Pathogen
(1) Morphology of Pinworms: Pinworms belong to the Oxyuridae family and the Enterobius genus. The adult worms are small, milky-white, and thread-like. The cuticle on both sides of the anterior end of the body expands to form cephalic alae, with transverse striations on the cuticle. The buccal capsule is not prominent, with three lip-like structures surrounding the oral opening, and the pharyngeal tube ends in a bulbous shape. Male worms measure about 2–5 mm in length, with the tail curved ventrally and a tubular reproductive organ. Female worms are 8–13 mm long, with a long and sharply pointed tail and a double-tubed reproductive organ.
The eggs are colorless, transparent, and oval-shaped, measuring 50–60 μm in length and 20–30 μm in width, with asymmetrical sides—one flat and the other slightly convex. The eggshell is thick and transparent, composed of an innermost lipid layer and two chitinous layers, with a smooth protein membrane on the chitinous layer. When the eggs are expelled from the worm, they already contain a tadpole-shaped larva.
(2) Life Cycle of Pinworms: After mature eggs are ingested, they hatch in the duodenum, and the larvae migrate down the small intestine to the colon, where they develop into adult worms. The process from egg ingestion to adult development takes 15–28 days. Adult worms mate in the lower part of the small intestine or the upper part of the large intestine, after which the male worms die and are excreted in feces. Some female worms may also be excreted in feces. Pregnant female worms migrate to the cecum, where their heads can penetrate the mucous membrane to absorb nutrients and even blood. Female worms generally do not lay eggs inside the intestine; instead, when the host is asleep, they crawl out of the anus and, stimulated by air, begin to lay large numbers of eggs, with each female containing about 5,000–17,000 eggs. Most female worms wither and die after laying eggs. Eggs adhering to the perianal area can develop into infective-stage larvae in about 6 hours under suitable temperature and humidity conditions.bubble_chart Pathological Changes
Different developmental stages of the parasite in the intestine can stimulate the intestinal wall and nerve endings, leading to gastrointestinal nerve dysfunction. Adult worms attached to the intestinal mucosa can cause local inflammation, while female worms penetrating deeper layers of the intestinal mucosa can result in ulcers, bleeding, and submucosal abscesses. In rare cases, pinworms can invade the intestinal wall and extraintestinal tissues, forming granulomas centered around the parasite (or its eggs). Ectopic lesions caused by pinworms can affect a wide range of areas, most commonly the female reproductive system, pelvic cavity, and abdominal organs. Damage to the lungs and prostate has also been reported. Depending on the affected organ, patients may exhibit diverse clinical symptoms and signs, often leading to misdiagnosis. Pinworm granulomas appear as small nodules with a white center and slight yellow hue to the naked eye. Histological sections reveal an outer layer of collagen fiber membrane and an inner layer of granulation tissue surrounding a central necrotic area containing the parasite or its eggs.
(1) Perianal or perineal cutaneous pruritus: Caused by toxic substances produced by pinworms and mechanical irritation, especially at night, affecting sleep and causing children to cry and become restless. Due to intense itching, scratching can lead to perianal skin peeling, congestion, rashes, and eczema, and may even induce suppurative infections.
(2) Digestive symptoms: Pinworms burrowing into the intestinal mucosa, as well as mechanical or chemical irritation in the gastrointestinal tract, can cause symptoms such as loss of appetite, nausea, vomiting, abdominal pain, and diarrhea.
(3) Neurological symptoms: Metabolic products excreted by pinworms in the body can lead to mental excitement, insomnia, restlessness, and night terrors or finger-biting in children. Pica symptoms are most common in enterobiasis patients, such as cravings for dirt, coal cinders, or salt.
(4) Other symptoms: Caused by ectopic pinworm infestation, such as vaginitis, salpingitis, endometritis, etc. Pinworms may also invade the appendix, leading to appendicitis or even peritonitis.
If there is frequent intense itching around the anus or perineum, and the child is restless at night, the possibility of enterobiasis should be considered. The diagnosis can be confirmed if the worms or eggs are detected.
(1) Egg Examination Methods: Due to the unique egg-laying habits of pinworms, the positive rate of detecting eggs in feces is less than 5%. Methods for examining eggs outside the anus include:
1. Swabbing Method: Place a cotton swab in sterilized saline solution, wring it dry before use, and swab around the anus. Mix the swabbed material on a slide with a drop of 50% glycerol solution and examine under a microscope. Alternatively, use the flat end of a toothpick soaked in 50% glycerol or 1% sodium hydroxide solution to scrape the folds around the anus. Transfer the scraped material to a slide with a coverslip, add a drop of 50% glycerol or 1% potassium hydroxide, and examine under a microscope.
3. Cellophane Tape Method: In the morning before defecation, apply cellophane tape to the skin around the anus and examine under a microscope at low magnification. Repeat this for three consecutive days, achieving a positive rate of up to 79.4%. This method is simple and suitable for mass screening.
(2) Worm Examination Method: Examine the child’s anus 1–3 hours after falling asleep. If worms are seen crawling out, use tweezers to collect them into a small bottle containing alcohol for preservation. Since pinworms do not necessarily crawl out to lay eggs every night, continuous observation for 3–5 days is required.
bubble_chart Treatment Measures
Since patients with enterobiasis are the source of pestilence for this disease, and enterobiasis is highly susceptible to self-infection, contact infection, inhalation infection, etc., it is prone to widespread prevalence and exhibits characteristics of collective mechanical clustering among children and family clustering in distribution. Therefore, collective medication should be administered simultaneously during treatment to achieve the goal of eradication.
(1) Oral medication: Mebendazole (Vermox) is one of the broad-spectrum vermifugal medicinals widely used in clinical practice in recent years. After oral administration, 5–10% of the dose is absorbed in the intestines, with the majority excreted in feces. A single dose of one tablet (100mg) is administered, followed by a repeat dose after 2 or 4 weeks. Pregnant women should avoid its use whenever possible. Fast-acting Vermox (compound formula mebendazole) contains 100mg of mebendazole and 25mg of levamisole. Adults take 2 tablets administered at draught, achieving an egg-negative conversion rate of 98.5% after one week. Albendazole tablets, whose main component is albendazole, work by inhibiting the polymerization of the cytoplasmic microtubule system in the intestinal wall cells of Chinese Taxillus Herb worms, blocking the absorption of various nutrients and glucose by the parasites, leading to energy depletion and death. In addition to killing adult worms and larvae, this drug also prevents eggs from hatching. Dosage: children aged 2 and above and adults take 2 tablets (400mg) administered at draught; children aged 1–2 take 1 tablet; it is not suitable for children under 1 year old or pregnant women. Chinese medicinals: Quisqualis Fruit, peeled and stir-fried. Daily dose: 1g (one and a half grains) per year of age, divided into three doses per day for 3 days. Do not drink water after taking it to avoid hiccups. Combining it with an equal amount of stemona root enhances its efficacy.
(2) Topical medication: ① Apply 2% white mercuric ointment or 10% zinc oxide ointment to the anus to relieve itching and reduce self-heavy body reinfection. ② Insert a small amount of 0.2% Chinese Gentian violet and 3% stemona root medicinal paste into the anus for several consecutive days. ③ Anal insertion of Miraculous Pill of Six Ingredients: For Chinese medicinals Miraculous Pill of Six Ingredients, children under 7 years old take 5 pills, and those 8 years and older take 10 pills, once daily for 5 days, achieving a cure rate of up to 97.10%. ④ Enema: Dilute vinegar with three parts water and perform a rectal infusion of 50–60ml nightly for 3–5 consecutive days. Chinese medicinals enema: Boil 30g of raw stemona root and 15g of Smoked Plum in 300ml of water until reduced to 100ml. Use 50–100ml for retention enema nightly, with a course of 5–10 treatments.
Pinworms have a relatively short lifespan, typically surviving only 1 to 2 months in the intestines. If reinfection can be prevented by maintaining good personal hygiene, the condition may resolve on its own without special treatment. However, pinworms are highly resilient and quickly develop into the infective stage. They do not require an intermediate host and can reinfect without leaving the human body. Therefore, the principle of prevention measures is to simultaneously implement treatment and prevention, as well as individual and collective control efforts. It is essential to widely publicize the dangers of enterobiasis, modes of infection, and the importance of prevention and treatment. Parents, teachers, and caregivers should be fully informed to educate children on developing good hygiene habits, such as washing hands before meals, trimming nails regularly, and avoiding finger-sucking. Underwear and bedding should be changed and washed frequently. In group childcare settings, strict separation of sleeping areas is necessary, with adequate spacing between beds. Clothing, toys, and eating utensils should be disinfected regularly. A 0.5% sulfur solution can be used for 5 minutes, or a 0.05% iodine solution for 1 hour, to kill all eggs. These low-concentration iodine solutions are non-irritating to human skin and serve as effective yet simple disinfectants. Prevention of enterobiasis emphasizes the application of comprehensive control measures to effectively prevent reinfection and ultimately eradicate the disease.
