Overview
Dracunculiasis, also known as Guinea worm infection, is a parasitic disease caused by adult guinea worm parasites in the human body, the adult parasites in the deep connective tissues and subcutaneous tissues of the human body, which can extend out of the body. The main clinical manifestation is chronic skin ulcers. In tropical areas, especially in West Africa, the Nile Valley, India, Pakistan and other places popular. The infection rate is closely related to the dry climate, lack of water, drinking habits. Residents of endemic areas like to bathe, wade, wash and gargle in ponds, so there are many chances of being infected. Some areas are used to drinking raw water, and the Indian religious habit of washing the mouth with raw water during fasting and bathing also increases the chances of infection. Therefore, there is a close relationship between the way people in endemic areas obtain and consume water and the prevalence of the disease.
Causes
Guinea worm is a large nematode. The size of female nematode is (60-120) cm×(0.9-2) mm; the length of male nematode is 12-40 mm, width is 0.4 mm. female nematode discharges larvae into water, larvae can live for 7 days in the water, and develop into infected larvae in the body after being ingested by the intermediate host, Daphnia magna. If a person mistakenly drinks water contaminated with infected larvae of the cyclops, he will be infected. The infective stage larvae migrate and develop in the patient’s body without any lesions at the site. When mature, they migrate downward through the connective tissue. There are often no obvious clinical symptoms until the adult worms migrate to the surface of the skin and are ready to expel the larvae. When they migrate to the surface of the skin, the front end of the worm lyses the tissue and releases a large number of metabolites into the host, causing a metamorphic reaction.
Symptoms
The incubation period of the disease is 8 to 12 months, and the impregnated female worms migrate to the subcutaneous tissues of the lower legs, feet or scrotum, etc., and local erythema, edema, itching and other symptoms may appear, accompanied by nausea, vomiting, dizziness, etc. The female worms stay in the subcutaneous tissues for 1 year, and then they are released into the host. After the worms stay in the subcutaneous 1 month, a large number of larvae are released from the anterior end of the worms, and microred papules appear on the local skin surface, followed by the development of blisters of several centimeters. Inside the blisters, yellow plasma scarf has a large number of macrophages, lymphocytes, eosinophils, neutrophils and larvae. Blister formation, often accompanied by local itching and intense burning sensation. The blisters rupture and the metaplasia diminishes, followed by abscess formation. If there is no secondary bacterial infection, the abscess gradually shrinks, leaving a small hole where the female worm extends and retracts. After all the larvae are drained, the female dies, is absorbed by the tissue or calcified, and gradually heals. Secondary infection is the most common complication of the disease. Locally, acute subcutaneous abscesses, chronic ulcers, cellulitis and sepsis can occur if secondary bacterial infection is present, and fibrosis occurs when the infection subsides. Peripheral blood eosinophils are often markedly elevated as the worms migrate through the tissues.
Examination
1. Finding larvae at the blisters: drop a small amount of water on the lesion site, take the liquid there and put it on the carrier film after a few moments, and then examine it with low magnification, the first stage larvae can be seen.
2. Check for female worms: they can often be seen protruding from the lesion.
3. Increased eosinophils in the blood.
Diagnosis
Examination of the ulcerated surface and larvae is the most reliable method to confirm the diagnosis of the disease. In endemic areas, if the patient is found in the subcutaneous tissues of the lower limbs, there are long, hard, smooth, hard bands of worms that should be considered as a possible cause of the disease. The diagnosis of the disease can be confirmed by finding adult worms in the holes of the ulcerated surfaces or larvae in the milky plasma discharged from the holes or in the aseptic fluids of the neighboring tissues or articular cavities. Sometimes the patient can feel the worms in the skin before the formation of a typical papule but they should be differentiated from subcutaneous parasitic schizothoracic larvae. Dead calcified worms can be diagnosed retrospectively on the basis of radiographs. Early in the infection, blood eosinophils are elevated. Immunologic tests are still in the exploratory stage, including intradermal tests for worm antigens and fluorescent antibody tests, which are useful for diagnosis.
Treatment
There is no specific treatment for this disease. Extraction of the worm is the only reliable method.
1. Albendazole, for 2 or 3 days, or metronidazole for 10-20 days, can rapidly relieve the symptoms and reduce local inflammation and edema, and promote the worms to be discharged on their own or easier to remove.
2. Take the worm therapy, the endemic area residents are accustomed to use this effective treatment method, the exposed worm head end wrapped in a small rod, slowly winding its body each time the worm can be rolled out 5cm long repeated once a day, about 3 weeks can be completely rolled out of the body. If the whole body is already in the skin or in the deep abscess, it can be removed by surgery.
3. Symptomatic treatment, including anti-allergy, pain relief, anti-infection and tetanus antitoxin, and topical hydrocortisone ointment can be applied to the skin.
Prognosis
Generally, the prognosis is good, but paraplegia can be caused if the worms invade the central nervous system.
Prevention
The prevention of this disease should start with improving hygiene habits, changing the way of collecting water, and forbidding drinking raw water. Boiling or chlorination to kill cyclops in water is an easy way to avoid drinking water infection. Biological methods can be used to breed cyclops-feeding fish (e.g., willow fish) in waters where cyclops is present.