Dracunculiasis is a helminthic invasion caused by a round worm, a guinea worm, parasitizing in the intermuscular tissue and subcutaneous tissue. Clinical symptoms include allergic reactions (urticaria, suffocation), fever, joint swelling, burning pain, erythema formation, blisters and ulcers at the site of the parasite’s exit from under the skin. The diagnosis is confirmed by the detection of the helminth head at the bottom of the ulcer and serological studies. Treatment involves careful extraction of helminth from subcutaneous tissue by gradually winding on a gauze roller, taking anthelmintic and antihistamines.
Dracunculiasis (guinea worm) is a helminthiasis caused by a nematode – guinea worm and occurring with damage to connective tissue and subcutaneous tissue. Translated from Latin, the term “dracunculiasis” means “defeat by small dragons”, which reflects the nature of the clinical manifestations of helminthic invasion. Guinea worms parasitize in soft tissues, coming to the surface of the skin through painful ulcers. The disease is registered in the countries of Central, Eastern and Western Africa, Asia, the Middle East, South America. In these regions, the infestation of the local population with dracunculiasis varies from 7-9% to 50-80%.
Guinea worm, or Dracunculus medinensis is a round helminth (nematode) of filamentous shape. Female worms reach a length of 30-120 cm, males – 12-30 mm. Adults parasitize in the human body, less often – animals (predators, monkeys, dogs, cats). Guinea worm females spawn larvae, which are swallowed by freshwater crustaceans-cyclops, acting as intermediate hosts of the helminth. In the body of cyclops, the larvae undergo molting and reach the invasive stage after 4-14 days.
Human infection with dracunculiasis occurs when ingesting water containing invaded cyclops. In the gastrointestinal tract of the final host, mature larvae (microfilariae) penetrate through the intestinal wall and migrate through soft tissues into the intermuscular space. Here, after 3-4 months, the parasites reach sexual maturity. After fertilization, the males of the causative agent of dracunculiasis die (calcify in soft tissues or dissolve), and the female continues to grow and migrates into subcutaneous tissue. Having reached the skin with her head end, the female secretes a special secret, under the action of which a pseudofuruncle forms on the human skin, and then the skin breaks. Through a defect in the skin, the uterus of the helminth protrudes; when it comes into contact with water, it breaks, and a tissue exudate containing small larvae of the parasite comes out. One female releases up to 3 million into the aquatic environment . larvae, after which it dies.
The duration of parasitization of guinea worm in the human body can reach 18 months. Once in the water, the larvae are swallowed by cyclops – this is how a new cycle of helminth development begins. Dracunculiasis is more common among men of various age groups; women and young children are infected less often. Usually a person develops an invasion by one helminth, however, cases of multiple dracunculiasis with simultaneous parasitization of 17 and even 50 helminths have been described. The incidence of dracunculiasis is promoted by unsanitary conditions, lack of running water and sewerage, the use of raw water from open water sources. Contamination of reservoirs with helminth larvae can occur during water intake, bathing, ritual ablutions. Pathogenic effects in dracunculiasis are caused by the sensitization of the body by the products of the parasite’s vital activity, mechanical injury to tissues and the layering of secondary infection.
Symptoms of dracunculiasis
The stage of clinical manifestations occurs 9-14 months after infection. Usually, dracunculiasis manifests itself by the development of allergic reactions (urticaria, itching, attacks of suffocation, puffiness of the face), dizziness, nausea, vomiting, fever. There are local edema of soft tissues at the location of the helminth, swelling of the joints, regional lymphadenitis.
8-10 days after the development of general symptoms, erythema and dense infiltrate appear on the surface of the skin at the site of the future exit of the female guinea worm, from which a blister is then formed. This bubble is filled with a yellowish liquid containing leukocytes, eosinophils and helminth larvae. After a few days, the bladder opens with the rejection of necrotic masses and the formation of ulcers. The head end of the female parasite appears from under the skin. These processes are accompanied by unbearable itching and burning pain, which subside a little after contact with cold water. It is this fact that makes patients with dracunculiasis seek salvation from painful symptoms by dipping into reservoirs. When the affected parts of the body are immersed in water, there is a mass release of larvae and contamination of the reservoir.
The favorite localization of risht is the subcutaneous tissue of the lower extremities (shins, ankles), less often – the upper extremities, abdomen, back, buttocks, scrotum, mammary glands and other parts of the body. With an uncomplicated form of dracunculiasis, the ulcerative skin defect heals quickly. If a single helminth parasitizes in the body, then after 4-6 weeks the clinical manifestations of dracunculiasis subside, and the disease ends with recovery.
The nature of complications of dracunculiasis depends on the localization of the guinea worm and the addition of a secondary infection. The course of dracunculiasis can be complicated by arthritis, synovitis, contractures and ankylosis of the joints, and in the case of bacterial infection – abscess, phlegmon of soft tissues, gangrene of the limb, sepsis. Cases of pericarditis, pleurisy, epididymitis, orchitis, tetanus caused by previous invasion of guinea worm have been described.
Diagnosis and treatment
In endemic areas, it is possible to suspect dracunculiasis in patients with characteristic skin manifestations, palpation of a cord-like formation under the skin, detection of an anterior end of the guinea worm at the site of rupture of the blister. When the helminth is placed in water, larvae are isolated, which can be examined by microscopy. It is also possible to detect guinea worm larvae in the separated from the opened bubbles. Calcified parasites can be detected by X-ray examination of tissues. In order to confirm this diagnosis, it is possible to conduct an intradermal allergic test, serological studies. Clinical manifestations must be distinguished from a boil, abscess, phlegmon.
After the appearance of the helminth from under the skin, it can be extracted by winding it on a gauze roller or stick. In order to avoid the breakage of the helminth, this should be done carefully and gradually, stopping extraction when a feeling of resistance appears. Usually it is possible to extract 5-10 cm of the filamentous parasite at one time – in this case, the procedure is repeated the next day. When the helminth breaks, its surgical removal is performed. Preliminary course of anthelmintic therapy for dracunculiasis with metronidazole, niridazole, tiabendazole facilitates the extraction of the dead parasite. The appointment of antihistamines, corticosteroids, and antimicrobial drugs for bacterial complications is also indicated. Tetanus toxoid is injected into patients with dracunculiasis.
Prognosis and prevention
Dracunculiasis has a long course, leading to disability for a long time. In the uncomplicated form of helminthiasis, the outcome is favorable; in the case of secondary complications, the prognosis may be variable. The fight against dracunculiasis is carried out in two directions by influencing the main and intermediate host. The first direction includes the treatment of patients, improving the sanitary culture of the population of endemic foci, improving the water supply system and improving living conditions. As part of the impact on the intermediate host of guinea worm, it is necessary to treat water sources with pesticides that destroy cyclops.