Dracunculiasis
Introduction
Introduction to dragon nematode Dracunculiasis (dracontiasis), also known as guineaworm infection, is a parasitic disease caused by the parasite of the guinea worm, which is parasitic in the deep connective tissue and subcutaneous tissue of the human body. Out of the body. The main clinical manifestation is chronic skin ulcers. basic knowledge The proportion of illness: 0.002% Susceptible people: no special people Mode of infection: digestive tract spread Complications: Synovitis Arthritis
Cause
Cause of dragon nematode
(1) Causes of the disease
The adult Dracunculus medinensis is long cylindrical, white, smooth, with a rounded front end, a small end, and is curved to the ventral surface. The head is raised, the mouth is triangular, and there are six internal papillae around the mouth. (two on each side of the abdomen, one on each side), 4 pairs of external ring mastoids, short mouth capsules, followed by esophagus, the distal end of the esophagus is slender sarcoplasm, the back end is a growing glandular part, flat intestine, female The size is (60 ~ 120) cm × (0.9 ~ 2) mm, female ovaries, fallopian tubes and uterus are paired, the uterus contains a large number of first-stage larvae; males are 12 to 40 mm long and 0.4 mm wide.
The female vents the larva into the water. The larva can live in the water for 7 days. After being swallowed by the intermediate host, the squid, the larvae pass through the intestinal wall and move to the body cavity. After 25 to 14 days at 25 °C, Secondary peeling is infectious. If a person accidentally drinks water contaminated by sword scorpion containing infected larvae, the larva escapes from the corpus callosum and reaches the duodenum in the stomach of the host. In the experiment, the escaped larvae penetrated into the intestinal wall of the dog after 13h, reached the mesentery 10 to 12 days, reached the chest and abdomen muscles in 15 days, and moved to the subcutaneous tissue in 21 days, reaching the armpit and groin area within 3 and a half months after infection. The larvae undergo the third peeling during the migration process and become adult worms. They are mated in parallel. The fertilization time of the females is about 3 months after infection. The males die after mating, and the mature females are 8th after infection. 10 months to migrate to the subcutaneous tissue of the host limb, the insect head is facing the skin outward, due to the pressure of the worm and the secretion of toxins, the local skin produces papules, which in turn become blister rupture, and the worm body migrates to the ground. (geotropism), often front end facing the ground To the lower limbs, when the diseased part is in contact with water, the female is stimulated, and the front end of the worm body protrudes from the ulcer. Due to internal pressure and aging, the anterior body wall is broken, and the uterus is prolapsed from the rupture, into the water. A large number of larvae can be discharged, the number of which can exceed 500,000 times/time. After the host leaves the water source, the females retract the subcutaneous tissue, and the process is repeated until the next time the water is in contact with the larvae, and the females die quickly. Absorbed by the organization.
(two) pathogenesis
The site often invaded by D. elegans is the connective tissue of the extremities and trunk. During the migration and development of the infected larvae, there is no pathological change in the site. When the adult matures, it passes through the connective tissue and moves downwards, 85%. The parasitic part of the case is below the calf (between the tibia, sole or ankle), but it can also occur in the reproductive organs, buttocks, upper limbs or back, occasionally in other parts, often before the adult moves to the surface of the skin and prepares to discharge the larvae. Obvious clinical symptoms, when moving to the surface of the skin, the licking pimples can be seen in the lying position of the female. After a few days, the damaged part is blisters, the blister can be as large as several centimeters, and the blister is yellow liquid with a single Nuclear cells, eosinophils, polynuclear cells and a considerable number of larvae, blister formation is often accompanied by local itching and severe burning pain, after the blister rupture, a painful superficial ulcer is formed, the wound diameter is 1.25 ~ 1.8cm, A tiny hole can be seen in the center. The hole diameter is like the size of a common probe head. Sometimes some of the body of the adult can be seen to protrude from the hole. At this time, if the ulcer comes into contact with water, it will flow out. There is a milky liquid of larvae, and the larvae are excreted in a gap. If there is no secondary infection, the female will die about 10 days, and it will be easily taken out. The ulcer will heal after 4 to 6 weeks. In the case of local lesions, some patients may have allergic symptoms. Such as urticaria, nausea, vomiting, diarrhea, dyspnea, and even asthma, which may be caused by the body's absorption of histamine-releasing toxins released by females. Animal experiments have also confirmed that these symptoms are allergic reactions, and the goats are injected with adults. Leachate can produce similar symptoms, and the injection of adrenaline can quickly eliminate these symptoms. After the blister ruptures, the systemic symptoms are alleviated. Sometimes the adult dies before it reaches the maturity stage. Careful examination can be performed under the skin and a hard hovering. The cord can be calcified after a few months.
Prevention
Dragon worm disease prevention
Prevention of this disease should start from improving the health habits. The water that the patient has contacted should be treated with insecticide to avoid polluting the water source. Do not drink raw water or dirty water. An easy way to avoid drinking water infections is to kill the sword otters in the water by boiling or chlorination. Or use a cheesecloth (a coarse cloth) to filter the drinking water. Drug prevention optional ethylamine 5mg / kg daily for 3d, a course of medication a month.
Complication
Dragon worm disease complications Complications Synovitis
Secondary bacterial infection, can be complicated by synovitis, epididymis, aseptic arthritis.
Symptom
Symptoms of dragon nematode common symptoms abscess joint stiffness acupoint edema calcification paraplegia muscle contracture
Secondary infection is the most common complication of this disease. If the worm ruptures in the tissue, it can cause severe cellulitis and form an abscess around the worm. When the adult protruding from the skin is damaged or chapped, it is localized. Pain, inflammation and edema can occur in the skin. Staphylococcal, streptococcal infection, cellulitis, and infection with Clostridium tetani, causing tetanus in skin ulcers, is quite common in rural areas of Africa. Uterine destruction causes larvae to enter adjacent tissues to cause closed aseptic lesions. Sometimes larvae enter the joint cavity to cause aseptic arthritis. In addition, it can cause synovitis, epididymitis, muscle contracture and joint rigidity, and worm body. If the central nervous system is invaded, it can cause paraplegia. There have also been reports of adult and its caused lesions in the eye, heart and genitourinary system.
Examine
Long-term nematode examination
Eosinophils in the blood increased, and the adult larvae were found in the cavernous cavity of the ulcer, or in the milky slurry discharged from the hole, or in the adjacent tissue, aseptic fluid in the joint cavity.
X-ray examination reveals dead calcified worms.
Diagnosis
Diagnosis and identification of nematode disease
diagnosis
Check the ulcer surface and larvae as the most reliable method for the diagnosis of this disease. In the epidemic area, if the subcutaneous tissue of the lower limbs of the patient is found to have a sliding and hard long banded worm, the disease may be considered. For example, the adult is found in the hole of the ulcer. , or in the milky slurry discharged from the hole, or in the adjacent tissue, the larvae in the aseptic fluid of the joint cavity can be diagnosed, sometimes the patient can feel the worm inside the skin before the formation of typical papules, but should Different from the subcutaneous parasitic mites, the death calcifications can be retrospectively diagnosed according to the X-ray film. In the early stage of infection, the blood eosinophils are increased. The immunological test is still in the exploration stage, including the intradermal test of the worm antigen and Fluorescent antibody examination has a diagnostic significance.
Differential diagnosis
It should be differentiated from the subcutaneous parasitic mites.
