cercariae dermatitis
Introduction
Introduction to cercaria dermatitis In addition to human schistosomiasis, there are many animal schistosomiasis in nature. Their cercariae can invade human skin and produce cercaria dermatitis, which mainly includes schistosomiasis in birds and mammals. Most of the common rice dermatitis in China is caused by Schistosoma cercariae, which is a common and frequently-occurring disease. basic knowledge The proportion of sickness: 0.003%-0.004% (more common in those who like half-cooked pork) Susceptible people: no special people Mode of infection: contact spread Complications: erythema, urticaria, papular urticaria
Cause
The cause of cercaria dermatitis
Schistosomiasis in birds and mammals (30%):
The pathogens of cercaria dermatitis are very similar. Because of the wide variety of schistosomiasis in birds and mammals, it can cause dermatitis. The pathogen of rice dermatitis, which is widely prevalent in southern China, is mainly the schistosomiasis of the genus Parasitoid, which is especially parasitic. T. paoi, the adult parasitic in the portal vein of the duck, the intermediate host is Lymnea, and the duck is infected with the hairy worm after 10 to 12 days of development, that is, it can lay eggs, The ends of the trematode eggs are long and pointed, and the center is broad and has a fusiform shape. There are mature edulis inside. After the edulis hatch, they invade the snails. After about 1 month, they release the cercaria and infect the new ducklings. To complete his life history, the hairy genus has a point of eye, is phototaxis, and has 5 pairs of puncture glands.
East worm (25%):
The number of testes in the genus Diptera is high, and the ovary is characterized by a twisted spiral. The intermediate host of the shellfish is Radix ovata, which is found in ponds and ditch with slow water flow, water plants and reeds. After infection with edulis, radish snails develop and multiply after 22 to 25 days, and the cercariae escape. The genus cercariae has no eye points, and there are 5 pairs of puncturing glands that invade from the skin.
Schistosoma japonicum (25%):
In addition, foreign reports of Schistosoma spindale, S. bovis and S. matthei cercariae can also cause cercaria dermatitis.
There is a schistosomiasis cercariae caused by Austrobilharzia. The final host is a variety of waterfowl. The crustaceans in the seawater are intermediate hosts. The cercariae of the genus Schistosoma japonicum has 6 pairs of puncture glands and lives in seawater.
Pathogenesis
After invading the skin, the cercariae is surrounded by a large number of white blood cells, causing an inflammatory reaction. Initially it may be the action of the secretion of the cercaria puncture gland. Later, due to the stimulatory reaction after the death of the worm, the animal experiment proves that this is an allergic reaction, the first infection of the skin. Lighter, repeated infections produce a strong inflammatory response, a large number of mononuclear cells infiltration and edema in the epidermis and dermis.
Prevention
Otitis dermatitis prevention
Personal protection: Avoid contact with infected water, especially those with a history of cercaria, to prevent recurrence. Apply a layer of highly viscous ointment such as petrolatum or eucalyptus oil to the water-immersed parts such as hands and feet before the water is launched in the epidemic area to prevent the scorpion from getting into the skin. After contact with the infected water, quickly dry the skin and try scrubbing with ethanol.
Cut off the route of transmission: carry out the sanitation work to eliminate snails and scorpions in endemic areas. There are currently no practical and effective measures for dermatitis caused by Schistosoma japonicum.
Complication
Otitis dermatitis complications Complications, red spotted urticaria, papular urticaria
Occasion dermatitis often secondary bacterial infection after sputum rupture, cercaria dermatitis is located in the hands and feet.
Symptom
Otitis dermatitis symptoms common symptoms edema herpes pruritus plague bacterial infection skin pain papule erythema (border clear
The human skin is in contact with the water containing the tail plague. After the water evaporates, the patient feels a local tingling of the skin, accompanied by erythema. Allergic patients who have repeated infections may have urticaria local or systemic. After about 1.5 hours, the skin lesions subsided. A small amount of rash was left. After a few hours, it was severely itchy and edematous. It turned into papules and herpes. It was most severe on the 2nd to 3rd day after infection. After that, it gradually subsided, but after itching, dermatitis can appear again. Often secondary to bacterial infections, cercariae dermatitis is located in the hands and feet.
Examine
Examination of cercaria dermatitis
In the early stage of infection (preferably within 2 to 3 hours), the cercaria can be found, and eggs or hatching mites can be found in the feces.
Diagnosis
Diagnosis and differentiation of cercaria dermatitis
According to epidemiological history and clinical manifestations, it can be diagnosed by finding eggs and hatching in the feces.
Clinically, it is necessary to distinguish between rice dermatitis and insect bite dermatitis caused by avian cercariae.
