Schistosomiasis Japanese: causes, symptoms, diagnosis, treatment

Schistosomiasis of Japan is a chronic tropical trematode of South-East Asia, characterized by a predominant lesion of the gastrointestinal tract and liver.

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Epidemiology of Japanese schistosomiasis

Sexually mature helminths parasitize in the vessels of the system of the portal and mesenteric veins of man and some domestic and wild animals: large and small cattle, dogs, cats, mice, rats, rabbits, pigs, monkeys, etc. Laying of eggs begins by the female 4 weeks after infection. For a day, each female is able to postpone 1500-3000 eggs. Eggs pass through the intestinal wall and stand out together with feces. In feces, eggs appear 6-10 weeks after infection. Intermediate hosts are shallow freshwater mollusks of the genus Oncomelania. The duration of development of larval stages of schistosomes in mollusks is 4-12 weeks. Cercariae live in water up to 3 days, but they retain invasive ability only for the first 30 hours.

Japanese schistosomiasis is registered in Asian countries: Indonesia, China, Malaysia, the Philippines, Japan, and Korea. It is common both in the rain forest zone and in the subtropical regions. Schistosomiasis, found in Cambodia, Laos and Thailand, is called mekong. It is more common in children under 10 years old.

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What causes schistosomiasis in Japan?

Japanese schistosomiasis is caused by Schistosoma japonicum. The size of the male is 12-20 mm, the female is 12-28 mm. Cuticle of male smooth, without tubercles. Intestinal branches connect in the back of the body. Testes in the amount of 6-8, medium size. The female uterus occupies about half of the body, contains 50 to 100 eggs. Eggs broadly oval, with a short lateral spine, their size 70-100 x 50-65 μm, contain mature miracidia.

Pathogenesis of Japanese schistosomiasis

The pathogenesis of Japanese schistosomiasis is similar in many respects to the pathogenesis of S. Mansoni. However, S. Japonicum lays about 10 times as many eggs and allocates them at the same time in large batches, which leads to a massive introduction of eggs into various organs: the liver, lungs and others, in which severe damage to blood vessels and tissues develops. Accumulations of eggs in the intestinal walls begin to calcify after a few months, which leads to the formation of granulomas, the formation of which is accompanied by exudation and necrosis. Intensive production of eggs leads to the development of violent allergic reactions. 1-7 years after infection usually develops liver fibrosis with portal hypertension. Characteristic is the defeat of the central nervous system, which is noted in 2-4% of cases. The development of granulomas is found in both gray and white substances of the brain.

Symptoms of Japanese schistosomiasis

In the acute phase of the disease with intensive invasion 2-3 weeks after infection, the body temperature rises in the patients, skin rashes with angioedema appear. There are the following symptoms of schistosomiasis of Japan: headaches in the abdomen, diarrhea up to 10 times a day with mucus and blood. During this period, the development of bronchitis and bronchopneumonia is possible. The liver and spleen are enlarged. In the peripheral blood is determined by high eosinophilia, leukocytosis, increased ESR.

In the chronic period of the disease, the leading symptoms are schistosomiasis of the Japanese, associated with the lesion of the thick intestine. Diarrhea with an admixture of mucus and blood is noted. Sometimes there is an intestinal obstruction due to the accumulation of eggs. There are severe lesions of the upper parts of the digestive tract with the formation of stomach and duodenal ulcers, as well as with malignant formations in these organs. The defeat of the liver leads to the development of portal hypertension. When CNS is affected, neurologic symptoms may appear as early as 6-8 weeks after infection. Often recorded Jackson epilepsy, possibly the development of meningoencephalitis, paralysis. Without treatment and a long course of the disease, cachexia develops.

Diagnosis of Japanese schistosomiasis

Diagnosis of Japanese schistosomiasis consists in the detection of eggs in feces by the same methods as in intestinal schistosomiasis of Manson. In the late period, rectal biopsy is crucial in many cases.

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Treatment of Japanese schistosomiasis

Japanese schistosomiasis has a less favorable prognosis than other intestinal schistosomiasis. In this regard prazikvantel appointed in an increased daily dose - 60-75 mg / kg and divide it into three doses during the day. The effectiveness of treatment is 60%. Symptomatic and pathogenetic treatment of Japanese schistosomiasis is also used.

How to prevent Japanese schistosomiasis?

Prophylaxis of schistosomiasis of the Japanese is the same as with genitourinary schistosomiasis. In addition, additional detection of infected pets and their treatment are carried out. Faeces of livestock on farms and in places of grazing of infected animals should be disinfected. Cattle must be provided with drinking water, free of cercaria.