Intestinal schistosomiasis Manson: causes, symptoms, diagnosis, treatment

Manson intestinal schistosomiasis is a chronic tropical intestinal trematodosis with predominant damage to the digestive system.

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Epidemiology

The life cycle of Manson's intestinal schistosomiasis is similar to the life cycle of S. haematobium. After active penetration of cercariae through the skin and complex migration of schistosomula through the lymphatic and blood vessels, sexually mature helminths are localized in the branches of the portal vein. Most of them migrate to the small branches of the inferior mesenteric vein, where the females begin to lay eggs. With the help of a sharp spine and cytolysins, some of the eggs penetrate the wall of the vessels and the tissue of the mucous membrane into the lumen of the intestine and are excreted with feces. Many parasite eggs are retained in the intestinal wall. The average life expectancy of a female parasite is 3-5 years, but there are cases of patients excreting intestinal schistosome eggs without re-infection for more than 20 years.

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Reasons

Intestinal schistosomiasis Manson is caused by Schistosoma mansoni. The size of the male is 6-14 mm, the female - 12-16 mm. The testes of the males are small, in the amount of 8-9. The ovary of the female is located in the front part of the body. The uterus is short, contains 1-4 eggs. The eggs are oval in shape, with a lateral spine. The size of the eggs is 120-160x60-70 µm.

Intestinal schistosomiasis is widespread in African countries (Egypt, Sudan, Zambia, Tanzania, Central African Republic, Congo, Cameroon, Liberia, etc.). In South America, the disease is found in Venezuela, Guyana, Brazil, the islands of Haiti, and Puerto Rico.

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Symptoms of Manson's intestinal schistosomiasis

Helminth antigens have a sensitizing effect on the host organism.

The acute stage of schistosomiasis occurs as a consequence of allergic restructuring of the body. Symptoms of intestinal schistosomiasis appear 2-16 (usually 4-6) weeks after infection. An irregular fever occurs, appetite worsens. Patients are bothered by frequent loose stools, sometimes with blood and mucus, abdominal pain. Nausea and vomiting are often observed. The liver and spleen increase in size. Cough with sputum may appear, in small children - shortness of breath, cyanosis, tachycardia, hypotension. Eosinophilia and leukocytosis are detected in the blood. An itchy rash appears on the skin, local edema of the skin is noted. Lesions of the nervous system (adynamia, agitation, sometimes a comatose state) are rarely observed.

In the chronic stage, the schistosome eggs remaining in the tissues cause inflammatory reactions, granulomatous and fibrotic processes. The greatest pathological changes develop in the wall of the colon, liver and lungs. There are three main forms of the chronic stage of intestinal schistosomiasis: interstitial, hepatosplenomegaly and pulmonary. The interstitial form is associated with damage to the large intestine, especially its distal sections. Loose stools appear, alternating with constipation. Characteristic symptoms of Manson's intestinal schistosomiasis: aching abdominal pain, anal fissures often form, hemorrhoids develop. Hepatosplenomegaly with portal hypertension develops 5-15 years after infection, signs of liver and spleen dysfunction appear: patients complain of a feeling of heaviness and pain in the hypochondrium, loss of appetite, weight loss, development of edema of the lower extremities and ascites. Esophageal and gastric bleeding occurs. With a long course of the disease, cirrhosis develops. Further development of pathological processes leads to the death of the patient from liver failure, thrombosis of the liver vessels, bleeding, or as a result of acute cardiovascular decompensation. In 5-10% of patients, the pulmonary form of intestinal schistosomiasis develops. In this case, patients complain of shortness of breath, increased fatigue, tachycardia, dizziness, pain in the chest. The formation of granulomas and the proliferation of fibrous tissue around the schistosome eggs entering the liver through the portal system creates a presinusoidal block, leading to the development of portal hypertension. Varicose veins of the esophagus and stomach, splenomegaly occur. In conditions of stagnation in the portal vein system, schistosome eggs are carried to the lungs and other organs. The introduction of eggs can cause damage to the appendix, gall bladder, pancreas, genitals, spinal cord and, rarely, the brain. Complications may include bleeding from the veins of the esophagus, gastric bleeding, phlegmon and abscesses of the stomach and intestines, adhesive disease, polyposis of the rectum and sigmoid colon, development of pulmonary heart syndrome, etc.

Intestinal intercalary schistosomiasis

Chronic intestinal schistosomiasis, common in tropical regions of Africa, is pathogenetically and clinically similar to Manson's intestinal schistosomiasis, but differs from it in its more benign course.

What causes chronic intestinal schistosomiasis?

The causative agent is Schistosoma intercalatum, morphologically similar to S. haematobium. The eggs are somewhat larger. Their dimensions are 140-240 x 50-85 µm. The eggs are excreted with feces.

The disease chronic intestinal schistosomiasis is registered in Zaire, Gabon, Cameroon, and Chad.

Epidemiology, pathogenesis, symptoms, treatment and prevention are the same as for Manson intestinal schistosomiasis.

Diagnosis of intestinal schistosomiasis Manson

Manson's intestinal schistosomiasis should be differentiated from amebiasis, bacterial dysentery, and balantidiasis.

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Laboratory diagnostics of intestinal schistosomiasis Manson

Parasitological diagnostics of intestinal schistosomiasis Manson is based on the detection of eggs in the feces. To detect eggs, large smears should be made on glass slides. A sample of feces from the smear should be taken from the surface of the feces, which was in direct contact with the intestinal mucosa, from where the eggs came out. If the results of coproscopy are negative, rectal mucus is examined after defecation. A method for detecting schistosome larvae in feces based on their phototropism is also used. In this case, the patient's feces are kept in a glass flask under special conditions, under which after 2 hours and a temperature of 25 ° C, miracidia hatch from the schistosome eggs, which, due to positive phototropism, accumulate on the illuminated surface of the flask and can be detected with a magnifying glass or the naked eye. To detect inactive schistosomiasis, a biopsy of a piece of the intestinal mucosa at a distance of 10 cm from the anus is sometimes performed during rectoscopy. In positive cases, schistosome eggs are detected. In recent years, serological reactions based on ELISA have been widely used abroad. Laparoscopy, liver biopsy, etc. can be used as additional methods.

Treatment of intestinal schistosomiasis Manson

The drug of choice is praziquantel or azinox, which are prescribed in a daily dose of 40 mg/kg in two doses during the day (the effectiveness in case of intestinal schistosome invasion is 60%). Treatment of intestinal schistosomiasis Manson consists of prescribing the highly effective drug oxamniquine. Adults are prescribed the drug orally in a daily dose of 15 mg/kg in one dose. Its effectiveness reaches 85-95%. Niridazole can also be used in a daily dose of 25 mg/kg in a course of treatment of 5-7 days. Symptomatic and pathogenetic treatment of intestinal schistosomiasis Manson is also used to improve the functions of the affected organs and systems. In case of secondary infection, antibiotics can be used.

Prevention

Manson's intestinal schistosomiasis is prevented in the same way as urogenital schistosomiasis.