Schistosomiasis enteropathy

Introduction to schistosomiasis Schistosomiasis is a disease caused by schistosomiasis. It is now known that there are five species of schistosomiasis that are parasitic in humans: Schistosoma japonicum, Schistosoma japonicum, Schistosoma mansoni, interstitial schistosomiasis and Schistosoma japonicum. In addition, there are parasitic cases such as bovine schistosomiasis and Schistosoma japonicum (S.matteei). The history of contact with epidemic areas should consider the possibility of schistosomiasis, so the patient's birthplace, occupational and epidemic water contact history is an important reference for the diagnosis of this disease, especially for patients with asymptomatic and no signs. basic knowledge The proportion of illness: the incidence rate is about 0.0003%-0.0008% Susceptible people: no specific population Mode of infection: fecal-mouth transmission Complications: ascites

The cause of schistosomiasis

Infection (30%):

The cercariae, larvae, adults and eggs of schistosomiasis can cause certain damage to the human body, but the eggs are most harmful to humans, mainly causing lesions of the large intestine and liver, and the eggs are deposited in the tissues of the human intestinal wall. There is cell infiltration around it, forming granuloma of eggs, which is the root cause of chronic liver and intestinal lesions due to schistosomiasis. The pathological process of granuloma formation and development is closely related to the development of eggs, and the eggs have not yet formed. When the surrounding tissues are unresponsive or have only a slight reaction; when the oocysts develop, the tissue sputum begins to develop an inflammatory reaction; after the oocysts mature, the enzymes secreted from the mites, proteins and sugar secretions (worms) Egg soluble antigen) causes tissue necrosis and acute inflammatory reaction. Endocarditis often forms in the egg pool and forms eosinophilic abscess. In severe cases, neutrophil pus can also be formed. Schistosoma japonicum granuloma often contains The eggs of the family are so serious that they cause more serious damage than other schistosomiasis.

Birthplace (20%):

People living in rivers and sewage are greatly affected by infection. People who have a history of contact with epidemic areas have a high probability of getting sick. Therefore, the occurrence of this disease is related to the patient's place of residence.

Occupation (30%):

Occupational exposure to sewage is prone to this disease.

Schistosomiasis prevention

First, eliminate the source of infection: treat patients with sick animals, strengthen manure management, and avoid fresh manure polluting water sources. Such as the construction of a harmless septic tank; or the combination of excrement and urine storage, so that urea is broken down into ammonia, can kill eggs. Adding quicklime or bicarbonate to the feces can also kill eggs.

Second, the elimination of the intermediate host snail: the snail should be based on the ecological characteristics and geographical conditions of the snail, according to local conditions, to change the nail environment, combined with physical and chemical drugs to eliminate snail method. The physical snail-killing method includes shovel, fire, and soil burial. Chemical snail-killing drugs include niclosamide, sodium pentachlorophenol, and nicotinamide.

Third, personal protection: try to avoid contact with infected water, if you must work in the infected water, you must take protective measures, the skin is coated with protective drugs, such as niclosamide or dibutyl phthalate ointment, emulsion, or wear Waterproof rubber shoes, plastic protective pants, etc.

Schistosomiasis complications Complications ascites

A small number of patients have ascites formation, which is caused by the inflammatory exudate produced by the acute egg nodules and the extensive lesions in the liver caused by the eggs, which causes the blood flow in the liver to be poor, and the lymphatics increase and leak into the abdominal cavity. Others may have Liver, splenomegaly, etc.

Symptoms of schistosomiasis intestinal diseases Common symptoms Abdominal pain Malnutrition edema Ascites dysentery-like stools Diarrhea Mucosa Congestion in the stool or rectum s... Hematopoietic constipation edema

(1) Medical history:

The history of contact with epidemic areas should consider the possibility of schistosomiasis, so the patient's birthplace, occupational and epidemic water contact history is an important reference for the diagnosis of this disease, especially for patients with asymptomatic and no signs.

(2) Clinical manifestations:

1. Acute schistosomiasis: In epidemic areas, patients with a history of exposure to obvious water contact about 1 month before onset, long-term fever, accompanied by the following characteristics should consider the possibility of acute schistosomiasis:

1 history of cercaria dermatitis, hepatomegaly and tenderness, diarrhea, etc.;

2 The total number of white blood cells and eosinophils in the blood increased significantly;

3 sigmoid colonoscopy found rectal mucosa congestion, edema, yellow granular egg nodules.

2. Chronic and advanced schistosomiasis: Chronic patients have no obvious symptoms, or the symptoms have been forgotten in the past, and these symptoms are also difficult to be associated with this disease as a reference for diagnosis. In the endemic areas, there are long-term unexplained abdominal pain or blood in the stool, liver. Splenomegaly, blood eosinophils increased significantly, young adults have seizures, acute or chronic appendicitis attacks, cirrhotic portal hypertension, such as spleen, ascites or hematemesis and dwarfism, should consider The possibility of schistosomiasis and confirmed by pathogens.

Circulating antigens have been detected in the serum of infected mice. For more than a decade, domestic and foreign scholars have carried out many studies on circulating antigens, and have obtained few results for reference. The detection of circulating antigens provides a method for finding the efficacy of schistosomiasis. The new approach is currently still in the exploration phase.

Within a few hours to 2 to 3 days after exposure to the infected water, a bite-like red punctate rash appears in the invagination of the cercariae. It is a dermatitis of the tail, itching, and it retreats after a few days. The cercaria can cause coughing, hemoptysis, and schistosomiasis. The clinical manifestations of the disease are very complicated and diverse. The location of the optic ovum, the severity of the infection and the body's response may be divided into acute, chronic and advanced schistosomiasis according to their course of disease and main clinical manifestations.

(1) Acute schistosomiasis: Acute schistosomiasis is a seasonal infectious disease, which is more common in summer and autumn. It is more common in young men and young adults. Most of them have no immunity in the past and a large number of new cercaria infections, mainly in contact with infected water. Because of this, the patient's infection history is more obvious, and most of them have a history of cercaria dermatitis. The main symptoms of the system are fever and allergic reactions, which are caused by the metabolites of egg toxin and tissue destruction, due to the massive deposition of eggs in the intestine. Acute colitis, abdominal pain in patients, diarrhea accounted for more than half, diarrhea 2 to 3 times a day, feces thin, can carry blood and mucus, sigmoidoscopy can be seen mucosal congestion, edema, and can be found yellow small particles (for insects Egg nodules), this is a unique pathological change in the acute phase. In the early part of the disease, only constipation can be caused. In severe cases, due to the massive deposition of eggs in the serosal layer and mesentery of the colon, it can cause peritoneal irritation, abdominal abdomen. Swelling, flexibility and tenderness, easily misdiagnosed as tuberculous peritonitis, a small number of patients have ascites, which is caused by acute egg nodules Effusion and eggs caused extensive lesions in the liver, the liver poor blood flow, and increase lymphatic leak into the abdominal cavity caused by other liver, splenomegaly and so on.

(2) Chronic schistosomiasis: Schistosomiasis patients do not necessarily have a history of acute exacerbation. Farmers in epidemic areas are exposed to river water since childhood, and there are small repeated infections. Most of them are chronic schistosomiasis. Because of different degrees of infection, whether there is chronic schistosomiasis Symptoms and symptoms.

1. Asymptomatic patients: Asymptomatic patients account for the majority of asymptomatic patients, and their health and labor can be unaffected. They are only found by chance when they are collectively censused or treated for other diseases. Most of the schistosomiasis seen in cities are also In this class, patients are mostly asymptomatic and non-positive, and a small number of patients may have mild liver or spleen enlargement.

2, symptomatic patients: sigmoid colon and rectum are the main parts of schistosomiasis lesions, so diarrhea and dysentery-like stool is quite common, its light and heavy varies from infection to light, usually patients with occasional diarrhea, daily 2 ~ 3 times, between the middle or the stool with blood, severe cases may have abdominal cramps, urgency and sensation, dysentery-like stool, etc., sigmoid colon thickening due to egg gingival fibrosis and fibrosis, and tenderness, easy to find schistosomiasis eggs in the feces, and increase Thick omentum, mesentery and enlarged mesenteric or retroperitoneal lymph nodes are also often due to egg granulation, granuloma formation, and fibrosis and tangles of different sizes and shapes, which are hard and fixed. The following abdomen is more, most patients show different degrees of anemia, weight loss, malnutrition and labor decline, patients with liver and spleen cut swelling, in the early liver than the spleen, the surface is smooth, slightly hard, the infection is lighter can stop at this Stages instead of progress, severe cases and long-term disease can develop into cirrhosis, the liver gradually shrinks, but still can be affected, especially the left lobe, hard, uneven surface, nodules of varying sizes, and then Dirty gradually in congestive enlargement.

(3) Advanced schistosomiasis: due to repeated infection, the condition gradually worsens, cirrhosis occurs, portal vein pressure increases, ascites, spleen enlargement, lower esophageal or gastric varices, some patients often have fever, abdominal pain, diarrhea and diarrhea, loss of appetite , weight loss, etc., and often anemia, dystrophic edema, children with serious infection, can affect development, can form dwarfism, some patients often have fever, generally not more than 38 ° C, may be associated with the disease of the egg disease Destruction-related, in addition, sexual function tends to decline, men have loss of libido and impotence, women have amenorrhea and infertility, which is caused by severe liver damage caused by systemic malnutrition and the elimination of hormones, so that the function of the pituitary is inhibited, The gonads and other endocrine glands also caused different degrees of atrophy. The patient's face was old and thin, and the appearance was larger than the actual age. There were often facial brown pigmentation. In the late stage, the liver was reduced, the surface was uneven, the quality was hard, and the spleen Gradually congestive swelling.

Examination of schistosomiasis enteropathy

(a) stool examination

The detection of eggs or hatching of edema from the feces may diagnose and evaluate the curative effect, but those with mild infection, advanced patients and language therapy are not healed, the number of eggs in the feces is small, and the detection rate is low, so the fecal test negative can not rule out schistosomiasis disease.

(two) intestinal mucosa biopsy

The sigmoidoscopy or proctitor is inserted from the anus according to the routine. The changes of the intestinal mucosa are observed by the naked eye. The acute phase is mainly due to congestion and edema. In the chronic phase, the mucosa is pale, hypertrophy and scar formation. Typical nodules and small spots can be seen in each stage. Then, the mucosal lesions of the suspected egg-like nodules were taken and pressed between the two slides for microscopic examination. For the untreated patients, the detected eggs were confirmed to have a diagnosis value. In patients, only the diagnosis of live eggs or recent degenerative eggs is diagnostic.

(3) Immunological examination

Including ring egg precipitation reaction test, cercaria membrane reaction, indirect hemagglutination test of egg antigen, schistosomiasis circulating antigen (CAg) and the like.

(4). Pathogen examination

1, stool examination: the detection of eggs or hatching from the feces may be diagnosed and evaluated for efficacy, but mild infection, advanced patients and language therapy did not heal, the number of eggs in the feces is small, the detection rate is low, so the feces Negative tests cannot exclude schistosomiasis.

(1) Direct smear method: The detection effect is very low, only the early patients with severe infection can be found, and the smear part of the pus blood mucus can be picked up, which can increase the chance of detection.

(2) Incubation method:

1 natural precipitation method: this method is better than the direct smear method, but the patient with less eggs in the feces is still missed. Take the bamboo stick and pick up the feces about 30g (egg size) and put it in the beaker. Add a small amount of water to the glass. Into a paste, add more water to dilute the feces, place a copper wire sieve on the cone measuring cup, pour the manure into the sieve and filter, then wash the dung in the sieve with a small amount of water for 1 or 2 times, add in the cone measuring cup Clear water to the mouth of the cup, let stand for 20 minutes, pour the upper liquid to leave the dregs, so change the water repeatedly until the upper liquid becomes clear, and after pouring the last upper liquid, take a small amount of dregs as a smear with a straw. Check the eggs.

2 hatching method: If you use the natural precipitation method for microscopic examination, you can further use this method, pour all the slag into a 250 or 125ml Erlenmeyer flask, add water to the mouth of the bottle about 1cm, (suitable pH is pH7.2 ~ 7.6), set the flask in a light incubator at 20 ~ 30 ° C, such as room temperature up to 20 ° C or more, can be placed indoors to light hatching, after 4 hours buckle began to use the naked eye, magnifying glass, the hair is grayish white, point It is often used for linear motion near the surface of the water. It is considered to be negative after 24 hours of no hairiness.

2. Intestinal mucosa biopsy: sigmoidoscopy or proctoscopy is inserted from the anus according to routine. The changes of intestinal mucosa are observed by naked eyes. The acute phase is mainly due to congestion and edema. In the chronic phase, the mucosa is pale, hypertrophy and scar formation. A typical nodule, small spot, and then the mucosal lesions of the suspected egg nodule are taken and examined between the two slides. For the untreated patients, the detected eggs are dead or alive. The value of diagnosis; for patients with a history of treatment, only the diagnosis of live eggs or recent degenerative eggs is diagnostic.

(5) Immunodiagnosis

1. Ring egg precipitation reaction test: It is a specific immune serological test with blood-sucking whole eggs as antigen. The antigenic substance excreted in the egg mites or embryos excreted through the egg-shell micropores and binds to the specific antibody of the sample. A special complex precipitate can be formed around the eggs. The intensity of the reaction is judged under light microscope and the percentage of reactive eggs is counted. The conventional method is carried out by using a carrier slide or a concave slide. After adding the sample serum, pick the appropriate amount. Fresh eggs or eggs (100 to 150, isolated from infected animal liver), covered with 24 × 24mm cover sheets, surrounded by paraffin wax, placed at 37 ° C for 48 hours, low magnification observation, if necessary, need to observe 72 After the reaction, the typical positive reaction is blister, finger-like, flaky or slender curled refractive index, the edges are neat, and it is firmly adhered to the egg shell. The negative reaction must be observed in the complete film. 100 mature eggs were calculated for the ratio of the ring rate and the reaction intensity. The classification intensity was interpreted as: + is the bubble shape of the egg circumference, the area of the finger sediment is less than 1/4 of the area around the egg, and the flaky sediment is less than 1/2. Slender ribbon The long diameter of the insufficiency egg, "++" is a bubble shape, the total area of the finger-shaped sediment is larger than 1/4 of the egg circumference, the flaky sediment is larger than 1/2, and the ribbon-shaped sediment is equivalent to or exceeds the length of the egg. The diameter, "+++" is a bubble shape, the finger-like precipitate is larger than 1/2 of the circumferential product, the area of the sheet is equal to or exceeds the size of the egg, and the ribbon-like sediment exceeds the length of the egg several times.

The ovarian dry egg antigen tablet (or membrane) ring egg sedimentation test is an improved method developed in recent years. Using the heat-resisting properties of the ring egg antigen active substance, the isolated pure egg is ultrasonically and heat-treated, and quantitatively added. Baked dry fixed slides or pre-made polyethylene film sheets. These dry egg membranes have a long storage time (4 ° C for half a year). They are commercially available. Only serum samples should be added during the test and incubated in a wet box. The interpretation result is the same as the conventional method. The dry egg membrane method also has the advantages of simplifying the operation procedure, improving the specification of the egg antigen, and long-term preservation.

2, cerebral palpebral reaction: take the subject 2 drops of serum about 10 cercariae mixed on the slide, add cover glass sealed with paraffin, set at 25 ° C constant temperature for 24 hours and observe under low magnification, positive reaction There is a gelatinous membrane around the cercariae. After the serum is inactivated, the reaction is weakened. The serum that has been stored for more than 3 days needs to be supplemented. It is considered that this reaction is a part-dependent antigen-antibody reaction, which is of great value for the early diagnosis of new infections. The positive rate is more than 95%. In the absence of reinfection, the antibodies to the cerebral palpebral membrane can be naturally decreased, resulting in more false negatives. Therefore, it is not appropriate to use this test as an investigation method for the old infections in the basic elimination areas. In patients with rice dermatitis infected with poultry cercaria, cross-reaction may occur, and the test should be avoided in the rice dermatitis season. The positive conversion time is later than the ring egg precipitation reaction, so the reference value for applying the evaluation effect is not large.

3, indirect hemagglutination test of egg antigen: indirect hemagglutination positive reaction stool test positive early, and high sensitivity, high glutaraldehyde fixed human "O" type red blood cells or sheep red blood cells, after treatment with tannic acid, then use frozen The phagemid cold egg immersion antigen solution is sensitized, and then freeze-dried. The lyophilized antigen can be stored at 4 ° C for more than 1 year. During the test, 6 drops of blood are collected in the earlobe or finger, and only one drop of serum is required to have different dilutions. Shake well on the hemagglutination plate and 2.5% red blood cell suspension, and let stand for 15 to 30 minutes at room temperature. If the test serum has the corresponding egg antibody, agglutination reaction occurs, and the dilution is 1:10 positive. Significance, the positive rate is above 95%, the greater the reaction intensity, the fecal examination is easy to detect, the low titer positive may have false positive, the false positive rate is 1% to 3.5%, and the cross reaction with paragonimiasis is higher, up to 14 %84.2%, because the serum of schistosomiasis patients does not cross-react with the paragonimus antigen in the complement fixation test, it can be identified by this. The indirect hemagglutination test is easy to operate and the recognition result is rapid, which is the sensitivity of large-scale on-site screening. Check the disease One.

4, schistosomiasis circulating antigen (CAg): was one of the first methods for the investigation of schistosomiasis in Japan.

Diagnosis and identification of schistosomiasis enteropathy

diagnosis

It can be diagnosed based on medical history, clinical symptoms and laboratory tests.

Differential diagnosis

Acute schistosomiasis has fever, hepatomegaly tenderness, abdominal pain, diarrhea and other symptoms, need to be identified with typhoid, amoebic liver abscess, sepsis and tuberculous peritonitis; concurrent with pulmonary ectopic lesions need to identify with miliary tuberculosis, blood The significant increase of eosinophils has important differential diagnostic value. Chronic and advanced schistosomiasis should be differentiated from jaundice-free syphilitic hepatitis. The latter has decreased appetite, fatigue, liver pain and liver function loss, and eosinophils. No increase, hepatitis B surface antigen test positive, schistosomiasis patients with diarrhea and blood in the stool should be identified with amoebic dysentery and chronic bacillary dysentery, the former fecal hatching hairy sputum positive, advanced schistosomiasis with spleen and ascites are not easy to be portal And the identification of necrotizing cirrhosis, the former often has a history of chronic diarrhea, jaundice, spider mites, liver palm is less common, liver function loss is lighter.

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