Trypanosomiasis

Introduction to trypanosomiasis Trypanosomiasis (trypanosomiasis) is caused by two types of protozoa, African and American. It is a tropical disease and has not been reported in China. Popular in Africa, caused by T. gambiense and T. rhodeeshense, called African trypanosomiasis, also known as sleeping sickness. Popular in the Americas, caused by trypanosomacruzi, called American trypanosomiasis. There is usually no rash in the early stage of the disease. After 2 weeks, fever, headache, joint pain, rash and other systemic symptoms, itching are obvious, and eyelids, hands and feet may have transient edema and pain. If you are untreated for 1 year, you may have a drowsiness when it invades the central nervous system. In severe cases, it may cause death. The conjunctiva is often the gateway to invasion. If the trypanosomes can be detected, the acute phase can be treated with suramin sodium (Babor 205). basic knowledge The proportion of illness: the incidence rate is about 0.003% - 0.005% Susceptible people: no specific population Mode of infection: blood transmission Complications: congestive heart failure, arrhythmia, ventricular premature contraction, right bundle branch block, aneurysm, thrombosis, pulmonary embolism, sudden death

Cause of trypanosomiasis

(1) Causes of the disease

Trypanosomiasis (trypanosomiasis) is caused by two types of protozoa, African and American. It is a tropical disease. The blood-sucking mites are infected by sucking the blood of animals or humans containing trypanosomes. The inhaled trypanosomes are in the intestines of the locusts. Proliferate and excrete with the feces. When the insect bites the wound or the damaged skin is contaminated by infectious insects, the trypanosomes can be transmitted to the host. The hunting worm is commonly known as vinchuca in Argentina. "The fall", the insects live on the walls and roofs of the home, and can fall to the person sleeping underneath when they ask for food at night, often biting the eye circumference, when the trypanosomes in the feces enter the human body through the skin, The human body is infected, and the skin lesion caused by entering the skin through the skin is called chagas nodule. In addition, the disease can also be transmitted through blood transfusion or congenital, but both of these pathways are rare.

(two) pathogenesis

1. Pathogenesis The pathogenesis of this disease is unknown. The positive rate of detection of trypanosomes in patients who died of the disease is not high. Some people have proposed the autoimmune mechanism of the disease, which is believed to be produced in vivo after infection with trypanosomes. Autoreactive cytotoxic T lymphocytes, the latter can dissolve normal cells of the host, in addition, various antibodies against myocardial cell sarcoplasmic reticulum, fibrin and other cellular components may also be associated with the occurrence of Chagas myocarditis, cardiac parasympathetic Denervation is thought to be the cause of chronic Chagas disease.

2. Pathological changes The nerves and autonomic ganglia often have abnormal changes, and megacolon and giant esophagus may appear. The pathogenic manifestations of the disease caused by different strains of Trypanosoma cruzi have regional differences, such as giant esophagus and megacolon are common in Brazil. However, it is rare in Venezuela. Patients with chronic Chagas disease have denervation of the cardiac parasympathetic nerve. Cardiac pathological examination shows whole heart enlargement and cardiac hypertrophy. More than half of the left ventricle (occasionally right ventricle) has thinned apex. Bulging, like a ventricular aneurysm, this is a characteristic change of the heart of Chagas disease, thrombosis may occur in the heart chamber, common thrombus fills the apex, and there is often a thrombus in the right atrium.

Trypanosomiasis prevention

Do a good job in environmental sanitation, pay attention to personal hygiene, pay attention to washing hands after contact with infected rats, cats, dogs and pigs, avoid rubbing your eyes and prevent fly bites.

1. Eliminate the habitat and breeding sites of cone mites in the epidemic areas, reduce their quantity, and timely spray the drugs to kill the mites to control the media, improve the living conditions of the residents, not live in the huts, hang mosquito nets, and reduce the chance of disease.

2. Strengthen the examination of blood donors and maternal blood trypanosomes and serum anti-trypanosome antibodies in the epidemic areas to reduce the incidence of Chagas disease and congenital Chagas disease after transfusion.

3. Closely observe the performance of cardiomyopathy during the period of 10 to 20 years after the occurrence of trypanosomiasis, early detection and active treatment.

Trypanosomiasis complications Complications Congestive heart failure arrhythmia ventricular premature contraction right bundle branch block aneurysm thrombosis pulmonary embolism sudden death

1. Congestive heart failure Chronic trypanosomiasis is characterized by enlarged heart, extensive myocardial damage, and abnormal cardiac structure. In addition to long-term arrhythmia or ventricular aneurysm, congestive heart failure can occur in the advanced stage of the disease.

2. Arrhythmia This disease is very easy to be complicated by malignant ventricular arrhythmia, especially ventricular premature contraction, ventricular tachycardia, ventricular fibrillation, etc.; 2 / 3 patients have heart block, often right bundle Conduction block and so on.

3. The ventricular aneurysm can be seen in the myocardium of the patient with myocardial fibrosis, cardiac hypertrophy, dilatation of the atrioventricular cavity, and aneurysm-like protrusion and thrombosis in the apex.

4. Embolization of the apex of the apex and the atrial thrombus can cause brain or pulmonary embolism, and severe cases of sudden death.

Symptoms of trypanosomiasis Common symptoms White halo Hepatosplenomegaly Itching Trypanosome "Haw" Edema Drowsiness Myalgia Nodules Joint pain

1. African trypanosomiasis (African trypanosomiasis) The disease usually has no rash at the beginning, sometimes at the bite, the skin is red, swollen, tender, forming nodules, may have white halos, lasting for several days, starting to heat after 2 weeks, headache , joint pain, rash and other systemic symptoms, itching is obvious, eyelids, hands and feet, etc. may have transient edema, accompanied by pain.

If you are untreated for 1 year, you may have a drowsiness when it invades the central nervous system. In severe cases, it may cause death.

2. American trypanosomiasis can cause transient urticaria in the acute phase. The conjunctiva is often the portal of invasion. One side of the eyelid edema, conjunctivitis, lacrimal gland inflammation, and the Romana sign (ie conjunctivitis, upper and lower eyelid edema) With ipsilateral pre-auricular lymphadenitis), 2 to 3 weeks after infection, some systemic symptoms, such as fever, myalgia, local swelling and pain, hepatosplenomegaly, can cause myocarditis and encephalitis.

Examination of trypanosomiasis

1. Directly check the pathogens that can be used for fresh blood examination in the acute phase, or use the Giemsa stain to check the thick blood smear, or centrifuge the blood to check the supernatant floating on the blood clot to find the trypanosomal flagellum. A tissue biopsy can be used to find the amastigotes in the pseudocysts.

2. Animal vaccination confirms the "golden index", so that the laboratory-trained stag beetle sucks the blood of the person infected with Trypanosoma cruzi. After 4 to 6 weeks, the rectum of the stag beetle is examined, and trypanosomes can be found. Specific, as long as there is a very small amount of trypanosomes in the peripheral blood to confirm the diagnosis.

3. Polymerase chain reaction A DNA fragment specific to the Trypanosoma cruzi in blood and tissues. Using this method, one trypan to 10 ml of blood can be found. As with animal vaccination, the specificity of the method is as high as 100. %, sensitivity is also very high, and can even replace animal vaccination, but the sensitivity of patients with advanced, chronic Chagas disease is not satisfactory.

4. Serum test is the main clinical diagnosis method. It can detect the IgG antibody against the Trypanosoma cruzi antigen in the infected person. This antibody appears 4 to 6 weeks after infection and survives, despite this method. It has a high value in diagnosis, but its titer has nothing to do with the severity of the disease, and there is no evidence of how the antibody affects the course of the disease. Common methods are: complement binding assay, indirect immunofluorescent antibody assay, and enzyme Combined immunosorbent assay, electron microscopy, finding trypanosomes, help confirm the diagnosis.

5. Right ventricular endocardial myocardial biopsy This method is used to understand the degree of myocardial damage in mild or advanced cases, but trypanosomes are usually not found.

6. X-ray examination can show the giant esophagus and megacolon, can be found in the heart enlargement and special apical aneurysms and other signs.

Diagnosis and identification of trypanosomiasis

diagnosis

Cardiac trypanosome infection can be confirmed by pathological examination of cardiac tissue or animal vaccination, but the positive rate of pathological diagnosis is very low, animal vaccination can not be widely used, and it is not sensitive to advanced patients, so it is usually based on epidemics The data, serological examination and clinical manifestations are considered together to make a diagnosis. The main criteria are as follows (in non-popular areas, the standard should be enforced more strictly):

1. I have lived in a prevalent area of Chagas disease.

2. The serological test of Trypanosoma cruzi is positive.

3. The clinical manifestations of the heart are consistent with Chagas heart disease.

4. Although various cardiac manifestations can be attributed to other heart diseases, there is no evidence of these heart diseases, and trypanosomes can be diagnosed.

Differential diagnosis

Should be differentiated from coronary heart disease, idiopathic dilated cardiomyopathy, alcoholic cardiomyopathy.

1. Coronary heart disease This disease, like the trypanopathic myocarditis, can affect the myocardium, causing the heart to expand, and can have arrhythmia, heart failure, etc. Coronary heart disease is more common in men over 45 years old and post-menopausal women, older people More common, coronary heart disease often has a variety of disease factors, such as hyperlipidemia, hypertension, diabetes, obesity, family history, etc., while trypanosomiasis has been in the epidemic area of Trypanos In the history of living, the serological test of Trypanosoma cruzi is positive, and the clinical manifestations of Chagas heart disease can often be distinguished from the disease.

2. Dilated cardiomyopathy may have a family history, long course of disease, slow progress, heart of dilated cardiomyopathy often enlarged, may have arterial embolism, negative virus isolation, serum virus neutralizing antibody titer does not increase in a short period of time, ECG often There are various arrhythmia, sometimes pathological Q waves, late heart enlargement and heart failure symptoms. Trypanosomiasis has lived in the epidemic area of Trypanosoma, the serology of Trypanosoma cruzi Experimental positive and typical clinical signs and symptoms.

3. Alcoholic cardiomyopathy Patients with this disease have a lot of drinking, long-term drinking history (more than 10 years, the amount of pure ethanol per day 125ml); heart enlargement, arrhythmia, chest pain, high blood pressure, etc., congestive heart can occur in the late stage Depletion, although similar to some of the symptoms and signs of the disease, it should be identified from the epidemiological history, the serological test of Trypanosoma cruzi and the multiple organ expansion.

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