Toxoplasmosis

Introduction to Toxoplasmosis Toxoplasmosis (toxoplasmosis) is a zoonotic protozoan caused by Toxoplasmagondii. This disease is a systemic disease with a worldwide distribution. The population is generally susceptible, but most of them are latent infections. The parasitic parts of the toxoplasma and the reactivity of the body are different, the clinical manifestations are more complicated, and there is a certain mortality rate and congenital defect rate. In recent years, this disease has been identified as an important fatal opportunistic infection of AIDS. basic knowledge The proportion of illness: 0.03% Susceptible people: no specific population Mode of transmission: mother-to-child transmission of blood transmission Complications: pneumonia myocarditis orchitis meningitis

Cause of toxoplasmosis

Toxoplasma infection (90%)

The toxoplasma is a spore-like coccidia. In 1971, Hutchison confirmed that the toxoplasma has a dual-host life cycle with a wide range of hosts, including reptiles, fish, insects, birds, mammals and other animals; Only cats and felines, divided into trophozoites according to developmental morphology, cysts (developed in intermediate and final host tissues), schizonts, gametophytes and oocysts (developed in terminal host intestinal mucosal epithelial cells) The oocysts are produced in the cat family, spherical or oval, and the mature oocysts contain 2 sporangia, each containing 4 sporozoites. The sporangia are more tolerant to the environment and can survive for more than 1 year. After the intermediate host swallows, the sporozoites in the intestine escape and diffuse through the intestinal wall with the bloodstream or lymphatic system to the whole body, and can invade the nucleated cells of various tissues, and then proliferate by the internal diploid method, and then form multiple The corpus luteum of the worm body contains the trophozoite (tachyzoite), which is typically crescent-shaped, with a nucleus near the obtuse round end and a small subnucleus at the other end, which is a common form of acute infection. After the host cell ruptures, multiple trophozoites can be released. Invasion of other cells, such repeated proliferation, resulting in pathological damage, can cause clinical onset, but more is that host immunity affects the rate of reproduction, and because the body secretes to form a capsule with a rich elastic wall, containing more The worms are called euphratica. The cysts are more common in the brain and skeletal muscles. They are the final form of the toxoplasma in the middle of the host. They can survive for months to years or even the host's life. It is a recessive infection. In recent years, human toxoplasmosis has been discovered. There are three types of Toxoplasma genotypes, Type I strains are more common in congenital toxoplasmosis, Type II strains are mainly found in general toxoplasmosis including AIDS patients, and Type III strains are mainly found in animals.

Pathogenesis:

The toxoplasma trophozoite can secrete a penetration-enhancing factor, and the active attack causes the cell wall to change and enter the cell, causing it to be damaged. The host can produce certain immunity against it, destroy some of the worm body, and some un-destroyed worms often dive. It is hidden in the brain, eyes, and forms cysts. When the host's immunity is reduced, the eubolic nucleus that escapes after the rupture of the capsule enters other cells for fission, forming a new spread, and the toxoplasma after infection. It can inhibit the function of T cells and B cells in the host, so that there is a high concentration of circulating antigen in the acute infection period, but it can lack antibodies, and the protective effect of specific antibodies is limited, and the titer is high and low to protect the body. No significant significance, there is still the possibility of reinfection, due to inhibition of cellular immune response, T cell subsets can be significantly changed, the symptoms are obvious, the T4/T8 ratio is inverted, and the NK cell activity is increased first and then inhibited, but the immunity The protective effect is not obvious. In recent years, it has been found that both IFN and IL-2 have the effect of protecting the host against toxoplasma. The immune responses II, III and IV are quite important in toxoplasmosis. use.

The toxoplasma directly damages the host cell, and the host's immune response causes the allergic reaction to be its pathogenesis. Invasion from the worm causes bacteremia, spreads to the whole body organs and tissues, and rapidly fissures within the cell, causing necrosis. Lesions and delayed allergic reactions, the formation of granulomatous inflammation, and more along the small blood vessel wall and easy to cause embolic disease, the main part of the toxoplasma invasion of the intestine generally does not cause inflammation, the most common lesions are non-specific lymphadenitis, lymph Follicular hyperplasia; interstitial inflammation or hepatocyte damage in the liver, acute myocarditis, interstitial pneumonia; infarct necrosis and peripheral inflammation in the multiple cortex in the early stage of the central nervous system, microglia hyperplasia can form nodules , thrombosis and ductal membrane ulcers, resulting in obstruction of the water tube, the formation of hydrocephalus, retinal choroiditis is more common.

Toxoplasmosis prevention

1. Properly dispose of the feces of domestic animals and domestic pets (especially cats) to prevent contamination of food water sources and wash hands carefully after exposure to animal waste. Personal attention to food hygiene, do not drink raw water, do not eat uncooked meat, do not mix the knives and cutting boards for raw and cooked food. Children should not play with animals such as cats and dogs. Drug prevention for cats and dogs can be carried out in severely endemic areas.

2, do a good job in food hygiene, do not eat uncooked meat, milk eggs, do not play with animals such as cats and dogs, prevent their feces from contaminating utensils, fruits and vegetables food and drinking water, strengthen publicity and education, carry out necessary serological tests for susceptible people, give activities Sexually infected persons are treated as necessary, especially women of childbearing age and pregnant women, to prevent the spread of blood products and organ transplants.

Toxoplasmosis complications Complications pneumonia myocarditis orchitis meningitis

Concurrent pneumonia, myocarditis, orchitis, meningitis.

Toxoplasmosis symptoms Common symptoms Joint pain rash jaundice Hypothalamic damage Dead fetus Toxoplasma infection Coma High fever Visual impairment convulsion

Acquired toxoplasmosis can produce specific antibodies 8 to 10 days after infection, most of which are asymptomatic occult types, which are clinically ill in the case of severe infection or immunodeficiency. Chronic infection can lead to recurrence when the capsule is ruptured. Congenital toxoplasmosis, which occurs when there is active infection in pregnant women, the clinical manifestations are complex, and the condition depends on the virulence, quantity, age and immune status of the strain.

1. Congenital toxoplasmosis: 40% of pregnant women infected with toxoplasmosis can be passed to the fetus, such as early pregnancy, embryo developmental disorders, can cause miscarriage, premature delivery, stillbirth and various deformities; Dyeing, although the fetus can develop normally, it can survive at birth, but many months after birth, several years or more, symptoms of toxoplasmosis may occur, eye damage, cerebral palsy, mental symptoms, epilepsy, mental retardation For its important clinical features, such as hydrocephalus, brain calcification and microcephaly, retinitis is called "toxoplasmosis quadruple", pregnant women with toxoplasmosis receive sulfonamides, spiramycin, pyrimethamine If the treatment, such as time, treatment, improper dose, can still show impaired performance, such as pregnant women who have teratogenic or stillbirth due to toxoplasmosis infection, the next fetus can continue to be harmed if it is not treated with effective insect resistance. Congenital toxoplasma infection directly affects prenatal and postnatal care. In recent years, studies have revealed that men infected with toxoplasma can cause changes in sperm quality and quantity. Therefore, prevention and treatment of congenital toxoplasma infection requires both male and female measures.

2. Toxoplasmosis: mainly manifested as retinal choroiditis, it is reported that 90% of children before 5 years old and 30% to 40% of retinal choroiditis in adults are caused by toxoplasmosis infection, and domestic data is also above 10%. For congenital infections, the activation of immune function may also be a primary infection, clinically central exudative retinitis is common, due to destructive inflammation and allergic reaction, self-healing tendency and recurrent, often Can leave permanent scars, severely affect vision, and can occur retinal detachment, cataract, strabismus and nystagmus, secondary nipple atrophy, glaucoma and other diseases, and even eventually blindness, congenital toxoplasmosis can still lead to eye loss, Small eyeballs, cataracts, cortical blindness and other diseases.

3. Toxoplasmic encephalitis: more common in children with congenital toxoplasma infection, can also occur in middle-aged and elderly people, an important fatal opportunistic infection for AIDS patients, accounting for the central nervous system and most of the disease, acute acquired arch There are many cases of meningitis, meningitis, meningitis, common focal or whole brain abnormalities, acute onset, high fever above 39 °C, and then symptoms of brain and brain stem damage, meningitis and cranial nerve signs, according to Depending on the location of the lesion, the pressure on the lumbar puncture was slightly elevated or normal, and the number of cells increased (<1000×106/L), mainly lymphocytes; protein content increased, sometimes protein and cell separation; chloride decreased; Normal or reduced sugar, toxoplasma can be detected in CSF, about half of the patients can detect specific antibodies, not parallel to the antibodies in the serum, because the production depends on the adjacent meninges, EEG is focal damage, The recovery is very slow. X-ray examination is seen in scattered calcification. CT examination shows single or multiple spherical lesions. More than 90% of them are ring-shaped or nodular. Magnetic resonance imaging (MRI) is better in CT. Resolution, in severe cases, such as Rescue is not timely, it can die in a few days, and there are many sequelae in non-dead. Congenital toxoplasmic encephalitis often occurs within a few days or months after birth. Chronic toxoplasmosis in adults or the elderly may also show symptoms of encephalitis. Such as high intracranial pressure, basal ganglia damage, symptoms of diencephalon and hypothalamic damage, nystagmus, visual impairment, pyramidal tract signs, seizures and psychiatric symptoms, often progressive or recurrent, easily misdiagnosed as brain tumors, arched Somatic encephalitis generally has no purulent performance, and clinical features are lacking. Therefore, some people think that the possibility of toxoplasmosis infection should be considered for encephalitis with unknown sporadic causes. AIDS complicated with toxoplasmosis encephalitis, although it is considered to be recessive. Activation of infection does not rule out acute primary infections, but it can all contribute to accelerated death.

4. Toxoplasmic lymphadenitis: very common, can be one of the manifestations of acute systemic toxoplasmosis, can also be "lymph node toxoplasmosis", the former often indefinite or single or multiple lymph nodes in the body cavity With continuous high fever, or hepatosplenomegaly and other systemic symptoms, the latter are mostly chronic, the neck or other parts vary in size, no obvious red hot pain or only a slight tenderness of the lymph nodes, the course of several weeks, months Even more than a year, it is easy to be confused with malignant reticular diseases such as tuberculosis or Hodgkin's disease.

5. Toxoplasmic cardiovascular disease: more common in congenital toxoplasma infection, can cause congenital cardiovascular malformations, clinical reports of congenital toxoplasmic myocarditis 3 days after birth, adult patients with myocarditis can appear before the heart Area suffocation pain, ECG similar to coronary dysfunction; hemorrhagic pericarditis and constrictive pericarditis caused by pathological repair of toxoplasmosis after calcification is also seen in the literature, functional disorders or conduction disorders caused by arrhythmia Reports are more common in room sex.

6. Toxoplasmic hepatitis: Congenital toxoplasmosis infection can be manifested as post-hepatitis syndrome in infants. Children with jaundice and hepatomegaly at birth or several days after birth can also have splenomegaly. Acquired toxoplasmosis can be used. Qualitative or hepatocellular, such as the primary acute and acute onset, often begins with "intestinitis" symptoms, less lymphadenopathy, secondary occurs more often after toxoplasmic lymphadenitis, often progressive disease May be accompanied by splenomegaly, long course of disease, easy to relapse, cirrhosis may occur, jaundice is rare, ALT is mildly increased, and acute, chronic viral hepatitis, especially when both diseases are present, it is difficult to judge.

7. Systemic severe toxoplasmosis: occurs mostly in children or adults with immunodeficiency, high fever, severe joint pain, muscle cramps, skin rash, headache and lymphadenitis, and may have neurological symptoms such as convulsions and coma. Simultaneous myocarditis, interstitial pneumonia, with hepatosplenomegaly, proteinuria, severe anemia and other clinical symptoms, the course of disease is 10 to 15 days, can also be as long as several months, severe cases can be fatal, patients with malignant tumors, accept Immunosuppressive therapy and immune-compensatory diseases or severe trauma, primary infection during primary surgery or activation of the original latent infection can occur, especially in malignant tumors and AIDS patients, once concurrently, it directly leads to The danger of death is often greater than the primary disease.

8. Toxoplasmic pneumonia: Toxoplasmic bronchitis and pneumonia have been reported at home and abroad. Clinical manifestations of lobar pneumonia or obstructive pneumonia can also be seen. In patients with impaired immune function, it can be one of the causes of death.

9. Blood transfusion, organ transplantation complicated with toxoplasmosis: In recent years, blood donors (or organs) have been confirmed to have toxoplasma infection, which can cause infection or complicated acute toxoplasmosis, due to the parasitic nucleated cells. In the case of component transfusion, especially when entering white blood cells, it is more likely to be infected.

10. Other types: Toxoplasmic immune complex nephritis has been reported, skin toxoplasmosis can be spotted, scarlet fever-like dermatitis (more common in the limbs of the trunk) or nodules, such as myositis, orchitis, polyneuritis There are also reports in the literature.

Examination of toxoplasmosis

Routine examination of blood, white blood cell count increased slightly, the proportion of lymphocytes or eosinophils increased, and sometimes visible atypical lymphocytes.

1. Etiology : a variety of body fluid concentrated thick smear or lymph node puncture and other pathological tissue materials, Ji's stain can detect toxoplasma trophozoites or pseudo-sacs, and can be found in cells or even nuclear, detected The rate is different, the patient's body fluid or pathological tissue is homogenized, and the mice are inoculated into the abdominal cavity to separate the worms. If the first generation is not detected, it should be transferred, once a week, at least 4 to 5 generations have not seen the disease, also The worm body can be terminated without any inspection of the worm body, and the worm body can also be isolated by the tissue culture method.

2. Immunological examination : If the method is correct, the judgment of the result is exact, which can provide an important basis for diagnosis. At present, the serum immunological diagnosis of toxoplasmosis is divided into two categories according to the characteristics of the antigen used.

(1) Using the whole worm as an antigen to detect antibodies against the epidermal membrane in serum, such as DT, DAT, IFAT, after the initial infection of the toxoplasma, the antibody appears quickly, reaching a peak after 2 to 3 months, and can maintain 6 In the month, the titer slowed down and continued for a low titer stable period after 2 to 3 years. Some patients may be detected throughout life, and the antibody reapplied when reburning is activated.

(2) The extracts obtained by lysing the worms are antibodies for detecting cytoplasmic components of antigens, such as IHA, CFT, ELISA, etc., and their improved methods, but at present, IHA and ELISA are highly recommended at home and abroad, and IHA has better Specificity and sensitivity, but the reproducibility is poor when the quality control is not strict. Most of the antibodies detected appear 1 month after infection, and then reach a peak after 2 to 4 months. The ELISA series measures the antibody response to early infection. Before IHA, its detection of specific IgM is generally considered to be an early feature of the primary immune response, but may be false positive due to the presence of antinuclear antibodies, rheumatoid factor or high titer IgG, and in recent years Observed that it can measure the titer for 1 year or longer, thus reducing the significance of the analysis of the results, such as the detection of specific IgM in cord blood, showing the presence of intrauterine congenital infection, the detection of circulating antigen is the presence of pathogens Indications, the antigens that induce the immune response of the patients in different stages of the disease, the quality and quantity of the antigens are different, and the serum antibody spectrum can be identified by the toxoplasma specific components for early diagnosis. PCR technology has been widely used, although it can be effectively used. Amplification of toxoplasma DNA 1pg containing only real existence, and about quite two worms), but the need to prevent contamination caused the false positive; and PCR-positive should not be alone, that is, for the diagnosis of the disease must be a comprehensive analysis of clinical symptoms, prevent misleading.

Histopathological tissue thin sections of HE or PAS staining can be used to detect typical or atypical worms or fragments; however, histomorphological changes are not specific.

Diagnosis and diagnosis of toxoplasmosis

There is no unified classification standard for toxoplasmosis. How to judge active infection, recessive infection and primary recurrence remains to be discussed. Congenital and acquired infections are sometimes not easy. Acute acquired toxoplasmosis can be a certain An organ lesion is the main disease, often with lymphadenopathy and other acute lesions. Atypical lymphocytes can be seen in the peripheral blood. Congenital toxoplasmosis is more common in concealment. It can be asymptomatic from birth, but congenital malformation, intelligence. Low inferior neurological lesions are seen, toxoplasmic encephalitis, post-hepatitis syndrome, hemorrhagic pneumonia can also be seen. The most characteristic feature of ocular toxoplasmosis is that the lesions are progressive, recurrent, and severely impaired immune function. Opportunistic infections of the toxoplasm often lead to fatal acute toxoplasmosis or toxoplasmic encephalitis.

Toxoplasmic lymphadenitis should be differentiated from lymph node metastasis of bacterial lymphadenitis and malignant lesions. If other signs and systemic symptoms are present, it should be differentiated from infectious mononucleosis and malignant lymphoma. Cat scratching, hare fever and systemic or fungal infection, lymphocytic leukemia, sarcoidosis, eosinophilic lymphogranuloma and other diseases.

Toxoplasmic central nervous system lesions should be differentiated from meningoencephalitis caused by other pathogens, and cerebrovascular disease and intracranial space-occupying lesions are different. The long-term treatment of neurasthenia and the mental disorders of the brain toxoplasmosis should be It is distinguished from symptomatic psychosis of other causes.

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