Congenital toxoplasma infection in neonates

Introduction to congenital toxoplasmosis in newborns Congenital toxoplasma infection is closely related to pregnancy. After the mother is infected with toxoplasma during pregnancy, both the dominant and the latent infection can infect the fetus through the placenta, which directly affects fetal development and is teratogenic. Congenital toxoplasma infection, systemic acute infection after birth, toxoplasmosis (toxoplasmosis) is caused by Toxoplasma gondii caused by zoonotic parasitic diseases, widely distributed throughout the world. Congenital toxoplasmosis has become the most serious disease in human congenital infections, which can cause fetal malformations, premature birth, and stillbirth. basic knowledge Sickness ratio: 0.0001% Susceptible people: children Mode of transmission: digestive tract spread, mother-infant vertical transmission Complications: hydrocephalus congenital heart disease epilepsy

Neonatal congenital toxoplasmosis infection etiology

(1) Causes of the disease

About half of the pregnant women infected with toxoplasma can infect the fetus through the placenta, and the dominant infection of the newborn is mostly congenital. The mother of congenital toxoplasmosis is infected by the placenta after infection in the pregnant woman. Although it does not show obvious symptoms after infection, it can cause serious adverse consequences of the fetus, such as miscarriage, premature delivery, stillbirth and severe deformity. It can also leave the central nervous system disorder in the child, causing death shortly after birth.

1. Source of infection: All mammals with toxoplasma in the body, birds and other animals can be the source of infection, of which infected cats and felines are the main source of infection.

2. Route of transmission

(1) Oral infection: acquired infection, mainly by oral transmission, the feces of infected animals can be infected after oral ingestion. In addition, cats, dogs, sheep, and chickens have almost toxoplasma in their organs. Tooth and mutton contain toxoplasma cysts. Carnivores can be infected by mouth. Raw meat and raw milk containing toxoplasma can be eaten raw. , eggs, aquatic food, etc. and infected with Toxoplasma gondii.

(2) Transplacental infection: pregnant women who are infected with the toxoplasma for the first time can be transmitted to the fetus through the placenta. It is an important source of congenital teratogenicity. The health of the fetus is largely controlled by the mother's life and eating habits. I like or eat cold foods, including vegetables, fruits, especially pregnant women who like to eat raw meat. They are very susceptible to parasites such as toxoplasma, frequent contact with animals, and drinking milk that has not been autoclaved. It is also a parasitic disease. The risk factor.

(3) Others: People are in contact with cats, dogs and other animals infected with Toxoplasma gondii. When the hands and face are licked or bitten, they can be infected. The blood of the blood donors containing the toxoplasma can be entered, and the toxoplasma can be infected after kidney transplantation.

(two) pathogenesis

In the early stage of infection, Toxoplasma gondii spread to the whole body organs and tissues, causing the corresponding lesions. In the late stage of infection, the body gradually produces specific antibodies against Toxoplasma gondii, and the Toxoplasma gondii forms cysts in the tissues, and the original lesions gradually become static. The condition of toxoplasmosis depends on the interaction between the pathogen and the body. After invading the human body, some people do not produce symptoms, which are recessive infections. Only a small number of patients have latent infections or patients whose lesions are still, when the immune function is low. Time (or treatment with immunosuppressive drugs) can lead to disease activity.

After the pathogen proliferates in the host cell, the cell denatures and swells, causing the cell to rupture, emitting a toxoplasmic body, and then invading other cells, thus repeatedly causing damage to the tissues and organs, mainly due to inflammation of the necrotic foci and surrounding tissues due to vascular embolism. Cell infiltration, these are the basic pathological changes, the lesions are caused by trophozoites, and the cysts generally do not cause inflammation. The lesions are usually found in the brain, eyes, lymph nodes, heart, lungs, liver, spleen and muscles.

After being infected by Toxoplasma gondii during pregnancy, the mother invades the placenta and the blood circulation of the fetus through blood, causing fetal infection, or hiding in the endometrium of the mother of chronic infection, or the worm in the myometrium, entering the amniotic cavity, with amniotic fluid. After being swallowed by the fetus, it causes fetal infection. After Toxoplasma gondii invades the fetus, it is easy to parasitize into brain cells and progeny in immature immature cells, which impair the growth and development of embryonic cells, and the severity of the damage of Toxoplasma gondii infection to the fetus. In the period of infection with the mother, the virulence of the infected strain, the formation of the mother antibody, and the migration of the antibody to the fetus, the fetus infection rate of the primary infection of Toxoplasma gondii in the early, middle and late pregnant women was 17.0%. 25.0%, 65.0%, the degree of fetal damage is inversely related to gestational age, that is, the earlier the infection.

The more severe the fetal damage, when the infection occurs in the first 3 months, causing miscarriage, stillbirth or developmental defects, the survivor's mental development is also seriously affected. If the infection occurs in the second trimester, there are still stillbirths, premature birth and severe brain, eye Diseases, if infected in the third trimester, because the fetus has gradually matured, the fetus can develop normally, can also have premature birth, or symptoms appear after birth, because the infection of Toxoplasma gondii in early pregnancy often leads to abortion, stillbirth and other outcomes, so in the survival In patients with congenital toxoplasma, the incidence is high in the last 3 months of pregnancy, followed by mid-pregnancy. Women who have been chronically infected before pregnancy have fewer chances of getting a fetus. Mothers infected with Toxoplasma usually only have one pregnancy. The outcome is normal, and the next fetus is normal, which may be related to the migration of protective antibodies produced by the mother to the fetus. In addition, Toxoplasma infection may increase pregnancy complications. It should be noted that only a few fetuses are acute after infection in late pregnancy. Infection, about 80% of cases are occult infections, asymptomatic at birth, and occur in a few months, years or even adulthood, followed by It is characterized by chronic recurrent disease, mainly affecting the nervous system and the eye. Some scholars have found that many primary brain diseases in childhood are actually related to toxoplasmosis infection. After birth, the tissue is inactivated due to encapsulation activity in the body. Cells, can appear mental retardation, seizures, vision loss, strabismus, blindness and other symptoms.

Neonatal congenital toxoplasmosis infection prevention

Prevention and treatment of infection during pregnancy: preventive treatment includes termination of pregnancy and preventive medication. Serological examination of toxoplasma antibodies should be performed on women of childbearing age and pregnant women. About one-third of the fetuses with congenital toxoplasmosis can be found by ultrasound examination. Pregnant women who are positive for serum antibody positive or toxoplasma gene detection (PCR) and found to be damaged by ultrasonography should be given preventive treatment if the infection is found early in pregnancy, and should be given prophylactic treatment in the middle and late pregnancy. If the pregnancy is negative, the pregnancy is positive. In particular, those who are within 3 to 4 months of pregnancy should be aborted; if they are found to be positive for more than 5 months during pregnancy, oral administration of spiramycin should be given, and the infants should be followed up for at least 4 months, and the package formed after infection. The capsule will eventually survive, and there is no specific drug elimination.

In some countries, serological examinations are included in the statutory pre-marital check-up items. For example, in Paris, France (1985), the fetal blood of pregnant women aged 20 to 26 weeks was used for pathogenic and serological tests, and positive cases were induced by abortion.

Neonatal congenital toxoplasmosis infection complications Complications hydrocephalus congenital heart disease epilepsy

1. Hydrocephalus: The debris of the necrotic tissue of the brain falls off, enters the lateral ventricle, and circulates with the cerebrospinal fluid, causing obstruction of the cerebral aqueduct, or lesions on the wall of the cerebral aqueduct, which can produce obstructive hydrocephalus.

2. Congenital malformations: can be up to many organ deformities, such as brain calcification and congenital heart disease, facial defects and so on.

3. sequelae: If it can be improved, the lesions are limited, can cause vision, hearing damage, cerebral palsy, developmental delay, epilepsy, mental retardation, choroidal retinitis and other sequelae.

Neonatal congenital toxoplasmosis symptoms common symptoms jaundice systemic infection symptoms of sputum hepatosplenomegaly edema lymph nodes swollen papules hydrocephalus twitching eye muscle paralysis

Congenital arch disease mainly manifests as symptoms of systemic infection and central nervous system and ocular lesions. Most of the neonatal dominant infections are acquired congenitally. The infection is near the time of delivery, and the baby can develop symptoms after several weeks, such as during the fetal period. Obtaining a certain amount of antibodies in the mother, it has certain immunity to the disease after birth, but it is still not enough to stop the disease, and the course of the disease is protracted. The toxoplasma can invade all organs of the body, but with the central nervous system, eyes, lymph nodes, heart and lungs. Liver spleen and skeletal muscle are the main symptoms, the main symptoms are as follows:

1. Systemic manifestations of systemic infections are more common in neonates, often with fever, anemia, vomiting, cyanosis, edema, maculopapular rash, body effusion, hepatosplenomegaly, jaundice, pneumonia, myocarditis, lymphadenopathy and digestive system damage, etc. Often can die quickly, the so-called neonatal Toxoplasmosis syndrome is mainly characterized by anemia, jaundice, hepatosplenomegaly.

2. The central nervous system is manifested in the central nervous system after the birth of the fetus, the most common manifestations of central nervous system damage, hydrocephalus, brain calcification and various brain malformations as the main symptoms, showing meningoencephalitis, common convulsions, limb rigidity, brain Neural crest, movement and disturbance of consciousness, mental retardation, etc.

3. Ocular lesions are more common in eyeball lesions, the most common manifestation is chorioretinitis, followed by ophthalmoplegia, iridocyclitis, cataract, optic atrophy, occasionally the entire eyeball is invaded, resulting in smaller eyeballs, deformity And blindness, which usually occurs on both sides of the eyeball.

Concealed congenital toxoplasmosis is also more common, accounting for about 80%, can be asymptomatic at birth, but has parasitic cysts in the nervous system or the choroidal retina, and the nervous system appears in several months or years. Or choroidal retinitis symptoms.

Examination of congenital toxoplasmosis in newborns

1. Pathogen examination: The diagnosis is established by finding the protozoa in the patient's body fluid or diseased tissue, and the patient's blood, cerebrospinal fluid, urine, sputum, amniotic fluid, etc. are taken to check the trophozoites and the pseudo-encapsulated capsule.

(1) Direct smear or sediment smear: Take the smear of the above materials to find trophozoites under high power microscope; or use gamma staining or Reiter staining to find trophozoites and pseudo-encapsulated capsules under oil mirror. Positive method The rate is lower.

(2) Separating the toxoplasma: the material to be tested is inoculated into the peritoneal cavity of the mouse, and the toxoplasma is separated from the chicken embryo yolk sac or the monkey kidney cell tissue.

(3) DNA hybridization and PCR technology: both have high sensitivity and specificity.

2. Immunological examination: The increase of antibody level in serological examination is simpler than the above method, and the sensitivity and specificity are high. It is the most commonly used method. The detection of toxoplasma circulating antibody can be used as a specific diagnostic method for early acute phase. Detection of Toxoplasma IgM and IgG antibodies in children's serum, antibody titer is high or more than 4 times higher in the course of disease, or IgM antibody positive, all suggesting recent infection, neonatal serum IgM positive suggestive of congenital infection, detection Methods such as staining test, complement binding test, indirect coagulation test, indirect immunofluorescence test, enzyme-linked immunosorbent assay and indirect latex agglutination test.

(1) Methylene blue staining test: It starts to be positive in the early stage of infection (10-14 days), and the titer can reach the peak in the 3rd to 5th week, which can last for several months to several years. The low titer can generally represent chronic or past. The infection, the antibody obtained from the mother disappears within 3 to 6 months after birth. Therefore, after the child is 4 months old, the antibody can be repeatedly stained and determined. If the titer remains high, it can be proved due to infection.

(2) Indirect immunofluorescence test: The antibody tested was anti-Toxoplasma IgG, and its reaction and duration were similar to the methylene blue staining test.

(3) IgM-immunofluorescence test: it is a modified indirect immunofluorescence test. It has a positive result after 5 to 6 days of infection, which lasts for 3 to 6 months. It is suitable for early diagnosis. Because of the large molecular weight of IgM, the mother's IgM is generally Can not pass the placenta to the fetus, such as neonatal serum containing anti-toxoplasma IgM, you can consider the diagnosis of congenital toxoplasmosis.

(4) Direct agglutination reaction: It is mainly used to measure anti-Toxoplasma IgM, which is positive by 1:16 agglutination, and can be positive after 5-6 days of infection.

(5) Enzyme-linked immunosorbent assay and soluble antigen-fluorescent antibody technology: easy to operate and fast, the former can be applied to large-scale screening, and its sensitivity and specificity are satisfactory. The latter can detect antibody levels with one dilution. Its sensitivity is similar to that of immunofluorescence.

3. Cerebrospinal fluid examination: cerebrospinal fluid is yellow, lymphocytes and protein can be increased.

4. Live histopathological section: Take the patient's bone marrow, lymphatic puncture, lymph node biopsy and organ tissue of the corpse to check trophozoites and fake cysts.

5. Animal inoculation test: The inoculated materials were inoculated into the peritoneal cavity of mice, the embryonic yolk sac or the monkey kidney cells were separated into toxoplasma, DNA hybridization and PCR technology, both of which have higher sensitivity and specificity.

6. B-ultrasound: hepatosplenomegaly.

7. X-ray examination: visible lung lesions.

8. Fundus examination: manifested as posterior pole, limited local necrosis, retinal choroiditis, diameter of optic disc 1 to 6 months, gray-white hyperplasia in the central part, local edema, accompanied by subretinal exudation and hemorrhage.

Diagnosis and diagnosis of congenital toxoplasmosis in neonates

diagnosis

The clinical manifestations of this disease are complex, and the diagnosis is difficult. If it is born, it will show microcephaly, small eye disease, etc., in the newborn or infancy, jaundice persists, hepatosplenomegaly, retinal choroiditis, etc. Epidemiological data, such as maternal abortion, premature delivery, history of stillbirth, close contact with cats or eating unripe meat, eggs, milk history, clinical considerations of this disease, the diagnosis must rely on laboratory tests.

Differential diagnosis

Congenital toxoplasmosis should be differentiated from other diseases in TORCH syndrome (rubella, cytomegalovirus infection, herpes simplex and toxoplasmosis), in addition to syphilis, Listeria or other bacterial and infectious encephalopathy, Fetal polycythemia, sepsis, infectious mononucleosis, lymph node tuberculosis, etc., mainly rely on pathogens and immunological examination to confirm the diagnosis.

1. Congenital cytomegalovirus infection: congenital toxoplasma infection, performance and prognosis similar to CMV infection, mainly relying on laboratory tests for differential diagnosis.

2. Other pathological jaundice: mainly depends on the performance characteristics of clinical systemic organ damage and laboratory identification.

3. Other meningoencephalitis: clinical features of laboratory damage and laboratory identification.

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