Pathology of Varicella
The definition of Varicella
Varicella is a primary infection caused by varicella-zoster virus and is an acute infectious skin disease characterized by systemic herpes herpes. More common in children, with a high degree of contagious, easy to cause a small area of the epidemic, the future will be lifelong immunity.
Symptoms and signs of varicella
- Varicella clinical symptoms: the incubation period of about 12 to 21 days, an average of 14 days. The incidence of acute, predisposing period of low or moderate fever, headache, muscle pain, joint pain, general malaise, loss of appetite, cough and other symptoms; a few hours after onset, or in 1 to 2 days, that rash. The whole course is short for a week, long for several weeks.
- varicella rash characteristics: varicella rash more, hundreds to thousands of ranging. Generally first appeared in the face, scalp and trunk, the distribution was centripetal to hair, chest more, less limbs face, palm foot occasionally. Nose, pharynx, mouth, vulva and other parts of the mucosa can also rash.
- Varicella clinical classification: According to the clinical characteristics of patients, can be divided into the following types of Varicella:
(1) common type: the majority of patients with Varicella, the prognosis is good. In general, systemic symptoms of varicella patients are relatively minor.
(2) progressive disseminated varicella: can be seen for a variety of reasons leading to weakened resistance, for example, suffering from leukemia, lymphoma and other malignant tumors, or long-term use of various immunosuppressive agents, adrenal cortex hormones in patients. Such patients are susceptible to the development of progressive disseminated varicella, the condition is serious; the performance of viremia for a long time, with high fever and systemic symptoms of poisoning, systemic rash and more intensive, and the emergence of new rash. Herpes larger, can be formed to each other blister blisters, or hemorrhagic herpes is not easy to scab, and even rash local skin and subcutaneous tissue necrosis.
(3) primary varicella pneumonia: the incidence of multiple patients with adults, primary varicella pneumonia occurred in the first disease to the first 6 days, but the severity of different. Light no obvious symptoms; severe may have high fever, cough, chest pain, hemoptysis, difficulty breathing and cyanosis. Chest signs are not obvious, or a small amount of dry, wet rales and wheezing; X-ray can be seen diffuse nodules of lung diffuse nodules, hilar and lung at the Department of the more significant.
(4) varicella encephalopathy: rare, suffering from patients in the rash after 3 to 8 days of clinical manifestations of encephalitis, there are a few seen in the rash before 2 weeks to rash after 3 weeks. Generally 5 to 7 years old children, male more than female.
(5) Other: severe varicella infection can lead to liver tissue necrosis, liver cells and bile duct epithelial cells within a typical nuclear inclusion body, the clinical manifestations of varicella hepatitis, patients with liver enlargement, abnormal liver function, with There is jaundice.
Pathological causes of varicella
Varicella virus in the host of long-term latent, the incidence of systemic or local skin and mucous membrane of herpes lesions, easy to relapse for its common characteristics. Varicella – zoster virus is a diameter of about 150 ~ 200nm spherical virus particles, outside the double layer of lipoprotein capsule. Varicella – zoster virus is only one serotype, human is the only natural host. The varicella-zoster virus VZV is less resistant to the in vitro environment and is soon active in the dry herpes crust. However, in the herpes solution, it can be stored at -65 ° C for long-term survival. The virus can be cultured in vitro using human embryonic fibroblasts, but not in general animal tissues such as chicken embryos.
Varicella disease diagnosis
Severe varicella with the spread of herpes simplex, disseminated herpes zoster identification, identification difficulties to rely on laboratory diagnosis, such as virus isolation and culture, Tzanck smear, PCR method to determine the existence of VZV. Light varicella should be identified with the following diseases.
- Papular urticaria scattered in the distribution of solid edema papules, itching, any part of the body can be rash, easy to relapse.
- impetigo occurs in the face and limbs exposed parts, mainly pustules, systemic symptoms are not obvious, rash no part of the emergence of the characteristics, not involving the mucosa.
Preventive care of varicella
- Isolated varicella patients: VZV infection after the clinical manifestations of varicella or herpes zoster, but the two main source of infection are varicella patients, isolation of varicella patients is the key to the prevention of VZV infection.
- Cut off the transmission of VZV infection: ventilation should be strengthened in public places, or ultraviolet radiation indoor air disinfection. Contact with patients after thoroughly wash their hands, is to prevent VZV infection in the hospital simple and effective measures.
- Immune protection measures for susceptible persons: For pregnant women who are not infected with VZV, children and immunocompromised persons should take appropriate immunization protection according to different circumstances to avoid the occurrence of fetal malformations or severe Varicella infection.
(1) passive immunization: 72 hours after exposure with high titer VZV immunoglobulin 5ml intramuscular injection, the prevention of Varicella effect. Due to the inherent safety of blood products, the scope of application of VZV immunoglobulins is limited to those exposed to varicella patients: immunocompromised, long-term immunosuppressive agents, severe diseases such as leukemia, lymphoma and other Malignant tumor. The reason for this is that these patients, once infected with VZV, may experience severe varicella, the severity of the disease will exceed the risk of blood products may bring some risk.
(2) automatic immunization: In recent years in the trial VZV inactivated vaccine or attenuated live vaccine, mainly used for high susceptibility to varicella susceptibility, have a certain preventive effect, allegedly for more than 10 years of protection.