What is varicella-zoster virus? The transmission route, complications and prevention principles of varicella-zoster virus？

What is varicella-zoster virus? The transmission route, complications and prevention principles of varicella-zoster virus

What is varicella-zoster virus? The transmission route, complications and prevention principles of varicella-zoster virus？

Varicella-zoster virus

Varicella-zoster virus (VZV) refers to chickenpox caused by the initial infection in children. After recovery, the virus lurks in the body. A few patients re-emerge in the adult and cause herpes zoster, so it is called chickenpox. Herpes zoster virus.

Chickenpox is a highly contagious disease in children. It occurs in 2 to 6 years old. The source of infection is mainly patients. The acute phase of varicella content and respiratory secretions contain viruses.

Varicella-Zoster virus English name varicella-zoster virus Multiple groups Infants and young children Common symptoms Herpes zoster Transmission route Air, skin, etc.

Biological trait
VZV is identical in morphology to HSV. There is only one serotype. The genome has 71 genes encoding 67 different proteins, including 6 glycoproteins (gpI ~ gpVI), which are now collectively named gE, gB, gH, gI, gC and gL. Among the infected cells, glycoproteins gE, gB and gH are extremely abundant, and these glycoproteins are also present in the membrane of virions.

VZV commonly used human fibroblasts and a variety of cells of monkeys, typical cytopathic changes occur within 3 to 2 weeks, such as inclusions in the nucleus and formation of multinucleated giant cells. The virus spreads between cells and cells, and then infects neighboring cells.

Pathogenicity
VZV has no animal storage host, and humans are the only natural host. The skin is the main target organ of the virus.
There are two types of VZV-infected humans, namely, the original infection of varicella (varicella) and recurrent infection of zoster.

Chicken pox
The virus enters the body through the respiratory mucosa or conjunctiva. After two viremias, the virus replicates and spreads throughout the body, especially the skin and mucous membranes. After about 2 weeks of incubation period, due to swelling of epithelial cells, balloon-like changes, accumulation of tissue fluid, papules and blisters appear on the whole body skin, and some develop pustules due to infection. The rash is distributed centripetally, with more trunks than the face and limbs.

Rare encephalitis and pneumonia complications in healthy children. Adult varicella symptoms are more serious, often complicated by pneumonia, and the mortality rate is higher. Immune-deficient children and non-immune newborns are infected with chickenpox, which is dangerous and may be a fatal infection. Such as pregnant women suffering from chickenpox in addition to serious illness, and can cause fetal malformations, miscarriage or death.

Herpes zoster
Herpes zoster is a common disease in adults, the elderly, or immunocompromised and immunosuppressed patients, caused by the activation of latent viruses.

In patients who have had chickenpox, a small amount of virus lurks in the sensory ganglia of the posterior root ganglia or cranial nerves of the spinal cord. Trauma, fever and other factors can activate the virus that is lurking in the ganglion. The activated virus passes down the sensory nerve fiber axon to the inner skin area, which causes herpes zoster after proliferation. At the beginning, the local skin has abnormal feeling, itching and pain, and then rash and herpes appear in a series. The torso and the facial area are more common, and the unilateral distribution is about 3 weeks, and the few can reach several months. Long.

Complications include encephalomyelitis and conjunctivitis.
The clinical manifestations of a few cases are not typical, and there are common ones:

• Incomplete herpes zoster (stunned type), only erythema, papules, and no typical blisters.
• Bullous herpes zoster, can form blister to large peas.
• Hemorrhagic herpes zoster, blister content is bloody.
• Gangrenous herpes zoster, rash in the center of the rash, formed into a black suede is not easy to peel, leaving scars after the recovery.
• Disseminated herpes zoster, in patients with malignant tumor-tumor or frail elderly, within a few days of local rash, the body appears similar to acne itch rash, often accompanied by high fever, can be complicated by lung, brain damage, disease Sexually serious, can cause death.

In addition to the above-mentioned atypical herpes zoster, certain special sites or special types of herpes zoster can be seen clinically, as follows:

• Eye herpes zoster: eye herpes zoster is mostly scattered, more common in September-November. Clinical findings of herpes zoster with the first branch of the ipsilateral trigeminal nerve, visible eyelid swelling, conjunctival hyperemia, blisters and ecdysis, may involve ulceration of the keratitis of the cornea, and later blindness due to scar formation. In severe cases, full ocular inflammation, encephalitis, and even death can occur.
• Ear herpes zoster: also known as Ramsay-Hunt syndrome, is due to VZV invasion of the facial nerve and auditory nerve, the clinical features of the ear acute pain and the same side of the sputum, accompanied by hearing, dizziness and so on. May be associated with fever, local lymph node swelling and mumps.
• Herpes zoster meningitis: the virus directly from the spinal nerve anterior and posterior retrograde invasion of the central nervous system. Mostly seen in patients with cranial nerve, neck or upper thoracic spinal cord segment. Table shows headache, vomiting, convulsions or other progressive sensory disturbances, and there may be ataxia and other cerebellar symptoms.
• Visceral herpes zoster: the virus from the spinal cord heel invades the sympathetic and parasympathetic splanchnic nerve fibers, causing gastrointestinal or urinary tract symptoms, when invading the pleura, peritoneum, then irritating symptoms or even effusion.

Immunity
The antibodies induced by the three major glycoproteins of VZV can neutralize the virus. The glycoprotein gB is the same as the 49% amino acid of gB of HSV, but the immune relationship is unclear. Specific humoral and cellular immunity, as well as cytokines such as interferon, play a major role in limiting VZV proliferation and varicella and herpes zoster recovery. Among them, specific cellular immunity is more important, but does not prevent herpes zoster. Lifetime immunization after varicella disease.

Microbiological examination
Clinically typical varicella or herpes zoster, generally does not require laboratory diagnosis. However, for patients with no immune response and atypical symptoms, herpes liquid can be used for rapid electron microscopy or cell culture to isolate the virus; or immunofluorescence test can be used to detect herpes virus base antigen on the base of the herpes base and biopsy tissue; or PCR was used to amplify VZV DNA from cerebrospinal fluid. These methods all help to confirm the diagnosis.

Principle of prevention

Passive immunity
Injecting varicella-zoster immunoglobulin (VZIG) or high-valent VZV antibody preparations can prevent the development of infections and diseases of neonates, unimmunized pregnant contacts or immunocompromised contacts to a certain extent. Prevent outbreaks in hospitals, schools, etc. But there is no therapeutic value.

Vaccine
The live attenuated varicella vaccine has been used in Japan, Germany, the United States and other countries for many years. Immunization of children and adults who have not had chickenpox for more than 1 year old can produce specific antibodies in the body for 10 years, and the protection rate is 68%~100%. In some areas of China, children over the age of 1 are also being tested for varicella vaccine. Immunosuppressed children and adults with diffuse herpes zoster can be treated with nucleoside analogues such as acyclovir (ACV), vidarabine and IFN. Acyclovir can prevent the development of the disease.

Symptom characteristics
The incubation period is 12-21 days, with an average of 14 days. It can cause chickenpox in the first infection of children. After recovery, the virus lurks in the body, and the virus in the latent body is stimulated (such as: tired, hot, cold, X-ray, etc.) Recurrence causes herpes zoster, which is more common in adults and the elderly, so it is called varicella-zoster virus.
VZV is a herpesvirus genus whose biological trait is similar to herpes simplex virus (HSV) but has only one serotype. VZV commonly used human fibroblasts and various cells of monkeys, typical cytopathic changes occur around 3-14 days, such as the formation of multinucleated giant cells (CPE) and the production of eosinophilic inclusion bodies in the nucleus of infected cells.

Way for spreading

The route of transmission of varicella-zoster virus is as follows:
Humans are the only natural host of varicella-zoster virus, and skin epithelial cells are the main target cells. The virus enters the body through the respiratory tract or contact infection. After two viremias, the virus replicates and spreads throughout the body, especially the skin and mucous membranes. After about 2 to 3 weeks of incubation period, papules, vesicular rash and pustular rash appear widely in the whole body. The distribution of rash is centripetal, with more trunks and can develop into herpes.

The blister rash contains a large amount of virus, and the scars disappear after the disappearance of the chickenpox. The condition is generally mild, but occasionally complicated by interstitial pneumonia and post-infectious encephalitis. Children with cellular immunodeficiency, leukemia, kidney disease or long-term use of corticosteroids and antimetabolites have severe symptoms and even life-threatening varicella. Adults with varicella, 20% - 30% with pneumonia, the general condition is serious, the mortality rate is also high. Pregnant women suffering from chickenpox are also more serious, and can cause fetal malformations, miscarriage or stillbirth.

Misunderstanding
Herpes zoster is a common skin disease caused by varicella-zoster virus. The disease mainly invades the skin and nerves, and the skin herpes is present, clustering unilaterally, often accompanied by obvious tingling. Folks are often referred to as "snake sore, entangled fire Dan". The disease has no special effects before liberation, treatment is very difficult, the effect is not good, and there are many opportunities for legacy sequelae. Therefore, there are many methods and misunderstandings that seem to be out of place. Here are some of these misunderstandings.

Herpes zoster is a skin disease caused by a virus. In the past, the economic conditions were poor, the medical consciousness was weak, and the understanding of the disease was not sufficient. After the illness, the timely treatment was not obtained, and there was no special antiviral drug. The result was not good, and there were more chances of leaving the sequelae. Thereby promoting the birth of various soil methods. The specific method is: when the sky is bright, facing the east, remembering the words, and then taking the knife to make the pre-prepared straw rope into several segments, and then taking the ink to circle the affected area once a day for four or five days. The only merit of this method is to use the ink to coat the affected area. In the traditional Chinese medicine, Jingmo has the effect of clearing away heat and detoxification and can be used for the treatment of this disease. However, the current ink does not have this effect, and has not been disinfected, and it is easy to be secondary to infection after external use. With the advancement of society and the development of science and technology, in recent years, many antiviral drugs with good curative effect and small side effects have been developed, such as acyclovir, famciclovir, valacyclovir and the like. They are very effective and have few side effects. As long as the patient can see a doctor in time, regular medication, most of them can be cured quickly. Of course, some elderly patients with frailty and low immune function, if not found in time, timely medication, may still leave more obvious post-herpetic neuralgia, give The patient has significant pain.

Herpes zoster is caused by the varicella-zoster virus. After the virus infects the human body, varicella or invisible infection occurs, and then lurks in the neurons of the posterior root ganglia of the spinal cord. Under the stimulation of various predisposing factors (trauma, infection, overwork, etc.), it can recur, nerve damage occurs in the injured nerve, and the herpes is caused by the skin. Contagious.
Most of the herpes zoster is cumulatively unilateral, banded, with neuropathic pain and skin damage that does not affect life. Only a small number of patients with low immunity, old and frail or tumors will develop. These patients may have systemic damage such as lung and brain, which will endanger life.

The treatment of herpes zoster is mainly based on internal medicine, antiviral drugs are first-line drugs, varicella and herpes zoster are contraindicated with glucocorticoids, because glucocorticoids may cause the spread of the virus and aggravate the condition, and can be combined with topical drugs, such as Stone lotion, acyclovir cream, penciclovir cream, etc. can be used. The royal yellow, Ji Desheng snake tablets, Liushen pills, etc. of Chinese medicine are also available. However, it is necessary to prevent the occurrence of infection. Patients with post-neural pain can cooperate with traditional Chinese medicine, acupuncture, phototherapy and other methods.