Smallpox

Smallpox Introduction Smallpox is a potent infectious disease caused by smallpox virus, which is highly contagious and has a high mortality rate. The clinical manifestations of extensive rash appear in batches, which develop into rash, papules, herpes, pustular rash, accompanied by severe viremia; pustular scars, dislocation, and residual scars for life. The variola virus belongs to the orthopoxvirus. The virus in the genus Poxvirus is very similar in shape, size, structure, resistance to the outside world, immunological characteristics, etc. The acne produced by smallpox and variola virus is small, the edge is intact and protruding, and the vaccinia virus produces The larger, the margin is not neat, the variola virus is more pathogenic, but the cytopathic effect is slightly slower than the vaccinia virus, smallpox, smallpox, vaccinia virus can proliferate in a variety of cell tissue culture, variola virus causes typical smallpox . basic knowledge Sickness ratio: 0.0001% Susceptible people: no specific population Mode of infection: respiratory tract transmission, contact transmission Complications: Cellulitis, conjunctivitis, corneal ulcer, otitis media, laryngitis, bronchial pneumonia, pleurisy, myelitis, nephritis, orchitis, abortion, hemorrhoids

Smallpox cause

Virus infection (80%):

The variola virus belongs to the orthopoxvirus. The virus in the genus Poxvirus is very similar in shape, size, structure, resistance to the outside world, immunological characteristics, etc. The acne produced by smallpox and variola virus is small, the edge is intact and protruding, and the vaccinia virus produces The larger, the margin is not neat, the variola virus is more pathogenic, but the cytopathic effect is slightly slower than the vaccinia virus, smallpox, smallpox, vaccinia virus can proliferate in a variety of cell tissue culture, variola virus causes typical smallpox .

Environmental factors (20%):

The appearance of smallpox virus is brick-shaped, about 200 micrometers × 300 micrometers. It has strong resistance and can resist dryness and low temperature. It can survive for several months to one and a half years in molting, dust and clothing. The variola virus is highly contagious. Sex, people who have not had smallpox or have not been vaccinated with smallpox, can affect smallpox regardless of gender, including newborns, and smallpox is mainly transmitted by inhalation or direct contact with droplets.

Pathogenesis

Inhalation through the respiratory tract is the main route of transmission of smallpox. The variola virus is adsorbed on the surface of the epithelial cells of the upper respiratory tract of the susceptible person and invades rapidly. It reaches lymph nodes such as local lymph nodes and tonsils, and is copied into the blood to form the first transient viral blood. Symptoms, through the bloodstream, infect whole body mononuclear macrophages, and continue to replicate and release into the blood, leading to the second viremia, through the blood circulation, the virus spreads more widely to the whole body skin, mucous membranes and internal organs Tissue, at this time the patient has high fever, general malaise, after 2 to 3 days of prodromal symptoms, there is a smallpox pox, because the variola virus is not heat-resistant, so after the patient's fever, viremia only lasts for a short period of time, fever On the day of the patient, it is generally difficult to detect the virus in the blood. The virus mainly exists in tissues with low temperature such as skin. After the variola virus invades the skin tissue cells, it first proliferates in the dermis, causing the dermal layer to expand, and the cytoplasm is empty. Bubble, nuclear concentration, disappearance, clinical appearance of macules; subsequently, the virus invades the epidermal cells to proliferate, causing local swelling, skin Thickening, papules appear, after which cell degeneration, necrosis, fluid exudation between cells, formation of herpes, destructive cells become separated in herpes, forming many small houses; due to the traction of deep cell walls, the central part of herpes Under the umbilical, under the microscope, the cytoplasm of the epithelial cells around the herpes, the clear inclusions in the perimeter are round, with a diameter of 1 ~ 4m, when a large number of inflammatory cells infiltrate into the blister, it becomes pustular rash, pustular rash After the liquid is absorbed, hard sputum is formed. Due to rupture and scratching, pustular rash is prone to secondary bacterial infection, which worsens the deep lesions of the local skin, and also aggravates the toxic symptoms of the whole body, pustular period, liver. The spleen can be swollen. If the oral cavity and the nasopharynx are secondary infection, it can cause cervical lymphadenopathy. If the pustule only invades the epidermis, the scar after dislocation is not obvious; if it involves the dermis or has secondary infection , the formation of a lifelong depression scar, due to the lack of the stratum corneum, the mucosal lesions are broken faster than the skin damage, mucosal lesions are easy to form different depths of ulcers, without the formation of herpes The virus is easily excreted from the ulcer; therefore, mucosal lesions play an important role in the early infectiousness of the patient. Mucosa in the respiratory tract, digestive tract, urinary tract, and vagina can be affected, due to the significant inflammatory reaction around the ulcer. Can cause serious symptoms, if it affects the cornea, can cause corneal opacity, ulcers, or secondary bacterial infections, resulting in blindness.

Smallpox prevention

The patients with smallpox should be strictly isolated, and the clothes, quilts, utensils, excretions, secretions, etc. of the patients should be thoroughly disinfected. In addition to symptomatic therapy and supportive therapy for patients, the focus is on preventing complications, oral, nasal and pharyngeal diseases. Keep your eyes clean, and inoculation of smallpox vaccine is the most effective way to prevent smallpox.

Because of the danger of variola virus being used as a bioterrorist weapon, although the eradication of smallpox has been announced in 1980, medical workers should not be relieved of their vigilance, especially when the world has stopped vaccination. Patients with early typical or atypical smallpox should be able to recognize and handle them promptly.

1. Control the source of infection

If a patient or a suspicious case is found, the patient must be immediately and closely quarantined, and all the articles of clothing that the patient has been exposed to should be strictly disinfected. Low-value items may even be considered for incineration. At the same time, the telephone is used to report the epidemic to the local disease control center. Diagnosis and investigation of the source of the disease.

2. Contact processing

Quickly search all contacts to register, allocate quarantine for 16 days, and immediately grow pox. For those who can not grow pox, give high-priced anti-small immunoglobulin intramuscular injection. If the contact person leaves the infected area, he should immediately notify the area. It implements pox.

3. Implement traffic quarantine

Traffic quarantine is carried out on the main roads, temporary checkpoints are set up, and checkpoints are set up to prevent smallpox from spreading along the traffic lines.

Smallpox complications Complications Cellulitis, conjunctivitis, corneal ulcer, otitis, laryngitis, bronchial pneumonia, pleurisy, myelitis, nephritis, orchitis, abortion, acne

Smallpox complications often occur in severe patients, usually secondary bacterial infections, often Staphylococcus aureus, hemolytic streptococcus and pneumococcal, etc., can occur cellulitis, soft tissue abscess, conjunctivitis, corneal ulcer, full eyeball Inflammation, otitis media, laryngitis, bronchial pneumonia, pleurisy, etc., may be complicated by encephalomyelitis, nephritis, orchitis, miscarriage, hemorrhoids, etc.

Typical smallpox patients often leave a depressed scar for life, especially with a face that is more obvious, leading to disfigurement, commonly known as "pock surface", often causing severe psychological shock to the patient, corneal ulcer, full eyeball inflammation may lead to blindness.

Symptoms of smallpox Common symptoms High fever, depression, scar, toxemia, nasal congestion, maculopapular papules, red pustules, itching

symptom

The incubation period is generally 8 to 12 days. Sudden onset, with high fever, headache, vomiting and other systemic symptoms. On the first 1-2 days of onset, transient measles may appear in the lower extremities, inside the thighs, under the armpits and on the sides of the waist. Scarlet fever-like rash (pre-external rash), on the 3rd to 4th day of onset, the body temperature drops rapidly, the symptoms are relieved, and the ectopic rash appears at the same time, that is, the head, the face, the ends of the extremities are more dense than the trunk, and the initial dark red spots The rash turns into a papule after a few hours. On the 6th to 7th day of the disease, it becomes a blister. The central depression is surrounded by redness. At this time, there are also rashes in the mouth, throat, corners of the eyes, conjunctiva, etc. 9 days, the blister turned into pustules. At this time, the body temperature rose again, and the symptoms of poisoning increased. On the 11th to 12th day of the disease, the pustules gradually dried up, forming a yellow-green thick sputum, consciously itchy, and the body temperature gradually decreased. Better, after 2 to 4 weeks of illness, start dislocation and leave scars.

The above-mentioned positive-type smallpox (referred to as common type) is found in those who have never been vaccinated with vaccinia, in addition to light and heavy-duty smallpox, the light-type one is infected with a weakly venom-like variola virus or occurs when the vaccinia has been vaccinated but the antibody has been reduced. Systemic symptoms are light, rash is less, generally can not develop into blisters or pustules, so the course of disease is short, no scars after the recovery, severe, systemic symptoms, rash is hemorrhagic or pustule fusion, complications, complications: Skin and mucous membrane secondary bacterial infections are more common, severe cases can cause sepsis, meningitis, etc., can also be associated with laryngitis, otitis media, bronchial or pneumonia, corneal opacity ulcers, leading to insomnia.

Staging

The course of typical smallpox can be divided into three stages: the prodromal phase, the rash phase and the scarring phase.

Precursor period

Sustained for 3 to 4 days, acute onset, chills, high fever, fatigue, photophobia, headache, lower back and limb pain, abdominal pain; some patients may have mild symptoms of upper respiratory tract, children may have vomiting, high fever For 2 to 5 days, the patient presented with severe illness, painful expression, conjunctival congestion, sometimes tears, mild swelling of the liver and spleen, fever 1 to 2 days, in the lower abdomen, groin, inner thigh, waist and abdomen and armpit There may be a transient "predecessor rash", which is measles-like, scarlet-like heat-rash-like, urticaria-like or bleeding rash; because it is not many, it will retreat after a few hours, so it is easy to be ignored.

2. The rash period

The time, location and order of the rash of the smallpox have a certain regularity. On the third to fourth days of the onset, the body temperature drops slightly; at this time, the rash appears, starting from the face and spreading rapidly to the neck, forearm, upper arm, hand , chest, abdomen, and finally the lower limbs and soles of the feet, throughout the body within 1 to 2 days, the rash is eccentrically distributed, with more exposed parts such as the head and limbs, more upper part of the body, scarring of the underarm and waist rash or No rash.

Initially, the rash is a red rash, but it quickly becomes a 2 to 4 mm in diameter, a firmer texture of the papules, deep inside the skin, in the thicker palms and soles of the stratum corneum, forming a hard pale erythema during the disease. On the 6th to 7th day, the papules became herpes, surrounded by a hard red blush, surrounded by herpes, and a central depression, called "pox umbilical". Herpes is multi-atrial, hard as a bowl of beans, uniform in size, blistering, At this time, the body temperature gradually increased, and the condition became worse again.

At the same time as the skin rash, there are mucosal rashes in the oropharynx, upper respiratory tract mucosa, conjunctiva, etc. The mucosa of the trachea, esophagus, urinary tract, vagina, etc. may also be affected, because the mucosa is a squamous squamous epithelium. During the transformation of herpes, the epithelial layer of the mucosal rash quickly ruptures, and herpes formation is often invisible. Mucosal lesion rupture not only forms small ulcers of inflammation, but also causes severe symptoms and drooling due to significant inflammation around the ulcer. , hoarseness, photophobia, nasal congestion, tearing, sore throat, difficulty swallowing, urinary irritability and other clinical manifestations.

On the 8th to 9th day of the disease, herpes continued to fill, and the blister fluid was turbid. In about 24 hours, the blister fluid turned yellow purulent, herpes became pustular herpes, the redness around herpes was more pronounced, the skin became red and swollen, and the subcutaneous tissue was loose. Departments such as eyelids and other edema, in the skin and subcutaneous tissue tight parts, such as the amount of head, palm and other edema can cause local obvious pain, at this time the body temperature rises further, the symptoms of poisoning continue to increase, if combined with bacterial infection, the symptoms are more serious Can be complicated by pneumonia, shock and death.

3. Knot period

In the course of 10 to 12 days, the pustules began to shrink and dry, and the surrounding redness disappeared. The herpes gradually dried up and formed a yellow-green thick sputum. The local often appeared unbearable itching. At this time, the body temperature gradually returned to normal and began to dislocate. The whole body condition improved. After the second to fourth weeks of the disease, the clam shells fell off. If the skin damage was deep, the scars that existed for life were left. After the appearance of the smallpox rash from the head and face, it developed into a rash and a papule. Herpes, pustules and crusting, from rash to crusting, usually about 8 days. During the same period, the same part of the rash often changes in the same form, but the rash can sometimes stop at a certain stage, not necessarily into pustules. And crusting.

4. Clinical type

Due to the immune status of the patient's body, the virulence and quantity of variola virus, the clinical manifestations of smallpox are different, and can be divided into common type, light type and heavy type.

(1) Ordinary smallpox: that is, the typical symptoms mentioned above, about 90% of patients who have not been infected with acne are of this type.

(2) variola minor: includes the following types.

1 variola sine eruptione: also known as pharyngeal smallpox, or transient smallpox, common in patients who have partial immunity to smallpox, such as those who have ever planted vaccinia, but did not plan to replant, as There are short-term fever, headache, myalgia, low back pain, and pre-existing rash, but no typical smallpox rash, no rash-type smallpox patients are contagious, clinical diagnosis is difficult, mainly based on serological examination to confirm the diagnosis.

2 modified smal1pox: mild condition, low body temperature, less rash, generally does not form pustules, no scar formation, short course, about 10 days crusted.

3 kinds of smallpox (alastrim): caused by variola virus infection, due to weak virulence, the incubation period can be as long as 20 days, the disease is mild, the disease course is short, the mortality rate is less than 1%, the rash is less, no scar is left. Herpes simplex is easy to break, sometimes can be a single room, easily misdiagnosed as chickenpox.

(3) variola major: high mortality, up to 20% to 50%, can be divided into two types of fusion and hemorrhagic.

1 Confluent smallpox: Contaminated smallpox: widespread rash, rapid development, pustules merge with each other, the inflammatory reaction around the pustules causes the skin to swell significantly, with the face, back of the hand and back of the foot as the weight, mucosal ulcer, redness and swelling Obviously, the patient suffers from abnormal pain, with severe symptoms of toxemia, high fever, and exhaustion.

2 hemorrhagic smallpox: also known as black smallpox, mostly caused by coagulopathy, skin mucosa may have defects, ecchymosis, severe internal bleeding, easily misdiagnosed as bleeding disorders, due to high fever, irritability and collapse When the symptoms of severe infections are severe, most patients have rashes that have not developed to herpes, which may have died.

Smallpox inspection

According to the characteristics of its rash, distribution and development process, combined with epidemiological conditions, the diagnosis of typical cases is not difficult. The diagnosis of difficult cases depends on the examination of virus and serum immunology.

Blood picture

The total number of white blood cells in the prodromal phase was slightly lower, the lymphocytes were relatively increased, and the total number of white blood cells and neutrophils in the pustule stage increased.

2. Pathogen examination

(1) Direct smear examination of variola virus inclusion body: Take the herpes liquid, or the bottom swab of the herpes ulcer on the slide, dry it and stain with hematoxylin-eosin (HE), observe the cells of epithelial cells under light microscope. Quality, if it is a smallpox patient, you can find the scorpion virus eosinophilic inclusion body, but the negative smear can not exclude smallpox.

(2) Electron microscopy: The material was taken from the lesion and observed by electron microscopy. The variola virus was brick-shaped and could be diagnosed within a few hours.

(3) Chicken embryo inoculation or cell culture: Take herpes liquid, sputum suspension, blood or nasopharynx secretion, inoculate virus into chicken chorioallantoic membrane; or inoculate monkey kidney cells or amniotic cells for culture, 12h After seeing most of the tiny inclusion bodies, the inclusion bodies increased significantly after 48 hours, and sometimes the inclusion bodies in the nucleus were visible.

3. Serological examination can be used in the complement binding test, erythrocyte agglutination inhibition test, neutralization test to detect the presence of specific antibodies in the patient's serum to help diagnose, smallpox patients can appear variola virus antibodies in serum as early as the fourth day of the disease, On the 7th day after the disease, most patients had a positive test for complement fixation. The titer on the 10th to 11th day was 1:640, while in non-small patients with a history of acne, the titer rarely exceeded 1:40. If a suspicious patient with a history of acne has a serum antibody titer that is four times higher than the early stage at the end of the course, it is of diagnostic value.

Pathological changes: the epidermis has reticular degeneration, balloon-like degeneration or coagulative necrosis. Because of the obvious reticular degeneration, most of them produce multi-atrial blister. The Guamieri body can be found in the early affected cytoplasm, which is round or oval. It is eosinophilic and Feulgen-positive, and it is often surrounded by a transparent area that is not colored. In addition, intranuclear eosin inclusion bodies are common in old skin lesions, except for mild inflammation in the dermis. .

Smallpox diagnostic identification

diagnosis

According to the characteristics of clinical manifestations of various stages, prodromal symptoms, the sequence, nature, transformation and regression of the rash site during rash, the body temperature showed a bimodal curve, sepsis, etc.; combined with epidemiology, vaccination, etc. Diagnosis, but since the smallpox has disappeared from the world for many years, vaccination against vaccinia has long since ceased to be implemented, and smallpox is a potent infectious disease classified as Class A management. Therefore, the diagnosis of the first case must be positive and very cautious. Check for virus and serum immunology.

Before the rash, it is similar to other infectious diseases such as flu, encephalitis, meningitis, typhoid fever, and toxic scarlet fever. It can only be reported according to the epidemic situation, otherwise it is difficult to distinguish.

Differential diagnosis

Typical smallpox should be differentiated from chickenpox, monkeypox and vaccinia and vaccinia during the rash period. In addition, it should be differentiated from skin impetigo.

1. Chickenpox (chickenpox) Systemic rash appears in batches within 1 to 2 days after fever, and its distribution is centripetal. The rash undergoes stages of rash, papules, herpes, followed by dryness and crusting in 1 to 2 days. Different forms of rash can coexist in the same part of the patient's body at the same time. The typical herpes is oval in shape, the wall is thin and easy to break, and there is no umbilical concavity in the central part of herpes. As long as there is no secondary infection, herpes does not purulent, then no scar remains. Most patients with chickenpox are infants and young children. Except for patients with progressive disseminated varicella or visceral varicella, systemic symptoms are generally not heavy.

2. Monkeypox (monkeypox).

3. Vaccinia and vaccinia (cowpox) is a contagious disease caused by vaccinia virus. It is prevalent in cattle and can be transmitted to humans. It occurs mostly in cattle-related farms, slaughterhouse workers, and vaccinia. The biological characteristics of the virus are similar to the vaccinia virus in many respects. The incubation period of vaccinia is 5-7 days. The rash occurs mostly on the fingers, face, forearm, etc., starting from papules, and soon becomes blisters and pustules. Pustules have Umbilical recess, surrounded by redness and edema, lesion epidermal necrosis is slower, there is more bleeding; in the subepidermal cells can be seen in the cytoplasmic inclusions, but larger than the small body of the small lesions, herpes can be multiple Sex, but not many, may have fever, local lymphadenitis and lymphangitis, but the condition is mild, usually after 3 to 4 weeks, according to the history of contact with cattle, a small number of skin herpes, umbilical concavity Pustules, mild systemic symptoms, etc., can make a clinical diagnosis, the diagnosis depends on the virus culture, paravaccinia (also known as milk cow nodules) is a vaccinia virus (also known as pseudo vaccinia virus, pseudocowpox virus Contagious The disease is prevalent in the herd. The milking workers are inevitably exposed to the sick cows and are often infected. The slaughterhouse workers can also be infected. After the contact with the sick cattle, the incubation period is 5 to 14 days, which occurs in the hands and forearms. Single or several skin lesions, dark red papules, post-nodules, no pustules, no pain, rashes are usually only seen in the hands and forearms that touch the body of the diseased cow, local lymph nodes can be swollen, but the whole body Mild symptoms, skin damage can go through six periods, each period lasts about 2 weeks, namely:

1 red maculopapular period.

2 In the target period, the center of the rash is red, with a white ring outside, and then surrounded by a blush, so its appearance is like a circular target.

3 acute exudation period, the rash is obviously congested and edema, surrounded by inflammatory redness.

4 In the nodule stage, the rash turned into a hard, non- tender, hemispherical nodule. In some patients, after the nodule appeared on the skin, erythema rash appeared in the upper limb, lower leg and neck of the forearm, which was an allergic reaction. The performance can be resolved within 1 to 2 weeks.

5 papillary, uneven surface of the nodules, become papillary pale red sputum, similar to purulent granuloma.

6 regression period: damage naturally subsides, no scars, according to the above characteristics of the vaccinia, it is not difficult to identify with vaccinia, the vaccinia virus can grow in the tissue culture of cattle, but can not be cultured in monkey or human tissue cells, This is also different from vaccinia virus. There is no specific treatment for vaccinia and para-vaccinia. The principle of treatment is symptomatic treatment and prevention and treatment of secondary infection.

The material in this site is intended to be of general informational use and is not intended to constitute medical advice, probable diagnosis, or recommended treatments.