What is Smallpox?

Smallpox (lat. Variola, Variola vera) or, as it was called earlier, black smallpox is a highly contagious (infectious) viral infection that only people suffer. It is caused by two types of viruses: Variola major (mortality 20-40%, according to some data – up to 90%) and Variola minor (mortality 1-3%). People who survive after smallpox can partially or completely lose their sight, and almost always there are numerous scars on the skin in places of former ulcers.

Only small people get sick with smallpox, experimental infection of laboratory animals is difficult. The causative agent of smallpox is a filtering virus, antigenically related to vaccinia, vaccinia virus, whose fine structure and propagation patterns are well studied. The incubation period for smallpox lasts from 8 to 14 days, usually approx. 11–12. Patients are contagious to others during the entire period of rash and, apparently, even a few days before the rash appears, for a total of about three weeks. The virus is released from the bursting and drying bubbles on the skin, from the oral cavity, and is found in the patient’s urine and feces. The causative agent of infection is transmitted by direct contact, by airborne droplets, from healthy carriers and animals, and can maintain viability on clothing and bedding. All unvaccinated people are susceptible to infection; There is no natural immunity to smallpox. Although the disease is possible at any age, children under four years of age are especially vulnerable.

Causes of Smallpox

The causative agent of smallpox belongs to the family of viruses Poxviridae, subfamily Chordopoxviridae, genus Orthopoxvirus; contains DNA, has a size of 200-350 nm, multiplies in the cytoplasm with the formation of inclusions. The variola virus has antigenic kinship with the erythrocytes of group A of human blood, which causes weak immunity, high morbidity and mortality of the corresponding group of persons. It is resistant to the effects of the environment, especially drying and low temperatures. For a long time, for a number of months, it can be stored in crusts and scales taken from pock marks on the skin of patients, in a frozen and freeze-dried state remains viable for several years.

Pathogenesis during Smallpox

In typical cases, smallpox is characterized by general intoxication, fever, peculiar rashes on the skin and mucous membranes, successively passing through the stages of the spot, blister, pustules, crusts and scar.

Smallpox belongs to anthroponoses and is a highly contagious, especially dangerous infection. All people are susceptible to smallpox if they do not have the immunity resulting from a previous illness or vaccination. Smallpox was widespread in Asia and Africa. It is an airborne infection, however, it is possible to inoculate the virus in direct contact with the affected skin of the patient or infected objects. Contagiousness of the patient is observed throughout the entire disease – from the last days of incubation to the rejection of crusts. Dead bodies of smallpox also remain highly infectious.

When inhaled contaminated air, viruses enter the respiratory tract. Infection through the skin is possible with variolation and transplacental. The virus enters the nearest lymph nodes and further into the bloodstream, leading to viremia. The epithelium is infected with hematogenous, the virus multiplies here, with which the appearance of enanthema and exanthema is caused. Weakening of the immune system leads to activation of the secondary flora and the transformation of vesicles into pustules. Due to the death of the germ layer of the epidermis, deep suppurative and destructive processes, scars are formed. Infectious toxic shock may develop. For severe forms characterized by the development of hemorrhagic syndrome.

Symptoms of Smallpox

With a typical course of smallpox, the incubation period lasts 8-12 days.

The initial period is characterized by chills, fever, severe tearing pains in the lower back, sacrum and extremities, severe thirst, dizziness, headache, vomiting. Sometimes the onset of the disease is mild.

On the 2nd-4th day, on the background of fever, an initial skin rash appears either in the form of hyperemia sites (cory-like, roseolous, erythematous), or a hemorrhagic rash on both sides of the chest in the region of the pectoral muscles to the armpits, and also below the navel in the region inguinal folds and inner thighs (“Simon’s triangle”); hemorrhages look like purpura and even ecchymosis. The spotted rash lasts for several hours, hemorrhagic – for a longer time.

On the 4th day, a decrease in body temperature is observed, the clinical symptoms of the initial period are weakened, but typical ospins appear on the scalp, face, torso and extremities, which go through the spots, papules, vesicle, pustules, formation of crusts, rejection of the latter and scar formation. At the same time, pockmarks appear on the mucous membrane of the nose, oropharynx, larynx, trachea, bronchi, conjunctiva, rectum, female genital organs, urethra. They soon turn into erosion.

On the 8th-9th days of the disease in the stage of suppuration of the vesicles, the state of health of the patients worsens again, there are signs of toxic encephalopathy (impaired consciousness, delirium, agitation, in children – convulsions). The period of drying and falling crusts takes about 1-2 weeks. Numerous scars are formed on the face and scalp.

The change in blood is characterized by leukocytosis, in severe forms there is a sharp shift to the left with the release of myelocytes and young cells into the blood.

Severe forms include drain form (Variola confluens), pustular-hemorrhagic (Variola haemorrhagica pustulesa) and pox purpura (Purpura variolosae).

In vaccinated with smallpox vaccine, smallpox flows easily (Varioloid). Its main features are a long incubation period (15-17 days), moderate symptoms of malaise and other signs of intoxication; true smallpox rash is not abundant, pustules are not formed, there are no scars on the skin, recovery occurs in 2 weeks. There are mild forms with short-term fever without a rash and severe well-being disorders (Variola sine exanthemate) or only in the form of a small rash (Variola afebris).

Possible complications include encephalitis, meningoencephalitis, pneumonia, panophthalmitis, keratitis, iritis, sepsis.

Diagnosis of Smallpox

Clinical manifestations of the disease are the basis for specific studies. For analysis, take the contents of the vesicles, pustules, crusts, smears of mucus from the mouth, blood. The presence of the virus in the samples is determined by electron microscopy, microscopic agar in an immunofluorescence method, using PCR. A preliminary result is obtained after 24 hours, after further research – the isolation and identification of the virus.

Treatment of Smallpox

For the treatment of this disease, antiviral drugs are used (metisazone, 0.6 g, 2 times a day, a course of 5-6 days), a smallpox immunoglobulin 3-6 ml intramuscularly. To prevent bacterial infection, antiseptic preparations are applied to the affected skin. In the presence of bacterial complications, broad-spectrum antibiotics are prescribed to patients (semi-synthetic penicillins, macrolides, cephalosporins). Measures are being taken to detoxify the body, these include the introduction of colloidal and crystalloid solutions, in some cases, ultrafiltration and plasmapheresis are performed.

The prognosis depends on the clinical form of the disease, age and premorbid state. Mortality ranges from 2% to 100%. With a mild course and vaccinated prognosis is favorable. Convalescents are discharged from the hospital after a complete clinical recovery, but not earlier than 40 days from the onset of the disease. After mild forms, patients are discharged without changing the category of shelf life. After severe forms, fitness for military service is decided by the IHC depending on residual effects (visual impairment and others) or they are granted sick leave for a period of up to 1 month.

Prevention of Smallpox

Variolation (vaccination of the early, unsafe vaccine) has been known in the East at least since the early Middle Ages: records of the 8th century remained in India, and in the 10th century in China. This vaccination technique was first brought to Europe from Turkey by the wife of the British ambassador to Istanbul, Mary Wortley Montague, in 1718, after which the British royal family was imparted.

In Russia, variolation was introduced after the death of 14-year-old Emperor Peter II from smallpox.

At the end of the XVIII century, the English doctor Edward Jenner invented the smallpox vaccine based on the cowpox virus, which was massively vaccinated in Europe.

The first vaccinated against smallpox in Russia were Catherine II the Great, Grand Duke Pavel Petrovich, Grand Duchess Maria Feodorovna, and a few days later the grandchildren of Catherine Alexander and Konstantin Pavlovichi. A peasant boy, Markov, from whom the small-pox was imparted to the empress, was given the nobility, the name Pouspen and the coat of arms.

In America, Asia and Africa, smallpox lasted for almost two hundred years. In the 18th century, every seventh child died of smallpox in Russia. In the XX century, the virus claimed the lives of 300-500 million people. In the late 1960s, smallpox affected 10–15 million unvaccinated people.

In 1967, WHO decides on the eradication of smallpox through mass vaccination of mankind.

The last case of smallpox infection in a natural way was described in Somalia in 1977. In 1978, the last case of laboratory infection was recorded. Officially, the eradication of smallpox was announced in 1980 at the WHO Assembly, which was preceded by the corresponding conclusion of a commission of specialists issued in December 1979.

Smallpox is the first and so far the only infectious disease, defeated by mass vaccination. Vaccinations against smallpox in the USSR ceased in 1978-1980.

Smallpox is a particularly dangerous infection. Patients and suspects for this infection are subject to strict isolation, clinical examination and treatment in special hospitals. Medical staff working in anti-plague clothing type III with a mask. Conduct a thorough current and final disinfection of the room where there is (was) the patient, household items and places of general use with 5% lysol solution. The dishes are soaked with a 3% solution of chloramine, then boiled. All trash and waste are incinerated.

Quarantine for persons who were in contact with a sick (suspicious) smallpox, set for 17 days. All of them are vaccinated against smallpox, regardless of the duration of the previous vaccination. They are given a single-dose donor gamma-globulin in an amount of 3 ml and are prescribed inside methysazone: adults, 0.6 g 2 times a day, children — a single dose at the rate of 10 mg per 1 kg of body weight of the child 4-6 days in a row.