Smallpox
The content of the article:
- Causes
- Forms of the disease
- Disease stages
- Symptoms
- Diagnostics
- Smallpox treatment
- Possible complications and consequences
- Forecast
- Prevention
- Video
Smallpox (smallpox) is an especially dangerous highly contagious infectious disease of viral origin. It is characterized by airborne transmission, two-wave fever, severe intoxication, staged appearance on the skin and mucous membranes of a thick vesicular-pustular rash, after the resolution of which characteristic deep scars (pockmarks) remain.
The mention of smallpox was found in the most ancient written medical sources of Egypt, India, China, it was described in detail by such outstanding doctors of antiquity as Hippocrates and Galen, but the first reliable study is considered the work of the Arab scientist Razes "On smallpox and measles", created in IX- X centuries A. D. e. He considered measles a kind of smallpox. The famous Avicenna established the distinction between these two diseases.
Smallpox has been known since ancient times, in the Middle Ages it more than once assumed the scale of epidemics
The smallpox virus is highly contagious, so the incidence often took the form of epidemics. Every third of the sick died, and according to rough estimates, from the 5th to the 20th century, smallpox claimed from 400 to 600 million lives. A breakthrough in the fight against the disease was the discovery of the smallpox vaccine by the English physician Edward Jenner in 1796. He found that milkmaids who had direct contact with cows with vaccinia did not fall ill during epidemics of “human” smallpox. In support of his theory, he publicly rubbed the purulent contents of smallpox pustule into an 8-year-old boy, inoculating him in this way with vaccinia, and after a month and a half he attempted to infect him with smallpox, but the boy remained healthy - this is how not only a safe vaccine against smallpox was discovered, but and the method of vaccination itself (the name comes from the Latin word vacca - cow).
Smallpox is considered to be an infection that has been eradicated worldwide. On May 8, 1979, 155 member countries of the World Health Organization (WHO) approved the conclusions of the Global Commission and witnessed the elimination of the disease, namely:
- Smallpox eradication has been completed worldwide.
- There is no evidence of the possibility of smallpox reappearing as an epidemic disease.
Later, in February 1979, the Global Commission recommended that smallpox virus culture be preserved in several laboratories for scientific purposes. It is currently stored in two laboratories - in the USA and in Russia.
Causes
The main causative agent of smallpox is Variola major, a DNA-containing virus of the Poxviridae family, distinguished by its large size (210–260 nm). The Variola major virus is responsible for the most severe and most virulent form of smallpox. Also, the disease can be caused by the Variola minor virus (Alastrim), in this case, although it has all the signs of smallpox, it is less severe and less often fatal (in 1% of cases versus 30% of the lethality of Variola major). Speaking of smallpox, they usually mean its severe form, since the variant of the disease caused by Variola minor was recorded only in West Africa and, in isolated cases, in America.
In the cells of the skin and mucous membranes, the virus forms clusters called Guarnieri bodies. The variola virus is resistant to temperature fluctuations, retains its vital activity for a long time at low temperatures, and lives at room temperature for about two years. It tolerates drying well, in this form it is resistant to adverse factors, for example, it can withstand boiling for 10 minutes. Resistant to antibiotics, inactivated within 1 hour with 3% chloramine solution.
The source of human infection can only be a sick person or a virus culture brought in from the outside. A person is a source of infection from the very onset of the disease and until the crusts formed after the abscesses dry out completely. Presumably, the patient is already contagious during the incubation period, before the first signs of the disease appear, and with the onset of the rash, he becomes highly infectious.
Smallpox rash is a breeding ground for the virus, it is released as soon as vesicles and pustules break. Therefore, the more rashes, the more dangerous the patient is to others. The contents of smallpox elements are mixed with the saliva and sputum of patients and spread during coughing and sneezing. It can also serve as a source of infection, remaining on the linen and other things of the sick.
The most significant way of spreading the virus is through airborne droplets, since the virus can be spread through the air over long distances, far outside the room where the patient is. Since the virus is resistant to desiccation, the infection can also be transmitted by airborne dust, i.e. carried by dust. You can also get infected through damaged skin, things, by direct contact, insects, including flies, can transmit the virus.
Forms of the disease
| The form | a brief description of |
| Classic | The most common type (90%), characterized by extensive rashes on the skin and mucous membranes, is difficult. |
| Hemorrhagic, or black pox | There is generalized erythema, skin and mucous hemorrhages, an admixture of blood is contained in the smallpox elements - darkening, the blood gives a black color to the skin and mucous membranes. The current is heavy. |
| Malignant | It is characterized by the appearance on the skin of extensive flat lesions without the formation of pustules. The course is severe, in a few survivors, desquamation (exfoliation) of the epidermis is observed. |
| Alastrim | A mild form caused by Variola minor. Symptoms are similar to the classic form, but less pronounced, the rash is not so intense, the course is mild or moderate. |
| Varioloid | A mild form, sometimes developing in vaccinated people. It is characterized by a long incubation period, mild malaise, short-term fever or its absence, absence of rashes or rare rashes without the formation of pustules. Resolution occurs in two weeks, no scars remain on the skin. |
More rare forms of the disease:
- heavy: confluent (Variola confluens); smallpox purpura (Purpura variolosae);
- lungs: no rash (Variola sine exanthemata); with slight rash (Variola afebris).
Disease stages
During natural smallpox, the following stages are distinguished:
- Incubation period. Lasts from 5 to 17 days, more often 8-14. This is the time from infection until the first symptoms appear, during which the virus multiplies in the body.
- Prodromal period. Lasts 2-3 days. The first, still nonspecific symptoms of the disease appear (fever, headache, back pain, severe malaise, abdominal pain and vomiting).
- The onset of the disease. It is characterized by the appearance of rashes that look like spots and bumps (maculopapular rash) on the mucous membranes and skin.
- It's high. Rashes on the mucous membranes evolve into ulcers, then the skin elements change, turning first into vesicles (vesicles), and then into round dense pustules (vesicles with purulent contents).
- Exodus. In a favorable case, in the second or third week, the pustules begin to dry out, becoming covered with crusts. Intoxication decreases, the crusts at the site of the pustules fall off, leaving deep scars. In case of unfavorable development, massive inflammation and intoxication lead to multiple organ failure, shock and death.
Symptoms
In the classic version, the onset of the disease is acute: chills, severe malaise, aching muscles and joints, intense pain in the lumbar region, fever up to 40-41 ° C. Then the temperature drops to subfebrile values and remains at this level for 3-4 days. At this time, rashes appear on the face, scalp, hands, interdigital spaces of the hands and feet. On the second day from the onset of the rash, the rash spreads to the trunk, then to the limbs. Initially, the rash looks like small (up to 3 mm in diameter) rounded pink spots, which turn into papules after 5-6 hours.
After 1-2 days, papules are transformed into vesicles with turbid contents. Vesicles are multi-chambered, with a dense bottom, have an oblong shape, surrounded by a strip of hyperemia.
Smallpox eruptions densely cover the skin and mucous membranes
After 1-2 days, the contents of the vesicles become purulent, pustules are formed, the temperature again reaches febrile values, and then high fever accompanies the entire period of existence of the pustules. The bubbles burst, pus flows out of them, causing skin irritation and severe itching. The patient's condition during this period is extremely difficult. All body systems suffer from intoxication, especially the cardiovascular system, itchy skin causes insomnia. Often trying to get rid of it, patients themselves pierce the purulent vesicles, thereby spreading the rash to healthy areas of the skin.
Gradually, the pustules, from which pus has flowed out, become covered with dry brown crusts, which begin to fall off by 3-4 weeks from the onset of the disease, scars remain in their place.
The blood picture is characterized by leukopenia, lymphocytosis, thrombocytopenia.
Diagnostics
Previously, the disease was diagnosed based on the epidemiological situation and the characteristic clinical picture. In the XX century, to confirm the diagnosis, a study of biological material (scraping from papules, the contents of vesicles and pustules) was carried out for a specific antigen of the pathogen, conducting a reaction of counter diffusion and precipitation in the gel. For the purpose of emergency diagnostics, a passive hemagglutination reaction was used. Confirmation of the diagnosis was the result of the study of paired blood sera in the reaction of inhibition of hemagglutination and the detection of the virus using electron microscopy.
Currently, if smallpox is suspected, PCR (polymerase chain reaction) and electron microscopy are recommended.
Smallpox treatment
All patients are subject to strict isolation in a hospital. Etiotropic therapy was carried out with the use of methisazone, but its effectiveness was insignificant. The main treatment is pathogenetic. Since the formation of pustules, they were treated with a cotton swab soaked in a 2% solution of potassium permanganate. The skin of the eyelids was treated with a 1% solution of boric acid, sodium sulfacyl was instilled into the eyes, and tetracycline ointment was applied every other day. The oral mucosa was treated with a 3% sodium tetraborate solution in glycerin. They used antipyretic and analgesic drugs, sleeping pills, carried out vitamin therapy, detoxification and maintenance of the cardiovascular system (intravenous infusion of saline solutions, plasmapheresis). Weakened patients underwent antibiotic therapy to prevent secondary infection.
Throughout the treatment, it is necessary to strictly adhere to the sanitary and hygienic requirements for underwear and bed linen, as well as the room in which the patient stays.
In 2018, an effective drug was created for the effective treatment of smallpox - tecovirimat (TPOXX®). The therapeutic effect is due to the inhibition of the function of the main protein of the viral envelope, which is necessary for the survival of viruses outside the cells. The purpose of the drug is to prevent the possibility of bioterrorism and virus re-induction in natural conditions.
Possible complications and consequences
Complications of smallpox can be encephalitis, meningitis, pneumonia, severe eye damage (keratitis, iritis, panophthalmitis), up to blindness, sepsis. Smallpox usually resulted in irreversible skin defects caused by scars remaining in place of the pustules.
Smallpox can result in significant skin defects and irreversible eye damage.
Forecast
The prognosis for smallpox is always very serious, in 30% of cases the disease ends in death.
Prevention
The main measure of disease prevention is vaccination. Since the eradication of the smallpox virus has been announced, the mandatory vaccination is no longer required for all children. Currently, only people whose occupation is associated with the risk of contracting smallpox (employees of bacteriological laboratories where the viral culture is preserved) are subject to vaccination.
Secondary prevention includes hospitalization and isolation of patients, quarantine measures, isolation of people in contact with patients for 17 days. Medical personnel who come into contact with a patient must wear a double medical uniform, medical masks, and surgical gloves.
Video
We offer for viewing a video on the topic of the article.
Anna Kozlova Medical journalist About the author
Education: Rostov State Medical University, specialty "General Medicine".
The information is generalized and provided for informational purposes only. At the first sign of illness, see your doctor. Self-medication is hazardous to health!
