Smallpox natural

The natural smallpox (variola vera) - an acute infectious disease characterized by typical fever, phenomena of intoxication, the development of original-papular pustular rash on the skin and mucous membranes.
Dissemination. In the absence of specific preventive measures, the disease takes a wide spread, accompanied by high rates of mortality (10-30% and above). Smallpox natural is logged on all continents. According to who, in the last 4 years identified the following number of patients (table. 1).
The spread of smallpox in the 1960 - 1984
According to preliminary data, all over the world with 1.1. on H 1965 registered 35 222 cases of smallpox natural.
The first place by the number of diseases and mortality (30%, 1963) is Asia. India, Indonesia, Pakistan, Afghanistan, etc. remain endemic O. N. America 96% of diseases O.N. observed in Brazil. Widespread O. N. in recent years and in some African countries (Congo - Kinshasa, Tanzania, Zambia, Nigeria, Malawi and others). In several countries as a result of extensive vaccination in recent years, the number of patients has decreased sharply (Iran, Burma). In Chile, Bolivia and Paraguay in the last 3 years cases O. N. not registered. Diseases O. N. wearing invasive character, I marked in Europe. In 1960-1963 registered in Poland - 131 disease, UK - 70, Germany - 43, Sweden - 27, Spain - 17, Belgium-1, "USSR - 46, Switzerland - 1. L.
Etiology. The smallpox virus was first described in 1906, when the fluid out of lesions were detected particles oval in shape (Fig. 1), named after the discoverer of them researcher calves Paschen. The virion size 240-260 X 150 MMK consists of nucleoid surrounded by three membranes, and contains DNA; poorly agglutinate erythrocytes some breeds of chickens. Variola virus, breeding in sensitive cells, causes in the cytoplasm and rarely in the nucleus of cells education inclusions - Taurus Guarnieri, varying in form and quantity. When the virus O. N. newborn mice and suckers can be fatal encephalitis. In monkeys develop a mild form of generalized disorder of the type of varioloid person. Rabbits receptive when corneal and skin infections.
In the first case after 36-48 hours. develops pox keratitis, in the second - soft expressed, not asserway infiltration. The virus O. N. multiplies in the cells of the chorion-allantoina shell chicken embryos in her small, dense, separated from the surrounding tissues whitish plaques (pock marks). Multiplies it also in cells in vitro. In primary and human cultures (from humans and apes) variola virus causes a pronounced cytopathic effect with the formation of simpleton and Taurus Guarnieri.
The most sensitive cells of epithelial origin.
Cells infected with the virus have strong haemadsorbing properties.
The causative agent of smallpox belongs among highly resistant viruses. In obtained from the patient (slomannyh) crusts of the virus at room temperature in the dark persists over a year, on the world - more than 2,5 months. The virus O. N. for many days is saved in the dust of the room, on the domestic utensils, linen. Killed by heating: when temperature 60 OC for 30 minutes at temperature 55 degrees - in 1 hour at temperature 70 to 100 OC after 1-5 minutes; at 2 degrees from - 20 up to -70° remain viable for more than 5 years; glycerin contained in the darkness, when temperature 0-5 OC for over a year. 3% solution of chloramine destroys the virus within 3 hours, 5%- in 2 hours, activated bleach in 1% concentration and 7% of phenol - for 1 hour. Alcohol, ether, acetone, hydrochloric acid (1 : 1000) neutralize the virus within 30 minutes Ultraviolet rays destroy the virus during irradiation over b hour.
Epidemiology. The source of infection of smallpox is a sick man. It is considered potentially contagious during the whole period of the disease from the prodromov till full recovery (the fall of crusts). The timing and degree of epidemiological danger of a patient are determined by the individual phases of the pathogenesis of - the beginning of viraemia, introduction of the virus into the internal organs, the formation of anantam and akzente. The greatest gain popularity is observed, as a rule, on 7-9 th day of illness, at the height of development of anantam. Epidemiological role of patients with severe infectious process is determined by the allocation of massive doses of the pathogen. However, of even greater importance patients with mild form of smallpox, because in them is difficult diagnosis of the disease, especially in cases of invasive outbreaks. Evolving in the course of the disease tissue and humoral immunity leads to quick cleansing of the organism recover from the pathogen. Any forms of carriage (reconvaleszentov, healthy) with O. N. does not exist. Susceptibility to O. N. is universal.

In natural conditions are observed smallpox in many species of animals and birds. Activators of a smallpox various animals are in the nearest genetic connection. It is established that the vaccine viruses (cowpox), Ovine (sheep), equine (horses), asinine (Asses), oviny (birds), and so on, and smallpox are a Separate species, included into the group Poxvirus (19.53). All of them are strictly specific. The exception is the smallpox virus of cows that many sensitive animals. When infected with this virus human survivors are immune to smallpox. The mad cow disease smallpox, as a rule, is of a professional nature: the infection occurs during milking and care of animals.
Distribution O. N. carried out in various ways (drip, dust, through objects, flies, and so on). Of primary importance droplet infection. Lesions of the mucous membranes of the patient, covered with a thin layer of the epithelium, easy materirals. A large amount of virus in the early stages of the disease gets in the saliva and mucus nasopharynx (3-9 day of the disease). In future, when sharp respiratory movements (talking, coughing, sneezing) virus in aerosol form is excreted into the environment, polluting the air around the patient. The continued presence of the virus in the elements of smallpox exanthema (up to 17-th day of illness or longer) also leads to infection of the external environment (in mechanical destruction of pustules, apostasy scales and crusts and so on). Infected people may be stool and urine of the patient. The resistance to drying and its long-term preservation of the objects of the external environment determine the probability of transmission dust infection through contaminated objects (clothes patient, toys, furniture and so on), less frequently flies.
The epidemic process of smallpox has two forms, a permanent high incidence (in the endemic countries of this infection) and individual invasive outbreaks. Endemic foci O. N. observed in countries where the population is poorly covered by specific vaccination and are not carried out in full other anti-epidemic measures. In these countries, high morbidity among children, often expressed its seasonal rises associated with more favorable conditions of transmission in closed premises in a cold season.
Alien outbreak of smallpox occur in areas free from O. N., in cases of importation of the disease from countries where it still is endemic. Over the last 15 years registered more than 40 relatively large invasive outbreaks in the cities of Europe and North America (table 2).

Table 2. Alien outbreak of smallpox in Europe and America (1945 -1960)
Country The number of flashes The number of diseases
Total 40 1113

In recent years in several countries decreased attention to opepreveria, and some of them (England) is still not compulsory vaccination. At the same time one of the most important conditions invasive outbreaks O. N., dissemination and significant mortality in them is the availability of enough high population immunity. The spread of diseases also contribute to the late identification and isolation of the first patients. In the distribution of cases by age, professional groups, seasonality, etc., to mark any regular patterns is not possible.