ALASTRIM (portug. alastrar — to cover, cover; synonym: variola minor, milk pox, Kaffir pox, amaas) — the acute infectious disease which is a kind of natural smallpox, differing from it in an easy current and smaller contageousness. In 1929 at the International sanitary conference it was decided to combine smallpox and And. under the patrimonial name variola, distinguishing them on a specific name: variola major (natural smallpox) and variola minor (alastrim).
In 19 and the beginning of 20 century. And. it was widespread in the countries of South America and Africa. As a result of a drift large epidemics were observed in Australia (1913), on the Azores (1923) and in countries of Western Europe (1919 — 1921). In the territory of the USSR this disease was not registered.
Etiology. An infestant is the virus A., belonging to the poxviridae family, the sort poxvirus. Because of proximity to a virus of natural smallpox and lack of until recently reliable criteria for differentiation not all researchers allocate a virus A. in an independent look. Virus A. it is for the first time allocated in pure growth in 1935 [Torres and Teysheyra (S. M. of Torres, J. Page of Teixeira)] on chorion-allantoisnoy to a membrane of the developing chicken germ.
On an antigenic structure virus A. it is similar to viruses of natural smallpox and a vaccine. At introduction on chorion-allantoisnuyu the membrane of chicken germs is caused by education on its surface of the dot, acting over the level of healthy fabric round pockmarks of white color. The infected chicken germs by the time of opening (72 — 96 hour), remain live. In cultures of cells a virus A. causes cytopathic effect and development of a phenomenon of hemadsorption. Pathogenicity for animals is expressed poorly: virus A. patogenen only for monkeys and newborn white mice. In infected with a virus A. cells (fig.) cytoplasmic inclusions (Guarniyeri's little body) form. Virus A. has very weak hemagglutinating activity.
Epidemiology. A source of an infection at And. the sick person is. Virus A., as well as the virus of natural smallpox, is transmitted in the drop way. Infection can occur as well through the infected objects.
Clinical picture. The incubation interval proceeds from 8 to 17 days. The beginning of a disease is characterized by bystry rise in temperature, a headache and pain in a sacrum, prodromal rash is observed seldom, an enanthesis and mucous membranes begins on 2 — the 5th day of a disease. Papular and bubble rash acts as hl. obr. on a face and extremities. Bubbles have no impression in the center, are located superficially; at falling away of crusts of hems does not remain. Only the depigmentation within several months is observed.
The development cycle of skin defeats occurs quicker, than at natural smallpox. Repeated rise in temperature, as a rule, does not happen in view of absence or weak expressiveness of suppurative process. Main distinctive features of clinic and epidemiology And. are: disease, rather easy in comparison with natural smallpox, even at not vaccinated against smallpox, a lethality is not higher than 1%; a contagious index at And. is much lower, than at natural smallpox. Had natural smallpox gain quite durable, most likely, lifelong immunity to And.
Diagnosis. At laboratory diagnosis And. morphological, serological and biological methods are used. Morphological methods are based on detection of a virus by means of light and a submicroscopy. In the first case in painted (most often silvering) a smear from skin defeats determine presence of virions of a virus A by M. A. Morozov., accurately contrasting round little bodies (Pashen's little body) which are coming to light in the form of. During the use of more effective method — a submicroscopy — the diagnosis is made on the basis of smallpox group of a form, characteristic of viruses, and the sizes of virions of a virus A.
From serological methods precipitation tests in agar gel, indirect hemagglutination (detection of smallpox antigen in material from patients) and hemagglutination-inhibition reaction have practical value (identification of antibodies in blood serum of the patient).
Morphological and serological methods, however, do not allow to differentiate a virus A. from other viruses of smallpox group. Differentiation of a virus A. from viruses of a vaccine, vaccinia and smallpox of monkeys it is provided with use of biological methods (allocation of a virus on a horionallantoisny membrane of 12-day chicken germs and infection of culture of cells). In the first case the diagnosis is made on the basis of type of pockmarks, in the second — on morphology of plaques and terms of their development. Differentiation And. from a virus of natural smallpox it is carried out by definition of distinctions in temperature limit of development of defeats in chicken germs and in cultures of cells. For a virus A. it makes respectively 37,5 and 37,0 °. Other differential and diagnostic reception is definition of accumulation of a virus in a liver of the infected chicken embryos: virus A. the virus of natural smallpox collects in a liver less, than.
Treatment — symptomatic.
Prevention. Patients And. or persons, suspicious on this disease, are subject to immediate isolation. The persons which were in direct communication with the patient A., shall be imparted by a smallpox vaccine regardless of the previous vaccination or a revaccination and are isolated for 17 days from the moment of the last communication with the patient. The persons which were not in direct contact are subject to immediate vaccination or a revaccination and medical observation at home within 17 days.
A question of scales of smallpox vaccination (see) in the settlement where the patient A was revealed., decides on site responsible for actions in the center-faced depending on an epidemic situation and a condition of antismallpox immunity of the population. Vaccination protects from a disease And. more reliably and for more long term, than at natural smallpox.
See also Smallpox natural .
Bibliography: The multivolume guide to microbiology, clinic and epidemiology of infectious diseases, under the editorship of N. N. Zhukov-Verezhnikov, t. 8, page 471, M., 1966; The Guide to laboratory diagnosis of viral and rickettsial diseases, under the editorship of P.F. Zdrodovsky and M. I. Sokolov, page 297, M., 1965.
I. D. Ladny; S. S. Marennikova (vir.).