Infollowing an historic global campaign of surveillance and vaccination, the World Health Assembly declared smallpox eradicated — the only infectious disease to achieve this distinction. The Smallpox Eradication Programme - SEP WHO The period since eradication has been defined by a lengthy and complex debate focussed on the destruction of the last remaining stocks of live variola virus. Inat the 49th WHA, Member States decided to have this stock destroyed in Juneonly to allow for temporary retention for further research in subsequent years.
Species Variola virus Smallpox was caused by infection with variola virus, which belongs to the genus Orthopoxvirusthe family Poxviridae and subfamily chordopoxvirinae. Evolution The date of the appearance of smallpox is not settled.
It most likely evolved from a terrestrial African rodent virus between 68, and 16, years ago. One clade was the variola major strains the more clinically severe form of smallpox which spread from Asia between and 1, years ago. A second clade included both alastrim minor a phenotypically mild smallpox described from the American continents and isolates from West Africa which diverged from an ancestral strain between 1, and 6, years before present.
This clade further diverged into two subclades at least years ago. If the mutation rate is assumed to be similar to that of the herpesvirusesthe divergence date between variola from Taterapox has been estimated to be 50, years ago.
Better estimates of mutation rates in these viruses are needed. Diversification of strains only occurred in the 18th and 19th centuries. Four orthopoxviruses cause infection in humans: Variola virus infects only humans in nature, although primates and other animals have been infected in a laboratory setting.
Vaccinia, cowpox, and monkeypox viruses can infect both humans and other animals in nature. Poxviruses are unique among DNA viruses in that they replicate in the cytoplasm of the cell rather than in the nucleus.
In order to replicate, poxviruses produce a variety of specialized proteins not produced by other DNA virusesthe most important of which is a viral-associated DNA-dependent RNA polymerase.
Both enveloped and unenveloped virions are infectious. The viral envelope is made of modified Golgi membranes containing viral-specific polypeptides, including hemagglutinin. It was transmitted from one person to another primarily through prolonged face-to-face contact with an infected person, usually within a distance of 1.
Rarely, smallpox was spread by virus carried in the air in enclosed settings such as buildings, buses, and trains.
The English aristocrat and writer Lady Mary Wortley Montagu () is today remembered particularly for her letters from Turkey, an early example of a secular work by a Western woman about the Muslim Orient. Smallpox. Smallpox History Smallpox is an infectious (air-borne) and contagious disease that is caused by a virus occurring in two variants; variola minor and variola major (CDC, ). Smallpox is an acute contagious disease caused by the variola virus, a member of the orthopoxvirus family. It was one of the world's most devastating diseases known to humanity. The last known natural case was in Somalia in
The virus can be transmitted throughout the course of the illness, but this happened most frequently during the first week of the rash, when most of the skin lesions were intact. The overall rate of infection was also affected by the short duration of the infectious stage.
In temperate areas, the number of smallpox infections was highest during the winter and spring. In tropical areas, seasonal variation was less evident and the disease was present throughout the year.
Vaccination immunity declined over time and was probably lost within thirty years. Microscopicallypoxviruses produce characteristic cytoplasmic inclusions, the most important of which are known as Guarnieri bodiesand are the sites of viral replication.
Guarnieri bodies are readily identified in skin biopsies stained with hematoxylin and eosin, and appear as pink blobs. They are found in virtually all poxvirus infections but the absence of Guarnieri bodies could not be used to rule out smallpox.
All orthopoxviruses exhibit identical brick-shaped virions by electron microscopy. Definitive laboratory identification of variola virus involved growing the virus on chorioallantoic membrane part of a chicken embryo and examining the resulting pock lesions under defined temperature conditions.
Serologic tests and enzyme linked immunosorbent assays ELISAwhich measured variola virus-specific immunoglobulin and antigen were also developed to assist in the diagnosis of infection. Chickenpox and smallpox could be distinguished by several methods.
Unlike smallpox, chickenpox does not usually affect the palms and soles. Additionally, chickenpox pustules are of varying size due to variations in the timing of pustule eruption: A variety of laboratory methods were available for detecting chickenpox in evaluation of suspected smallpox cases.
In contrast to the rash in smallpox, the rash in chickenpox occurred mostly on the torso, spreading less to the limbs.Nov 23, · Bioterrorism: Smallpox Smallpox is a highly infectious and fatal disease caused by the Variola virus.
It causes extremely painful pustules to sprout across the entire body. Spread from human to human, it has since been eradicated from the world through the efforts of the World Health Organization.
An attempt at a new analysis of the mortality caused by smallpox and of the advantages of inoculation to prevent ity Daniel Bernoulli analysis of the mortality caused by smallpox and of the advantages of inoculation to prevent it.’ In Smallpox Inoculation: An Eighteenth Century Mathe-.
Smallpox is an acute contagious disease caused by the variola virus, a member of the orthopoxvirus family. It was one of the world's most devastating diseases known to humanity.
The last known natural case was in Somalia in The smallpox pandemic of – may have been responsible for the sudden decline in unvaccinated and vaccinated cases over 30 years of age (figure 5) (a sensitivity analysis that excluded all cases over 30 years of age led to estimates of µ = percent per year and φ = percent per year, which correspond to even longer protection.
Health Condition: In , there were approximately 10 to 15 million cases of smallpox in more than 50 countries, and to 2 million people died of the disease each year. Smallpox has been eradicated from the globe, with no new cases reported since The English aristocrat and writer Lady Mary Wortley Montagu () is today remembered particularly for her letters from Turkey, an early example of a secular work by a Western woman about the Muslim Orient.