Smallpox variola minor

The global eradication program was effective, eliminating natural smallpox infections from the world. The last case occurred in the United States in 1949. The United States discontinued routine smallpox vaccinations in 1972. Five years later, in 1977, international efforts eradicated smallpox from the world. The last case of Variola Major was in Bangladesh in 1975 the last Variola Minor case occurred in Somalia in 1977. There are no animal reservoirs or vectors for smallpox. 

Smallpox (also known by the Latin names Variola or Variola vera) is a highly contagious disease unique to humans. The causative virus has two variants called Variola major and Variola minor. V. major is the more deadly form, with a typical mortality of 20-40% of those infected. The other type, V. minor, only kills 1% of its victims. Many survivors are left blind in one or both eyes from corneal ulcerations, and persistent skin scarring—pockmarks—is nearly universal. Smallpox was responsible for an estimated 300-500 million deaths in the twentieth century. In 1967, for instance, still prevailing worldwide in spite of massive inoculations, the WHO estimated that 15 million people contracted the disease and that 2 million died in that year [245]. 

Smallpox is caused by the virus variola. It is a highly infectious disease. The most severe form of the virus, variola major can cause death if the victim is not treated and has not been vaccinated before exposure. The other type of the virus, variola minor, however, produces a molder form of smallpox. Outbreak of this disease in the past has caused many deaths worldwide. Today, this disease is almost eradicated from most parts of the world. 

Variola minor, the milder form of the smallpox does not produce high fever and the sores on the skin are smaller and fewer. Smallpox can be distinguished from other viral rashes such as chickenpox and allergic dermatitis. Variola major sores develop all at once into the same stage everywhere on the body. In case of chickenpox while some sores may be forming others may be drying out. 

For the past century, two distinct types of smallpox have been recognized. Variola major, the prototypical disease, was prevalent in Asia and parts of Africa. Variola minor, or alastrim, was distinguished by milder systemic toxicity and more diminutive pox lesions (Figure 27-2). Variola minor was found in Africa, South America, and Europe before the eradication of endemic disease, and caused 1% mortality in unvaccinated victims. 

Fig. 27-2. Variola minor in an unvaccinated woman 12 days after onset of rash. The facial lesions (a) are more sparse and evolve more rapidly than those on the arms (b) or legs (c). Reprinted with permission from Fenner F, Henderson DA, Arita I, Jezek Z, Ladnyi ID. Smallpox and Its Eradication. Geneva, Switzerland World Health Organization 1988 36. Photographs by I. Arita.

Wolff HL, Croon JAB. Survival of smallpox virus (variola minor) in natural circumstances. Bull WHO. 1968 38 492 493. 

There are two clinical forms of smallpox. Variola major is the severe and most common form of smallpox, with a more extensive rash and higher fever. There are four types of variola major smallpox ordinary (the most frequent type, accounting for 90% or more of cases) modified (mild and occurring in previously vaccinated persons) flat and hemorrhagic (both rare and very severe). Historically, variola major has an overall fatality rate of about 30% however, flat and hemorrhagic smallpox usually are fatal. Variola minor is a less common presentation of smallpox, and a much less severe disease, with death rates historically of 1 % or le.ss. 

Smallpox 7-17 days 4 weeks Variola minor <1% Variola major 20-50% YES (high) Very Stable... 

The means to achieve this apparently unattainable goal had their origins in the centuries-old observation that those who were actively involved with dairy cows rarely contracted smallpox. Jenner s seminal contribution was to establish that this was linked to their contraction of cowpox, a relatively minor variola-induced disease that caused cows to become moderately unwell and produced eruptions on their udders. Milkmaids and others who milked infected cows usually became unwell with a slight fever and (in Jenner s own words) ... 

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