Variola major

Slow-acting, contagious Variola major (smallpox) Flu-like symptoms 12 to 14 days... 

Viral agents, such as the alpha virus that causes Venezuelan equine encephalitis (VEE) or variola major (the causative agent for smallpox). 

This section addresses the viral forms of biological agents that would most likely be considered by terrorists. They include variola major (smallpox), Venezuelan equine encephalitis (encephalitis), Crimean Congo hemorrhagic fever, and Rift Valley hemorrhagic fever. 

Variola major Eruption of skin or rash (begins with... 

Smallpox A (variola major) Orthopoxvirus 7-1 7 days Yes (variola major) Airbo ne High fever, V, HA, backache, skin rash/ lesions 20-25 days Supportive Cidofovir has been shown to be effective in vitro... 

In the variola major type of smallpox, complications in children include blindness, scarring, and bony deformities (Kortepeter, Rowe, Eitzen, 2002). 

Efforts were therefore made towards developing treatment strategies that might generate immunity to infection. An early development was the attempted control of smallpox (variola major) through the deliberate introduction, under the skin of healthy individuals, of material taken from active... 

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. 

The Variola major rash presents in four distinct ways, ordinary, modified, flat, and hemorrhagic. The type of rash presentation is probably associated with the strength of the immune response. Ordinary smallpox is most frequent, whereas the mild modified form, seen primarily in previously vaccinated patients, is uncommon. The most severe presentations, flat and hemorrhagic, are usually fatal but are fortunately rare. Smallpox infection can also occur without a rash. A mild but uncommon variation of variola infection, variola sine eruptione (meaning smallpox without a rash) occurs generally in previously vaccinated people and involves a febrile illness alone. Asymptomatic infections are also possible, yet rare. 

The virus that causes smallpox. Variola major, is a Category A biological threat agent (CDC 2007). It is a double-stranded DNA orthopoxvirus. It is a widely held opinion among infectious disease professionals that, historically, smallpox has been responsible for more deaths than all other infectious diseases combined. After aggressive efforts by the World Health Organization to immunize the world s population, and because the virus is unable to survive for more than a week outside of its only host, humans. Variola was declared eradicated in 1980 (Murray et al. 2005). The smallpox vaccine can prevent or lessen the severity of the disease if administered within 96 h of exposure. The duration of effectiveness of the vaccine used to eradicate smallpox is not known, and there are reported mild to life-threatening risks are associated with the vaccine. Once a victim is symptomatic, medications and intravenous fluid can be administered to make the patient more comfortable, but there are no antivirals available for unvaccinated infected individuals (Henderson et al. 1999). 

There are currently two known stocks of the virus, one at the U.S. Center for Disease Control and Prevention in Atlanta and the other at the State Research Center of Virology and Biotechnology in Koltsovo, Russia. It is widely known that from 1980 until the mid-1990s researchers in the Soviet Union developed a highly virulent strain of Variola major for use as a biological weapon, with a significantly reduced incubation period (Henderson and Fenner 2001). 

Members of the poxvirus, herpesvirus and retrovirus families produce homologues that mimic RCA proteins and are thus able to escape complement action.20 The smallpox virus Variola major causes a serious, virulent infection in humans, while the virus that is used for vaccination against smallpox, vaccinia virus, usually causes only a very mild or even unapparent infection, at least in individuals with an intact immune system. 

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]. 

The Variola major virus is very stable and survives in exudates from patients for many months. The virus is unlikely to survive in dried crusts for more than a year [266]. Yet, it can be preserved in sealed ampules at 4°C for many years, and indefinitely by freeze-drying. This leads to the presumption that the virus still may be preserved alive within bodies of victims buried in permafrost. Much more feasible, however, the practical employment of smallpox virus for bioterrorism purposes is remarkably worrisome and reckoned to be a prime threat. 

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