Variola major virus

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. 

Tick-borne encephalitis complex viruses Variola major virus (smallpox virus)... 

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

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]. 

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. 

Bedson HS, Dumbell KR. Hybrids derived from the viruses of variola major and cowpox. J ffygiene. 1964 62 147— 148. 

Methisazone 6.19) (l-methylisatin-3-thiosemicarbazone, Marboran ) inhibits the multiplication of vaccinia virus in experimental animals. The antiviral action is extraordinarily high. Mice infected intracerebrally with 1000 mean lethal doses (LD50) of vaccinia (cowpox) virus required only 0.5 mg/kg for protection, and only 10 mg/kg was needed for protection against variola major... 

Bacillus anthracis Clostridium botulinum (toxin) Yersinia pestis Vibrio cholerae Francisella tularensis Burkholderia mallei Burkholderia pseudomallei Brucella melitensis Chlamydia psittaci Coxiella burnetti Japanese B encephalitis virus Eastern equine encephalitis virus Variola major... 

The consensus among experts in bioterrorism is that there are two agents most likely to be used by terrorists. The first is Bacillus anthracis, the bacterium that causes anthrax. The second is Variola majors the virus that causes smallpox. In this section, we ll take a brief look at just these two agents. (Chapter 7 has more technical details on these and other biological agents, such as botulism, plague, and tularemia.) But here we ll concentrate on how anthrax and smallpox measure up as threats, and examine the steps that have been taken to respond to their possible use in attacks. 

At present, the only known repositories of smallpox virus are in the United States and the former Soviet Union at the Centers for Disease Control and Prevention in Atlanta, Georgia, and the Russian State Research Center of Virology and Biotechnology near Novosibirsk, in Siberia. Other nations such as North Korea and Iraq may also have viable stocks of Variola major stored at undeclared sites, possibly for use as biological weapons. 

Variola can be a major threat in any biological warfare or bio-terrorism because the virus if highly contagious and the majority of the population all over the world including the USA have no immediate protection. The vaccine is in short supply. The virus is known to have been used in wars in the past. Although banned at present, some countries still have clandestine stockpiles of this agent. 

Smallpox is a disease caused by the variola virus. The disease is transmitted from person to person but is not transmitted by animals or insects. In the past, smallpox caused major epidemics worldwide, but (except for laboratory specimens) the virus wreis eradicated by 1980. There have been no reported cases of smallpox in the world since 1977 (Somalia). The last case in the United States was in 1949. There is a vaccine that is very effective, but immunization of civilians and the military wreis stopped in the 1980s because, out of millions vaccinated, there would... 

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