The question of the origin of smallpox, one of the major menaces to humankind, is a constant concern for the scientific community. Smallpox is caused by the agent referred to as the variola virus (VARV), which belongs to the genus Orthopoxvirus. In the last century, smallpox was declared eradicated from the human community; however, the mechanisms responsible for the emergence of new dangerous ...

The mode of infection transmission has profound implications for effective containment by public health interventions. The mode of smallpox transmission was never conclusively established. Although, "respiratory droplet" transmission was generally regarded as the primary mode of transmission, the relative importance of large ballistic droplets and fine particle aerosols that remain suspended in...

Smallpox apparently arose through transfer of variola virus to humans from another animal species. By causing a brief infection that required close contact for transmission and engendered solid immunity, the agent was always vulnerable to simple isolation measures. The high replicative fidelity of the viral DNA polymerase limited variola's ability to adapt to humans and preserved orthopoxviral ...

A proposed new small-animal (rodent) model for studying the pathogenesis and treatment of severe orthopoxvirus infections is described. Thirteen-lined ground squirrels (Spermophilus tridecemlineatus) were infected intraperitoneally and intranasally with monkeypox virus (MPXV). A fulminant illness developed in all animals, and they died 6-9 days after infection. Virus was cultured from the blood...