Variolavirus

Variolavirus is a species of virus belonging to the genus Orthopoxvirus within the family Poxviridae. It is the causative agent of smallpox, a highly contagious and historically devastating disease that was eradicated globally in 1980. Variolavirus is a large, enveloped, double-stranded DNA virus. Its structure is complex, featuring an outer membrane, a core containing the viral genome, and lateral bodies.

The virus is transmitted primarily through respiratory droplets expelled by an infected individual, such as during coughing or sneezing. Close contact with infected individuals or contaminated materials can also lead to transmission. The incubation period typically ranges from 7 to 17 days, followed by a prodromal phase of fever and malaise. This is then succeeded by the characteristic rash, which progresses through macules, papules, vesicles, pustules, and finally scabs. The disease was often fatal, with mortality rates varying historically but generally around 30%.

Variolavirus exists in several forms, including the common and often severe "ordinary" form, the more severe "hemorrhagic" and "malignant variola" forms, and milder forms like "alastrim" or "paralytica." Natural infection conferred lifelong immunity. Efforts to combat smallpox relied heavily on vaccination, with the development of the smallpox vaccine in the late 18th century marking a significant milestone. Global vaccination campaigns, coordinated by the World Health Organization, ultimately led to the official declaration of smallpox eradication in 1980, a major public health triumph. Despite eradication, samples of Variolavirus are still maintained in secure laboratories for research purposes.

---