IMMUNOLOGY

Detailed explanation-1: -Before smallpox was eradicated, it was a serious infectious disease caused by the variola virus . It was contagious-meaning, it spread from one person to another. People who had smallpox had a fever and a distinctive, progressive skin rash.

Detailed explanation-2: -Smallpox was an infectious disease caused by variola virus (often called smallpox virus) which belongs to the genus Orthopoxvirus.

Detailed explanation-3: -Poxviruses are brick or oval-shaped viruses with large double-stranded DNA genomes. Poxviruses exist throughout the world and cause disease in humans and many other types of animals. Poxvirus infections typically result in the formation of lesions, skin nodules, or disseminated rash.

Detailed explanation-4: -Smallpox, caused by the variola virus, was a highly contagious infectious disease that caused infected individuals to develop a fever and a progressive, disfiguring skin rash. Three of out 10 individuals infected with smallpox died. Many survivors have permanent scars, often on their faces, or were left blind.