Smallpox Virology, Symptoms, Variolation, Vaccination & Eradication

What virus causes smallpox?

Variola virus, an orthopoxvirus.

What is the genetic material of smallpox virus?

Double-stranded DNA.

What are the two principal clinical forms of smallpox?

Variola major and variola minor.

Which form of smallpox is more severe?

Variola major.

What is the mortality rate of variola minor?

Less than 1%.

What approximate fatality rate is associated with variola major?

About 30%.

How does smallpox usually spread?

Close face-to-face respiratory exposure and contact with infected material.

What contaminated objects can spread smallpox?

Clothing and other fomites.

What is the usual incubation period for smallpox?

About 10-12 days.

What are the early symptoms of smallpox?

Fever, malaise, headache, muscle pain, backache, and nausea/vomiting.

Where do the first characteristic lesions of smallpox develop?

Mouth, throat, and tongue.

Where do skin lesions often begin in smallpox?

On the forehead, then spread over the body.

When is smallpox most contagious?

About 7-10 days after the rash appears.

How long can a person remain contagious with smallpox?

Until the rash/scabs have resolved.

What happens to typical smallpox lesions?

They become raised and fluid-filled, then scab over.

What characterizes flat/malignant smallpox?

Slow-maturing, relatively flat lesions; extremely high fatality.

What characterizes hemorrhagic smallpox?

Bleeding beneath skin and into internal tissues; extremely high fatality.

What long-term disabilities can smallpox cause?

Scarring, blindness, and arthritis.

How did smallpox affect the Aztec Empire?

Devastating epidemics weakened populations and armies during Spanish conquest.

What is variolation?

Deliberate exposure to smallpox material to induce immunity; it carried serious risk.

What related infection was important in developing vaccination?

Cowpox.

Who is associated with the first successful modern smallpox vaccination?

Edward Jenner.

Why can vaccination shortly after exposure help?

It may prevent disease or reduce severity if given soon enough.

Which antivirals are FDA-approved for smallpox?

Tecovirimat and brincidofovir.

What is the major public-health achievement associated with smallpox?

Global eradication of naturally occurring smallpox.

What year was the last naturally occurring case of smallpox?

1977.

What organization coordinated the global eradication effort of smallpox?

The World Health Organization.