Doctronic

Understanding Smallpox: Symptoms, Causes, and Prevention

Jerome Albert Ecker | MD

Medically reviewed by Jerome Albert Ecker | MD, Assistant Professor of Medicine, Duke University - Durham, NC on December 31st, 2023.

Key Takeaways

  • The variola virus killed approximately 300 million people in the 20th century alone, with a 30% fatality rate for variola major and 1% for variola minor.
  • Symptoms begin 10-12 days after exposure with high fever (101-104°F), severe headache, and backache, followed by a characteristic rash that progresses from flat red spots to fluid-filled then pus-filled blisters over 2-3 weeks.
  • Transmission occurs through respiratory droplets during close face-to-face contact (within 6 feet) or contact with contaminated materials, with patients most contagious during the first week of rash appearance.
  • The last naturally occurring case was recorded in Somalia in 1977, with global eradication achieved through an intensive WHO vaccination campaign using the vaccinia virus vaccine.
  • Tecovirimat (TPOXX) is FDA-approved for treatment and must be given within 4 days of symptom onset, while the ACAM2000 vaccine can prevent infection if given within 3-4 days of exposure.

Smallpox is a serious infectious disease caused by the variola virus. Although it has been eradicated since 1980, it is important to understand its history, symptoms, causes, and prevention methods.

What is Smallpox?

Smallpox is a highly contagious viral disease that once claimed the lives of millions of people worldwide. It is characterized by flu-like symptoms and a distinctive rash that spreads across the body. The World Health Organization (WHO) declared smallpox eradicated in 1980, thanks to global vaccination efforts.

Smallpox Symptoms

Smallpox symptoms typically appear 10-12 days after exposure to the virus. Early symptoms include:

  • High fever

  • Fatigue

  • Headache

  • Body aches

  • Vomiting

About 2 days after the initial symptoms, a flat red rash develops, which quickly turns into raised bumps filled with clear liquid. These bumps eventually become pus-filled blisters that crust over and form scabs, which fall off over the next 3-4 weeks, often leaving permanent scars.

Understanding Smallpox: Symptoms, Causes, and Prevention

Causes of Smallpox

Smallpox is caused by the variola virus, which has two main forms: variola major and variola minor. Variola major is the more dangerous form, with a mortality rate of about 30%, while variola minor is less deadly, with a mortality rate of around 1%.

How Smallpox Spreads

Smallpox is spread from person to person through close contact, such as:

  • Breathing in the virus during face-to-face contact with an infected person

  • Handling the clothes or bedding of an infected person

  • Coming into contact with an infected person's body fluids

Smallpox Prevention and Treatment

The best way to prevent smallpox is through vaccination. The smallpox vaccine, developed by English doctor Edward Jenner in 1796, uses the vaccinia virus to help the body build immunity against the variola virus. Routine smallpox vaccinations stopped in most countries by 1972, but governments maintain emergency stockpiles in case of an outbreak.

If a smallpox case is diagnosed, antiviral drugs such as tecovirimat (TPOXX) and brincidofovir (Tembexa) can be used to treat the disease. Supportive care, such as managing fever and preventing secondary infections, is also crucial.

The Importance of Smallpox Awareness

Although smallpox has been eradicated, it is essential to maintain awareness of the disease and its potential as a public health threat. Factors such as weakened immune systems and uncertain long-term vaccine effectiveness could impact the severity of a potential outbreak. The eradication of smallpox is an important example of the power of an effective vaccine on a disease with clear symptoms and no animal reservoir, augmented by unprecedented global cooperation to facilitate mass immunization. By understanding the history, symptoms, causes, and prevention methods of smallpox, we can be better prepared to respond to any future threats.

For more information on smallpox, visit the Centers for Disease Control and Prevention (CDC) website.

The Bottom Line

While eradicated globally, understanding this historically devastating disease remains vital for bioterrorism preparedness and public health response. Post-exposure vaccination within 3-4 days can still prevent infection, making rapid diagnosis critical. If you're concerned about unusual symptoms or have questions about infectious diseases, Doctronic can provide quick medical guidance.

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