What causes smallpox

What Causes Smallpox?

Smallpox is a serious, contagious disease that was caused by the variola virus. This virus belongs to the genus Orthopoxvirus, which is part of the Poxviridae family of viruses. While there are several types of poxviruses, the variola virus is the specific agent responsible for the devastating illness known as smallpox. Thankfully, smallpox was eradicated globally in 1980 after a successful vaccination campaign led by the World Health Organization (WHO).

Understanding the Variola Virus

The variola virus is a large, brick-shaped DNA virus. It exists in several forms, with two main clinical types historically recognized: variola major and variola minor. Variola major was the more severe and common form, causing a higher mortality rate, while variola minor was less severe and rarely fatal.

How the Variola Virus Spreads

The variola virus is highly contagious and spreads from person to person. The primary mode of transmission is through respiratory droplets. When an infected person coughs, sneezes, or talks, they release tiny droplets containing the virus into the air. These droplets can be inhaled by people in close proximity, leading to infection.

Beyond respiratory droplets, smallpox can also spread through direct contact with the infectious rash, scabs, or bodily fluids of an infected person. For example, touching the sores of someone with smallpox or sharing personal items like bedding or clothing that have been contaminated with the virus can lead to transmission.

In rare cases, smallpox could also spread through aerosols, which are smaller particles that can remain suspended in the air for longer periods and travel further distances. This mode of transmission was less common but contributed to the virus's ability to spread rapidly in crowded conditions.

Historical Context and Eradication

Smallpox has plagued humanity for centuries, causing an estimated 300 to 500 million deaths in the 20th century alone. Its distinctive rash, which progresses from spots to fluid-filled blisters and then to pustules before scabbing over, was a hallmark of the disease. Survivors often bore permanent scars and sometimes blindness.

The development of the smallpox vaccine by Edward Jenner in the late 18th century was a monumental breakthrough. However, it wasn't until the mid-20th century that a concerted global effort, spearheaded by the WHO, began the systematic eradication of the disease. Through widespread vaccination campaigns and vigilant surveillance, the last known natural case of smallpox occurred in 1977, and the world was declared free of the disease in 1980.

Why Understanding Smallpox Remains Important

Although smallpox is now extinct in the wild, the variola virus still exists in secure laboratory facilities for research purposes. The possibility of its deliberate release as a bioweapon or accidental escape from a lab, however remote, necessitates continued vigilance and preparedness. Understanding how the virus spreads and the disease it causes is crucial for public health authorities to respond effectively should such an event ever occur.

The success of smallpox eradication serves as a powerful testament to what can be achieved through international cooperation and scientific advancement in combating infectious diseases. It provides valuable lessons for tackling other global health challenges.