The Fascinating Story Behind the Discovery of Chickenpox

Chickenpox, also known as varicella, is a highly contagious viral disease that most commonly affects children. Characterized by an itchy, blister-like rash, chickenpox has likely been around for centuries. But who actually discovered this common childhood illness? The origins of chickenpox have been documented as far back as the 16th century, but the differentiation of chickenpox from smallpox and the identification of the causative virus occurred much later. Let’s take a look at the key milestones in unraveling the mystery behind chickenpox.

Early Documentation of Chickenpox

Even though chickenpox wasn’t recognized as a separate disease until the late 1800s, a rash that looked like chickenpox had been written about as early as the 1500s. In 1546, the Italian doctor Giovanni Filippo Ingrassia (1510–1580) gave the first clear description of the disease, calling it a “papular eruption.”

In 1767, more than 200 years later, English doctor William Heberden (1710–1801) showed that chickenpox was not the same as smallpox, even though he thought they were both types of the same disease.

These early discoveries made it possible to tell the difference between chickenpox and smallpox, which is much worse.

Differentiating Chickenpox from Smallpox

For centuries, chickenpox was conflated with smallpox, a far more dangerous disease with a mortality rate of about 30%. Without a clear differentiation, effective treatment was impossible.

In 1875, Hungarian dermatologist Ferenc von Bókay (1822-1884) built upon Heberden’s earlier observations and definitively showed that herpes zoster (shingles) was different from varicella (chickenpox). In 1888, his compatriot Károly Schuch demonstrated that chickenpox and shingles were caused by the same virus.

These results showed that chickenpox and smallpox were two different diseases. This helped doctors understand and treat chickenpox better.

Discovery of the Causative Virus

Now that chickenpox was established as its own illness, the race was on to identify the underlying virus. Significant progress was made in the early 20th century by several researchers:

• In 1909, American virologist Howard Taylor Ricketts (1871-1910) first suggested an invisible microbe caused chickenpox.

• In 1911, Polish pediatrician Alfred Leszczynski (1868-1939) induced chickenpox in children by injecting fluid from chickenpox blisters.

• In 1920, French physician and bacteriologist Adrien Loir (1862-1937) transmitted chickenpox from infected patients to monkeys, hinting at a virus.

But it wasn’t until the 1950s that the varicella-zoster virus (VZV) was finally isolated:

• In 1952, Thomas Huckle Weller (1915-2008) and John Franklin Enders (1897-1985) cultivated the virus in human tissues.

• In 1954, Weller and colleague Nobel laureate Gertrude Belle Elion (1918-1999) successfully isolated VZV.

This discovery of the virus enabled the later development of the chickenpox vaccine.

Development of the Chickenpox Vaccine

Isolation of the VZV virus paved the way for preventing chickenpox through vaccination. Key innovations included:

• In 1958, Polish virologist József Gedeon Matolcsi László (1908-1993) published the concept of using live, attenuated VZV as a vaccine.

• In the 1970s, Japanese researchers Michiaki Takahashi (1928-2013) and his mentor Dr. Shigeyoshi Uchida attenuated the Oka strain of VZV after passing it through embryonic guinea pig cell cultures.

• In 1974, Takahashi’s team began clinical trials in healthy children using the live attenuated Oka strain vaccine.

• In 1984, the varicella vaccine was approved for widespread use in healthy Japanese children.

• In 1995, the chickenpox vaccine was approved by the U.S. Food and Drug Administration (FDA) for use in children over 12 months and adults.

Thanks to this pioneering research, especially Michiaki Takahashi’s breakthrough live virus vaccine, chickenpox cases declined dramatically in immunized populations.

• Early observations in the 1500s first described the illness
• Differentiation from smallpox began in the 1700s
• The causative virus was finally isolated in the 1950s
• Successful vaccines were developed in the 1970s and approved for widespread use in the 1990s

While chickenpox itself has likely existed for millennia, piecing together its viral origin and preventive vaccine took hundreds of years and findings by researchers from many nations. Thanks to their persistance, what was once a ubiquitous childhood illness is now largely preventable through a simple vaccine. The story of chickenpox demonstrates that significant medical advances are often the result of cumulative knowledge gained slowly but surely over decades or even centuries.