Understanding Smallpox and Chickenpox & Their Difference

Understanding Smallpox and Chickenpox and Their Differences

Chickenpox and smallpox are conditions caused by viruses that sound similar and may initially exhibit similar symptoms. However, they are two completely different diseases. Understanding the difference is essential to undertake the proper precautionary measures and seek correct medical care. Chickenpox is still a common condition and is not too deadly, whereas smallpox is a severe and fatal condition; however, this virus has been eradicated. If you wonder if smallpox is the same as chickenpox, keep scrolling to understand these diseases and how they differ.

What Is Chickenpox?

What Is Chickenpox?

It is a disease caused by a virus called Varicella Zoster that belongs to the herpes virus family. This DNA virus can cause latent infections. This means that the virus is not eliminated from the body, but the person does not exhibit any clinical manifestations of the virus. The virus usually resides in the cranial nerves and the dorsal nerve root ganglia.

Chickenpox is a painful and highly contagious infection. It is common in children below the age of 10 years and adults who weren’t infected in childhood, for whom it is more severe. After being infected once, the body develops an immunity to this virus, and a second attack is rare.

How Does Chickenpox Spread?

Chickenpox is a highly contagious disease. It transmits through respiratory droplets and direct contact with lesions caused by the disease. However, the scabs, that is, the chickenpox lesions that have crusted, are non-infective. It is more infectious and severe in adults, immunocompromised persons, and pregnant women. After its incubation period of 14-21 days, the initial symptoms of the disease begin to appear.


Post the incubation period, the symptoms of chickenpox begin to appear, starting with rashes and blisters. The symptoms of chickenpox include:

  • Vesicular and pustular eruptions- These are small fluid-filled sacs and pus collections on the top layer of the skin that become painful. They usually appear in the center of the body.
  • Rash with severe itching and fever
  • Loss of appetite and exhaustion
  • Inflammation around the vesicles
  • The rash begins to evolve rapidly
  • Scabs begin to form within 4-7 days of the rash


The disease is treated with Antiviral medication, and the lesions and rash can be soothed with some calamine lotion. Aspirin should not treat the fever during chickenpox as it can severely affect the liver and brain.

What Is SmallPox?

What Is SmallPox?

It is a disease caused by viruses Variola Major and Variola Minor and affects only human beings. It causes a severe rash and fever, followed by vesicular and pastoral eruptions that don’t collapse if you puncture them. However, smallpox has now been eradicated with the use of the live attenuated vaccina virus. The World Health Organisation has a reserve stock of the vaccine for an emergency. The last known naturally occurring case of smallpox was in October 1975.

How Does SmallPox Spread?

Smallpox is transmitted through respiratory droplets released into the air when an infected person sneezes, coughs, or talks. These droplets enter the respiratory tract through these processes. Its incubations period is 7-17 days, after which the symptoms appear.

What Are The Differences Between Smallpox and Chickenpox?

It is normal to wonder if chickenpox and smallpox are related because they have similar names and may exhibit similar symptoms. However, they are different infections that have vastly different outcomes. Here are the differences between chickenpox and smallpox:

1. The Virus

While both smallpox and chickenpox are viral diseases, their causative agents are different. The Variola Major causes smallpox, and Variola Minor virus is commonly referred to as the Pox Virus. In contrast, the Varicella Zoster causes chickenpox and is commonly referred to as the Herpes Virus. However, both viruses are transmitted in the same manner through respiratory droplets of an infected person while coughing, sneezing, or talking that enter into the respiratory tract of a non-infected person.

2. Incubation Period

The incubation period in smallpox or chickenpox is almost similar; however, it is slightly longer in chickenpox. The incubation period for smallpox is 7-17 days, whereas chickenpox symptoms take 14-21 days to develop.

3. Smallpox vs. Chickenpox Vaccine

The vaccine for chickenpox is administered to 1-year old children and a booster dose is given at 4-6 years of age. The smallpox vaccine is no longer administered as the disease has been eradicated. The last people to be vaccinated against smallpox in the US were those born before 1972.

4. Severity

Chickenpox is not a deadly disease and might be more severe in immunocompromised persons and pregnant women. Cases in adulthood may also be severe. However, the disease is not as fatal as smallpox. Before being eradicated, smallpox killed millions — 30 out of every 100 persons infected died from the disease.

5. Symptoms

Smallpox is associated with high fever and malaise, followed by a development of rash. The lesions usually show on the face and extremities, including the palms and soles. They progress at the same time.

Chickenpox is associated with vesicular eruptions and rash, and fever only occurs when there is a fresh crop of the rash. Lesions usually appear on the torso, in clusters and progress successively as they don’t all appear at the same time. They quickly progress and get resolved, turning into non-infective scabs.

6. Isolation Guidelines

Since smallpox is more infectious and deadly, the isolation measures are more stringent but are largely similar to those of chickenpox. Both diseases are transmitted similarly. The Centre for Disease Control recommends contact isolation and airborne isolation, and precautions like wearing gloves and a gown while entering a patient’s room must be adopted. Respiratory protection is not mandatory for healthcare workers tending to chickenpox patients if they are immune.

Here is a Smallpox vs Chickenpox comparison:

Smallpox Chickenpox
Causative Agent Variola Virus (Pox Virus) Varicella Zoster Virus (Herpes Virus)
Incubation Period 7-17 days 14-21 days
Fever prodrome 2-4 days Minimal/none
Distribution on the body Face and extremities. The rash commonly develops on the palms and soles. The torso and sometimes the face and arms. Palms and soles are rarely affected.
Severity Deadly, severe Less deadly
Lesions Appear in the throat or mouth, progress to the face and extremities. They develop at the same time and look alike. Appear first on the face or trunk and develop successively.
Prevalence Eradicated Still prevailing


Chickenpox and smallpox are both highly infectious viral diseases. However, while one is a very real and common threat, the other is eradicated and should not be a cause of worry. It is important to understand the difference between these two conditions so that there is no cause for panic. However, being informed about these diseases and making an accurate diagnosis is helpful. It can lead to adopting the correct cautionary measures so that these viruses can be treated accordingly.

Also Read:

Essentials to Help You Fight Through the Flu Season
Coronavirus Vs Common Flu
Home Remedies for Chickenpox

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