Poxviruses Explained: Smallpox, Mpox, Cowpox, Buffalopox & More
Student & Competitive Exam Edition: Learn the Poxviridae family, important Orthopoxviruses, vaccination history, smallpox eradication, the latest mpox status, and common exam traps in one easy chapter.
APPSC UPSC SSC RRB Banking Police SI / Constable General Science
📝 Introduction
Poxviruses are large DNA viruses belonging to the family Poxviridae. Several medically and historically important viruses belong to this family. The best-known example is variola virus, which caused smallpox. Other important members include mpox virus, cowpox virus, vaccinia virus, camelpox virus and viruses associated with buffalopox and rabbitpox.
Poxviruses are especially important for competitive examinations because their history connects infectious disease, vaccination, zoonoses, public health and disease eradication. Edward Jenner’s vaccination experiment in 1796 ultimately opened the way for the global campaign that eliminated smallpox.
Chickenpox is NOT caused by a poxvirus. Chickenpox is caused by varicella-zoster virus (VZV), which belongs to the herpesvirus group. The word “pox” in the name does not make chickenpox a member of the Poxviridae family.
🔬 Poxvirus Basics
Poxviridae
Double-stranded DNA (dsDNA)
Orthopoxvirus
Smallpox – caused by variola virus
Smallpox eradication endorsed by WHO in 1980
Mpox – caused by monkeypox virus (MPXV)
📊 Important Poxviruses at a Glance
| Disease / Virus | Virus / Group | Main Host / Relevance | High-Yield Exam Fact |
|---|---|---|---|
| Smallpox | Variola virus – Orthopoxvirus | Humans | WHO declared smallpox eradicated in 1980. |
| Mpox | Monkeypox virus (MPXV) – Orthopoxvirus | Zoonotic; humans and animal reservoirs | Virus discovered in 1958; first human case documented in DRC in 1970. |
| Cowpox | Cowpox virus – Orthopoxvirus | Rodents are important natural reservoirs; cows/humans may be infected | Historically linked to Jenner’s 1796 vaccination experiment. |
| Vaccinia | Vaccinia virus – Orthopoxvirus | Vaccine virus | Vaccinia, not variola, became the virus used in modern smallpox vaccines. |
| Buffalopox | Buffalopox virus, closely related to vaccinia | Buffaloes; zoonotic infections can occur | First recorded in Lahore in undivided India in 1934. |
| Camelpox | Camelpox virus – Orthopoxvirus | Dromedary and Bactrian camels | Recognized by WOAH as an important camel disease. |
| Horsepox | Horsepox-related Orthopoxvirus / vaccinia lineage | Historical and evolutionary importance | Possible relationship to historical smallpox vaccine strains remains an important research topic. |
| Rabbitpox | Vaccinia-related Orthopoxvirus | Laboratory rabbits | Recognized in laboratory rabbit outbreaks in the early 20th century; useful as a research model. |
1️⃣ Smallpox – The Eradicated Human Disease
Smallpox
Cause: Variola virus
Historical existence: WHO states that smallpox existed for at least 3,000 years.
Major form: Variola major historically had a case-fatality rate of around 30%.
Smallpox was one of the most devastating infectious diseases in human history. It caused fever followed by a characteristic rash and pustular lesions, and survivors could be left with severe scarring.
Edward Jenner and Vaccination
In 1796, English physician Edward Jenner used material associated with cowpox to protect against smallpox. This experiment became a landmark in the history of vaccination. Over time, vaccinia virus replaced cowpox virus as the virus used in smallpox vaccines.
Edward Jenner → 1796 → Smallpox vaccination → historically associated with cowpox.
How Smallpox Was Eradicated
- 1967: WHO intensified the global smallpox eradication programme.
- 1977: Last known naturally transmitted case occurred in Somalia.
- 1979: Global eradication was certified.
- 8 May 1980: The World Health Assembly endorsed the declaration of global eradication.
2️⃣ Mpox – Formerly Called Monkeypox
Mpox
Cause: Monkeypox virus (MPXV)
Virus first discovered: 1958 in captive monkeys
First documented human case: 1970 in the Democratic Republic of the Congo (then Zaire)
The disease historically known as monkeypox is now called mpox. WHO recommended the new disease name in November 2022. The virus itself continues to be called monkeypox virus (MPXV).
Mpox can spread through close contact with an infected person, contaminated materials, or infected animals. The disease can produce fever, swollen lymph nodes and a characteristic skin or mucosal rash, although presentation can vary.
Disease name: Mpox
Virus name: Monkeypox virus (MPXV)
Family: Poxviridae
Genus: Orthopoxvirus
🌍 Mpox – Current Status as of August 2026
WHO ended the 2024 mpox Public Health Emergency of International Concern (PHEIC) on 5 September 2025. However, this did not mean that mpox disappeared. WHO continues to monitor it as an active multi-country outbreak.
WHO’s 31 July 2026 external situation report recorded 63,692 confirmed cases and 256 deaths reported globally from 1 January 2025 to 30 June 2026, across 105 reporting countries.
3️⃣ Cowpox – The Jenner Connection
Cowpox
Cause: Cowpox virus
Importance: Closely associated with the origin of vaccination against smallpox.
Cowpox is a zoonotic orthopoxvirus infection. Although the name suggests cattle are the natural source, modern research indicates that rodents are important natural reservoirs, while cats, cows and humans may become infected.
Jenner’s famous vaccination work used material from a cowpox lesion. However, students should know that the virus eventually used in the global smallpox vaccination programme was vaccinia virus, which is genetically distinct from cowpox virus.
4️⃣ Vaccinia Virus – The Smallpox Vaccine Virus
Vaccinia Virus
Importance: Became the principal virus used for vaccination against smallpox.
Vaccinia virus is closely related to other orthopoxviruses but is genetically distinct from both variola and cowpox viruses. Vaccinia-based vaccines played a central role in the successful eradication of smallpox.
The exact evolutionary origin of vaccinia remains historically complex. Research has explored possible relationships with cowpox and horsepox-related viruses.
Variola virus → causes smallpox.
Vaccinia virus → used as the smallpox vaccine virus.
These two are related, but they are not the same virus.
5️⃣ Buffalopox – Important Indian Connection
Buffalopox
First recorded: Lahore, undivided India – 1934
Hosts: Mainly buffaloes; humans in close contact can also be infected.
Buffalopox is particularly relevant for Indian competitive examinations. Scientific reviews record the disease in buffaloes in the Indian subcontinent from 1934. It can cause skin lesions in buffaloes and may reduce milk production. Zoonotic infections have also been documented among people in close contact with infected animals.
6️⃣ Camelpox – Disease of Camels
Camelpox
Cause: Camelpox virus
Main susceptible animals: Dromedary and Bactrian camels
Camelpox is an orthopoxvirus disease of camels. It is recognized by the World Organisation for Animal Health (WOAH). Rather than memorising a doubtful single “first found in Asia in the 1970s” claim, students should focus on the reliable exam fact that camelpox is caused by an Orthopoxvirus and primarily affects camels.
7️⃣ Horsepox – Important but Historically Complex
Horsepox
Importance: Closely related to the vaccinia lineage and relevant to research on the historical origin of smallpox vaccines.
Older accounts sometimes state that horsepox directly “created” the smallpox vaccine. Modern historical and genetic research shows a more complicated picture. Cowpox and horsepox-like material were both used historically, and some old vaccine strains show close genetic relationships to horsepox. However, the exact origin of modern vaccinia virus remains unresolved.
8️⃣ Rabbitpox – A Research Model
Rabbitpox
Historical recognition: Laboratory rabbit outbreaks were described in the early 20th century.
Rabbitpox is a severe disease of laboratory rabbits associated with a vaccinia-related orthopoxvirus. Historical outbreaks in research rabbit colonies made it useful as an experimental model for studying systemic orthopoxvirus infection and evaluating vaccines and antiviral approaches.
🐔 Chickenpox – Why It Is NOT a Poxvirus
VZV is a herpesvirus, not a member of Poxviridae.
Primary VZV infection → Chickenpox (varicella)
Reactivation of latent VZV → Shingles (herpes zoster)
CDC records that VZV was isolated in cell culture in 1954 by Thomas Weller. The live attenuated varicella vaccine was developed in Japan in the 1970s. This is a useful comparison because competitive exams may test whether students confuse disease names ending in “pox”.
📌 Smallpox vs Mpox vs Chickenpox
| Feature | Smallpox | Mpox | Chickenpox |
|---|---|---|---|
| Virus | Variola virus | Monkeypox virus (MPXV) | Varicella-zoster virus (VZV) |
| Virus Family | Poxviridae | Poxviridae | Herpesviridae |
| Genus / Group | Orthopoxvirus | Orthopoxvirus | Varicellovirus |
| Status | Eradicated | Still circulating | Still occurs; vaccine-preventable |
| Major Exam Date | Eradicated – 1980 | First human case – 1970 | VZV isolated – 1954 |
🎯 Key Facts for Competitive Exams
| S.No. | Exam Fact | Correct Answer |
|---|---|---|
| 1 | Smallpox causative agent | Variola virus |
| 2 | Smallpox virus family | Poxviridae |
| 3 | Edward Jenner’s vaccination year | 1796 |
| 4 | WHO intensified smallpox eradication programme | 1967 |
| 5 | Last natural smallpox case | Somalia, 1977 |
| 6 | Smallpox eradication endorsed | 1980 |
| 7 | Mpox virus discovered | 1958 |
| 8 | First human mpox case | DRC (then Zaire), 1970 |
| 9 | WHO recommended “mpox” disease name | 2022 |
| 10 | Buffalopox first recorded | Lahore, undivided India – 1934 |
| 11 | Chickenpox causative agent | Varicella-zoster virus |
| 12 | Modern smallpox vaccine virus | Vaccinia virus |
Variola → Smallpox | MPXV → Mpox | Vaccinia → Vaccine | VZV → Chickenpox | Buffalopox → India 1934
⚠️ Do Not Confuse – Exam Traps
- Chickenpox ≠ Poxvirus. It is caused by a herpesvirus.
- Smallpox virus ≠ vaccine virus. Variola causes disease; vaccinia is used for vaccination.
- Mpox disease name ≠ virus renamed. Disease is called mpox, while the virus remains monkeypox virus (MPXV).
- 1958 ≠ first human mpox case. Virus was discovered in captive monkeys in 1958; first documented human case was in 1970.
- Smallpox eradication: last natural case 1977; global eradication certified 1979 and endorsed by the World Health Assembly in 1980.
- Cowpox ≠ vaccinia. They are distinct orthopoxviruses.
📝 10 Important MCQs
✅ Show Answer
Answer: B – Variola virus. Variola virus belongs to the Orthopoxvirus group in the family Poxviridae.
✅ Show Answer
Answer: C – Chickenpox. Chickenpox is caused by varicella-zoster virus, a herpesvirus.
✅ Show Answer
Answer: B – 1796.
✅ Show Answer
Answer: D – 1980. The last known naturally transmitted case occurred in Somalia in 1977.
✅ Show Answer
Answer: A – DRC in 1970. The country was then known as Zaire.
✅ Show Answer
Answer: C – 2022.
✅ Show Answer
Answer: B – Vaccinia virus.
✅ Show Answer
Answer: B – Lahore, undivided India.
✅ Show Answer
Answer: C – Shingles (herpes zoster).
✅ Show Answer
Answer: B – Somalia.
📌 One-Minute Quick Revision
- Poxviridae = family of large dsDNA viruses.
- Smallpox = Variola virus.
- Mpox = Monkeypox virus (MPXV).
- Chickenpox = Varicella-zoster virus; NOT Poxviridae.
- Jenner = 1796 vaccination landmark.
- WHO intensified smallpox eradication = 1967.
- Last natural smallpox case = Somalia, 1977.
- Smallpox eradication = 1980.
- First human mpox case = DRC, 1970.
- WHO disease name “mpox” = 2022.
- Vaccinia = smallpox vaccine virus.
- Buffalopox = first recorded in Lahore, undivided India, 1934.
❓ Frequently Asked Questions
1. Is chickenpox a poxvirus disease?
No. Chickenpox is caused by varicella-zoster virus (VZV), which is a herpesvirus.
2. What virus causes smallpox?
Smallpox was caused by variola virus, an Orthopoxvirus belonging to the Poxviridae family.
3. Is monkeypox now called mpox?
Yes. WHO recommended “mpox” as the disease name in 2022. The virus itself is still called monkeypox virus (MPXV).
4. Is mpox still a WHO PHEIC in 2026?
No. WHO determined on 5 September 2025 that the 2024 upsurge no longer constituted a Public Health Emergency of International Concern. However, mpox continues to circulate and WHO continues international surveillance and response activities.
5. Which virus was used to eradicate smallpox through vaccination?
Vaccinia virus became the principal virus used in smallpox vaccines during the modern vaccination era.
6. What is the Indian exam connection with buffalopox?
Buffalopox was first recorded in Lahore in undivided India in 1934 and remains an important zoonotic and veterinary poxvirus topic.
📚 Reliable Sources for Students
- World Health Organization (WHO) – Smallpox.
- WHO – History of Smallpox Vaccination.
- WHO – Recommendation of the name Mpox.
- WHO – Mpox current information and situation reports.
- WHO – Mpox External Situation Report No. 68, 31 July 2026.
- CDC – Varicella (Chickenpox) and VZV.
- WOAH – Camelpox.
- NCBI / Peer-reviewed Review – Buffalopox Virus.
🧠 Conclusion
Poxviruses are an excellent example of how infectious-disease biology connects with world history and public health. Smallpox demonstrated that a deadly human infectious disease could be eradicated through vaccination and surveillance. Mpox remains an important contemporary zoonotic disease, while cowpox, vaccinia, buffalopox, camelpox, horsepox and rabbitpox are useful for understanding poxvirus evolution, animal-human transmission and vaccine science.
Variola → Smallpox → Eradicated 1980 | MPXV → Mpox → Human case 1970 | Vaccinia → Vaccine | VZV → Chickenpox, NOT Poxvirus | Buffalopox → Lahore 1934.
Educational revision content for competitive examinations. Current mpox information updated using WHO material available through 31 July 2026. Updated on 20 August 2026.
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