Overview
Devastating viral disease declared eradicated in 1980, caused by variola virus, with vaccine stockpiles maintained for bioterrorism preparedness.
Overview
Smallpox was a devastating viral disease caused by the variola virus. It was declared eradicated by WHO in 1980 following a successful global vaccination campaign — the first human disease to be eradicated. Vaccine stockpiles are maintained for emergency preparedness.
Overview
Smallpox was one of the most feared diseases in human history, killing an estimated 300 million people in the 20th century alone. The WHO declared global eradication in 1980, following an intensive vaccination and surveillance campaign.\n\nThe variola virus now exists only in two authorized research laboratories (CDC in Atlanta, USA and VECTOR in Novosibirsk, Russia). Routine vaccination ceased in the 1970s–1980s. Smallpox remains a concern as a potential bioterrorism agent, and vaccine stockpiles are maintained by multiple countries.
Emergency Signs
In the extremely unlikely event of a suspected case:\n- febrile illness with characteristic deep, firm vesicular rash (centrifugal distribution, all lesions at same stage)\n- history of potential exposure to variola virus\n- THIS IS A GLOBAL HEALTH EMERGENCY — immediately isolate the patient, notify local and national health authorities, and contact WHO\n- do not attempt to collect specimens without proper biosafety protocols
Detailed Symptoms
Most common signs and symptoms
Historical clinical presentation:\n\nProdrome (2–4 days): High fever (38.5–40.5°C), severe headache, intense backache, malaise, and prostration.\n\nRash phase: Macules (flat spots) → papules (raised bumps) → deep, firm vesicles (fluid-filled blisters) → pustules → crusts. The rash is centrifugal — more prominent on face and extremities than trunk. A key distinguishing feature: all lesions are at the same stage of development simultaneously, unlike chickenpox.
Knowing the symptoms is the first step to a quick response.
Course of Disease
Historical course: incubation 7–19 days (typically 12–14 days). Prodromal phase lasted 2–4 days. Rash appeared and evolved over 2–3 weeks through distinct stages. Scabs separated in 3–4 weeks. The patient was infectious from rash onset until all scabs fell off. Total illness duration was approximately 4–6 weeks.
Diagnosis
How this disease is identified
Diagnosis was based on characteristic clinical features: centrifugal rash distribution, deep firm lesions, all lesions at the same developmental stage. Laboratory confirmation by electron microscopy, PCR, and viral culture of lesion material. Any suspected case of smallpox is a global public health emergency — immediately contact local and national health authorities and WHO.
Treatment
Available treatment methods
No specific antiviral was available historically. Tecovirimat (TPOXX) has been approved based on animal studies for treatment of smallpox. Supportive care includes fluids, pain management, and prevention of secondary bacterial infections. Vaccination within 3–4 days of exposure may prevent disease or reduce its severity. Any suspected case would trigger emergency public health response protocols.
Most cases are effectively treated with early diagnosis.
Prevention Details
How to protect yourself
- the disease is eradicated — routine vaccination is not needed or recommended\n- smallpox vaccines (ACAM2000 and MVA-BN/Jynneos) are stockpiled by multiple governments for emergency use\n- ring vaccination strategy (vaccinating contacts and contacts of contacts) would be the primary response to any outbreak\n- post-exposure vaccination within 3–4 days of exposure can prevent or lessen disease
Preparation is the best protection.
Travel Advice
- no natural travel risk exists — smallpox has been eradicated\n- no routine smallpox vaccination is recommended for any traveler\n- travelers should be aware that smallpox is a recognized bioterrorism concern but the risk is considered extremely low\n- previously vaccinated individuals should not assume continuing protection
How common is it?
Statistics and geographic data
ERADICATED worldwide since 1980. The last natural case occurred in Somalia in 1977. No natural transmission exists anywhere in the world. The only remaining risk is from a hypothetical laboratory accident or deliberate release (bioterrorism). The vast majority of the current world population (born after 1980) has no immunity to smallpox.
Risk Factors
Who is most at risk
- unvaccinated individuals (the vast majority of the current global population)\n- immunocompromised persons (would likely develop more severe disease)\n- relevant only in the context of deliberate release or laboratory accident\n- historically vaccinated individuals (before ~1980) have waning or no remaining immunity
Complications Details
Potential complications
Historical complications included secondary bacterial skin infections, corneal ulceration leading to blindness (approximately 1% of cases), encephalitis (rare), and death (~30% for variola major). Hemorrhagic smallpox was nearly 100% fatal. Survivors typically had severe, permanent pock-mark scarring on the face and body. Arthritis could develop during convalescence.
Recovery & Outlook
Expected outcomes and recovery
Variola major (the more common and severe form) had approximately 30% mortality. Variola minor (alastrim) had approximately 1% mortality. Hemorrhagic and malignant (flat-type) forms were nearly always fatal. Survivors frequently had permanent deep pock-mark scarring and could develop blindness from corneal involvement.