Understanding Monkeypox and How Outbreaks Spread

The global eradication of smallpox more than 40 years ago was one of the greatest achievements in public-health history, vanquishing a cause of death, blindness and disfigurement that had plagued humanity for at least 3,000 years. On the downside, it also led to the end of a global vaccination program that provided protection against other pox viruses. That includes monkeypox, which has been spilling over from its animal hosts to infect humans in West and Central Africa with increasing frequency since the 1970s. Now monkeypox has sparked unprecedented outbreaks worldwide, demonstrating again how readily an infectious agent in one region can mushroom into a global emergency.

Monkeypox is a misnomer that results from the fact that it was discovered at the Statens Serum Institut in Copenhagen in 1958, when outbreaks of a pox-like disease occurred in monkeys kept for research. While monkeys are susceptible to it, just like humans are, they aren’t the source. The virus belongs to the Orthopoxvirus genus, which includes the variola virus, the cause of smallpox; and cowpox virus, also called vaccinia, which is used in the smallpox vaccine. Monkeypox is less contagious than smallpox and the symptoms are generally milder. About 30% of smallpox patients died, while the fatality rate for monkeypox in recent years has been about 3% to 6%, according to the World Health Organization. Death in outbreaks this year has been rare.