Human monkeypox is caused by a virus related to the smallpox virus. In fact, the two viruses are so similar that vaccination against smallpox virus also protects against monkeypox. However, there haven’t been any routine smallpox vaccinations since 1980, and in that time, monkeypox has resurged with a vengeance.
Anne Rimoin of UCLA and an international team of doctors and scientists have been tracking the rate of monkeypox infection in the Democratic Republic of Congo. They compared data gathered between 2006/2007 with data from 1981 to 1986, just after smallpox vaccination ceased. They found a 20-fold increase in human monkeypox in the region.
There have also been a few cases of monkeypox in the US, most notably in 2003, when 93 people were infected from domestic prairie dogs (none died). I should point out here, that despite the name, monkeypox is not exclusively a primate virus. It just happened to be first identified in laboratory monkeys. It actually spreads even more readily through rodents, which makes it a greater danger in most parts of the world.
Although monkeypox is generally milder than smallpox was, it does have a fatality rate of somewhere between 1 and 10%. In comparison, over 80% of infected children died of smallpox, and up to 60% of infected adults.Rimoin and her colleagues believe that the poor infrastructure within the Congo concealed the increase of monkeypox there. That doesn’t bode well for preventing the disease from spreading to the rest of the world, especially since populations are unlikely to resume smallpox vaccination.