Analysis of ancient skeletons tells us that the smallpox virus first began infecting humans approximately 10,000 years ago. This timing is not random. Rather coincides with the time when humans began living together in villages and cohabitating with newly domesticated livestock. When various mammals live in close proximity they often swap viruses. This process provides the viruses with ample opportunity to commingle their genetic material with that of their hosts, creating mutated strains of the virus. Most of the resulting mutations render the virus non-functional, but a select few can create deadly super bugs.

Archeological evidence suggests that smallpox began as a relatively mild virus before mutating into an efficient killer, with mortality rates that exceeded 30%. As early as 1,000 B.C. in India, inoculation procedures were attempted to protect people from smallpox.(1) Early techniques consisted of scraping smallpox scabs off of sufferers, grinding them up into a power, and having a healthy person sniff the power into their nose. While this sometimes resulted in deadly infections, those who survived the process were far less likely to contract smallpox in future epidemics.

The next big advance in fighting smallpox occurred in England in 1796, when Dr. Edward Jenner observed that people who had suffered from cowpox developed immunity to smallpox. He began injecting healthy people with liquid from cowpox lesions and found that this protected the recipients. Dr. Jenner was responsible for coining the term vaccination, based on the Latin word vacca meaning “from cows”. Over the next 183 years, with improvements in vaccines and steadfast global cooperation, smallpox was eradicated in 1979 and vaccinations ceased in 1980.

The smallpox vaccinations that those of us born before 1980 received also protect us against a broad range of other pox viruses, including cowpox and monkey pox. Since humans are the only host for the smallpox virus, vaccinating humans wiped out small pox.(2) Cowpox and monkey pox are far less particular about hosts than smallpox and infect a wide variety of mammals, particularly rodents. Since people born after 1980 were not vaccinated for smallpox they also lack immunity to these other pox viruses.

As you therefore might expect, infection rates of humans with cowpox and monkey pox have been steadily rising since 1980. While cowpox symptoms are generally limited to mild skin rashes, some strains of monkey pox have mortality rates approaching 10%. Furthermore, both cowpox and monkey pox are evolving in ways that have allowed them to begin infecting a wider array of mammals and to become more efficient in transferring from human to human. A 2003 outbreak of monkey pox occurred in the U.S. when rodents imported from Ghana infected a population of pet prairie dogs, which then infected their owners, who then infected their friends and relatives.

The current situation with monkey pox is quite similar to that for smallpox 10,000 years ago, a somewhat mild virus with many opportunities to spread and mutate. Of particular concern is evidence that pox viruses often undergo potentially harmful mutations when a sufferer is simultaneously infected with a retrovirus such as HIV. As luck would have it, sub-Saharan Africa, which seems to get the short end of the stick on nearly everything, has the world’s highest infection rates for both monkey pox and HIV. If no public health actions are taken, the number of people and regions affected will grow, giving monkey pox and its brother and sister viruses more and more chances to mutate into a modern-day “smallpox”. Since, unlike smallpox, monkey pox infects many different mammals, it is effectively impossible to eradicate. This suggests to me that at some point in the not-too-distant future, vaccination against pox viruses will resume. In the mean time, before you or anyone you know born after 1980 is travelling internationally, particularly if the destination is the Democratic Republic of the Congo, check the CDC and WHO websites regarding the incidence rate of monkey pox. The smallpox vaccine remains available and will provide the necessary protection.

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(1) This story touches on a theme I have addressed several times in the past. Our forebears were just as smart as we; they just had less accumulated knowledge to work with.
(2) Both the United States and Russia maintain frozen samples under heavy guard. Many have suggested that these samples be destroyed. The argument to keep them centers around the possible need to use them to make vaccine in the future.