Historical sources suggest that in the 1800s, when smallpox still posed a serious threat, the Micmac native Americans of Nova Scotia treated the disease using a botanical infusion derived from the insectivorous plant Sarracenia purpurea, a species of pitcher plant.

Now, Jeffrey Langland at Arizona State University in Tempe, US, and colleagues have conducted in vitro experiments with the herbal extract and found it inhibits replication of the variola virus, the causative agent behind smallpox.

Although, natural smallpox no longer poses a health threat, there is a remote possibility that unstable states or terrorist groups could have acquired stocks of the virus following the collapse of the Soviet Union, which had developed smallpox as a biological warfare agent.