Taterapox virus, for example, is another (remote) possibility—but it is not known to occur in humans, and some scholars consider it to be “cryptic,” as it is rarely detected even in its presumptive primary (rodent) hosts.29,30 When adjusting for the age of smallpox vaccination, the observed IgG seropositivity (6.3% in persons aged ≤ 37 years) was much lower than previous measures in Ghana (37%)20 and northern Republic of the Congo (49.1%),31 but higher than that reported in Sierra Leone (1.3%).32 Notably, one participant was IgM positive, indicating a recent exposure to an OPXV. Here, CD40LG is linked to smallpox.