This is the first appearance of Denobulans other than Phlox on the series.
In 2002, Viacom (owners of Paramount and "Enterprise") mandated all its TV series would devote at least one episode to the subject of AIDS awareness. Enterprise's response, aired in early 2003, was this episode. In the 1980's there were many religious zealots who believed that AIDS was God's punishment for male homosexuality, and even secular types referred to AIDS as "The cure, not the disease". Even Archer challenged one of the Vulcans upon learning ot T'pol's being recalled by asking, "is it the disease that you don't approve of, or how she got it?".
The Vulcan PADD is a reuse of the Bajoran PADD from Star Trek: Deep Space Nine (1993), and the scanner is a modified then-modern computer scanner.
One of the written languages seen on Dekendi III is a reuse of the Vidiian written language from Star Trek: Voyager (1995).