Alien Eyes. Alien Affairs, #2

Humanity was a sort of biology experiment conducted for a few million years by the aliens from Tau Ceti 4. The experiment is finished and the human race is no longer necessary, so they sent a team to release a synthetic virus to sterilize us, thus eliminating the species humanely, but the first attempt failed due to bad navigation over Roswell, New Mexico. Seventy years later a second team was on track to complete success until an alien named Deshler got a message from Carrie Player, the only person on earth who could speak his language.
She browbeat, cajoled and sweet-talked the single-minded alien into betraying his mission-at least in part. Now almost the entire human race is infertile, the aliens are on their way home and Carrie Player, head of the CIA's Department of Alien Affairs, is burdened with the task of finding a solution in the vast trove of alien data that Deshler left her. He also left her carrying his offspring who may or may not be the savior of the species.
At the same time, in another bureau of the spy organization, a team races to find the mastermind of a new kind of suicide bomber that is spreading a deadly epidemic in Southern California. No one suspects that their paths are converging.