Not quite true. Once the Goa’uld larva reacehs maturity, it is removed an implanted in a host. A Jaffa is NEVER considered a host. More of a “carrier” or a walking set of luggage, I guess. Anyhow, the Jaffa is then usually given a new larva to nurture to maturity. However, the life-extending process of the Goa’uld does not last forever, and at some point (usually after a couple hundred years) the Jaffa will not be eligible for a new larva, because he will be too weak.