Do Jaffa REQUIRE a Symbiote?

In Season 1, when we first meet Rya'c, Teal'c wants to stop the ceremony where Rya'c will receive his first symbiote BECAUSE he'll then be forever required to carry one.

Fast forward to Season 7 and the "Birthright" episode and Ishta's warriors are hunting Jaffa and taking their symbiotes implying that the young girls NEED one just to survive.

I know Rya'c was sick and that's why his mother bribed a priest so he could get a symbiote and Teal'c then gave Rya'c his symbiote to keep him alive.

What is your thinking on this? Do Jaffa just not have sufficient medicines, no herd immunity, etc, so they actually do NEED symbiotes (or Tretonin)? Or would the Jaffa just suffer for several generations while they build up their own societal immune systems?