I know we are told the sheep tapeworm is “of little economic importance” and not to worry about it, but these are my thoughts.
Other worms affect the meat, so reduce carcass value, hence have greater economic importance.
Some other worms cause diarrhoea, loss of condition, etc, so economic impact in keeping lambs for longer, feeding for longer.
However, a girt long tapeworm living in your gut must be taking in nutrients, which the farmer / keeper is paying for. Indirect costs and less than getting a leg condemned, but still a financial implication in my book.
However, a few sheep with a few worms that they can handle has to be balanced against the cost and stress of gathering and treating, the meds, using chemicals if that’s an issue for you, etc.
But in this particular instance, it is a concern that the flock were given meds which should have cleared out the tapeworm along with the more significant strongyles ten days previously. Therefore were the meds also not effective for other worms, as well as the tapeworms?