Of course that is true. For those entering the food chain.
As I said, I think, but no doubt you will correct me, that it is not an absolute requirement for those kept by the hunter, themselves, or another member of the Hunting Party, their family, or to be gifted, not sold, to friends for their personal consumption. Never to be sold . This is not "entering the food chain" There is no chain. It is straight from hunter to table.
Just as we may do the same with deer, small game, birds etc. without even being a Trained Hunter, qualified to prepare them, and examine them for disease. Even nowadays I'm not sure that all the Wild Game Meat Hygiene qualifications even touch upon tritch. testing of Boar, for example. The Lantra Level 2 qualification certainly appears not to, mentioning only deer.
Lantra Awards - Level 2 Award in Wild Game Meat Hygiene
Hunters doing this are not Food Business Operators. We are exempt from this, thanks to various bits of legislation.
https://www.legislation.gov.uk/uksi/2016/868/pdfs/uksiem_20160868_en.pdf
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Again, at the risk of repeating myself,
https://www.food.gov.uk/sites/default/files/media/document/trichinellatesting.pdf
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Finally, an explanation of the lifecycle of the nematode. Most likely route involves rats>pigs>humans, though other animals that we eat can have it too, But pigs are the most likely, since they'll eat anything. And rats, since they will also eat each other.