The thing about Listeria is that it is a very dangerous organism to unborn babies, which is why people go overboard in terms of prevention.
It isn't that rare, but if food is kept refrigerated properly it is unlikely to cause a problem. Listeria is unusual in that it happily grows at a temp range of 4-10 deg C, which means that cook-chill foods and foods that you don't cook (such as lettuce) are all potential carriers. Washing your lettuce should reduce the risk of catching Listeria from it.
If your pate is fresh, has been kept properly refrigerated etc., it is unlikely to be a problem - but there is that tiny risk. same with raw eggs.
Upwind - here are some contents of Vitamin A in certain foods (micrograms/100g food)
Halibut liver oil 900,000
Cod liver oil 18,000
Lamb?s liver 30,500
Sardines (canned) 7
Butter 1,000
Eggs boiled 190
Cheddar cheese 363
Whole milk 100ml 30
Fortified margarine 33
lamb's liver will be generally representative of liver, although not accurately - however, you can see that it is a couple of orders of magnitude higher in vitamin A than eggs.