I don't want to scaremonger people but all I can say is that if you take a risk be prepared to be the statistic that doesn't get away with it. I was sadly - but i have plenty of friends who ate rare steak throughout their pregnancy and were absolutely fine....my obstetrician made the point to me however that whilst an "official" might be ok with a risk of 1 in x, ask yourself whether you are happy with that becuase the person who writes the guidelines desn't have to live with the consequences. If you are well informed then of course everyone must make their own mind up - it's a very personal decision but pls don't advise others unless you have done the research or spoken to someone who specialises in fetal medicine.
Statistically the risk is low for toxo (I think it's about 1/500 pregnancies in the UK), and it's only dangerous if you catch it for the first time whist pregnant .... i grew up on a farm with 5 cats and the full range of farm animals (cows, sheep, ducks, chickens, horses, dogs). I have lived in france and ate steak tartare regularly before i got pregnant. Yet I was NOT immune to toxoplasmosis and managed to catch it despite living in Central London, zero contacts with cats or soil (although I can't rule out restaurant veg) and I literally ate two mouthfuls of one bloody steak - I was so sick with MS at this stage that i practically lived off crunchy nut cornflakes so trust me, I was stunned to learn that I'd picked it up. I know this all seems ridiculous because SURELY we must all be immune if it's that easy to get, but it seems we are not - I was told that about 25% of us are immune in UK apparently (compared to over 40% in France).
I was prepared to take a lot of the guidelines with a pinch of salt before this happened but knowing what i know now I would just advise people to do a bit of research and make their own minds up - i was incredibly unlucky and apparentyl defy all statistics, but the experience we went through was utter hell and i wouldn't want anyone else to go through it uneccessarily.
If the toxo had passed to my baby in the first trimester the damage would have been pretty devastating - I am told it would have most likely miscarried. I have been more relaxed about things like runny eggs and things that might make me sick (but not harm baby), but when it comes to toxo and listeria, the two things that are known to potentially affect the foetus I've become militant (although I will be eating a massive chunck of stilton as soon as the little darling is out)!
However, like all of these statistics they have to be taken in context - the risk of catching is statiscally low (although I suspect not as low as official stats - if I was having my baby on the NHS the toxo woudl never have been picked up and I woudl probably remain blissfully ignorant as will all other women for whom it doesn't transmit to baby). Also if you do get it, it's only a problem IF it transfers to baby (low risk early pregnancy, high risk later in pregnancy), and if it does transfer to baby, the effects ca be very small if later in pregnancy (but can cause devestating effects early on).
So my advice would be to make sure you are well informed. My obstetrician said he sees at least 2 cases of toxo infections per year (he tests everyone). If you are desperate to eat steak then go and get tested (it cost about £80 which seems cheap for peace of mind)- if you're immune then happy days!!