I too have had similar problems with the chicks that I received on 2/25
Out of the 23 I had left after 7 days (3 died due to shipping and were refunded), and additional 2 have died, and many more are sick (can't stand, having "sakes", and can only eat/drink if brought to the water and held so that they can stand). Here is the breakdown of how the different breeds have been handling it:
1 Buff laced polish male (dead)
2 Black Jersey Giants - both sick, can't stand or walk
3 Delawares - all sick, can stand and walk a little, have severe shakes - these birds showed symptoms first
4 Silver penciled rocks - 1 dead, 3 sick (mild symptoms)
3 partridge cochins 1 very sick, 2 mild symptoms
2 Speckled sussex - both sick (can't stand, have a hard time walking)
2 Golden polish - one healthy, one sick (can't stand or walk)
1 Houdan (mild symptons)
By mild symptoms, I mean that the chcks tend to lay around alot and are not very active. They also continue to stay squated on their haunches when they eat, and only seem to stand straight up when you attempt to grab them or to get water (I have the waterer set up higher to help aviod getting pine shavings or droppings in it). They still eat/drink okay on their own, and do not show the "shaking".
Healthy
3 Buff Oringtons
1 Frizzle Bantum Cochin (mystery chick)
1 Mille Fleur
The birds started showing signs just after turning two weeks old. I have seperated the sickest ones into there own brooder; but I do not have sufficient space to seperate the chicks showing mild symptoms from the healthy ones. I treated the chicks with the sulfa medication for coccidiosis (to make sure that I didn't cause the sickness from not keeping things clean enough), but after 4 days of treatment, none of the chicks showed any improvement. The experience has been very disappionting, considering that this is the first time I have ever had chickens. It is hard to have much enthusiasm or positivity, when you spend a majority of your first experiences with chickens hand feeding sick ones, and watching them slowly get worse (sigh).
Z