URIs in fostering.

Are shelters incapable of preventing the spread of URIs to their cats and kittens designated for foster care?  I tried fostering but now have twice received a cat and kittens very sick from upper respiratory infections.  The shelter seems to take it for granted that any animals in their care are exposed to infection.  Clavamox is readily provided, but nothing eliminates the fear I have about losing one of the fosters.  It seems to very unreasonable to just accept the fact these "rescued" animals will be sick.  I am giving up fostering for the shelter in question.  I am familiar with another shelter that is for cats and kittens only.  It is too far away for me to help.  But, I know they do isolate new arrivals to their shelter and also provide bleach trays for staff's shoes.  Why can't my local shelter at least try to implement some precautions?  What do other shelters do?

I had a foster mommy and five foster kittens. One of them had a  respiratory infection. I went to the shelter vet immediately and she got better. My other cats, and the mother cat, didn't get sick. I didn't know this could be so contagious? 

I have a special room in my house for the foster kittens and mommy's, so they are seperated from my own cats. Especially the first few weeks, I was quite strict when I went into the kitty room. I washed my hands before and after, cleaned the room every day (also steaming). 
Perhaps that worked for a bit. There is always a chance that your own cats can get sick because of foster kittens/cats are having some health issues. In my case I try to keep things as clean as possible. And my own cats are vaccinated on time. I don't know what else you can do honestly. 

I think what you described are good measures to implement.  I kept the fosters in a bedroom separate from my own cat, and my cat did not get sick from either set of fosters.  I think it must have been very good luck or? that only one kitten of your set got ill.  The last set I took was a mother cat and her three kittens.  The mother cat was quite sick and was running a fever and dehydrated when we took her to clinic.  She seemed to only get worse although she was now on Clavamox.  At the point I could not get her to eat, and we are talking every food including Gerbers, I gave up.  Plus, the kittens had started to sneeze.  I returned them to the shelter.  My shelter keeps the cats with kittens in cages in an area where there is much coming and going from all areas of the shelter.  I think they should hire someone or assign a particular person to oversee sanitation.  But, instead, they basically just accept the likelihood of infection.  Is there any immunity in that once the cat or kitten has recovered from a URI, the cat or kitten will not be sick again?  Or, is the illness more like having a cold?  Maybe I could foster cats or kittens who have recovered from URIs?  I hope things continue to go well for you.

I had one kitten left. The others were already adopted. Everything went well, all of the 5 kittens never had anything. One day I went to the room to cuddle with mommy and her baby. Her kitten made a very strange sound. At first I thought it was something outside, since it didn't sound really natural. But it was the kitten who had trouble breathing. I took her temperature and it was too high. She got antiobiotics and she did get better. In a few days you could see she felt better and better. Her breathing became normal again. When her antibiotic stopped, she went to her new owner, and she told me she never had URI again.

I don't know much about it though, so I can't help you with your last questions. Hope things will get clear for you soon!