Hello, my name is***** and I have over 20 years of experience as a veterinarian. I understand that you are concerned about seeing a worm coming from her anus.
I don't think this is a hookworm as dog hookworms are microscopic.
There are two types of worms that dogs can have that are large enough to see with the naked eye.
One is a roundworm. They are long white/tan spaghetti worms. They are transmitted by walking through stool contaminated with eggs and then licking their paws. They are the most common type of worms in puppies. They are easily treated with a medication called pyrantel, which is available in many pet stores.
Here is a link that shows roundworms: http://www.justanswer.com/view_image.aspx?href=http://t1.gstatic.com/images?q=tbn:ANd9GcQuh6uRNNoweY_ICBq59xaEfgXptVRZk6m5CdM0UVXARuwRTisOjg
The other type of worms that are easily seen are tapeworms. These look like small, grains of rice type worms. These are picked up by eating an infected flea. They can be passed with stool or crawl out of the anus on their own. Sometimes we see them stuck on the hair coat around the anus. Here is a link to a picture of tapeworms:
If your pup had fleas before that is likely where they came from. If you don't get rid of all the fleas they will continue to be a problem as she will continue to reinfest herself. They are easily treated with a medication called Praziquantal which is available online and at many pet stores.
Unless people eat stool they cannot catch most worms from dogs, children are more susceptible to getting worms because they aren't careful hand washers and are more likely to put their hands in their mouths after playing in dirt where eggs may be deposited. So make sure that if you have children they should wash their hands well after playing with your puppy and before eating.
Because tapeworms carried by dogs need an intermediate host (the flea), unless people eat fleas they cannot get the worm. The egg packets passed by dogs are not infective to people.
Worms rarely make a puppy sick, unless there are an overwhelming number of them.
Certainly she may be very quiet because she is in a new home with all sorts of new things to get used to. But we need to watch her very, very closely because she may truly be sick.
If she isn't eating the same food as the hone she came from fed that can also lead to stomach upset, loose stools and lethargy.
Let me know if you have any further questions.