Preventative Meds needed for Ecuador

Yellow fever is the main ailment that you must be immunized against.  Malaria will only occur below 5000ft so if you plan to live below this altitude you will need the pills.  If you get all your basic shots, Tetanus, Diphtheria, Polio, Mumps and Measles;  you should be fine.  I can not speak for the US medical system but in Canada I went to my GP and he gave me what was recommended.  He also suggest Hepatitis B and C.
As for getting them here, I was instructed that this was similar to closing the door after the horse has left.  You should be immunized before you get here and may have to show proof of that depending upon where you decide to settle.

In cuenca, malaria is not an issue so prevention pills are not really necessary.  That being said, if you plan to travel to the amazonas or the cost for a period of time, then you should consider it.  You will need a yellow fever shot.  AS well, you should be sure you are current on your hep A and B shots, tetnis shots, and bring a course of doxycyclin for travelers diareah and uti.   Some DOH's say to get a rabis vaccination, but they cost hundreds and as long as you live within 1 hour of a medical centre, you do not need it.  If you are living in the city with ETAPA water, you are good.  It is potable.  I live in the country and we have mountrain well water.  It is still great, i have never had diareah from it, but showering with it can cause UTI's so be aware.

Go to your local Department of health and they can give you an exact list of need vacinations.  If you plan to settle here, you also may need proff of HIV negativitiy so get that at DOH as well as they do those test anonymously (using a secret number) so that way getting healthinsurance later in life will not be affected by that.