All of the frogs sold by can be placed directly into the vivarium when you receive them. We feel that your frogs will do best for you placed directly into a finished tank that is properly set up for them. We spot check for ranavirus and chytrid in our frogs (even though we have never had a positive test, or had frogs that exhibited symptoms of these diseases). All dart frogs we sell are bred here, and kept in a clean, healthy environment while they are being raised up for sale.
The idea behind quarantining frogs is to ensure that any illnesses or parasites they may be carrying can be identified. Frogs may not show symptoms (or even test positive) for potential diseases or parasites they have at any given time, so 2-3 tests over a period of months may be needed to diagnose any problems, then follow-up tests after treatment are needed to confirm your frog is 'clean'. Unless the full testing, treating, and retesting schedule is followed through to completion, quarantining is largely pointless, and often offers a false sense of security.
In order to detect ranavirus or chytrid, samples will have to be swabbed from your frogs, then mailed off to a company that can run a PCR test (we use and recommend Research Associates Laboratory, which can be contacted via their website or at (972) 960-2221).
Parasites are generally detected via a fecal sample, which can be done by a qualified local vet (check out ARAV.org for exotics vets located near you). Dr. David Frye, DVM often runs fecals for people who mail samples in - he can be contacted via the Milan Area Animal Hospital's website or by phone at 734-439-CARE (2273). Most parasites that occur in captive bred frogs are located in the frog's intestinal tract. The amount of parasites excreted by the animal (and thus detectable by a fecal analysis) may vary, and it is possible for a frog to carry parasites but test negative.
Many exotics vets, most notably Dr. Kevin Wright, DVM, now believe that low levels of some parasites in frogs is perfectly natural (as frogs in the wild generally contain low levels of many different parasites. These parasites only seem to cause problems with the frogs when the frogs are stressed (ie from being kept improperly, rough handling, being maintained at improper temperatures or humidity, etc), and may actually serve beneficial purposes in healthy frogs (some pinworms in tortoises actually help those animals to gain more nutrients from their diets - the same may be true for frogs).