strongyloides typically causes problems only with immunocompromised (HTLV, organ transplant, high dose steroids) This can be life threatening in that the larvae are "autoinfective" meaning the infection is self sustaining and very high levels of infestation can be reached. The life cycle is not, however, unique, as some round worms, such as hook and ascarid share the same migratory path which is, the eggs hatch in the intestines, the larvae burrow into the GI tract vessels and disseminate throughout the body. The ones lucky enough to make their way to the lungs then migrate uo the throat or are coughed up and then swallowed to mature into adults, .with the entire process taking up to 1 month or more to complete. Lets not forget either the free living L3 larvae that may reinfect you through the skin as well. This appears to be a very poorly recognized part of the NORMAL parasite life cycle. As most MD's will ask you to take one dose of meds and declare you cured, while unleashing millions of fresh new larvae into their patients body. When they return months later sick again or worse and test positive again, they are declared "REinfected!!!!" I beg to differ. As far as the sputum casts, they need to be examined by LIVE wet mount. Meaning from your mouth to the slide to the eye, PERIOD. From there they can determine which larval form they are dealing with, or simply guess(probably). I hate to sound so jaded in this matter, but in my experiences, most docs have no understanding of the parasite life cycles, the sysmptoms, the meds, how they work or proper dosing. Even visual ID of a nematode or Tapeworm is nearly impossible for many labs and docs. So be prepared if you intend to go that route to educate them every baby step of the way. Anyway... so wet mount is best bet and diagnostic... probably hook works, as ascarids typically create utter havoc. In which case you will need albendazole ( NOT IVERMECTIN OR MEBENDAZOLE) READ extensively before agreeing to any drug regimen.