what exactly is a strigoi

also why does the Master have to change hosts?

I can't answer all of your questions, but I'll tell you what I can and then give you some advice.

The Master has to change to a new body when his old one is damaged/killed or when it's no longer useful for what he's doing at that time. The last time they found him and thought that they had killed him, they actually did cut off his head, but they didn't know that if you missed destroying the crimson (red) worm in him, he could still re-generate and live on. So, as of S02E08, we don't know what the Master looks like right now - male/female, old/young, black/brown/yellow/white, tall/short? We don't know.

Can't tell you anything really solid about the Ancients - clearly, they are very old and there is only a small number of them. See Advice at the end of this comment.

Yes, the worms cause the infection when they get under your skin. The worms do not live for very long outside of a body.

If I try to give you information about Strigoi right now, it might not be what you'd learn from this show because I've been watching movies about Strigoi.

The most important thing to remember is that when you ask how vampires behave, what they can do, what can kill them, etc. and you're wanting information that is relevant to this show, The Strain, you have to be certain that the answers are coming from this show and not "Z Nation," "Vampire's Academy," "The Vampire's Diaries," or any other movie or TV series (unless it has been said in your show of interest - our vampires are exactly like the vampires in the "X X" TV series.

Note of advice: I get surprised every time I encounter someone online asking such questions because they are using the greatest source of information available to most people! Every thing that you asked, is relatively easy to find the answer for online or in the show itself. Now, I will say that knowing many people might be watching these shows/movies on their smart phones and now having close to a year's experience with a smart phone - it's sometimes miserable to try and get good information from your smart phone. As a disabled, senior citizen I find my eyes crossing and then glazing over (and that's not a good look on anyone!) if I try to read very much from my phone screen. As for people who are watching on Apple or Google TV or through Roku or whatever other devices there are, I don't know if you have to have a computer to be here on IMDb asking these questions or not. What I am saying is that if you are using a computer, there is a universe of information available to you right at the tips of your fingers (you do have to learn how to discern what is reliable info and what should be ignored, but that's not all that hard and should increase your common sense). I was preparing to do a bit of research just to get the name of a movie I watched about 5 years ago about Strigoi when I decided that I didn't really want to read much online tonight just to help someone who probably has the same access as I do. You need to practice writing searches that are effective and it would probably help if you click on the "Advanced" link for your particular search engine so you can learn the particular operators that are accepted by it and check out any examples they offer.

I'm sure that someone will come along and provide all your answers right here, so you can just continue what you've been doing and expect others to provide the info to you, but is that what you really want to do? It's so much better when we know how to do things ourselves when we want something. One of the surprises I discovered when I was learning about the ancient computers we had in the dark ages of the late 70's and early 80's is that you learn more than you ever set out to learn when you make mistakes. No one should fear making a mistake on a computer. As you struggle to, first, find where the error is, and then search, search and search some more to find how to fix the problem, you'll look back and discover that you learned so much relevant information while you were trying to fix just one simple problem! By the time your head hits the pillow that night, you can feel as though you just finished a week long course. The more information you have, the better you will get in whatever subject you're pursuing at the time. And, most importantly, you will feel a nice, warm fuzzy feeling of self-confidence - knowing that the next time you need help, you can provide it to yourself.

Here's a couple of hints for your to pursue: There is a movie called "Strigoi" (2008 or 2009) available to view online. Strigoi and Moroi were explained in "Vampire Academy," but I don't know if those Strigoi are the same as the ones used in "The Strain." There is more than one Wiki type article that uses Strigoi as the subject. If you do just one carefully constructed search (Google, Bing, Yahoo, etc.) you will find links to all the items I used in this hint. As a beginner, I'd expect to have to do at least two searches, but you might discover that this is your thing and you have a hidden talent for it!

Have a great week,

Shauna & Ms. Phoebe, my God-given Happy Pill, loving, loyal & dedicated Staffordshire Bull Terrier, 11+ years and still learning and working

Strigoi are Italian vampires that broke off from the Boyardee and Ragu families back in the 1500s.

Later on, they merged with the Stromboli and the Ronzoni family, and took over.

Thus they became the Strigoi.