Provide the theme summaries for the following conversation: 

Emma: Guys, are you in Sucre now?
Kate: No, I'm still in Europe :P
Jose: Yes, why?
Emma: I thought about visiting
Marie: nice, come here
Jose: anything happened?
Emma: i think I'm experiencing some little troubles because of the altitude here
Jose: nausea? Headaches?
Emma: yes
Jose: it may be altitude sickness, Sucre is much lower but still quite high above see level
Jose: around 2800m and altitude sickness starts at 2500
Emma: yes, but La Paz is 3600m, I think it'll make a difference
Jose: sure! So come here as soon as possible :)
Emma: I'll check the connections and let you know, thanks!

Summary: 
Emma wants to visit Jose and Marie who are in Sucre because she thinks she's got altitude sickness in La Paz. Kate is still in Europe.