Guys, do you lose your sex drive when you are sick?

My boyfriend and I have not been dating very long, and he lives about 4 hours away from me. We both have very high sex drives, which makes the long distance difficult, but we usually keep ourselves entertaining through texting, phone calls, and skype. A week ago, he came down with mono, and I have the feeling that his sex drive has plummeted. He also barely texts me now because he is so tired. Is it normal for guys to lose their sex drive when they are sick? Do guys get annoyed if their girlfriends text them too much when they don't feel well? I've been checking in with him about once a day.