yes, it can take 3-4 weeks to see signs -- but you've been contagious this whole time -- so without knowing it you could be spreading it - what a wonderful disease
But they say that 80-90% of the population has had it & didn't even know it -- like I said earlier - we can all get it & think we have a bad case of the flew. Some cases of mono are very mild others are absolutely horrid & hang on for mths. Even milder cases can carry symptoms for mths, where you just tire out more easily, are more susceptible to things, etc.