Hi, "consequences of" is followed by a noun, but we can also use a gerund (verb which acts as a noun, usually verb+ing). "us" is unnecessary.

Consider this silly example: 1. "You always eat carrots when I give them to you so why not now? I can't remember you not eating carrots!" If I omitted the "you" in the second sentence, the meaning would change - the sentence would refer to me and not you. Consider this one: 2. "The reason for the people of England voting for that option is still not clear." If I omitted "the people of England", perhaps it would not be clear enough from the context.

OK, just remember that gerunds (taking) and objects (us) must follow prepositions. A simple sentence would be, "WE DON'T TAKE these problems seriously." Add the preposition, and we need to change a few things (mainly because the main verb and the subject are now a different part of the full sentence - it's no longer "we don't take"). "...the deadly consequences of US NOT TAKING these problems seriously." It's a very neat way of putting your ideas in a clear order. :)