I read that the actual numbers are probably much higher, due to under reporting. The BBC were saying that it was estimated to be 1300 babies alone.
I agree that it's worrying but I'm not sure what the cause is. I'm sure that environmental factors must play a significant part. I don't think it can only be down to the high infection rate, as their overall deaths per million are lower than ours (though catching up) - though, again, under reporting could be an issue here.