The Haemovores were vampire-like creatures who evolved from humans and lived on Earth in the year 500,000. The haemovores appeared in Earth of the past only when Fenric had taken the very last Haemovore back in time to the 10th century and let her loose; when this Ancient Haemovore fed on humans, those humans became more haemovores, etc.
the Doctor defeated Fenric and the Haemovores in 1943, but new haemovores might still exist which somehow survived the events of that story, or other haemovores might be brought back from the year 500,000 as the Ancient Haemovore was.
Of course, Haemovores are just one type of vampire in the Doctor Who universe; there are also plenty of other vampires out there in the Whoniverse which might pop up again sometime. One episode from the upcoming season is called Vampires in Venice, and it is not yet known if the vampires in that story will be one of these types of vampire or something new entirely.
Thanks, I hope they do appear in Series 5 of the revived Doctor Who.