Red Book says yes, it does cause aplastic crises in pts with chronic
hemolytic diseases.  Also says it causes fetal hydrops and death during pg.
Risk of fetal death is <10% after proven maternal infection in first half
of pg and less in the second half.  Would the reason we don't see many
problems with this is because most of us get it as children?  Red Book says
about 1/2 of adults show serologic evidence of past infection.
Also says humans are the only known host and that a lot of the infections
are asymptomatic or mild with no rash.  It reads like once you have the
infection (or show the rash) you are no longer infectious (unless you are
immune suppressed-they are infectious longer).  Droplet spread - household
contacts get more cases than school contacts, however it is probably the
school aged kid who brings it home!
Sounds to me as if the canine version is different.  Sincerely, Pat in SNJ