WALTRAUD is currently marked as QUARANTINED.  Ships that land there are subject to destructive decontamination, and passengers aboard those ships may also expect harsh scrutiny.  A miniscule parasitic creature native to Waltraud is capable of controlling the behavior of larger animals.  This "Waltraud worm" is scarcely visible to the naked eye, and can presumably enter a person through any exposed orifice.  Reports from those who have escaped the planet (and passed rigorous examinations) indicate that the most obvious symptoms of infestation are earsplitting screams of pain and/or terror.  These occur both initially and at irregular intervals, perhaps when the victim is able to briefly exert that small degree of autonomy.  Other than that, a host's natural will seems completely absent, as they go about seeking food and shelter but ignoring any attempts at communication.  No signals have been received from any survivors on the planet, so there is unlikely to be an official effort to save this isolated colony from its tragic fate.