US health officials are investigating the death of an Iowa resident as a suspected case of Lassa fever, a dangerous viral disease that is endemic in parts of West Africa but rarely seen in the US or Europe. The patient returned to the US from West Africa early this month but was not sick while travelling, so the risk to fellow airline passengers is “extremely low,” officials with the US Centers for Disease Control and Prevention (CDC) said. The patient, who died on Monday, had been hospitalised in isolation, and testing showed that they were presumptively positive for Lassa fever. Related Lass…