Five senior US Republicans have quarantined themselves after coming into contact with a person who tested positive for coronavirus.The members of Congress, who include Texas Senator Ted Cruz, self-isolated after they shook hands with an infected individual at a conference.President Donald Trump, who was also at the event last month, insists he is in good health and has not taken a test.One Democrat has also self-isolated after she met someone with the virus.There are more than 700 confirmed cases in the US and 26 people have died so far.