 The US FDA has approved two Chagas tests , including one approved in April 2010 , and has published guidelines that recommend testing of all donated blood and tissue products . While these tests are not required in US , an estimated 75 – 90 % of the blood supply is currently tested for Chagas , including all units collected by the American Red Cross , which accounts for 40 % of the U.S. blood supply . The Chagas Biovigilance Network reports current incidents of Chagas @-@ positive blood products in the United States , as reported by labs using the screening test approved by the FDA in 2007 . 
 The US FDA <a href='been_done' title='1'><mark>has</mark></a> approved two Chagas tests , including one approved in April 2010 , and <a href='been_done' title='2'><mark>has</mark></a> published guidelines <a href='null_relcl' title='3'><mark>that</mark></a>recommend testing of all donated blood and tissue products . While these tests are not required in US , an estimated 75 – 90 % of the blood supply is currently tested for Chagas , including all units collected by the American Red Cross , which <a href='uninflect' title='4'><mark>accounts</mark></a> for 40 % of the U.S. blood supply . The Chagas Biovigilance Network <a href='uninflect' title='5'><mark>reports</mark></a> current incidents of Chagas @-@ positive blood products in the United States , as reported by labs using the screening test approved by the FDA in 2007 . 
The US FDA done approved two Chagas tests , including one approved in April 2010 , and done published guidelines recommend testing of alll donated blood and tissue products . While these tests ain't required in US , an estimated 75 – 90 % of the blood supply is currently tested for Chagas , includingallll units collected by da American Red Cross , which account for 40 % of tdaU.S. blood supply . Thdahagas Biovigilance Network report current incidents of Chagas @-@ positive blood products in the United States , as reported by labs usin the screening test approved by thedaA in 2007 .