Deer ticks like this one can spread a parasite that causes babesiosis. And infected people can spread it through blood donations. Jim Gathany/CDC hide caption itoggle caption Jim Gathany/CDC Shots - Health News Babesia In The Blood? There Should Be A Test For That September 9, 2011 There's no test for a malaria-like parasite that has sickened people after blood transfusions. A recent report of illnesses tied to donated blood demonstrates the need for an assay, an American Red Cross researcher says.