Radiolabeled total parasite DNA probe specifically detects Trypanosoma cruzi in mammalian blood

A DNA-DNA hybridization procedure is described in which radiolabeled total parasite DNA is used to detect Trypanosoma cruzi spotted directly onto nylon membrane. Under conditions that favor hybridization of repetitive DNA sequences, the radiolabeled total DNA was able to detect as few as five parasites spotted onto nylon membrane. Trypanosomes were detectable in blood from mice with T. cruzi parasitemias spotted directly onto membranes. All 10 strains of T. cruzi examined, which came from different areas of the United States and South America, were readily detected with a total DNA probe from any 1 strain of the parasite. No signals were detected with up to 20,000 Trypanosoma rangeli, T. brucei, Crithidia fasciculata, or Leishmania parasites or with normal mouse blood or mammalian DNA. The hybridization method is sensitive, specific, rapid, and inexpensive and is potentially applicable to the detection of other parasites.