Detection of Leishmania parasites by DNA in situ hybridization with non-radioactive probes.

In situ hybridization techniques develop rapidly into diagnostic tools of considerable value for detection of viruses and bacteria. Here we report the application of this technique for the detection of Leishmania parasites. Biotin-labelled total promastigote DNA was hybridized to cultured Leishmania parasites and to blood and impression smears of infected mice. In promastigotes kinetoplasts were strongly stained, nuclei somewhat more diffuse. In amastigotes both nuclear and kinetoplast DNA hybridized strongly. Amastigotes were easily detected in tissue of infected mice by their stable configuration of kinetoplast and nuclei. Cross-hybridization was observed between Leishmania donovani and L. tropica, but not between these two and L. braziliensis or Trypanosoma cruzi. A minor aspecific staining of host cell nuclei in the smears did not interfere with the detectability of the parasites.