Use of polymerase chain reaction to diagnose the fifth reported US case ofautochthonous transmission of Trypanosoma cruzi, in Tennessee, 1998

In July 1998, the mother of an 18-month-old boy in rural Tennessee found a triatomine bug in his crib, which she saved because it resembled a bug show n on a television program about insects that prey on mammals. The gut conte nts of the Triatoma sanguisuga were found, by light microscopy and polymera se chain reaction (PCR), to be infected with Trypanosoma cruzi; PCR product s hybridized with T. cruzi-specific oligonucleotide probes. Whole-blood spe cimens obtained from the child in July and August were negative by buffy-co at examination and hemoculture but positive by PCR and DNA hybridization, s uggesting that he had low-level parasitemia, Specimens obtained after treat ment with benznidazole were negative. He did not develop anti-T. cruzi anti body; 19 relatives and neighbors also were seronegative, Two of 3 raccoons trapped in the vicinity had positive hemocultures for T. cruzi. The child's case of T. cruzi infection-the fifth reported US autochthonous case-would have been missed without his mother's attentiveness and the availability of sensitive molecular techniques.