The causative agent of Chagas' disease, Trypanosoma cruzi, was found in 23 or 3.4% of 675 conenose bugs collected from 1936 to 1959 in New Mexico. Sixteen infected insects from Tyrone and two from Chaco Canyon were Triatoma protracta protracta and five from Carlsbad Caverns were Triatoma gerstaeckeri.
Naturally-infected mammals discovered by field xenodiagnosis were one male southern plains wood rat, Neotoma micropus canescens, from near Tyrone; one male suckling white throated wood rat, Neotoma albigula albigula, from 12.5 miles west of Carrizozo; and one female rusty antelope squirrel, Citellus leucurus cinnamoneus, from Chaco Canyon.
White mice inoculated intramuscularly with bug feces equivalent to a single natural contaminative defecation acquired light transitory blood parasitemias. Microscopically undetected blood invasions of 9 experimental white mice were infective for 19 of 43 bugs used in xenodiagnosis. A 2-day-old white mouse injected intraperitoneally with one dropping from a naturally-infected Tyrone male Triatoma was sacrificed on the 31st day. Tissue sections revealed a minimal focal interstitial myocarditis in association with groups of leishmaniform Trypanosoma cruzi.