MICROBIOLOGY

• Trypanosoma cruzi, a hemoflagellate protozoan, causes American trypanosomiasis (Chagas disease).
  • Transmission occurs when triatomine feces contaminate the bite site or mucosal surfaces (not via the bite itself).
    • Important vectors are blood-feeding triatomine bugs, including species of Triatoma, Rhodnius, and Panstrongylus [Fig 1].
  • Enzootic transmission occurs in the southern U.S., with infected triatomines and mammalian reservoirs (especially dogs and wildlife); autochthonous human cases are rare but increasingly recognized.
    • Texas has the highest number of reported autochthonous human T. cruzi infections.
    • Risk factors include rural residence, history of hunting or camping, and agricultural or outdoor work.
    • Canines are an important domestic reservoir and sentinel species; direct contribution to human transmission is inferred but not well quantified[3].
  • See the Life cycle.