The University of Georgia College of Veterinary Medicine

Georgia Veterinary Scholars Program

GVSP Summer 2011 Scholars

Georgia Veterinary Scholar	Faculty Mentor

Leslie Shelnutt University of Georgia Class of 2014	Dr. Michael Yabsley Department of Wildlife UGA College of Veterinary Medicine

Comparability of different culture methods and xenodiagnosis for detection of T. cruzi in naturally-infected reservoirs

Leslie M. Shelnutt, Ellen M. Dotson, and Michael J. Yabsley

Trypanosoma cruzi, causative agent of Chagas disease, infects both humans and animals and causes nearly 50,000 human deaths a year in Latin America. In the United States, human cases are rare, but T. cruzi is relatively common in wildlife and domestic animals in some southern states. Transmission occurs when feces of infected hematophagus triatomine bugs come into contact with the mucus membranes or bite site. However, direct comparison of different culture methods for T. cruzi from US wildlife has not been conducted. Additionally, the probability of vectors becoming infected after feeding on naturally-infected wildlife hosts in the United States is unknown. To investigate the transmission rate from naturally-infected wildlife to non-infected vectors, 8-10 lab-raised Rhodnius prolixus were allowed to feed to repletion on eight raccoons (Procyon lotor), 15 opossums (Didelphis virginiana), and two nine-banded armadillos (Dasypus movemcinctus). We compared detectability of this xenodiagnostic method with three other culture methods including addition of whole blood (1ml) to liver infusion tryptose (LIT) and addition of equal volumes of a leukocyte fraction from the remaining blood (variable amounts) to LIT and DH82 canine macrophages. We hypothesize that xenodiagnosis will be more sensitive than artificial culture methods which may not support growth of all strains of T. cruzi. However, large numbers of bugs may need to be used because of small quantities of blood ingested by 5th instars of R. prolixus. Lack of infection of bugs would suggest that parasitemia levels in these hosts are low and repeated feedings are required for our reservoirs to infect bugs. Cultures are monitored weekly and we must wait three weeks before testing bugs. To date, one raccoon has come up DH82 culture positive. This study will help us better understand the transmission of T. cruzi and how it relates to culture-based prevalence.