Page Banner

United States Department of Agriculture

Agricultural Research Service

Research Project: MINING THE GENOME OF RHIPICEPHALUS MICROPLUS TO DEVELOP NOVEL CONTROL TECHNOLOGY AND VACCINES

Location: Tick and Biting Fly Research

Title: Molecular characterization of Trypanosoma spp. infecting cattle (Bos taurus), white-tailed deer (Odocoileus virginianus), and elk (Cervus elaphus canadensis) in the United States

Authors
item Fisher, Amanda -
item Schuster, Greta -
item Cobb, W. Jacob -
item James, Andrea -
item Cooper, Susan -
item Perez De Leon, Adalberto
item Holman, Patricia -

Submitted to: Veterinary Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 27, 2013
Publication Date: N/A

Interpretive Summary: Several species of single-celled organisms with a distinct membrane-bound nucleus containing DNA in a granule within the organelle supplying cellular energy that move in a corkscrew-like fashion belong to the genus Trypanosoma and are commonly known as trypanosomes. They live as parasites and are transmitted to humans and other animal hosts by blood feeding organisms such as insect, leech, or tick species that act as vectors. The benign trypanosomes of cattle and wild ungulates in the United States are designated Trypanosoma theileri and Trypanosoma cervi, respectively. Historically these parasites have been identified based on morphology, host, and vector, if known. No molecular characterization has been reported for T. cervi, and very limited information exists for T. theileri. In this study, the presence of Trypanosoma isolates from three different host species, cattle, white-tailed deer, and elk was investigated in south Texas counties and molecular approaches were applied to compare their DNA sequences to ascertain trypanosome identity. For most isolates, the cattle trypanosome sequences aligned together and white-tailed deer and elk trypanosome sequences aligned together, which indicates that deer and elk, and cattle likely have host-specific trypanosome species. However, exceptions occurred suggesting that there may be cross-over in host competency. In La Salle, Starr, Webb, and Zapata counties in south Texas a high proportion of white-tailed deer were positive for trypanosomes. Of the cattle screened in Webb County, 35% were positive. The drought conditions prevailing in south Texas during the period that the animals were screened suggests the possibility of another vector for Trypanosoma besides the deer ked and tabanid flies. The potential involvement of other vectors, such as ticks, is discussed.

Technical Abstract: The benign trypanosomes of cattle and wild ungulates in the United States are designated Trypanosoma theileri and Trypanosoma cervi, respectively. Historically these parasites have been identified based on morphology, host, and vector, if known. No molecular characterization has been reported for T. cervi, and very limited such information exists for T. theileri. In this study, Trypanosoma isolates from three different host species, cattle (Bos taurus), white-tailed deer (Odocoileus virginianus), and elk (Cervus elaphus canadensis), were compared by ribosomal DNA sequence analysis and trypanosome incidence was investigated in south Texas counties. For most isolates, the cattle trypanosome sequences aligned together and white-tailed deer and elk trypanosome sequences aligned together, indicating that wild ungulates (deer and elk) and cattle most likely have host-specific trypanosome species. However, exceptions occurred suggesting that there may be cross-over in host competency. In La Salle, Starr, Webb, and Zapata counties in south Texas a high proportion of white-tailed deer were positive for trypanosomes by 18S rDNA PCR. Of the cattle screened in Webb County, 35.4% were positive. The drought conditions prevailing in south Texas during the period that the animals were screened suggest the possibility of another vector for Trypanosoma besides the ked (Lipoptena mazamae) and tabanid fly (Tabanus spp. and Haematopota spp.).

Last Modified: 10/1/2014