Bovine fecal chemistry changes with progression of Southern Cattle Tick, Rhipicephalus (Boophilus) microplus (Acari: Ixodidae) infestation

Authors: RICH, BRIAN - Texas A&M University; Thomas, Donald; LONGNECKER, MICHAEL - Texas A&M University; TOLLESON, DOUGLAS - Texas A&M University; Angerer, Jay; Perez De Leon, Adalberto - Beto; TEEL, PETER - Texas A&M University

Submitted to: Veterinary Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/14/2022
Publication Date: 2/21/2022
Citation: Rich, B., Thomas, D.B., Longnecker, M., Tolleson, D., Angerer, J.P., Perez de Leon, A.A., Teel, P. 2022. Bovine fecal chemistry changes with progression of Southern Cattle Tick, Rhipicephalus (Boophilus) microplus (Acari: Ixodidae) infestation. Veterinary Parasitology. https://doi.org/10.1016/j.vetpar.2022.109679.
DOI: https://doi.org/10.1016/j.vetpar.2022.109679

Interpretive Summary: Surveillance of cattle for fever ticks within the quarantine zone along the south Texas border is an essential activity to protect the US livestock industry from tick borne cattle fever. Manual inspection of all individual cattle at regular intervals is time consuming. Technology to augment inspections for detection of tick infestations is desirable. Infestation by ticks induces chemical changes in the body of cattle which are then passed through and still detectable in the cattle droppings (feces). For this study a technology based on the light reflected from the droppings in the wavelengths near the infra-red spectrum could be used to detect these chemical changes in cattle infested with fever ticks. A shift in the chemistry was seen corresponding to before, during and after feeding (blood-sucking) by the tick population on the host animal. It is hypothesized that the chemical changes were related to the stress associated with being infested. Interestingly, non-infested animals adjacent to the infested ones exhibited contemporaneous chemical shifts, suggesting that a sympathetic stress was expressed in these companion animals.

Technical Abstract: Passive and active surveillance for cattle fever ticks is an essential activity in the US Cattle Fever Tick Eradication Program which prevents reestablishment of the vectors of bovine babesiosis. While tick surveillance includes physical inspection of restrained cattle by program inspectors, additional methods of detecting tick infested cattle could augment and improve surveillance. The objective of this study was to determine whether changes in fecal chemistry are induced through a single infestation of ~5000 Rhipicephalus (Boophilus) microplus larvae and detectable using near-infrared reflectance spectroscopy (NIRS). Fecal samples were collected daily from 6 tick-infested and 6 non-infested Bos taurus yearling heifers. Date of drop and daily sum of engorged female ticks was monitored. Two shifts in fecal chemistry were identified by three clusters of NIRS fecal spectra. The first cluster was comprised of samples from pre-infestation to 9 days after infestation inclusive of larval tick feeding period. The second cluster was comprised of samples from day 10 to 22 and inclusive of nymphal feeding, adult feeding, and early drop of engorged females. The third cluster was comprised of samples from days 23-46 and inclusive of the period of engorged female drop. Shifts in bovine fecal chemistry are explored in the context of tick-host interactions during blood feeding. Cluster, common factor, principal component and MANOVA analyses were used to define and assess fecal spectra changes associated with experimental stages. Results unexpectedly indicated two shifts in fecal chemistry for non-infested animals reflected by three fecal-spectra clusters occurring in synchrony with their tick-infested counterparts. Examination and discussion of experimental design, procedures, and barn facilities suggest a basis for physiological stress resonance among non-infested animals.