Surveillance for Mycobacterium bovis transmission from domestic cattle to wild ruminants in a Mexican wildlife-livestock interface area.

OBJECTIVE: To assess the prevalence of Mycobacterium bovis infection in cattle and wild ruminants (WRs) in a wildlife-livestock interface area (WLIA) of the Mexican highland plateau. ANIMALS: 24,400 cattle from 793 herds (including 17,351 commercially slaughtered cattle) and 142 WRs (110 white-tailed deer [Odocoileus virginianus], 20 red deer [Cervus elaphus], and 12 North American elk [Cervus canadensis]) harvested via controlled hunting. PROCEDURES: Cattle were serially tested for M bovis infection via caudal fold tuberculin and comparative cervical tuberculin tests during field surveillance. Carcasses of cattle and WRs were inspected for gross lesions; samples suggestive of tuberculosis were analyzed via histologic evaluation and mycobacterial culture (HMC). A PCR assay to detect Mycobacterium tuberculosis complex organisms was performed to confirm positive results of HMC. RESULTS: WRs had inflammatory lesions in lungs and lymph nodes, although HMC results did not indicate M bovis infection. Eight cattle had positive results for both tuberculin tests, and 31 had positive results for HMC of grossly detected lesions; all were from 7 herds, and ≥ 1 cow in each herd had positive PCR assay results. These 7 herds were depopulated; adjacent herds and herds related via commerce were quarantined. Calculated true prevalence of M bovis infection was 0.86% (95% confidence interval, 0.24% to 1.49%) in cattle; M bovis was not detected in any WRs. CONCLUSIONS AND CLINICAL RELEVANCE: M bovis infection was present in cattle. Although transmission to WRs in this WLIA was not detected, diagnosis and prevention activities should be implemented and consolidated to prevent potential M bovis transmission between cattle and WRs.

Histología del intestino de la garrapata (Boophilus microplus) en estado de semiingurgitamiento / Histology of the midgut of Boophilus microplus tick in semiengorged phase

El objetivo del presente trabajo fue identificar las estructuras histológicas del intestino de hembras adultas semiingurgitadas de la garrapata Boophilus microplus en una cepa de referencia en México. Se procesaron garrapatas y piezas de intestino de garrapatas hembras semiingurgitadas para su inclusión en parafina y por congelación, se practicaron cortes longitudinales que se tiñeron con hematoxilina y eosina y se realizaron las observaciones en microscopio compuesto. Se encontraron diferentes tipos de células epiteliales en el intestino, éstas resultaron similares entre la cepa estudiada y las descritas previamente en la literatura, las células identificadas fueron: células basofílicas y células digestivas en serie, integradas por células digestivas iniciales, células digestivas tardías y células digestivas maduras 1, todas ellas son descritas y se indica su equivalencia con las que se notificaron previamente en la literatura