Publications

paratuberculosis in cattle and free-living exotic deer.	paratuberculosis was studied among dairy cows and exotic deer that shared grazing areas at point reyes national seashore, california. of the 10 dairy herds tested, 5 (50%) were infected with mycobacterium paratuberculosis (based on results of fecal culture). mycobacterium paratuberculosis was cultured from 9 (8.7%) of the 103 bovine fecal samples and from 4 (3.9%) of the 103 bovine rectal mucosa scapings tested. of 89 fecal samples from 52 axis deer (axis axis) and 37 fallow deer (dama dama), 5 ...	1979	500426
mass screening of cattle sera against 14 infectious disease agents, using an elisa system for monitoring health in livestock.	mass screening elisa methods were developed for testing cattle serum for antibodies against 14 common livestock diseases simultaneously. the absorbance values were transformed to a %elisa (spectrophotometric antibody end point) by a computer interfaced with a microplate reader. a histogram indicating a cutoff point and a report for the veterinarian also was generated. the computer program produced a print-out of the antibody profile for each animal tested, the antibody concentration against each ...	1991	1767993
radiometric culture of mycobacterium avium paratuberculosis from the feces of tule elk.	to determine if mycobacterium avium paratuberculosis has persisted in tule elk (cervus elaphus nannodes) at point reyes national seashore (california, usa), 100 fresh fecal samples were collected. feces were cultured on a modified bactec 12b radiometric medium for detection of m. avium paratuberculosis. four samples, coming from two separate groups of elk tested positive for m. avium paratuberculosis. thus, a noninvasive technique was used to document the continued presence of m. avium paratuber ...	1997	9249713
seroprevalence of johne's-disease infection in dairy cattle in california, usa.	a total of 1,950 serum samples from dairy cattle in california, usa were tested for the presence of antibodies to mycobacterium avium subspecies paratuberculosis (map) using a commercial enzyme-linked immunosorbent assay (elisa) kit. the sampled animals came from 65 herds and were sampled to reflect the relative numbers and distribution of dairy herds within three geographic regions in the state. using the manufacturers suggested cut-off for a positive test, 89 animals (4.6%) were positive. the ...	2003	12900163
testing for mycobacterium avium subsp. paratuberculosis infection in asymptomatic free-ranging tule elk from an infected herd.	forty-five adult tule elk (cervus elaphus nannodes) in good physical condition were translocated from a population located at point reyes national seashore, marin county (california, usa), to a holding pen 6 mo prior to release in an unfenced region of the park. because infection with mycobacterium avium subsp. paratuberculosis (mptb) had been reported in the source population, the translocated elk underwent extensive ante-mortem testing using three johne's disease assays: enzyme linked immunoso ...	2003	12910759
evaluation of microbial culture of pooled fecal samples for detection of mycobacterium avium subsp paratuberculosis in large dairy herds.	to evaluate sensitivity of microbial culture of pooled fecal samples for detection of mycobacterium avium subsp paratuberculosis (map) in large dairy herds and assess the use of the method for estimation of map prevalence.	2004	15334839
detection of viable mycobacterium avium subsp. paratuberculosis in retail pasteurized whole milk by two culture methods and pcr.	cattle with johne's disease can shed live mycobacterium avium subsp. paratuberculosis (map) in their milk, and map can survive under simulated commercial pasteurization conditions. in several studies conducted in the united kingdom and canada, map dna has been detected in retail pasteurized milk samples; however, in one study in the united kingdom viable map was identified in commercially pasteurized milk. a double-blind study involving two laboratories was undertaken to evaluate retail pasteuri ...	2005	15895728
environmental sampling for detection of mycobacterium avium ssp. paratuberculosis on large california dairies.	environmental samples collected from each of 3 locations on 23 large california dairies were cultured to evaluate the utility of this approach for identifying herds infected with mycobacterium avium ssp. paratuberculosis. results were compared with concurrent elisa testing of > or = 60 animals in each herd, and with previously performed individual and pooled fecal cultures of 60 animals. the estimated proportions of infected herds did not differ significantly among the testing methods (environme ...	2006	16507690
mycobacterium avium subspecies paratuberculosis and mycobacterium avium subsp. avium infections in a tule elk (cervus elaphus nannodes) herd.	between 2 august and 22 september 2000, 37 hunter-killed tule elk (cervus elaphus nannodes) were evaluated at the grizzly island wildlife area, california, usa, for evidence of paratuberculosis. elk were examined post-mortem, and tissue and fecal samples were submitted for radiometric mycobacterial culture. acid-fast isolates were identified by a multiplex polymerase chain reaction (pcr) that discriminates among members of the mycobacterium avium complex (mac). histopathologic evaluations were c ...	2006	17255437
isolation of mycobacterium avium subsp. paratuberculosis from waste milk delivered to california calf ranches.	the objective of this study was to determine if viable mycobacterium avium subsp. paratuberculosis (map) was present in waste milk delivered and fed to calves on california calf ranches. four calf-raising facilities in the central valley of california that fed pasteurized waste milk to calves were enrolled. pre- and post-pasteurization waste milk samples were cultured for map using liquid and solid media over a 5-day period during each of four seasons. aerobic cultures were performed simultaneou ...	2008	18681799
reliability of environmental sampling to quantify mycobacterium avium subspecies paratuberculosis on california free-stall dairies.	the reliability of environmental sampling to quantify mycobacterium avium ssp. paratuberculosis (map) based on collector and time was evaluated. fecal slurry samples were collected using a standardized protocol simultaneously by 2 collectors of different experience levels. samples were collected from 30 cow pens on 4 dairies every other day on 3 occasions while cow movements between pens were minimal. the 4 study herds had moderate map seroprevalence and were housed in free-stall dairies in cent ...	2009	19620644
association between mycobacterium avium subspecies paratuberculosis infection and milk production in two california dairies.	the association between mycobacterium avium ssp. paratuberculosis (map) and milk production was estimated on 2 california dairies using longitudinal data from 5,926 cows. both study herds had moderate map seroprevalence, housed cows in freestalls, and had johne's disease control programs. cow map status was determined using both serum elisa and fecal culture results from cows tested at dry-off and from whole-herd tests. potential confounders were evaluated based on a causal diagram. mixed models ...	2010	20172223
correlation between herrold egg yolk medium culture and real-time quantitative polymerase chain reaction results for mycobacterium avium subspecies paratuberculosis in pooled fecal and environmental samples.	real-time quantitative polymerase chain reaction (qpcr) testing for mycobacterium avium subspecies paratuberculosis (map) in fecal samples is a rapid alternative to culture on herrold egg yolk medium (heym), the traditional antemortem reference test for map. although the sensitivity and specificity of these 2 tests have been estimated based on dichotomized test results, the correlation between real-time qpcr threshold cycle (ct) values and colony-forming units (cfu) on heym for fresh and thawed ...	2010	20807920
early-life exposures and johne's disease risk in zoo ruminants.	johne's disease, caused by mycobacterium avium subsp. paratuberculosis (map), is a chronic, progressive bacterial enteritis of ruminants that can cause serious losses in both livestock and exotic species. infection risk in exotic ruminants is associated with maternal infection status, but the effect of other herdmates on risk of infection has not been reported, to our knowledge. we conducted a retrospective cohort study to evaluate the association between map infection status and early-life cont ...	2018	28985710