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The objective of this study was to determine the association between mycoplasma mastitis and colonization of mycoplasma organisms at body sites of asymptomatic carriers. The investigation was done in a dairy herd with a first outbreak of mycoplasma mastitis. Milk and swab solution specimens from accessible mucosal surfaces of body sites from cows and replacements were sampled at quarterly intervals (Herd Samplings 1-4). Samples were cultured and Mycoplasma spp. were isolated, speciated and fingerprinted. During Herd Sampling 1 two cows with mycoplasma bovis mastitis were identified and all swabbing solutions of body site samples from 18 of 84 cows and 36 of 77 replacements were positive to Mycoplasma bovis and fingerprinted as the same strain. A case of clinical M. bovis mastitis developed during Herd Sampling 3. During Herd Samplings 2-4, 4 lactating cows and 12 replacements were positive to M. bovis at various body sites with 4 different strains. Three isolates of Mycoplasma californicum were found from swabbing solutions of three cows during Herd Samplings 3 and 4. Only one strain of M. bovis caused mastitis although four strains were isolated from body sites of animals. Isolation of M. bovis from a body site never preceded mastitis. No lactating cow developed mastitis during Herd Sampling 4 although some animals were colonized with the organism. It appears that during the initial outbreak of M. bovis mastitis colonization of body sites by the outbreak strain may be common. However, the prevalence of colonization subsides and colonization does not appear to precede mastitis.

In 1999 and 2000, 3 state health departments reported 4 outbreaks of gastrointestinal illness due to Salmonella enterica serotype Typhimurium in employees, clients, and client animals from 3 companion animal veterinary clinics and 1 animal shelter. More than 45 persons and companion animals became ill. Four independent investigations resulted in the testing of 19 human samples and >200 animal samples; 18 persons and 36 animals were culture-positive for S. Typhimurium. One outbreak was due to multidrug-resistant S. Typhimurium R-type ACKSSuT, while the other 3 were due to multidrug-resistant S. Typhimurium R-type ACSSuT DT104. This report documents nosocomial transmission of S. Typhimurium and demonstrates that companion animal facilities may serve as foci of transmission for salmonellae between animals and humans if adequate precautions are not followed.

Feed has been reported as a vehicle for transmission of Salmonella enterica in cattle and several lines of evidence suggest that feed can be a vehicle for transmitting Escherichia coli O157:H7 as well. To show whether microbial contamination of feeds could contribute to the populations of S. enterica and E. coli O157:H7 on a farm, we compared isolates from feed samples to bovine fecal isolates from the same farm using pulsed-field gel electrophoresis (PFGE). Four of 2365 component feed samples (0.2%) and 1 of 226 feed mill samples (0.4%) were positive for E. coli O157:H7. Twenty of 2405 (0.8%) component feed samples and none of 226 feed mill samples were positive for Salmonella. PFGE profiles from E. coli O157:H7 isolated from a component feed sample closely resembled that from a fecal isolate collected later from the same farm, and a similar observation was made of a Salmonella Tyhpimurium isolate from component feed on another farm. There were indistinguishable PFGE profiles from component feed Salmonella Tyhpimurium DT104 isolates and fecal isolates from the same farm. These results provide evidence for a role of cattle feed in transmission of E. coli O157:H7; S. enterica; cattle-bacteria.

Samples from cattle, other domestic and wild animals, flies, feeds, and water-troughs were collected from 12 cattle farms and tested for Escherichia coli O157. E. coli O157 was isolated from bovine fecal samples on all 12 farms with a within herd prevalence ranging from 1.1% to 6.1%. E. coli O157 was also found in 1 of 90 (1.1%) equine fecal samples, 2 of 65 (3.1%) canine fecal samples, 1 of 200 pooled bird samples (0.5%), 2 of 60 pooled fly samples (3.3%), and 10 of 320 (3.1%) water-trough sample sets (biofilm and water). No E. coli O157 were isolated from 300 rodents, 33 cats, 34 assorted wildlife, or 335 cattle feed samples. Indistinguishable pulsed-field gel electrophoresis patterns of XbaI digested chromosomal DNA and Shiga toxin types were observed for bovine and water-trough isolates from two farms and for one equine and two bovine isolates from one farm.

Telephone interviews were conducted to evaluate the association of teat chapping with combinations of premilking and postmilking teat disinfectants (predip and postdip), other management practices, and climatic conditions. Holstein dairies (n = 100) in the DHIA SCC program were randomly selected from three northwest regions. During nonwinter seasons, herd managers using an iodophor dip without skin conditioner both premilking and postmilking were 9.7 times more likely to report chapping than were those using iodophor with conditioner. The herd managers least likely to report chapping problems were those using conditioner in both the predip and postdip. Use of conditioner in postdip only was associated with intermediate frequency of reported chapping. No conditioner in either predip or postdip was associated with the greatest frequency of reported chapping. Herd managers using a different germicide in the predip and postdip reported more chapping than herd managers using the same germicide. The frequency of chapping was highest during winter in all regions, and the percentage of herd managers reporting chapping within a region was associated with the temperature extremes of the region. For seasons other than winter, characteristics of predip and postdip combinations and parlor exit or barn design were the management factors that best described an association with reported chapping.

An outbreak of cysticercosis in a south-central Idaho custom feedlot reached a peak prevalence of 11% in January 1993 and extended from October 1992 through March 1993. Of 5,164 cattle slaughtered from this feedlot during the outbreak, 457 (9%) were cysticercosis infected. Total discounts on the infected cattle at slaughter cost the feedlot $154,400. Most evidence was suggestive of feed-borne transmission of Taenia saginata eggs to the cattle in the feedlot. By use of logistic regression analysis of feedlot records, significant (P = 0.004) association of cysticercosis prevalence at slaughter with days on feed was revealed. Similarly, a decline in cysticercosis prevalence was significantly (P < 0.001) related to the number of days cattle were fed a ration not containing potato byproduct. Although sources other than potato byproduct were systematically evaluated during the investigation, findings suggested that potato byproduct fed in this feedlot was contaminated with T saginata eggs.