Comparison of multilocus sequence types found among North American isolates of Mycoplasma bovis from cattle, bison, and deer, 2007-2017.

A prior multilocus sequence typing (MLST) study reported that Mycoplasma bovis isolates from North American bison possess sequence types (STs) different from those found among cattle. The 42 bison isolates evaluated were obtained in 2007 or later, whereas only 19 of 94 (~20%) of the available cattle isolates, with only 1 from North America, were from that same time. We compared STs of additional, contemporary, North American cattle isolates with those from bison, as well as isolates from 2 North American deer, all originating during the same timeframe, to more definitively assess potential strain-related host specificity and expand our understanding of the genetic diversity of M. bovis. From 307 isolates obtained between 2007 and 2017 (209 from cattle, 96 from bison, 2 from deer), we identified 49 STs, with 39 found exclusively in cattle and 5 exclusively in bison. Four STs were shared between bison and cattle isolates; one ST was found in cattle and in a deer. There was no clear association between ST and the health status of the animal of origin. An MLST-based phylogeny including 41 novel STs identified in our study reveals that STs found in bison fall within several divergent lineages that include STs found exclusively in cattle.

Genome divergence and increased virulence of outbreak associated Salmonella enterica subspecies enterica serovar Heidelberg.

Salmonella enterica serotype Heidelberg is primarily a poultry adapted serotype of Salmonella that can also colonize other hosts and cause human disease. In this study, we compared the genomes of outbreak associated non-outbreak causing Salmonella ser. Heidelberg strains from diverse hosts and geographical regions. Human outbreak associated strains in this study were from a 2015 multistate outbreak of Salmonella ser. Heidelberg involving 15 states in the United States which originated from bull calves. Our clinicopathologic examination revealed that cases involving Salmonella ser. Heidelberg strains were predominantly young, less than weeks-old, dairy calves. Pre-existing or concurrent disease was found in the majority of the calves. Detection of Salmonella ser. Heidelberg correlated with markedly increased death losses clinically comparable to those seen in herds infected with S. Dublin, a known serious pathogen of cattle. Whole genome based single nucleotide polymorphism based analysis revealed that these calf isolates formed a distinct cluster along with outbreak associated human isolates. The defining feature of the outbreak associated strains, when compared to older isolates of S. Heidelberg, is that all isolates in this cluster contained Saf fimbrial genes which are generally absent in S. Heidelberg. The acquisition of several single nucleotide polymorphisms and the gain of Saf fimbrial genes may have contributed to the increased disease severity of these Salmonella ser. Heidelberg strains.

Necrotic pharyngitis associated with Mycoplasma bovis infections in American bison (Bison bison).

Mycoplasma bovis has emerged as a significant and costly infectious disease problem in bison, generally presenting as severe, caseonecrotic pneumonia. Three diagnostic cases in which M. bovis is associated with necrotic pharyngitis in bison are described in the current study. The bacterium was isolated from lesions of the pharynx or lung of 3 American bison (Bison bison), at 2 different locations in the upper Midwestern United States, with severe, necrotic pharyngeal abscesses. Chronic caseonecrotic inflammation typical of M. bovis infection in bovines was observed microscopically in the pharynxes of affected bison. A mixed population of bacteria was recovered from the pharyngeal lesions, and Trueperella pyogenes, a frequent secondary pathogen in ruminant respiratory disease, was consistently isolated from the affected animals. Distinctive histopathological features of the pharyngeal lesions favor causation by M. bovis, although a role for T. pyogenes in the clinical presentation cannot be excluded. Veterinarians and producers working with bison should be aware that M. bovis may be associated with pharyngitis in bison.

Bovine viral diarrhea virus multiorgan infection in two white-tailed deer in southeastern South Dakota.

The susceptibility of wild ruminants, especially cervids, to bovine viral diarrhea virus (BVDV) has remained an enigma. Two white-tailed deer (Odocoileus virginianus) were submitted to the Animal Disease Research and Diagnostic Laboratory (ADRDL) in the fall of 2003 by the South Dakota Game Fish and Parks for chronic wasting disease (CWD) testing. Both animals were CWD negative. The animals were necropsied and histopathology, viral antigen detection, and virus isolation were performed. A noncytopathic (NCP) BVDV was isolated from the lungs and several other tissues of both animals. Formalin-fixed ear notches from both animals were positive for BVDV antigen by immunohistochemistry. The BVDV isolates were typed with the use of polymerase chain reaction in 5' untranslated region (UTR) and one isolate was typed a Type 2a and the other a Type 1b. Future field surveys to determine the incidence of BVDV along with experimental studies to determine if white-tailed deer fawns can be persistently infected with BVDV are needed.

Clostridial abomasitis in calves: case report and review of the literature.

Infections by Clostridium perfringens type A are perhaps the most common causes of clostridial hemorrhagic enteritis in neonatal ruminants. Affected calves exhibit tympany, hemorrhagic abomasitis, and abomasal ulceration. Gram-positive bacilli are often found on affected mucosa and in submucosa. Aspects of etiology beyond the infecting organism are little understood, but probably include dietary issues, perhaps relating to overfeeding, feeding of barely thawed or contaminated colostrum, or conditions which effect decreased gut motility. Fatal hemorrhagic enteritis in a cloned gaur calf is illustrative of the syndrome. The calf developed pasty yellow and bloody diarrhea, and the abdomen became distended and painful. In spite of intensive therapy, the calf died approximately 48 h after birth. At necropsy, the distended abomasum contained clotted milk and bloody fluid, and the abomasal and omasal walls were thickened and hemorrhagic. The proximal duodenum was hemorrhagic and emphysematous, and microscopic examination revealed Gram-positive rods in association with acute, necrotizing, hemorrhagic mucosal inflammation. Isolates of C. perfringens from this calf were PCR positive for cpb2, the gene encoding beta2 toxin. This finding is of unknown significance; only 14.3% (8/56) of isolates from other calves with the syndrome have been cpb2 positive, and only 50% of cpb2 positive bovine isolates express CPB2. The most prominent needs to further our understanding of this problem are consistent experimental reproduction of the disease, elucidation of virulence attributes, and development and application of prevention and control strategies.

Bovine arsenic toxicosis.

A ranch in central South Dakota had a number of dead calves because of arsenic poisoning. The clinical picture included diarrhea, central nervous system signs, and death. Gross necropsy findings included adequate body fat, stomachs full of normal-appearing ingesta, and large amounts of greenish brown watery fluid in the intestine and colon. Microscopically there was severe lymphoid tissue necrosis in the mesenteric lymph nodes and gut-associated lymphoid tissue. Chemical analysis of kidneys showed no significant amounts of lead; however, kidney arsenic concentrations were 25 to 44 ppm. The source was a small pile of Paris Green (common name for cupric acetoarsenite) found in an old dump site in the pasture.