Spatial distribution of seropositivity to the causative agent of granulocytic ehrlichiosis in dogs in California

OBJECTIVE: To assess spatial and temporal patterns of seroprevalence among dogs in California to the causative agent of granulocytic ehrlichiosis (GE). SAMPLE POPULATION: Sera of 1,082 clinically normal dogs from 54 of 59 counties in California in 1997 to 1998. PROCEDURES: Serum-specific IgG reactivity to Ehrlichia equi was assessed by use of an immunofluorescent antibody assay, using E. equi-infected horse neutrophils as substrate. Data were analyzed, using a geographic information system. Spatial analysis of seroprevalence included first order Bayesian analysis of seroprevalence and second order analysis of clustering by K-function and Cuzick-Edwards tests. Monthly seroprevalence among dogs was examined by use of regression on monthly densities of Ixodes pacificus adults and nymphs. RESULTS: Seroprevalence among dogs to E. equi was 8.68%. Data were seasonally bimodal with highest prevalence in winter (when adult ticks were abundant) and a secondary peak in late spring (corresponding to nymphal ticks). Humboldt County had the highest seroprevalence (47.3%), and other northern coast range counties had seroprevalence from 15 to 30%. CONCLUSIONS AND CLINICAL RELEVANCE: The patchy distribution of exposure to Ehrlichia organisms is a subset of the distribution of the tick vector. This may reflect enzootic cycles or climatic or historical factors that limited the range of the disease. Dogs, horses, and humans from north coast range counties in California are at increased risk of GE. These data provide a background for assessing risk of infection in horses and dogs, depending on geographic location. Dogs may be sentinels for assessing risk of GE in humans.     

A review of coronavirus infection in the central nervous system of cats and mice

Feline infectious peritonitis (FIP) is a common cause of death in cats. Management of this disease has been hampered by difficulties identifying the infection and determining the immunological status of affected cats and by high variability in the clinical, pathological, and immunological characteristics of affected cats. Neurological FIP, which is much more homogeneous than systemic effusive or noneffusive FIP, appears to be a good model for establishing the basic features of FIP immunopathogenesis. Very little information is available about the immunopathogenesis of neurologic FIP, and it is reasonable to use research from the well-characterized mouse hepatitis virus (MHV) immune-mediated encephalitis system, as a template for FIP investigation, and to contrast findings from the MHV model with those of FIP. It is expected that the immunopathogenic mechanisms will have important similarities. Such comparative research may lead to better understanding of FIP immunopathogenesis and rational prospects for management of this frustrating disease.     

Miocene glaciomarine sediments from beneath the southern ross ice shelf, antarctica

Glaciomarine sediments with middle Miocene microfaunal assemblages are exposed at the sea floor below the southern Ross Ice Shelf. Plio-Pleistocene sediments are not present. Post-Miocene glacial sediments may have been deposited but removed by relatively recent ice shelf grounding. A meager Recent microfauna is present in some core tops.     

Bacterial flora on Cascades frogs in the Klamath mountains of California

Amphibians are experiencing global declines due in part to the infectious disease chytridiomycosis. Some symbiotic bacteria residents on frog skin have been shown to inhibit the growth of Batrachochytrium dendrobatitis (Bd) but few studies have attempted to fully describe the resident bacterial flora of frog skin. We cultured and sequenced 130 bacterial isolates from frogs collected from the California Klamath Range, recovering predominantly Gram-negative bacteria from 20 higher order taxa and 31 genera. There were also a large number of unclassifiable isolates. Forty-three isolates were assessed for their ability to inhibit the growth of Bd in vitro; of these, two had strong and three had slight anti-Bd activity. We suggest that many bacterial species may play a secondary role in Bd resistance, acting synergistically with inhibitory species. Future research is required in order to characterize these interactions. Understanding the relationships between bacterial strains may be important in predicting and managing the effects of future anti-Bd treatments such as antimicrobial compounds or probiotic bacteria.     

Canine Granulocytic Anaplasmosis: A Review

Anaplasma phagocytophilum is an emerging pathogen of humans, horses, and dogs worldwide that is transmitted by Ixodid ticks and maintained in a variety of small wild mammal species. Recent studies suggest that multiple strains of A. phagocytophilum may be circulating in wild and domestic animal populations, and these strains may have differential host tropisms and pathogenicity. The organism infects and survives within neutrophils by disabling key neutrophil functions, including neutrophil motility, phagocytosis, the oxidative burst mechanism, and neutrophil-endothelial cell interactions, as well as interfering with neutrophil apoptosis. Coinfections with other tick-borne pathogens may occur, especially Borrelia burgdorferi. A. phagocytophilum causes an acute febrile illness in dogs with lethargy and inappetence. Less frequent signs include lameness, coughing, polydipsia, intermittent vomiting, and hemorrhages. Diagnosis is based on finding morulae within granulocytes in the peripheral blood, the combination of acute and convalescent serology using immunofluorescent antibody techniques, and detection of the DNA of A. phagocytophilum using specific polymerase chain reaction assays. Whether persistent infection or reinfection with A. phagocytophilum occurs after natural infection requires additional study, with most reports suggesting that anaplasmosis is a self-limiting disease in dogs that responds well to a 2-week course of doxycycline therapy.