reported here are two cases of delayed postsurgical brucella abscess within the cranium, treated successfully by reoperation and appropriate medical therapy. both patients had an occupational exposure to the pathogenic organism. systemic symptoms of brucellosis became manifest postoperatively in case i and were present in case ii long before operation. the diagnosis was confirmed by serology an...

1 Studies conducted on natural host-pathogen metapopulations have revealed considerable diversity of host resistance phenotypes within populations. The resistance structure of non-infected populations has, however, been largely ignored and the role of among-population variation in resistance profiles in the dynamics of natural pathogen populations is poorly understood. 2 The Plantago lanceolata...

anthocoris nemoralis (f.) (hemiptera: anthocoridae) is one of the most prominent predators of the pear psylla, cacopsylla pyricola (forster) (hemiptera: psyllidae) and is considered as a biological control agent against this pest. in order to investigate the effects of plant varieties on predation of c. pyricola by a. nemoralis, the functional response of both the sexes of a. nemoralis to pear ...

Understanding how habitat heterogeneity may affect the evolution of plant pathogens is essential to effectively predict new epidemiological landscapes and manage genetic diversity under changing global climatic conditions. In this study, we explore the effects of habitat heterogeneity, as determined by variation in host resistance and local temperature, on the evolution of Zymoseptoria tritici ...

• The strength and consistency of genotypic differences in disease resistance determine the potential for resistance evolution in host populations that rely on vegetative reproduction. Here we surveyed infection intensity of host genotypes across space and time to estimate genotypic and environmental effects on quantitative disease resistance. • Cloned fragments of 12 Euthamia graminifolia geno...

If a host species shares a pathogen with competing species, the disease may provide a net benefit. Selection for resistance will depend on the trade-off between the damage done by the disease and the positive effects resulting from infection of competitors. This paper presents a simple, spatially explicit model of a plant that shares a disease with a superior competitor. The phenotypic evolutio...

In a wild plant-pathogen system, host resistance and pathogen virulence varied markedly among local populations. Broadly virulent pathogens occurred more frequently in highly resistant host populations, whereas avirulent pathogens dominated susceptible populations. Experimental inoculations indicated a negative trade-off between spore production and virulence. The nonrandom spatial distribution...

The extent to which parasites are locally adapted to their hosts has important implications for human health and agriculture. A recently developed conceptual framework--the geographic mosaic theory of coevolution--predicts that local maladaptation should be common and largely determined by the interplay between gene flow and spatially variable reciprocal selection. Previous investigation of thi...

Natural, agricultural and human populations are structured, with a proportion of interactions occurring locally or within social groups rather than at random. This within-population spatial and social structure is important to the evolution of parasites but little attention has been paid to how spatial structure affects the evolution of host resistance, and as a consequence the coevolutionary o...