Parelaphostrongylus tenuis and other parasitic diseases of the ruminant nervous system.

There are many parasites that affect the ruminant central nervous system. Clinical signs can vary dramatically based on the location and mobility of the parasite. Clinical disease can occur due to the physical presence of the parasite and the resulting host immune response or the toxin produced by the parasite. Differentiating the cause of disease is particularly important because prognosis,treatment, and subsequent control measures vary dramatically depending on the disease process. This article focuses on the pathogenesis,treatment, and control of some of the more common parasitic diseases of the ruminant central nervous system.     

Association between the strength of serologic recognition of bovine leukosis virus and lymphocyte count in bovine leukosis virus-infected cows

OBJECTIVE: To determine whether strength of serologic recognition of bovine leukosis virus (BLV) by use of ELISA is associated with blood lymphocyte counts. DESIGN: Prospective study. ANIMALS: 161 cows with positive results of ELISA for BLV. PROCEDURE: Sample-to-positive ratio (S:P), which is the ratio between the test sample and a positive control sample, was compared among lymphocytotic and nonlymphocytotic cows. A regression model was constructed to evaluate the association between blood lymphocyte concentration and S:P, age, and the interaction of these terms. RESULTS: Mean S:P differed significantly between lymphocytotic (2.58 +/- 0.36) and nonlymphocytotic (2.38 +/- 0.39) cows. Age and S:P were significantly associated with lymphocyte count. CONCLUSIONS AND CLINICAL RELEVANCE: Sample-to-positive ratio and lymphocyte count were related; however, cows with high S:P were not always lymphocytotic. Culling cows on the basis of S:P will reduce the herd load of infectious virus faster than random culling of ELISA-positive cows; however, culling on the basis of lymphocyte count will eliminate a greater proportion of the reservoir of infection.     

The association of titers to Haemophilus somnus, and other putative pathogens, with the occurrence of bovine respiratory disease and weight gain in feedlot calves.

Serum samples were obtained from 602 calves (from 19 groups in four feedlots: three in Ontario, and one in Alberta) upon arrival at the feedlot and 28 d later. Of these calves, 202 developed bovine respiratory disease (BRD) and 400 did not develop BRD. Based on high antibody titers noted upon arrival, we infer that most calves were exposed to Haemophilus somnus prior to arrival at the feedlot. Within a group, calves with high titers on arrival had a reduced risk of developing BRD later. Most calves did not experience titer increases after arrival; however, calves that had stable or increasing titers had a relatively low risk of contracting BRD. The calves at greatest risk of BRD were those with titers on arrival of less than 6.8 units and subsequent titer decreases of more than 1 unit. The effects of both the titer on arrival and the titer change after arrival were stable when the serologic effects of a number of viruses and Mycoplasma agents were considered. Neither antibody titer on arrival nor titer change was related to weight gain differences among calves. Calves with BRD or calves with lower weight on arrival had decreased weight gains in the first 28-day feeding period. The high titers on arrival may have protected most calves against further infection with H. somnus. However, since the calves that developed BRD had large titer increases to a number of viruses and to Pasteurella haemolytica, while having decreased antibody titers to H. somnus, we infer that the existing antibodies were "used up" in combatting the agents, including H. somnus, which may have "caused" the BRD. Calves which were able to increase their antibody levels to H. somnus tended to have a reduced risk of BRD.     

Salmonella Genomic Island 1 (SGI1) and genetic characteristics of animal and food isolates of Salmonella typhimurium DT104 in Hungary

To study the genetic characteristics of DT104 strains of Salmonella Typhimurium and the prevalence of Salmonella Genomic Island (SGI1) in Hungary, 140 recent Salmonella strains of food and animal origin were examined. For the first time in Hungary, the SGI1 was found in 17 out of 59 S. Typhimurium isolates (all proven to be DT104 phage type). These 17 strains were then subtyped by pulsed-field gel electrophoresis (PFGE) into 6 pulsotypes which were less correlated with the geographic origin than with the animal species of origin.     

Distribution of the spotted-wing drosophila (Drosophila suzukii) in the north-eastern part of the Carpathian lowlands

Drosophila suzukii (spotted-wing drosophila) spread rapidly during the first decade of the 2000s and then became widely distributed in Europe except for eastern countries. In Hungary, it was detected in 2012 for the first time, but its distribution in the eastern part of the country had been not studied. During the present investigation nine sampling sites in the north-eastern part of the Carpathian lowlands belonging to Hungary, Ukraine and Romania were studied with baited traps. D. suzukii was detected in all seven Hungarian sites and in the one Western Ukrainian site where sampling occurred. Amongst the Hungarian sites, six had not previously been studied and the data provided here are the first for Western Ukraine and the second for this country following the published record from Yalta (Crimea, south-east Ukraine).     

Rhizoctonia solani AG 2-1 as a causative agent of cotyledon rot on European beech (Fagus sylvatica)

Rhizoctonia solani was frequently isolated in the Italian Alps from nursery-grown European beech (Fagus sylvatica) seedlings displaying symptoms of cotyledon rot. Koch's postulates were verified and mode of infection of the associated isolates was investigated with light and scanning electron microscopy. Population structure of the pathogen was investigated by scoring the anastomosis reaction type in pairings between different isolates from the same seedbed. One pathogen genotype showed a large distribution area within the seedbed, this implying that the inoculum had been building up in the seedbed over a longer time period. Hyphal anastomosis tests and sequence analysis of the internal transcribed spacer (ITS) region of ribosomal DNA indicated that the pathogen belongs to AG 2-1 of R. solani. ITS sequence analysis indicates that the isolates from beech are closely related to R. solani isolates causing a disease on tulip. The striking similarities between the two diseases are discussed.