Cytologie bij zangvogels : een nuttige diagnostische tool

Disease outbreaks in Passeriformes housed in group are often of infectious origin. Clinical signs observed are often similar and non-specific. In these cases, cytology is an invaluable tool for developing a presumptive or definitive diagnosis that can guide disease management decisions within a flock. In the first part of this review, the basic principles of cytological sampling techniques and the evaluation of the cytological findings are described. In the second part, an overview of important infectious diseases in Passeriformes is given, in which cytology may lead to a definitive or presumptive diagnosis

Persistent goose hemorrhagic polyomavirus infection on a Belgian goose farm

Goose hemorrhagic polyomavirus (GHPV) is the causative agent of hemorrhagic nephritis enteritis of geese (HNEG), one of the major diseases of domestic geese in Europe. This case report describes a persistent outbreak of a GHPV infection on a Belgian goose farm. Clinical symptoms, necropsy lesions, and histopathologic lesions observed were compatible with previous reports of HNEG outbreaks. PCR analysis confirmed the diagnosis of GHPV. To our knowledge, this is the first report of an outbreak of a GHPV infection on a Belgian goose farm. This is evidence that GHPV is not only present in countries known for extensive waterfowl production, but disease outbreaks also occur in countries with less extensive goose production

Research note : lyophilization of hyperimmune egg yolk : effect on antibody titer and protection of broilers against Campylobacter colonization

Oral administration of antibodies is a promising strategy against various infectious diseases. Previously, it was demonstrated that passive immunization by providing hyperimmune egg yolk through the feed reduces Campylobacter jejuni colonization in broilers. Campylobacteriosis is the most commonly reported bacterial foodborne zoonosis worldwide, and poultry products are the number one origin of these bacteria for human infection. To date, no effective control measures exist to limit Campylobacter colonization in the chicken's intestinal tract. Here, the effect of lyophilization of hyperimmune egg yolk on protection of broilers against C. jejuni was investigated. During an in vivo trial, broiler chickens were prophylactically given feed with lyophilized hyperimmune or non-immunized egg yolk powder starting from day 1 after hatch. At day 11, broilers were inoculated with C. jejuni according to a seeder model. Five days later, all broilers were euthanized and cecal content was examined for C. jejuni colonization. No decrease in C. jejuni colonization was found. The freeze-drying resulted in a 16-fold decrease of the antibody titer in the yolk powder compared to the fresh yolks, presumably caused by structural changes in the antibodies. In conclusion, applying freeze-dried hyperimmune egg yolk failed to protect broilers against C. jejuni colonization, possibly because lyophilization affected the antibodies' functionality

België ontsnapt niet aan het 'rabbit hemorrhagic disease virus-2'

Since 2016, an extensive spread of RHDV2, a virus variant of the classical rabbit hemorrhagic disease virus (RHDV) is ongoing in the Belgian rabbit population. Both variants of the virus usually cause acute death without prior symptoms. Vaccination against both variants of the virus is possible. In Belgium, only a vaccine protecting against the classical RHDV has been registered. On their own responsibility, veterinarians are allowed to import a vaccine protecting against RHDV2 that is registered in another EU member state, in accordance with the so-called legislative waterfall-system. The current epidemiological situation warrants preventive vaccination of rabbits against RHD. It should be noted that myxomatosis is currently rather neglected in view of the increased attention for the RHDV2 spread. Myxomatosis also still causes a high mortality in both wild and domesticated rabbits. Veterinarians should correctly inform the public about the two important viral diseases in rabbits and the possibilities for prevention

Variation in hemolytic activity of Brachyspira hyodysenteriae strains from pigs

Brachyspira hyodysenteriae is the primary cause of swine dysentery, which is responsible for major economic losses to the pig industry worldwide. The hemolytic activity of 10 B. hyodysenteriae strains isolated from stools of pigs with mild to mucohemorrhagic diarrhea was compared and seven hemolysis associated genes were sequenced. Hemolysis induced by these strains varied from strong to near absent. One weakly hemolytic B. hyodysenteriae strain showed sequence changes in five hemolysis associated genes (tlyA, tlyB, hemolysin III, hemolysin activation protein and hemolysin III channel protein) resulting in amino acid substitutions. The occurrence of weakly hemolytic strains identifiable as B. hyodysenteriae should be taken into account in swine dysentery diagnostics. The presence of these strains may affect herd dysentery status, with great impact on a farms trading opportunities

Medium-chain fatty acids and plant-derived antimicrobials to prevent Campylobacter colonization in broiler chickens

Campylobacter jejuni is the most common cause of bacterial-mediated diarrhoeal disease worldwide. Because poultry products are a major source of C. jejuni infections in humans, efforts should be taken to develop strategies to decrease Campylobacter colonization of poultry during primary production. Organic acids and plant-derived antimicrobial compounds possess marked bactericidal activity toward C. jejuni in vitro and might therefore have potential as feed additives to control C. jejuni colonization in broiler chickens. In vitro screening of several plant-derived compounds revealed strong anti-Campylobacter activity for trans-cinnamaldehyde in particular, while medium-chain fatty acids (caproic, caprylic and especially capric acid) were shown to be the most potent organic acids. However, supplementing these promising additives to the feed of broiler chickens before (prophylaxis) or after (therapeutic) oral inoculation with C. jejuni, did not result in a reduction of the cecal Campylobacter load in these animals. In a cecal loop experiment, neither sodium caprate nor trans-cinnamaldehyde were capable of killing or inhibiting growth of C. jejuni, despite direct injection into the ceca at concentrations of several times their respective minimal inhibitory concentration. When incubated in chicken intestinal mucus, C. jejuni was less susceptible to the antimicrobial effect of capric acid, indicating a protective role for the intestinal mucus layer. Thus, despite the marked bactericidal effect of organic acids and trans-cinnamaldehyde in vitro, neither supplementing these compounds to the feed, nor direct injection in the ceca was able to reduce cecal Campylobacter colonization in broiler chickens. Probably, the mucus layer forms a protective niche rendering the bacterium unresponsive to the bactericidal effects of these compounds observed in vitro, making their potential use as feed additives for controlling Campylobacter in poultry doubtful