Serovar profiling of Haemophilus parasuis on Australian farms by sampling live pigs

Objective Investigate the diversity of serovars of Haemophilus parasuis (Hps) present in Australian pig herds. Design Nasal swabs were used to obtain multiple isolates of Hps, which were grouped first by genotyping and then by serotyping representative isolates. Procedure Swabs were taken from the nasal cavity of just-weaned healthy pigs from multiparous sows on 12 farms and from post-weaned pigs of multiparous sows on 1 farm. On 5 of the 13 farms, nasal swabs were also obtained from pigs showing clinical signs suggestive of Glässer's disease. On a further 7 farms, nasal swabs were obtained only from pigs with clinical signs suggestive of Glässer's disease. Results A total of 556 Hps isolates were genotyped, and 150 isolates were serotyped. Hps was detected on 19 of the 20 farms, including 2 farms with a long history of freedom from Glässer's disease. Isolates of Hps belonging to serovars regarded as potentially pathogenic were obtained from healthy pigs at weaning on 8 of the 10 farms with a history of Glässer's disease outbreaks. Sampling 213 sick pigs yielded 115 isolates of Hps, 99 of which belonged to serovars that were either potentially pathogenic or of unknown pathogenicity. Only 16 isolates from these 213 sick pigs were of a serovar known to be non-pathogenic. Conclusion Healthy pigs contain a range of Hps serovars, even on farms free of Glässer's disease. Nasal swabbing of both healthy and sick pigs seems a useful method of serovar profiling of farms.     

Antimicrobial sensitivity testing of Australian isolates of Bordetella avium and the Bordetella avium-like organism

SUMMARY: The in-vitro sensitivity of 16 Australian isolates of Bordetella avium and 15 isolates of B avium -like organism to 11 antimicrobial agents or combinations of agents was determined using a microtitre plate system to establish minimal inhibitory concentrations. All the B avium isolates were sensitive to ampicillin but resistant to erythromycin, lincomycin, spectinomycin, sulphamethoxazole, trimethoprim, and lincomycin + spectinomycin. Most of the B avium isolates were sensitive to tetracycline and resistant to streptomycin and sulphadiazine. All the B avium -like isolates were resistant to ampicillin, erythromycin, lincomycin, spectinomycin, streptomycin, tetracycline, trimethoprim, and lincomycin + spectinomycin. Most B avium -like isolates were sensitive to sulphadiazine, sulphamethoxazole and trimethoprim-sulphamethoxazole.     

An evaluation of the cross-protection afforded by inactivated infectious coryza vaccines

The cross-protection afforded by three inactivated infectious coryza vaccines was evaluated. Each vaccine contained one of the following strains of Haemophilus paragallinarum, HP31, HP60 and HP14. Strain HP31 belongs to Kume serovar C-2, strain HP60 belongs to Kume serovar C-4 while strain HP14 belongs to Kume serovar A-4. Four groups of twenty six-week-old specific-pathogen-free chickens were either given a single dose of an aluminium-hydroxide based vaccine (three groups) or left as unvaccinated controls. Three weeks after vaccination, all four groups were challenged with virulent H paragallinarum. One half of each group was challenged with the strain HP31 and the other half with strain HP60. The efficacy of the vaccines was assessed in terms of the prevention of the typical clinical signs and macroscopic lesions of infectious coryza as well as the prevention of any colonisation by the challenge organism. The serovar C-2 and serovar C-4 vaccines protected more than 50% of birds against either a serovar C-2 or C-4 challenge while the serovar A-4 vaccine protected less than 50% of birds.     

Are some weeds sleeping? Some concepts and reasons

Summary Sleeper weeds, a relatively new concept, are defined as a sub-group of invasive plant species for which their population sizes are known to have increased significantly more than 50 years after they became naturalized. The invasions of the European herb Hieracium pilosella into New Zealand, the northeast Asian Fallopia japonica and the Sicilian Senecio squalidus into Britain are presented as well-documented examples of sleeper weeds. While the concept of sleeper weeds has gained some acceptance with weed managers, its application remains a retrospective activity at present. Genetic factors, environmental suitability and anthropogenic disturbance are discussed as they affect sleeper weed status. Accurate botanical records for invasive species over long periods of time are relatively rare and limit documentation of the phenomenon. Some mathematical and ecological problems remain with the concept and its wider application to weed invasion, including the adequacy of the species level for determining sleeper weed status in genetically diverse and widely distributed groups of invasive plants.     

Cochlosoma infections in finches

Objective To survey finches in pet shops for Cochlosoma infection and evaluate the efficacy of antiprotozoal therapy with metronidazole or ronidazole.
Design A survey of pet shop finches and drug efficacy trials.
Procedure Finches in pet shops were randomly selected and their faeces examined microscopically for motile Cochlosoma sp trophozoites. Drug trials were carried out on 60 adult finches with naturally occurring infections. Body weight was measured and the faeces of each bird was examined for trophozoites at the beginning and 7 days after the end of treatment. In some birds, additional daily faecal examinations were done until three consecutive negative results were obtained. Metronidazole was administered at various dose rates by crop gavage or in drinking water to eight groups of five to ten finches each. Ronidazole was given in water for 7 days to ten finches. In addition, six finches whose faeces tested positive were necropsied and their tissues collected for histological examination.
Results Motile flagellates in the faeces were identified as C anatis -like protozoa. Red-headed parrot-finches, Bengalese and Lady Gould finches were found to be most commonly infected. Cochlosoma sp was also found in the blue-faced parrot-finch, zebra finch, painted finch, nutmeg mannikin and double-barred finch. Metronidazole and ronidazole were found to be effective against Cochlosoma sp. Histological findings on infected adult finches were normal, except for the presence of numerous flagellates between the colorectal villi and cloacal mucosal folds.
Conclusions Cochlosoma anatis -like organisms can infect several species of finches and in adult finches are confined to the colorectum and cloaca. Infection in adult finches was mostly subclinical and could be treated effectively with metronidazole or ronidazole.     

Disease of geese caused by a new herpesvirus

A goose flock farmed outdoors in south-eastern Queensland suffered an outbreak of peracute disease with high death rate (97%). Small button ulcers and large plaques overlying lymphocyte aggregates were present on the mucosa of the small intestine of affected birds. Small white foci of necrosis and focal haemorrhages were seen in the livers. Numerous intranuclear inclusion bodies were observed microscopically in hepatocytes and a herpesvirus which grew rapidly in chicken kidney cells was isolated from tissues. Duck virus enteritis (DVE) was suspected but DVE antiserums failed to neutralise the virus. Further serological studies with a limited range of known avian herpesviruses have failed to identify the virus. Experimental transmission resulted in high mortality in geese (100%), lower mortality in ducklings and nil mortality in chickens. Surveillance studies showed no evidence of infection in domestic and wild birds beyond the original farm and the infection appears not to have been established in the area. Wild ducks, which were frequent visitors to the farm dam, were considered the most likely source of the infection.