Zinc bacitracin enhances colonization by the intestinal spirochaete Brachyspira pilosicoli in experimentally infected layer hens

Brachyspira pilosicoli strain CPSp1 isolated from a chicken in a broiler breeder flock in Queensland was used to experimentally infect 40 individually caged 22-week-old laying hens. Another 10 birds were sham-inoculated with sterile broth. All chickens received a commercial layer diet, but 10 infected birds had 50 parts/10 6 zinc bacitracin (ZnB) incorporated in their food. Birds were kept for 7 weeks, and faecal moisture, egg numbers, egg weights and body weights were recorded weekly. B. pilosicoli was isolated from the faeces of only three of the 30 inoculated birds receiving the diet without ZnB, whereas seven of the 10 inoculated birds receiving ZnB in their diet were colonized. This difference in colonization rate was highly significant ( P = < 0.001). Dietary ZnB at 50 parts/10 6 therefore predisposed to colonization by B. pilosicoli. Despite colonization, no significant production differences were found between the birds in the three groups.     

Prevalence and disease association of intestinal spirochaetes in chickens in eastern Australia

Faecal samples (n = 1786) from chickens in broiler breeder (n = 28), layer (n = 22) or broiler (n = 19) flocks in the eastern states of Australia were cultured for intestinal spirochaetes. Overall, birds in 42.9% of broiler breeder and 68.2% of layer flocks were colonized with spirochaetes, but no birds in broiler flocks were infected. Colonization rates in infected flocks ranged from 10 to 100% of birds sampled. Faeces from colonized flocks were on average 14% wetter than those from non-colonized flocks. There was a highly significant association between colonization with spirochaetes and the occurrence of wet litter and/or reduced production. A subset of 57 spirochaete isolates from birds in 16 flocks were identified to the species level using a panel of polymerase chain reaction tests. Isolates from nine (56%) of these flocks were spirochaetes that are known to be pathogens of poultry: Serpulina pilosicoli was isolated from birds from five flocks, birds from two flocks were infected with Serpulina intermedia, and in two other flocks both species were identified. Isolates from the other seven flocks belonged to other Serpulina species, which are currently of unknown pathogenicity. This study indicates that infections with intestinal spirochaetes are a common but currently under-diagnosed cause of wet litter and/or reduced egg production in broiler breeder and layer flocks in Australia.     

Intestinal spirochaetes (Brachyspira spp.) colonizing flocks of layer and breeder chickens in Malaysia

Avian intestinal spirochaetosis causes problems including delayed onset of lay and wet litter in adult chickens, and results from colonization of the caecae/rectum with pathogenic intestinal spirochaetes (genus Brachyspira). Because avian intestinal spirochaetosis has not previously been studied in South East Asia, this investigation was undertaken in Malaysia. Faecal samples were collected from 25 farms and a questionnaire was administered. Brachyspira species were detected by polymerase chain reaction in 198 of 500 (39%) faecal samples from 20 (80%) farms, including 16 (94%) layer and four (50%) breeder farms. Pathogenic Brachyspira pilosicoli was identified in five (29%) layer and two (25%) breeder farms whilst pathogenic Brachyspira intermedia was detected in nine (53%) layer and one (12.5%) of the breeder farms. Twelve (80%) layer farms had egg production problems and 11 (92%) were positive for Brachyspira: three (25%) for B. pilosicoli and six (50%) for B. intermedia. Of three breeder farms with egg production problems, one was colonized with B. pilosicoli. Three of ten layer farms with wet litter were positive for B. pilosicoli and six for B. intermedia. Of four breeder farms with wet litter, one was colonized with B. pilosicoli and one with B. intermedia. No significant associations were found between colonization and reduced egg production or wet litter, perhaps because so many flocks were colonized. A significant association (P = 0.041) occurred between a high prevalence of colonization and faecal staining of eggs. There were significant positive associations between open-sided housing (P = 0.006), and flocks aged >40 weeks (P < 0.001) and colonization by pathogenic species.     

Natural Ascaris suum infections in swine diagnosed by coprological and serological (ELISA) methods

Paired samples of faeces and blood were collected from weaners (W), fatteners (F), lactating sows (S) and piglets (P) in 20 Danish sow herds. The samples were examined by a McMaster technique for Ascaris suum eggs and an indirect ELISA for anti-A. suum IgG. The coprological and serological results were significantly correlated for W and F (P<0.0001) but not for S (P=0.35). The coproprevalences were much lower (W␣4.0%, F 15.5%, S 7.4%) than the seroprevalences (W 20.3%, F 50.5%, S 65.4%). Thus, egg counts greatly underestimate the proportion and number of A. suum-exposed pigs even in the young susceptible age groups. The ELISA ODs of the piglets were closely correlated with those of their mothers (P<0.0001), although the mean OD decreased gradually from 111% of the mean sow OD in the 1st week of life to 48% at 5–6 weeks of age. It is concluded that the ELISA technique gives a more realistic impression of A. suum exposure levels in swine herds than do faecal egg counts. Received: 27 October 1997 / Accepted: 15 January 1998     

Periparturient rise in fecal egg counts associated with prolactin concentration increase in French Alpine dairy goats

Previous data on periparturient relaxation of immunity during gastrointestinal nematode infection in goats are scarce and conflicting; one study carried out in fiber (Angora) goats showed a positive association of fecal egg counts with prolactin concentrations around parturition, whereas the two other available studies dealing with dairy goats, gave divergent results. The objectives of the study were thus to assess the occurrence of a periparturient rise in fecal egg counts in dairy goats and to examine a possible relationship between the level of milk production and the intensity of the periparturient rise. A total of 28 French Alpine grazing dairy goats naturally infected with Teladorsagia, Trichostrongylus, and Oesophagostomum were allocated into two groups according to their reproductive status; group 1 (n = 7) consisted of nonpregnant lactating animals in the 3^rd month of lactation, whereas group 2 (n = 21) was composed of dry goats at 6 weeks before term. Fecal egg counts, pepsinogen and phosphate blood concentrations, blood eosinophil counts, and prolactin concentrations were individually monitored at weekly intervals for 12 weeks (from midwinter to early spring). The mean fecal egg counts were significantly higher in pregnant goats during the 2 weeks before (668 versus 242 eggs per gram of feces (epg), P < 0.05) and the 2 weeks after (962 versus 279 epg, P < 0.01) parturition as compared with nonpregnant lactating animals. No significant difference was seen in the composition of larval cultures between the two groups of animals, with Oesophagostomum infective larvae being found predominantly, particularly at the time of parturition. Pepsinogen and phosphate concentrations as well as blood eosinophil counts were similar between the two groups throughout the survey and indicated a moderate larval challenge. The mean prolactin concentration measured in pregnant goats was significantly higher (P < 0.01) at the time of parturition (298 versus 130 ng ml⁻¹) and at 4 weeks after parturition (387 versus 193 ng ml⁻¹) than that determined in nonpregnant animals. Furthermore, a significant correlation (r _s = 0.30, df = 79; P < 0.01) between fecal egg counts and prolactin concentrations was recorded for the pregnant goats during the 4-weeks period around parturition. Received: 2 April 1998 / Accepted: 8 June 1998     

In Vitro Cytokine Responses to Periodontal Pathogens: Generalized Aggressive Periodontitis is Associated with Increased IL‐6 Response to Porphyromonas gingivalis

Generalized aggressive periodontitis (GAgP) is an inflammatory condition resulting in destruction of tooth‐supporting tissues. We examined the production of IL‐1β, IL‐6, tumour necrosis factor (TNF)‐α, IL‐12 and IL‐10 in cultures of peripheral mononuclear cells (MNC) from 10 patients with GAgP and 10 controls stimulated with periodontal pathogens or a control antigen, tetanus toxoid (TT) in the presence of autologous serum. The pathogens used were Porphyromonas gingivalis, Prevotella intermedia and Fusobacterium nucleatum, either as type strains or bacteria isolated from the participants’ inherent oral flora. The P. gingivalis ‐induced production of IL‐6 was approximately 2.5‐fold higher in patients with GAgP than in healthy controls (P < 0.05), while the corresponding TNF‐α production was non‐significantly elevated. IL‐1β production induced by P. gingivalis, as all cytokine responses induced by Pr. intermedia, F. nucleatum and TT was similar in the two groups. A reduced IL‐12p70 response to Pr. intermedia and F. nucleatum was observed in smokers compared to non‐smoking patients (P < 0.02). To assess the role of serum factors in the elevated IL‐6 response to P. gingivalis, MNC from two donors free of disease were stimulated with this bacterium in the presence of the various patient and control sera. An elevated IL‐6 and TNF‐α response was observed in the presence of patient sera (P < 0.01 and P < 0.04, respectively). The data suggest that an exaggerated production of IL‐6 occurs in GAgP, and that pro‐inflammatory serum factors play an essential role in the response.     

Survival of intestinal spirochaete strains from chickens in the presence of disinfectants and in faeces held at different temperatures

This study aimed to evaluate the efficacy of some commonly used disinfectants in inactivating the pathogenic avian intestinal spirochaetes Brachyspira intermedia and Brachyspira pilosicoli, and to examine spirochaete survival in chicken caecal faeces held at 4°C, 25°C or 37°C. Six disinfectants were evaluated at their recommended working concentrations: alkaline salts, quaternary ammonium, iodine as an iodophor, chlorine from a chlorine-release agent, glutaraldehyde and hydrogen peroxide. All but alkaline salts inactivated two different concentrations of both spirochaete species in less than 1 min in the presence of organic matter. Both spirochaete species at three different cell concentrations survived in caecal faeces at 37°C for between 2 and 17 h. B. intermedia tended to survive for longer than B. pilosicoli, but the maximum survival time for both species at 4°C was only 72 to 84 h. Hence, avian intestinal spirochaetes are rapidly inactivated by several common disinfectants, and their survival time in chicken caecal faeces is much less than has been reported for porcine intestinal spirochaetes in porcine faeces. It should be relatively easy to break the cycle of infection between batches of laying birds by resting sheds for a few days, and by using disinfectants on any residual faecal matter.     

Synergistic pathogenic effects of co-infection of subgroup J avian leukosis virus and reticuloendotheliosis virus in broiler chickens

To study interactions between avian leukosis virus subgroup J (ALV-J) and reticuloendotheliosis virus (REV) and the effects of co-infection on pathogenicity of these viruses, 1-day-old broiler chicks were infected with ALV-J, REV or both ALV-J and REV. The results indicated that co-infection of ALV-J and REV induced more growth retardation and higher mortality rate than ALV-J or REV single infection (P < 0.05). Chickens co-infected with ALV-J and REV also showed more severe immunosuppression than those with a single infection. This was manifested by significantly lower bursa of Fabricius and thymus to body weight ratios and lower antibody responses to Newcastle disease virus and H9-avian influenza virus (P < 0.05). Perihepatitis and pericarditis related to severe infection with Escherichia coli were found in many of the dead birds. E. coli was isolated from each case of perihepatitis and pericarditis. The mortality associated with E. coli infection in the co-infection groups was significantly higher than in the other groups (P < 0.05). Among 516 tested E. coli isolates from 58 dead birds, 12 serotypes of the O-antigen were identified in two experiments. Different serotypes of E. coli strains were even isolated from the same organ of the same bird. Diversification of O-serotypes suggested that perihepatitis and pericarditis associated with E. coli infection was the most frequent secondary infection following the immunosuppression induced by ALV-J and REV co-infection. These results suggested that the co-infection of ALV-J and REV caused more serious synergistic pathogenic effects, growth retardation, immunosuppression, and secondary E. coli infection in broiler chickens.     

Variation in phenotypic resistance to gastrointestinal nematodes in hair sheep in the humid tropics of Mexico

The objective of the study was to evaluate phenotypic resistance against gastrointestinal nematodes in Blackbelly, Pelibuey and Katahdin ewes before pregnancy in the humid tropics of Mexico. Individual faecal and blood samples were taken in 59 Pelibuey, 69 Blackbelly and 73 Katahdin ewes. The egg count per gram of faeces (EPG) of gastrointestinal nematodes (GINs) was determined. The percentage of packed cell volume (PCV) and body condition score (BCS) of each animal were also recorded. The ewes were segregated as susceptible, intermediate or resistant based on the EPG using the quartile method. The data were analysed using the general linear method, and the means between breeds were compared by Tukey’s test. The relationships between the EPG, PCV and BCS were evaluated by Spearman correlation. The Katahdin ewes showed the highest EPG counts (3613.6 ± 5649) compared to the Blackbelly and Pelibuey ewes (576.1 ± 1009 and 56.8 ± 187, respectively, P < 0.01). The PCV values between breeds were similar (P > 0.05). The susceptible ewes had the highest EPG counts and the lowest PCV percentage (5069 ± 6404 and 22.8% ± 8.1% respectively) compared to the resistant ewes (P < 0.01). A higher percentage of Katahdin ewes were susceptible compared to the other breeds (P < 0.05). The main GIN species were Haemonchus contortus, Trichostrongylus colubriformis and Cooperia curticei. In conclusion, Katahdin ewes showed susceptibility to GIN compared to Blackbelly and Pelibuey ewes before the pregnancy period in the humid tropics of Mexico.

     

Schistosomal granuloma modulation

Recurrent experimental evidence indicates that schistosomal egg granuloma formation – at least in the murine model – results from a host response generated against both egg- and worm-derived antigens. Further experiments aimed at identifying the existence in vivo of cross-sensitization between Schistosoma haematobium worms and S. mansoni-derived egg antigens were performed with respect to S. mansoni egg antigen-induced granuloma formation and fibrogenesis in the liver. Male OF1 mice bisexually infected with S. haematobium or S. mansoni were hepatically challenged (cecal vein injection) with S. mansoni SEA (soluble egg antigen)-coupled Sepharose beads at the end of prepatent infection (8–10 days prior to the start of egg deposition). The mean granuloma volume (MGV) of in-vivo-generated synchronized hepatic granulomas (8 days old) and the fibrotic response were estimated. Just like S. mansoni-infected rodents, mice carrying an S. haematobium infection generated an accelerated hepatic granulomogenesis [respective MGVs 4.72 ± 0.56 and 5.41 ± 0.75 × 10⁶ μm³; P < 0.0001 versus unsensitized (MGV 3.00 ± 0.40 × 10⁶ μm³) mice] and an enhanced fibrotic response against S. mansoni SEA. They also had significantly enlarged spleens (P < 0.0001) and moderately enlarged livers (P = 0.02) as compared with S. haematobium-infected mice that were not challenged with SEA. From these observations we infer that in vivo, S. haematobium worms can positively modulate S. mansoni egg antigen-induced granuloma formation and hepatic fibrogenesis, resulting in more severe liver pathology. Received: 10 May 1999 / Accepted: 20 May 1999     

Prevalence,disease associations and risk factors for colonization with intestinal spirochaetes (Brachyspira spp.) in flocks of laying hens in north-eastern Italy

The present study investigated the occurrence of anaerobic intestinal spirochaetes of the genus Brachyspira in laying hen flocks in Treviso province, north-eastern Italy, with respect to prevalence, spirochaete species present, disease associations and risk factors for colonization. A total of 450 faecal samples from 45 sheds on 29 laying hen farms were cultured for intestinal spirochaetes. Nineteen sheds on 12 farms contained chickens with symptoms consistent with avian intestinal spirochaetosis, including reduced egg production, wet litter and/or pasty vents. Spirochaetes were isolated from 157 (34.8%) samples from 21 (72.4%) farms, and from 32 (71.1%) sheds. From these positive samples, 189 spirochaetal isolates were speciated using three polymerase chain reaction assays and a restriction fragment polymorphism analysis of 16S rDNA polymerase chain reaction products. Overall, 52 (27.5%) isolates were identified as pathogenic Brachyspira intermedia, 26 (13.8%) as pathogenic Brachyspira pilosicoli, 93 (49.7%) as non-pathogenic (Brachyspira innocens/Brachyspira murdochii), and 18 (9.6%) were unidentified. Faeces from 14 sheds (31%) on 10 farms (34.5%) contained B. intermedia and/or B. pilosicoli, and disease consistent with avian intestinal spirochaetosis was observed in nine of these sheds on seven farms. There was a significant association (P=0.042) between the presence of spirochaetes and using deep pits rather than conveyor belts for manure disposal. Sheds housing chickens >40 weeks of age were significantly more likely to contain spirochaetes (P=0.048) and pathogenic species (P=007) than sheds housing younger chickens. A significant association (P=0.02) was found between infection with pathogenic spirochaetes and reduced egg production.     

Growth enhancement in broiler chickens receiving CHEMEQRTM polymeric antimicrobial

This study investigated the use of CHEMEQ^RTM polymeric antimicrobial as a means of enhancing health and growth rates in broiler chickens. One-day-old Cobb-500 broilers were reared to 42 days. In trial 1, 100 birds received CHEMEQ^RTM polymeric antimicrobial via water, and 100 birds were untreated. Treated birds had significantly greater (P<0.0001) average daily gain (ADG), significantly lower (P<0.0016) feed conversion ratios, significantly lower (P<0.05) mortality, and a significantly lower (P<0.0042) viscosity of their ileal contents. In trial 2, three groups of 40 birds received reducing dosages of CHEMEQ^RTM polymeric antimicrobial, and a fourth group remained untreated. Groups receiving CHEMEQ^RTM polymeric antimicrobial had significantly greater (P<0.05) ADG, and two groups had significantly lower (P<0.05) feed conversion ratios than the controls. In trial 3, groups of 40 birds received either CHEMEQ^RTM polymeric antimicrobial, Salinomycin or Lasalocid in-feed, or were untreated. Birds receiving CHEMEQ^RTM polymeric antimicrobial had significantly greater (P<0.05) ADG than those receiving Salinomycin. CHEMEQ^RTM polymeric antimicrobial helped to maintain the health and to improve the growth performance of broiler chickens.     

Evaluation of haematological and serum biochemical parameters in Iranian camels (Camelus dromedarius) infected with haemotrophic Mycoplasma (Eperythrozoon) spp

Blood samples were collected from 67 adult Iranian dromedary camels naturally infected with Mycoplasma spp, and a control group comprised 20 healthy dromedary camels. Haematological and serum biochemical parameters were measured using standard techniques. In Giemsa-stained peripheral blood smears, Mycoplasma appears attached to the surface of erythrocytes. In infected camels, the number of red blood cells, haemoglobin concentration and haematocrit (packed cell volume) significantly decreased (P < 0.05).With regard to the values of mean corpuscular volume and mean corpuscular hemoglobin concentration, a normocytic and normochromic anaemia was observed in infected camels. In infected camels, the concentration of serum glucose was significantly lower as compared with controls (P < 0.05).     

Studies on the sexual behaviour, haematology and spermatogenesis of male rabbits infected with Trypanosoma brucei brucei

A total of 24 crossbreed buck rabbits (New Zealand White × chinchilla) were used to evaluate the effect of experimental infection with Trypanosoma brucei on symptoms, sexual behaviours, haematology and spermatogenesis. The rabbits were divided into two groups (A and B) of 12 rabbits each. Group A rabbits were infected with 1.25 × 10⁶ of T. brucei, whereas group B served as the uninfected control. The trypanosomes were detectable in the blood of all the infected bucks by day 7 post-infection (PI) with mean pre-patent period of 4.7 ± 0.85 days. The red blood cell (RBC) and packed cell volume (PCV) decreased significantly (P < 0.05) from day 8 to 28 PI. The values however improved from day 36 PI and were similar to the uninfected control. The reverse was the case of parasitaemia. Two rats died at the peak of the decrease in RBC and PCV and increase in parasitaemia. There was also significant (P < 0.05) loss in live and testis weights, reduced libido and impaired spermatogenesis in the infected group. The infected bucks showed clinical signs similar to that reported in other trypanosome-infected animals. It is concluded that susceptibility of crossbreed rabbits usually kept in Africa to pathogenic trypanosomes is characterised by an acute stage manifested by anaemia, high parasitaemia and death and chronic stage manifested by improved PCV and RBC, very low parasitaemia but high tissue damage and low productivity. Control of this disease in endemic areas for purpose of commercial rabbit production is advocated.     

Effect of egg clustering on the fitness of Rhipicephalus sanguineus larvae

Several biological aspects of Rhipicephalus sanguineus have been studied, but scant information is available on the effect of egg clustering on incubation period and larval survival. Herein, R. sanguineus eggs were separated in groups composed by 1 (GI), 10 (GII), 50 (GIII), 100 (GIV), 500 (GV) and 1,000 (GVI) eggs (10 replicates), and incubation and larval survival period were recorded. No correlation was observed between the amount of egg batches and hatching percentage. Larvae from GI hatched in a longer time (mean 17 days), than those of other groups (mean 14.9 days). This difference was significant in eggs from group GI vs. GV and GI vs. GVI (P?<?0.05). Conversely, GI displayed a shorter survival period (mean 28.7 days) compared with other groups (P?<?0.01). The maximum survival time was recorded in GV (mean 49.8 days). Data suggest that R. sanguineus egg clustering affects incubation period and larval survival.     

The influence of zinc in mice on infection with<Emphasis Type="Italic"> Angiostrongylus cantonensis</Emphasis>

BALB/cByJ mice were divided into zinc-deficient (ZD), high zinc-supplemented (ZH), adequately zinc-replete (ZA) and normal control groups by daily dietary control. The body weight in ZD and ZH mice became significantly less than that of normal control mice from 4 weeks (P<0.002) until 7 weeks (P<0.0001) after consecutive zinc control. The kinetics of change in body weight of ZD and ZH mice after infection with Angiostrongylus cantonensis were similar to that of uninfected groups mentioned above. The worms recovered at days 7, 14 and 21 after infection from ZD and ZH mice were significantly more in number than that in control mice (P<0.01). However, the worms from day 21 after infection were shorter in size than those in control mice (P<0.01). The production of interleukin (IL)-5 was significantly depressed in cultured spleen cells from uninfected and infected ZD and ZH mice, compared with that from respective control group (P0.02). Furthermore, significantly lower eosinophil counts were observed in the cerebral spinal fluid(CSF) of ZD and ZH mice 3 weeks after infection than in the CSF of control mice (P<0.001). The levels of immunoglobulins IgG, IgM, IgA and IgE in the supernatant of cultivated spleen cells and serum from ZD and ZH mice were all lower than those of control mice. Thus, the level of zinc correlated with the defence against infection by A. cantonensis, due to the influence of zinc on the growth of mice and their production of IL-5, eosinophils and immunoglobulins.     

Molecular and morphological description of Isospora sp. from the common mynah (Acridotheres tristis) and a preliminary survey of two anticoccidial drugs in natural infection

Coccidian parasites, especially Isospora, are prevalent parasites in Passeriformes. Isosporan oocysts from common mynahs (Acridotheres tristis) are incompletely described. Detailed knowledge on biology, prevalence, pathogenesis and treatment of avian isosporiasis is scant. In this study, isosporan oocysts isolated from common mynahs were morphologically and molecularly characterized. The medication efficiencies of diclazuril and sulfadiazine-trimethoprim in isosporiasis in naturally infected mynahs were evaluated. Isosporan oocysts from common mynahs were described morphologically by microscopic imaging. The 18S rRNA and COI genes were amplified using PCR and the resultant products were sequenced and analysed phylogenetically. To evaluate the efficiencies of diclazuril and sulfadiazine-trimethoprim, two experimental treatment groups and a null control were assigned. General health status, weight and oocysts per gram of faeces were evaluated. Oocysts from all birds contained isosporan oocysts that were morphologically and dimensionally similar (P?Isospora isolate in the same clade with Isospora spp. from other Passeriformes. Both of the anticoccidials were well tolerated by the birds, a rapid reduction in oocyst excretion was noted at the commencement of treatment and 72?h after drug administration, oocyst excretion zeroed in all treated birds. Based on morphological and molecular data, this isolate does not resemble any previously described isosporas, hence Isospora tristum n. sp. is proposed for the current species. Both evaluated anticoccidials seemed to be efficient in reduction of oocyst production and can be recommended for the treatment of mynah isosporiasis.     

Studies on a depressed egg production syndrome in Northern Ireland

A syndrome causing depressed egg production is described. It is characterised either by a failure to attain predicted production targets or by a fall in egg numbers. The depression in production can reach 30% and it may or may not return to normal. For a short period the eggs produced are smaller, lose colour, have poor egg shell strength and many soft shelled eggs are laid. The birds remain apparently healthy and there is a marked age incidence, with most flocks starting this depression in egg production at 29-31 weeks of age. This syndrome has been recently recorded in the Netherlands, but has not been seen before in Northern Ireland. Viruses which agglutinated fowl erythrocytes to very high titres were isolated in chick embryo liver cells from six affected flocks. Three of these isolates were from the oviduct, two from the upper respiratory tract and one from the faeces. These agents are similar to adenoviruses, but were not neutralised by antisera to 11 prototype fowl adenoviruses. In addition, 17 adenoviruses were also isolated from the flocks showing the syndrome described. These isolates fell into five serological types, in addition to nine which could not be typed using antisera to 11 prototype adenoviruses. Investigations of flocks with falls in egg production not conforming to this syndrome yielded five isolates. Six adenoviruses were also isolated from birds with diarrhoea.     

Experimental Challenge of Mallards (Anas platyrhynchos) with Brachyspira hyodysenteriae and “Brachyspira suanatina” Isolated from Pigs and Mallards

Brachyspira hyodysenteriae, the aetiological agent of swine dysentery, and a recently proposed and closely related enteropathogenic spirochaete “Brachyspira suanatina”, originally isolated from pigs or mallards (Anas platyrhynchos), were used to inoculate week-old mallard ducklings orally or cloacally. The colonization rate, clinical outcome, faecal dry matter content, blood leucocyte counts and gross, microscopical and electron microscopical features 14–16 days post-inoculation were investigated at necropsy examination. Strains of “B. suanatina” of pig and mallard origin and B. hyodysenteriae of mallard origin colonized the ducklings by oral inoculation, and colonization was also established by cloacal inoculation with a “B. suanatina” strain of mallard origin. The porcine reference strain of B. hyodysenteriae (B204^R) failed to colonize the birds. Unchallenged contact birds in one of the challenge groups were readily colonized by a strain of “B. suanatina” of mallard origin. The proportion of colonized birds differed significantly between the challenge groups (P < 0.0001). For each challenge group, the inoculum and a randomly selected subset of recovered isolates had an identical biochemical profile and banding pattern by randomly amplified polymorphic DNA (RAPD) analysis. None of the birds developed clinical signs of gastrointestinal disease during the trial. The faecal dry weight contents, body weights and total leucocyte and heterophil counts did not differ between the various groups of birds. At the microscopical and electron microscopical levels, the caecal mucosa in some of the Brachyspira culture-positive birds had sharply demarcated epithelial cell changes and there were features of irreversible cell damage in crypt necks coinciding with spirochaetal infiltration of the mucosa. The crypts in Brachyspira culture-positive birds were deeper than in culture-negative birds (median: 237 μm and 218 μm, respectively, P = 0.019). This challenge model was well suited for use in mallards and consistent with previous findings that strongly haemolytic Brachyspira spp. may cross the species barrier between pigs and birds.     

Comparison of the FLOTAC technique with the McMaster method and the Baermann technique to determine counts of Dictyocaulus eckerti L1 and strongylid eggs in faeces of red deer (Cervus elaphus)

The FLOTAC flotation technique has been introduced as a new diagnostic tool to detect parasitic elements from faeces. Samples from naturally infected young deer were used for counting Dictyocaulus larvae and strongylid eggs. The FLOTAC technique, using 11 different flotation solutions with specific gravities (sg) between 1.20 and 1.45, was compared with the Baermann technique and the saturated sodium chloride (sg 1.20)-based McMaster method. In addition, a comparison was made between the FLOTAC technique with magnesium sulphate (sg 1.28) and the Baermann technique for larval recovery from faeces that were examined on the day of collection or after 7 days storage at 4°C. On the whole egg counts between the FLOTAC using different flotation solutions and the McMaster were unremarkable. In contrast, variations of larval counts were detected between different flotation solutions as well as with the Baermann technique. Most flotation solutions with a specific gravity of 1.20 floated significantly fewer lungworm larvae (p < 0.05) compared to flotation solutions with a higher specific gravity. Magnesium sulphate (sg 1.28) consistently produced the highest mean larval counts in all conducted experiments. Larval counts using magnesium sulphate (sg 1.28) were higher than with the Baermann technique both on the day of collection and after 7 days. Overall, the use of magnesium sulphate (sg 1.28) with FLOTAC for larval counts resulted in higher counts than the Baermann recovery technique and was the better choice of those flotation solutions examined. Furthermore, magnesium sulphate (sg 1.28) was also reliable for strongylid egg detection with the FLOTAC apparatus.