Effects of Mycoplasma gallisepticum on reproductive success in house finches

Long known as a pathogen of poultry, Mycoplasma gallisepticum (MG) was first detected in house finches in 1994. The disease rapidly spread throughout the eastern United States and Canada and was associated with debilitating disease and high mortality in house finches. However, in the late 1990s, the proportion of infected finches dying as a result of infection with MG decreased, and asymptomatic infection was more common among wild birds than in the past. We documented MG infections in breeding house finches and concluded that adults of both sexes transmit the infection to dependent young, probably after hatch. MG infections of breeding adults occurred late in the breeding season and were found in birds completing significantly more nests than birds that never tested positive for MG, implying that higher rates of reproduction carry a cost in the form of increased risk of infection. We found evidence of an MG-induced delay in dispersal of nestlings from their natal area and demonstrated a significant impact of infection on nestling growth.     

Mycoplasma gallisepticum in house finches (Carpodacus mexicanus) and other wild birds associated with poultry production facilities.

Since 1994, an epidemic of conjunctivitis caused by Mycoplasma gallisepticum (MG) has spread throughout the eastern population of house finches (Carpodacus mexicanus). The adaptation of MG to a free-flying avian species presents potential problems for the control of mycoplasmosis in commercial poultry. To evaluate risks associated with this emerging problem, a field survey was conducted to assess prevalence of MG infection in house finches and other passerine birds associated with poultry farms. Between November 1997 and March 1999, 1058 birds were captured by mist net or trap at 17 farms and at 10 feeder stations in northeast Georgia. Birds were bled and screened by serum plate agglutination (SPA) for antibodies to MG. Birds with negative or weak positive SPA results were released at capture sites, and those with strong positive SPA reactions were kept for further evaluation. Necropsies were performed on selected house finches and individuals of 11 other passerine species, and samples were collected for MG testing by culture, polymerase chain reaction (PCR), hemagglutination inhibition, and histopathology. Testing revealed 19.1% of 671 birds caught at farms and 11.6% of 387 birds caught at feeder sites were SPA positive for MG. Three house finches captured on farms were positive for MG by culture and PCR, whereas three from feeder sites were positive only by PCR. No MG isolates were made from tufted titmice (Baeolophus bicolor), but 40% were positive by PCR. Individuals from 10 additional species were SPA positive only. Results suggest that MG persists at low levels in house finches in northeast Georgia and that tufted titmice may be nonclinical carriers of MG or a related mycoplasma. Positive SPA reactions in other species may be caused by nonspecific reactions or contact exposure. Current biosecurity recommendations should be sufficient to minimize risks of transmission between wild and domestic birds.     

Characterization of mycoplasma gallisepticum infection in captive house finches (Carpodacus mexicanus) in 1998

Since 1995, the epidemic of mycoplasmal conjunctivitis in eastern house finches has affected the Auburn, AL, house finch population. To better characterize the current status of this host-parasite interaction, we established a captive flock of 38 seronegative, healthy finches in fall 1998. After a minimum quarantine period of 4 wk, two Mycoplasma gallisepticum (MG)-infected house finches were introduced into this flock. Over a 12-wk period, the flock was captured every 2 wk and each bird was observed for conjunctivitis. Blood and choanal swabs were collected from each bird for serologic analysis and for the detection of MG by polymerase chain reaction. The infection spread rapidly through the flock just as it had in a similar study performed in 1996 at the height of the epidemic. Unlike the earlier study in which birds remained chronically infected, most of the birds in our study recovered rapidly, and only three of the birds died during the study. Two patterns of host response to infection with MG were observed. Twenty-seven birds (73%) experienced an acute conjunctivitis that resolved, and the birds appeared to clear the infection. Ten birds (27%) suffered prolonged clinical disease, and MG could be detected in these birds intermittently throughout the experiment. These results, in conjunction with our surveys of MG in the wild population, suggest an evolving host-parasite interaction.     

Pathogenicity and immunogenicity of three Mycoplasma gallisepticum isolates in house finches (Carpodacus mexicanus)

Mycoplasma gallisepticum (MG) has become a common cause of conjunctivitis in free-living house finches (Carpodacus mexicanus) since its emergence in the early 1990s. To date, temporal and spatial genotypic variation in MG has been documented, but phenotypic variation in pathogenicity and immunogenicity has not been examined. House finches were inoculated with MG isolates Virginia (VA)1994, California (CA)2006, or North Carolina (NC)2006, which were cultured from free-living house finches with conjunctivitis in 1994, 2006, and 2006, respectively. Infection with NC2006 resulted in the most severe eye lesions, highest pathogen loads, and highest levels of pathogen-specific lachrymal and serum antibodies. Infection with CA2006 caused the least severe eye lesions, lowest pathogen load, and lowest levels of antibodies. A small number of birds in each group developed protracted, severe disease in spite of robust antibody responses, suggesting that immunopathology may contribute to the lesions. Immunoblot analyses indicated that isolates are antigenically similar; thus, there may be partial cross-protection if a house finch encounters two or more strains of MG throughout the course of its lifetime. This study provides evidence that MG strains or strain variants circulating in house finch populations vary in their ability to cause disease, induce antibody responses, and persist in the host.     

Pathogenic effects on domestic poultry of a mycoplasma gallisepticum strain isolated from a wild house finch

Mycoplasma gallisepticum (MG) has been isolated from wild house finches. The pathogenic effects of MG finch strain (K4058) and MG R-strain were compared after exposure of chickens and turkeys. Gross and histologic lesions, reisolation of the organism, serology, and clinical disease were evaluated. Milder histologic and gross lesions, in addition to lower serologic titers, occurred in birds inoculated with the finch strain. Mortality, concurrent with clinical and gross respiratory signs and lesions, was observed only in chickens challenged with R-strain. Both the MG finch strain and MG R-strain were recovered from the respective challenge groups at 14 and 28 days postexposure. The results show that MG isolated from wild house finches may infect domestic poultry species but causes only mild disease and is less virulent than MG R-strain. Commercial enzyme-linked immunosorbent assay kits best detected the serologic response of chickens and turkeys to the MG finch strain.     

Maintenance of a captive flock of house finches free of infection by Mycoplasma gallisepticum

Since the beginning of an epidemic of conjunctivitis in wild house finches caused by Mycoplasma gallisepticum (MG), all captive colonies established by capturing free-ranging house finches from the eastern population have also either been infected at the time of capture or developed infection shortly after capture. In an attempt to avoid this infection in captive flocks being maintained for studies of the finches' behavior and ecology, we compared two different flock management strategies and were able to prevent the development of mycoplasmal conjunctivitis with one of the strategies. Single-sex flocks were built by introducing only seronegative wild-caught birds showing no clinical signs of conjunctivitis and covering their outdoor flight cages with netting to prevent interaction with other wild birds although only the female flocks were initially treated with a 6-wk course of tylosin tartrate (0.3 mg/ml). The female flocks never developed conjunctivitis although the disease did develop in the male flocks. Furthermore, serologic assessments of the healthy flock by serum plate agglutination assays for MG indicated that the females remained free of MG infection in the final 7 wk of the study, during which they were unmedicated. We conclude that any low-level MG infection not diagnosed by the initial test for seroconversion was cleared by the prolonged drug treatment.     

Candida albicans infection in free-living populations of hihi (stitchbird; Notiomystis cincta)

Abstract

AIM: To describe the occurrence of candidiasis in hihi (stitch-bird; Notiomystis cincta) nestlings, and investigate the carriage and impact of Candida albicans infection in a free-living population of hihi.

METHODS: Mortality of nestlings was investigated in a reintroduced population of the endangered, endemic hihi at Zealandia: Karori Sanctuary, Wellington, New Zealand. Oral and faecal samples were collected from live hihi nestlings, for microbiological examination, between October 2008 and April 2009. All hihi that died and could be recovered were submitted to the New Zealand Wildlife Health Centre (NZWHC) at Massey University, for post-mortem examination. The results were compared with data obtained retrospectively from the National Wildlife Mortality (NWM) database for two other reintroduced populations of hihi on Mokoia and Tiritiri Matangi Islands.

RESULTS: Fifty chicks fledged from 82 eggs hatched during the 2008–2009 breeding season at Zealandia: Karori Sanctuary. Thirty-four live nestlings were sampled from 11 nests, and C. albicans was isolated from gastrointestinal swabs of 13 live nestlings from four nest sites. Eight (62%) of those nestlings survived to fledge, compared with 17/21 (81%) of those that tested negative (p=0.254; Fisher's exact test). Of the 32 hihi nestlings that died during the period of the study, 25 were recovered for necropsy. Histopathological examination revealed candidiasis was a factor in the deaths of four nestlings. An adult hihi that died during the period of the study at Zealandia: Karori Sanctuary was also found to have candidiasis. Retrospective analysis of data from the NWM database revealed candidiasis was also a factor in the deaths of five nestlings aged between 1 and 10 days from Mokoia Island, and of three nestlings <5 days old and one adult from Tiritiri Matangi Island.

CONCLUSIONS: Candida albicans was isolated from 38% of hihi nestlings sampled in this study, and vertical transmission of this organism from parent to offspring is likely to occur. Some colonised nestlings developed ventriculitis associated with Candida spp., but survival to fledging was not significantly different between nestlings that tested positive or negative, although the fate of birds following fledging was unknown.     

Characterization of experimental Mycoplasma gallisepticum infection in captive house finch flocks

The use of controlled, horizontal-transmission experiments provides detailed information on the spread of disease within fixed social groups, which informs our understanding of disease dynamics both in an empirical and theoretical context. For that reason, we characterized in 2002, horizontal transmission of Mycoplasma gallisepticum (MG) in two flocks of 11 wild-caught house finches housed in outdoor aviaries over a 6-mo period. All birds were initially free of MG by a polymerase chain reaction (PCR)-based test, rapid plate agglutination (RPA), and the scoring of physical signs. We inoculated one flock member bilaterally in the palpebral conjunctiva and reintroduced it into its cage. Index birds developed conjunctivitis within 3 to 5 days but died 13 and 20 days postinfection (PI) possibly because of very severe weather. The proportion of birds with physical signs increased gradually, reached 40% at 6 wk PI, and fluctuated around 40% until 21 wk PI. By the time our experiment ended at 24.5 wk PI, 28% of the birds still exhibited physical signs. Across both flocks, 80% of the birds developed unilateral or bilateral conjunctivitis, and several birds relapsed. The appearance of physical signs in new individuals occurred between 10 and 144 days PI (median 41 days PI). Physical signs lasted 1-172 days (median 42 days). Birds that became infected earlier during the experiment developed more severe conjunctivitis, and there was a tendency for birds that developed bilateral conjunctivitis to develop physical signs earlier. Most birds that developed physical signs of MG were also PCR- and RPA-positive, although we detected a single asymptomatic carrier and a single symptomatic false negative. No birds died as a result of secondary MG infection.     

Characterization of a naturally occurring infection of a Mycoplasma gallisepticum house finch-like strain in turkey breeders

An outbreak of Mycoplasma gallisepticum (MG) in commercial turkeys involving very mild clinical signs was difficult to confirm by routine methods. In the first part of this study (trial A), we conducted a bioassay to increase the likelihood of detecting MG. Susceptible turkeys were inoculated with sinus exudates from four different affected commercial turkey flocks. Turkeys were evaluated for clinical signs, as well as by serology and culture of tracheal swabs, at 21 and 42 days postchallenge. An MG isolate from one of the sinus exudates used for inoculation, designated K5054, was very similar to isolates from house finches when characterized by random amplified polymorphic DNA analysis as well as DNA sequence analysis of portions of the phase-variable putative adhesin protein (pvpA) gene, a lipoprotein gene, and the cytadhesin gapA/mgc1 gene. The turkeys inoculated with the K5054 sinus exudate seroconverted in the absence of severe clinical signs. There was a single reisolation of K5054 from these turkeys 42 days postchallenge. Susceptible contact turkeys were commingled with the K5054-inoculated turkeys at 49 days postchallenge. We found no evidence of transmission of MG to the contacts by culture or serology at 7, 21, or 35 days after commingling. In the second part of this study (trial B), we challenged the contacts and K5054 sinus exudate-inoculated turkeys from trial A with virulent R strain 88 days after the K5054 sinus exudate inoculation. On necropsy 10 days postchallenge, the evaluation of gross and microscopic lesions, serology, and culture showed that the turkeys previously inoculated with K5054 sinus exudate were protected against disease and reinfection.     

Ecological influences on transmission rates of Ascaris suum to pigs on pastures

A study was conducted to determine the distribution and transmission rate of Ascaris suum eggs and Oesophagostomum dentatum larvae in a pasture/pig house facility, which during the preceding summer was contaminated with helminth eggs by infected pigs. In May, four groups of 10 helminth na?ve tracer pigs were exposed to fenced sections of the facility for 7 days and necropsied for parasite recovery 9-10 days later (trial 1). The highest rate of A. suum transmission (201 eggs per day) occurred in the pig house (A). On the pasture, egg transmission decreased with the distance from the house: 8 eggs per day in the feeding/dunging area (B); 1 egg per day on the nearest pasture (C); <1 egg per day on the distant pasture (D). Only a few O. dentatum infections were detected, indicating a poor ability of the infective larvae to overwinter. Soil analyses revealed that the highest percentage (5.8%) of embryonated A. suum eggs were in the house (A). Subsequently, the facility was recontaminated with A. suum eggs by infected pigs. A replicate trial 2 was conducted in the following May. A major finding was the complete reversal of egg distribution between the 2 years (trials 1 and 2). In contrast to previous results, the highest rates of transmission (569 and 480 eggs per day) occurred in pasture sections C and D, and the lowest transmission rates (192 and 64 eggs per day) were associated with the feeding/dunging sections and the house (B and A). Soil analyses again supported the tracer pig results, as the pasture sections had the highest concentrations of embryonated eggs. Detailed soil analysis also revealed a non-random, aggregated egg distribution pattern. The different results of the two trials may be due to the seasonal timing of egg deposition and tracer pig exposure. Many eggs deposited during the summer prior to trial 1 may have died rapidly due to high temperatures and dessication, especially when they were not protected by the house, while deposition in the autumn may have favored egg survival through lower temperatures, more moisture, and greater sequestration of eggs in the soil by rain and earthworms. The latter eggs may, however, not have become embryonated until turnout the next year. The results demonstrate that yearly rotations may not be sufficient in the control of parasites with long-lived eggs, such as A. suum, and that a pasture rotation scheme must include all areas, including housing.     

Evaluation and comparison of various PCR methods for detection of Mycoplasma gallisepticum infection in chickens

Four genetic Mycoplasma gallisepticum (MG) polymerase chain reactions (PCRs) (16s rRNA PCR, three newly developed PCR methods that target surface protein genes [mgc2, LP (nested) and gapA (nested)]) were compared for analytical specificity and sensitivity and for diagnostic sensitivity (Se) and specificity of detection from tracheal swabs. The licensed MG DNA Test Kit Flock Chek test (IDEXX, Laboratories, Inc., Westbrook, ME) was as well evaluated for the diagnostic specificity and sensitivity of detection from tracheal swabs. Analytical specificity was evaluated for the four generic PCR methods using a panel of DNA samples from microorganisms that may be isolated from the trachea of commercial poultry and other fowl. PCR methods mgc2, nLP, and ngapA only amplified DNA from MG, whereas 16S rRNA PCR amplified DNA from MG and Mycoplasma imitans. The analytical sensitivity of the four generic PCR methods expressed in color-changing units (CCU)/amplification reaction was estimated for each PCR method and ranged from 4 to 400 CCU/reaction; the sensitivities of single PCR methods 16S rRNA and mgc2 were estimated at 40 CCU/reaction, the nLP at 400 CCU/reaction, and the ngapA at 4 CCU/reaction. The diagnostic sensitivity and specificity of MG detection from tracheal swab pools, as compared to isolation from choanal cleft swabs, was evaluated for the five PCR methods using three groups of birds exposed to vaccine strains ts-11 and 6/85 and to challenge strain R. All PCR methods were able to detect the vaccine strains and the challenge strain R directly from tracheal swabs, indicating that PCR primers from the different methods amplified divergent MG strains. Isolation and PCR results correlated satisfactorily among the three experimentally infected groups, with agreement values (k) ranging from 0.52 to 1.00. The ngapA, IDEXX, and mgc2 PCRs showed the best sensitivity (Se) ratios for detection of M. gallisepticum strains as compared to isolation. Compared to the ngapA and IDEXX PCR methods, the mgc2 PCR has a faster turnaround time, since this test consists of a single amplification reaction and the amplification product is detected by gel electrophoresis. Therefore, among the PCR methods evaluated in this study, the mgc2 PCR is the method of choice to further validate in the field.     

Comparison of culturing Mycoplasma gallisepticum from fresh eggs and 18-day-old embryos

Twenty-four 70-week-old and sixteen 27-week-old white leghorn hens were challenged with R strain Mycoplasma gallisepticum (MG) by injection into the caudal thoracic air sac and infraorbital sinus. Eggs were collected daily and cultured within 7 days or incubated for 18 days. Vitelline membranes of eggs were cultured directly; in 18-day-old embryos, cultures were taken from the yolk sac, air sacs, and oral cavity. Culture of vitelline membrane of eggs within 2 days was compared with culture of eggs stored 10 days post oviposition. The first MG-positive egg was laid 2 days postinfection (PI). Hens continued to lay positive eggs to the end of the experiments. There was no significant difference in MG recovery between eggs cultured within 2 days and those cultured 10 days post oviposition. MG was isolated at a significantly higher rate from eggs than from 18-day-old embryos. MG was isolated at a higher rate from the yolk sac of 18-day-old embryos than from the air sacs or oral cavity of the same embryos.     

Laboratory infection of house sparrows (Passer domesticus) with Mycoplasma gallisepticum and Mycoplasma synoviae

House sparrows were infected by aerosol with Mycoplasma gallisepticum (MG) or M. synoviae (MS). MG was reisolated from 5 to 11 sparrows 10 days postinfection, but infection appeared to be temporary. Mycoplasma-free chickens reared in the experimental house became infected with MG during the trial. MS was recovered from only one sparrow. Serological tests were unsatisfactory for diagnosing infected birds. The results suggest that house sparrows may be temporary biological carriers of MG.     

Varied pathogenicity of a Hong Kong-origin H5N1 avian influenza virus in four passerine species and budgerigars

This investigation assessed the ability of the zoonotic A/chicken/Hong Kong/220/97 (chicken/Hong Kong) (H5N1) highly pathogenic avian influenza virus to infect and cause disease in zebra finches (Taeniopygia guttata), house finches (Carpodacus mexicanus), house sparrows (Passer domesticus), European starlings (Sternus vulgaris), and budgerigars (Melopsittacus undulatus) after intranasal administration. Zebra finches were the most severely affected of the five species, demonstrating anorexia, depression, and 100% mortality within 5 days of inoculation. Gross lesions in this species were absent or only mild. But histologic lesions and the corresponding viral antigen were observed in multiple organs, especially in the nasal cavity, brain, pancreas, spleen, adrenal glands, and ovary. Significant morbidity and mortality also were observed in both house finches and budgerigars. Affected birds of these two species demonstrated anorexia, depression, and neurologic signs and typically were moribund or dead within 2 days of the onset of clinical signs. Gross lesions were mild or absent in house finches and budgerigars. Histologically, the brain and pancreas were the most consistently and severely affected organs in house finches. The brain was the most affected organ in budgerigars. Unlike these three species, house sparrows suffered only mild transient depression, had no mortality, and lacked gross lesions. Viral antigen and microscopic lesions were observed only in the heart and testicle of a minority of birds of this species. Starlings demonstrated neither clinical disease nor mortality and lacked gross and histologic lesions. Viral antigen was not observed in any of the collected tissues from starlings. These results indicate that there is significant variation in the pathogenicity of the chicken/Hong Kong virus for different species of birds, including species within the same order. In addition, neurotropism is a recurrent feature among birds that eventually succumb to infection.     

Floor pen study to evaluate the serological response of broiler breeders after vaccination with ts-11 strain Mycoplasma gallisepticum vaccine

To determine the Mycoplasma gallisepticum (MG) rapid serum plate agglutination (RSPA) test response of broiler breeders after ts-11 strain vaccination, 55 Cobb pullets derived from a nonvaccinated, MG-negative, commercial, broiler breeder grandparent flock were monitored from 8 to 20 wk of age (over a 12-wk trial period). To evaluate the effect of lateral spread of the ts-11 vaccine strain on RSPA test results from commingled and adjacently penned birds, treatment groups included (A) birds vaccinated with ts-11strain MG at 8 wk of age, (B) commingled nonvaccinates in the same pen as the vaccinated birds, (C) nonvaccinates in a second pen separated from the first pen by a distance of 2 m, and (D) birds vaccinated with ts-11 strain MG at 8 wk of age and kept in a separate room. Rapid serum plate agglutination tests were performed once a week for 6 wk and then every 2 wk for 6 more wk, postvaccination. A polymerase chain reaction (PCR) assay specific fbr ts-11 strain MG was used to confirm vaccination, and a second PCR specific for non-ts-11 strain MG was used to confirm the absence of field infection. Seroconversion was first detected by the RSPA test 2 wk postvaccination and attained maximum positive rates of 58% at 12 wk postvaccination in treatment A and 60% at 8 wk postvaccination in treatment D. Seroconversion rates in nonvaccinated, commingled pullets was 10% at 5 wk and 30% at 12 wk after the vaccination of pen mates. The ts-11-specific PCR detected the vaccine strain in 80%-100% of the vaccinated birds 2 wk after vaccination. One of 15 nonvaccinated birds penned 2 m from vaccinated birds yielded ts-11 by PCR assay 12 wk after vaccination, which indicates that the spread of ts-11 over short distances may be possible in situations in which there is a common caretaker. PCR on tracheal swabs taken 12 wk postvaccination detected ts-l1 in 50% and 60% of the vaccinated birds in treatments A and D, respectively; in 30% of the commingled nonvaccinates; and in 6.6% of the separately penned nonvaccinates. In contrast, choanal swabs collected from vaccinated birds at 12 wk were 21% and 40% PCR positive for ts-11 strain MG, while those from nonvaccinates were negative. All samples were PCR negative for field strain MG. The pattern of seroconversion as measured by RSPA test in small groups of broiler breeders was different from that previously reported for leghorns. Lateral spread of the ts-11 strain to commingled pen mates occurred rapidly, causing RSPA seroconversion patterns that mimicked those of the vaccinated pen mates.     

Molecular variability of house finch Mycoplasma gallisepticum isolates as revealed by sequencing and restriction fragment length polymorphism analysis of the pvpA gene

Mycoplasma gallisepticum, a major pathogen of chickens and turkeys, has caused significant declines in house finch (Carpodacus mexicanus) populations in the eastern United States since it was first observed in this species in 1994. There is evidence that M. gallisepticum infection is now endemic among eastern house finches, although disease prevalence has declined, suggesting an evolving host-parasite relationship. Studies based on randomly amplified polymorphic DNA (RAPD) have documented the presence of a single, unique RAPD profile in house finch M. gallisepticum isolates, suggesting a single point source of origin, which agrees with the known epidemiologic observations. In the present study, we evaluated the molecular variability of 55 house finch isolates as well as 11 chicken and turkey isolates including reference strains of M. gallisepticum. Molecular variability was evaluated by polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) analysis and nucleotide sequencing of the pvpA gene, which encodes for the putative cytadhesin protein PvpA. Three different RFLP groups and 16 genotypes were evident from the 55 house finch isolates evaluated. Sequence analysis of pvpA gene PCR products showed that although most house finch M. gallisepticum isolates clustered more closely to each other, others clustered more closely to either turkey or chicken field isolates. These findings suggest that house finch isolates are more polymorphic than previously recognized by RAPD studies. This feature may allow us to learn more about the molecular evolution and epidemiology of this emerging disease host-parasite relationship.     

Preliminary data on efficacy of Mycoplasma gallisepticum vaccines containing different adjuvants in laying hens

Chickens were vaccinated subcutaneously twice, at 13 and 17 weeks of age. The vaccines used were the whole organisms of Mycoplasma gallisepticum (MG) adjuvanted with multilamellar positively charged (MPC) liposomes or oil-emulsion. Other chickens received the same bacterins but supplemented with Salmonella typhimurium cell wall protein mitogen (STP) (50 micrograms/dose). At 21 weeks of age, each bird was challenged in the right and left caudal thoracic air sacs. The challenge dose/chicken was 1.3 x 10(5) CFU of MG (R-strain). A significant immunoglobulin (Ig) response specific to MG was observed in sera of chickens collected 3 weeks after the first and second vaccination with MG adjuvanted with MPC liposomes or oil-emulsion. The same two treatments had highly significant MG-titers in eggs collected during the first and second month post challenge. Both groups had highly significant protection (P less than 0.05) against MG transmission in eggs layed during the first month post challenge. Vaccination with MG organisms adjuvanted to MPC liposomes or oil-emulsion resulted in higher egg production, during the first month following challenge, in comparison to the unvaccinated-challenged birds; the same two groups had higher egg production in the second month following challenge compared to unvaccinated-challenged birds, but not significantly different (P greater than 0.05). The addition of STP to bacterins containing MG organisms adjuvanted to MPC liposomes or oil-emulsion, resulted in a significant reduction (P less than 0.05) of the Ig-specific to MG in sera and in a significant drop in egg production (P less than 0.05) during the first month following challenge.     

Isolation of different serovars of Salmonella enterica from wild birds in Great Britain between 1995 and 2003

Postmortem examinations were carried out on the carcases of 779 wild birds. Salmonellosis was a common cause of death in greenfinches (Carduelis chloris), house sparrows (Passer domesticus) and chaffinches (Fringilla coelebs), and was also responsible for the deaths of other birds such as goldfinches (Carduelis carduelis), feral pigeons and different species of gulls. Most cases of salmonellosis in finches occurred between January and March, whereas salmonellosis in house sparrows tended to occur between October and March. Salmonella Typhimurium DT40 and DT56 (variant) predominated in finches and sparrows, DT41 and DT195 were the most common strains isolated from gulls, and DT2 and DT99 were recovered from feral pigeons. These "wild bird" strains of Salmonella made up less than 0.5 per cent of the isolates of Salmonella recovered from cattle, sheep, pigs, chickens or turkeys in Great Britain over the same period, but they made up nearly 3 per cent of the isolates from more extensively reared avian livestock such as gamebirds, ducks and geese.     

Examination of egg number and egg weight variables and their effects on daily management in aviary systems for laying hens

1. Characteristics of egg numbers and mean egg weight were examined for their usefulness in the daily management of aviary systems for laying hens.

2. A number of 3238 brown Isabrown/Warren hens were housed in 1 compartment, a separated part of the house where the hens could move around freely, of a tiered‐wired‐floor aviary system (TWF‐system). An automatic egg weighing and counting system (EWACS) was used to count and weigh eggs daily from 2 tiers of laying nests on 1 side of the compartment and the number of eggs for the whole compartment were counted daily by the farmer. Each tier was divided into 16 blocks of 5 individual laying nests. Two adjoining blocks were called a group. To prevent hens from walking along all the laying nests in a tier, partitions were placed on the perches in front of the laying nests, between nest groups 2–3, 4–5, and 6–7.

3. After the first 3 weeks of the laying period, the distribution of egg numbers over the nest groups within a tier became stable. If egg numbers were counted daily from only 1 nest group the coefficient of variation was 23.1%. If the eggs from the whole compartment were counted daily, the coefficient of variation for the number of eggs was 2.8%. The nest group, presence of a partition and tier level influenced the daily number of eggs.

4. The distribution of the mean egg weight over the different nest groups within a tier was stable for the whole laying period. The coefficient of variation of the daily mean egg weight for a nest group was 3.1%. The difference in mean egg weight between nest groups was small, between 0.1 and 0.6 g, and the level of tiers and the presence of partitions between nest groups had no effect on the mean egg weight.

5. It could be concluded that egg numbers could not be estimated reliably by taking samples from a group of laying nests or a tier, but that it was necessary to count all the eggs from a compartment. The daily mean egg weight, however, could be estimated reliably on the basis of a sample of eggs from a nest group or a tier. By using EWACS frequent samples could be taken, which diminished the coefficient of variation so that the reliability of the data increased.     

Wild Bonelli’s eagles (Aquila fasciata) as carrier of antimicrobial resistant Salmonella and Campylobacter in Eastern Spain

Wild birds have repeatedly been found to be involved in the dissemination of enteric bacterial pathogens in the environment. The aim of this study was to determine the occurrence of Salmonella and Campylobacter as well as the antimicrobial resistance in wild Bonelli’s eagles nestlings in Eastern Spain. In addition, we compared the efficiency of two sampling methods (fresh faecal samples from nest and cloacal swabs from nestlings) for detection of both bacteria. A total of 28 nests with 45 nestlings were analysed. In the nest, Salmonella occurrence was 61 ± 9.2%, while Campylobacter occurrence was 11 ± 5.8% (p < 0.05). In the nestlings, Salmonella occurrence was 36 ± 7.1%, while Campylobacter occurrence was 11 ± 4.7% (p < 0.05). Eight Salmonella serovars were identified, and the most frequently isolated were S. Enteritidis, S. Typhimurium, S. Houston, and S. Cerro. Only one Campylobacter species was identified (C. jejuni). Regarding antimicrobial resistance, the Salmonella strains isolated were found to be most frequently resistant to ampicillin and to tigecycline; however, the sole Campylobacter strain recovered was multidrug resistant. In conclusion, this study demonstrated that wild Bonelli’s eagles nestlings are greater carriers of Salmonella than of Campylobacter. Both Salmonella and Campylobacter isolates exhibited antimicrobial resistance. In addition, faecal samples from nests were most reliable for Salmonella detection, while cloacal swab from nestlings were most reliable for Campylobacter detection.