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.     

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.     

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.     

Monitoring Mycoplasma gallisepticum and Mycoplasma synoviae infection in breeder chickens after treatment with enrofloxacin.

Three experimental strains of breeder chickens were accidentally exposed to Mycoplasma gallisepticum (MG) and Mycoplasma synoviae (MS), presumably from a newly introduced group of leghorn-type pullets. The experimental strains subsequently became infected and were diagnosed positive for MG and MS by the serum plate agglutination (SPA) test and confirmed by the hemagglutination inhibition (HI) test and the polymerase chain reaction (PCR) of tracheal swabs. Treatment with 10 mg/kg enrofloxacin via drinking water for 14 days was elected. Before and after initiation of treatment, MG and MS were monitored for changes by SPA, HI, PCR, and culture, with sampling intervals ranging from 1 wk to 7 wk. MG and MS SPA, HI, PCR, and culture were performed at each sampling period, with the exception of weeks 1.0 and 6.5. Week 1.0 included SPA and His for MG and MS. Week 6.5 included PCR and culture for MG and MS. The MG and MS SPA results were positive throughout the 29-wk trial period. MG HI titers declined until the last sampling, whereas the MS HI titers did not decline significantly. PCR for MG yielded only one positive result, which occurred before treatment. MS PCR remained positive throughout the trial period. MG was never isolated from any sample; however, one MS organism was isolated during treatment. The treatment regimen was effective for MG on the basis of PCR results. Treatment with enrofloxacin did not eliminate SPA reactions during the 29-wk trial period. MG HI titers remained in the suspicious range throughout the remainder of the trial period. Four weeks after the treatment ended, MG HIs were reduced by approximately 40%, with MS HIs remaining high throughout the 29-wk period. PCR appeared to be a sensitive and specific test on the basis of correlation with HIs. On the basis of the isolation of MS during treatment and continued subsequent PCR positive reactions, the treatment for MS with enrofloxacin was not as efficacious as for MG.     

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.     

Field investigation of Mycoplasma gallisepticum infections in house finch (Carpodacus mexicanus) eggs and nestlings.

We conducted a field study to investigate the occurrence of Mycoplasma gallisepticum (MG) in eggs and nestlings from nests of house finches (Carpodacus mexicanus). Forty-three nests were located between the months of April and August 1998 and were followed with one to three sampling efforts. Vitelline membrane of fresh eggs, whole embryos, or swabs from the choanal cleft or conjunctiva of nestlings were inoculated into mycoplasma broth for MG isolation and polymerase chain reaction (PCR) testing. No isolation of MG was made from 39 eggs or 110 nestlings sampled during the study. Pooled choanal and conjunctival swab samples from two broods of nestlings, however, tested positive for MG by PCR. None of the nestlings examined showed clinical signs of conjunctivitis, and no nestling mortality could be linked to MG infection. Serologic tests from 37 older nestlings were negative for antibodies to MG. The results suggest transmission of MG is occurring between breeding adults and their dependent offspring (pseudovertical transmission). Evidence supporting transovarian transmission of MG was not found in these house finches.     

Evaluation of the specificity and sensitivity of two commercial enzyme-linked immunosorbent assay kits, the serum plate agglutination test, and the hemagglutination-inhibition test for antibodies formed in response to Mycoplasma gallisepticum

Two commercial enzyme-linked immunosorbent assay (ELISA) kits, seven serum plate agglutination (SPA) antigens, and the hemagglutination-inhibition (HI) test for antibodies to Mycoplasma gallisepticum (MG) were compared for sensitivity and specificity using known MG-positive and MG-negative sera from leghorn chickens. All SPA antigens proved to be highly sensitive when testing MG-positive sera. Laboratory-prepared SPA antigens yielded fewer positive reactions when testing MG-negative sera than commercial SPA antigens. Both MG ELISA kits showed high rates of positive reactions when testing sera from birds given commercial M. synoviae bacterin, fowl coryza (Haemophilus paragallinarum) bacterin, inactivated infectious bursal disease virus vaccine, and to a lesser extent fowl cholera (Pasteurella multocida) bacterin. Immunization with Frey's medium with 12% swine serum-in-oil or Staphylococcus aureus-in-oil resulted in sera which yielded numerous positive ELISA reactions. During the first 1 to 3 weeks, antibodies induced by experimental infection with MG were better detected by the SPA test than by the ELISAs and the HI test, thus confirming the SPA test's importance in Mycoplasma diagnostic serology. The HI test can serve to confirm positive SPA results.     

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.     

Discovery of a new avian bornavirus genotype in estrildid finches (Estrildidae) in Germany

Avian bornaviruses (ABV) are known to be the causative agent of proventricular dilatation disease (PDD) in parrots and their relatives (Psittaciformes). A broad range of ABV genotypes has been detected not only in psittacine birds, but also in other avian species including canary birds (Serinus canaria forma domestica) and Bengalese finches (Lonchura striata f. dom.), which are both members of the order songbirds (Passeriformes).During this study 286 samples collected from captive and wild birds of various passerine species in different parts of Germany were screened for the presence of ABV. Interestingly, only three ABV-positive samples were identified by RT-PCR. They originated from one yellow-winged pytilia (Pytilia hypogrammica) and two black-rumped waxbills (Estrilda troglodytes) from a flock of captive estrildid finches in Saxony. The ABV isolates detected here were only distantly related to ABV isolates found in passerine species in Germany and Japan and form a new genotype tentatively called ABV-EF (for “estrildid finches”).     

Neospora caninum and Toxoplasma gondii in brain tissue of feral rodents and insectivores caught on farms in the Netherlands

We investigated the presence of both Neospora caninum and Toxoplasma gondii in 250 brain tissue samples from 9 species of feral rodents and insectivores caught on 10 organic farms in the Netherlands in 2004. Collected samples were conserved in 4% paraformaldehyde solution and analysed by real-time PCR. For N. caninum, 31 samples originating from 6 species tested positive (12.4%): common shrews (33.3%), wood mice (17.6%), harvest mice (16.7%), house mice (15.4%), white-toothed shrews (10.8%) and common voles (4.2%). For T. gondii, the overall contamination level was 4%, and only three species were found to be positive: house mice (9.0%), common voles (4.2%) and white-toothed shrews (2.0%). Most N. caninum infected samples (27/31; 87%) were found on farms where dogs were present. Due to the observation that rodents and insectivores can contract both parasites, they might function as indicator species for the parasitic load on farms.     

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.     

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.     

Determination of the incidence of Salmonella spp., Campylobacter jejuni, and Clostridium perfringens in wild birds near broiler chicken houses by sampling intestinal droppings

Several methods were evaluated for collecting fecal and intestinal samples from wild birds found near broiler chicken houses. A few intestinal samples and cloacal swabs were obtained from European starlings and house sparrows. Most of the samples collected consisted of wild bird droppings found on or near the houses. Samples were collected from each of four farms of a broiler integrator during a grow-out cycle: a cycle in the summer for farm A, fall for farm B, and spring, summer, fall, and winter for farms C and D. Of the 25 wild bird intestinal and fecal samples collected from a broiler house on farm A during a grow-out cycle in July-August 1997, 24% were positive for Salmonella spp., 4% for Campylobacter jejuni, and 28% for Clostridium perfringens. Of the nine fecal samples collected from broiler house B in a grow-out cycle in September-November 1997, 33% were positive for Salmonella spp., 11% for C. jejuni, and 22% for C. perfringens. For farms C and D, of the 23 samples collected in March-April 1998, 0 were positive for Salmonella spp., 11% for C. jejuni, and 52% for C. perfringens; of 27 samples collected in June-July 1998, 4% were positive for Salmonella spp., 0 for C. jejuni, and 13% for C. perfringens; of 24 samples collected in August-October 1998, 14% were positive for Salmonella spp., 5% for C. jejuni, and 4% for C. perfringens; of 14 samples collected December 1998-January 1999, 0 were positive for Salmonella, 50% for C. jejuni, and 14% for C. perfringens. The incidence of these bacterial enteropathogens in wild birds near the broiler chicken houses suggests that wild birds that gain entry to poultry grow-out houses have the potential to transmit these pathogens to poultry.     

大兴安岭北部春季兴安落叶松林鸟类群落的垂直结构

2011年4月24～5月15日,在黑龙江省岭峰自然保护区对春季兴安落叶松林鸟类群垂直结构进行了研究,共观察到鸟类36种,分属6目17科,非雀形目鸟类6科13种,雀形目鸟类11科23种。雀形目鸟类的种类最多,占总数的63.89%,这和我国北方地区鸟类组成相一致。研究结果显示大兴安岭春季兴安落叶松林中,鸟类垂直分层现象较为明显,林冠层和地面(或水面)鸟类多样性较高,而乔木层和灌木层鸟类丰富度较高;草本层鸟类较少。分析显示造成这种结果的原因不仅与鸟类的食物资源分布有关,而且与鸟类的求偶、领域以及防御行为具有密切关系。本研究结果为鸟类保护和森林管理提供了依据。     

The occurrence of virus enteritis (duck plague) in wild birds]

296 samples from wild birds of 15 species were incorporated into long term exploration of duck plague on ducks in farms. By using virological and serological standard methods 9 virus carriers and 20 serum samples showing positive antibody titers could be detected. The epidemiology as well as the relation of the incidence of duck plague in wild birds and farm poultry is discussed.     

Experimental inoculation of European starlings (Sturnus vulgaris) and American crows (Corvus brachyrhynchos) with Mycobacterium bovis

The purpose of this series of pilot studies was to determine whether the passerine species studied are susceptible to infection with Mycobacterium bovis. Separate experiments were conducted on wild-caught starlings (Sturnus vulgaris) and American crows (Corvus brachyrhynchos). In each experiment, four birds were challenged intraperitoneally and four were challenged orally with microorganisms. Challenge dose was 1 x 10(5) colony-forming units of M. bovis cultured from a white-tailed deer (Odocoileus virginianus) case in Michigan. Birds were euthanatized at 1 and 2 mo postinoculation. Histologic lesions suggestive of mycobacteriosis, without the presence of acid-fast bacilli, were noted in all experimental groups. Mycobacterial cultures performed on pooled tissue samples were positive for M. bovis in only some of the intraperitoneal inoculates of each species.     

Logistical study in Hyogo prefecture on disposal of poultry carcasses infected with highly pathogenic avian influenza virus to prevent infection spreading to other flocks

Establishment of a disposal plan for carcasses in advance is important for prevention of epidemics. A disposal plan for contaminated goods such as poultry carcasses infected with highly pathogenic avian influenza (HPAI) virus was studied in Hyogo Prefecture, Japan. We investigated all poultry farms with over 1,000 birds for their locations, species and numbers of birds, structure and size of poultry facilities and land spaces of the farms. Moreover, we judged whether they could dispose of all the carcasses at their farms. In 2005, 5.5 million layers and 2.7 million broilers were being kept. If HPAI had broken out, 44.0% of the farmers could bury all the carcasses, and 65.6% could compost them at their farms. However, 23.4% could not dispose of them except by burning them at incineration facilities. We decided to choose burning first for rapid disposal as long as the virus was not a pandemic type.     

Sensitivity and specificity of Mycoplasma gallisepticum agglutination antigens prepared from medium with artificial liposomes substituting for serum

Three batches of strain A5969 Mycoplasma gallisepticum (MG) serum-plate-agglutination (SPA) antigen grown in regular Frey's medium with 12% swine serum, three batches grown in Frey's medium containing artificial liposomes instead of serum, and one commercial SPA antigen were evaluated for sensitivity and specificity. Sensitivity was measured using chickens exposed to MG by intraocular and intranasal inoculation. Specificity was measured in uninoculated controls and in groups inoculated with the oil-emulsion vaccines Haemophilus paragallinarum, infectious bursal disease inactivated virus vaccine, or Staphylococcus aureus. Sera were tested 1 to 8 weeks postinoculation. All SPA antigens had a perfect sensitivity score, except one liposome-grown antigen batch (LC). The two other liposome-grown antigen batches (LA and LB) maintained significantly higher specificity by yielding significantly (P less than 0.01) fewer false positive (FP) agglutination reactions than did the other antigens. The three antigen batches produced in medium with serum had intermediate levels of FP agglutination reactions. When known MG-negative sera were tested, MG SPA antigens LC and commercial SPA antigen yielded significantly (P less than 0.01) higher numbers of FP agglutination reactions than the other SPA antigens.     

Carbon footprint of poultry production farms in South Georgia: A case study

A study was conducted in South Georgia to assess the carbon footprint of poultry farms. The study included broiler grow-out farms, pullet farms, and breeder farms from one commercial broiler complex. Data collection included the fuel and electricity bills from each farm, house size and age, flock size and number of flocks per year, and manure management. Emissions were calculated using a greenhouse gas (GHG) calculation tool. The carbon dioxide, nitrous oxide, and methane (CH₄) emissions were computed and a carbon footprint determined. Carbon footprint comparisons were made based on house construction and age. Based on these results, an evaluation of the mechanical sources of emissions showed that approximately 96% of the emissions from the broiler and pullet farms were from propane use, while only 3.9% of the total mechanical emissions from breeder farms were from propane use. On breeder farms, 83% of mechanical GHG emissions were the result of electricity use, while the pullet and broiler grow-out farms accounted for 2.9 and 2.7%, respectively, of the total mechanical emissions from electricity use. The data collected from the farms and entered into the GHG calculation tool revealed that breeder houses had higher levels of CH₄ emissions from manure management when compared to emissions from broiler and pullet houses. Even though the GHG emissions from poultry production farms were minimal compared to other animal production farms, the different sources of emissions were identified, thereby enabling the farmer to target specific areas for mitigation.     

Comparison of learning ability and memory retention in altricial (Bengalese finch,Lonchura striata var. domestica) and precocial (blue‐breasted quail,Coturnix chinensis) birds using a color discrimination task

The present study sought to assess the potential application of avian models with different developmental modes to studies on cognition and neuroscience. Six altricial Bengalese finches (Lonchura striata var. domestica), and eight precocial blue‐breasted quails (Coturnix chinensis) were presented with color discrimination tasks to compare their respective faculties for learning and memory retention within the context of the two developmental modes. Tasks consisted of presenting birds with discriminative cues in the form of colored feeder lids, and birds were considered to have learned a task when 80% of their attempts at selecting the correctly colored lid in two consecutive blocks of 10 trials were successful. All of the finches successfully performed the required experimental tasks, whereas only half of the quails were able to execute the same tasks. In the learning test, finches required significantly fewer trials than quails to learn the task (finches: 13.5 ± 9.14 trials, quails: 45.8 ± 4.35 trials, P < 0.05), with finches scoring significantly more correct responses than quails (finches: 98.3 ± 4.08%, quails: 85.0 ± 5.77% at the peak of the learning curve). In the memory retention tests, which were conducted 45 days after the learning test, finches retained the ability to discriminate between colors correctly (95.0 ± 4.47%), whereas quails did not retain any memory of the experimental procedure and so could not be tested. These results suggested that altricial and precocial birds both possess the faculty for learning and retaining discrimination‐type tasks, but that altricial birds perform better than precocial birds in both faculties. The present findings imply that developmental mode is an important consideration for assessing the suitability of bird species for particular experiments.