鸽的病毒性感染

本文根据文献报道和临床经验,综述了家鸽(Columba livia domestica)主要病毒性疾病的最新研究进展。根据常见临床症状和感染的靶组织讨论了副粘病毒I型、腺病毒、轮状病毒、疱疹病毒I型、痘病毒和圆环病毒感染。由于鸽有时被认为是家禽,本文同时总结了鸽能够抵抗的家禽常见病毒性感染。希望能够通过本文对兽医及相关人员提供有用参考,并对鸽主要传染病的诊断、治疗和预防给予建议。     

鸽的病毒性感染

上期回顾:上期从疾病的临床病状、病变、诊断、预防和控制等角度介绍了鸽消化系统疾病中的副粘病毒、腺病毒和A群轮状病毒. 3 呼吸系统疾病 呼吸系统疾病是信鸽比赛性能低下的首要原因.早先,在鸽疱疹病毒Ⅰ型的重要作用被证实之前(Vindevogel等,1981b),鸽呼吸疾病的病因被错误地认为是白喉样细菌或衣原体(Chlamydial)感染(Volkert和Christensen,1954;Prip,1971).鸽的pAMPV-1感染病例临床呼吸道症状不明显或完全没有.     

Experimental Streptococcus bovis infections in pigeons.

Thirty pigeons were experimentally infected with Streptococcus bovis using an intravenous infection model. Ninety percent of the inoculated pigeons developed clinical disease. Disease signs included acute death, inability to fly, lameness, inappetence, emaciation, polyuria, and the production of slimy, green droppings. At necropsy, the septicemic character of the disease was evident. Typical lesions included extensive well-circumscribed areas of necrosis in the pectoral muscle, tenosynovitis of the tendon of the Musculus pectoralis profundus, and arthritis of the stifle, tibiotarsal, or shoulder joints. Focal myocardial necrosis also was seen. Meningitis and encephalitis occurred in the cerebrum and the cerebellum. Disease signs and lesions described here after experimental infection were similar to those in naturally occurring cases of S. bovis septicemia.     

Viral encephalomyelitis of pigeons: pathology and virus isolation

A previously unrecorded nervous disease in pigeons was investigated. The disease, characterized by paresis, paralysis of the extremities, head-shaking, and torticollis, is contagious and spreads slowly. The mortality rate of affected pigeons was very high. The disease appeared to spread among pigeon flocks in spring and summer. The predominant gross change in most cases examined was congestion of the visceral organs. Some cases had grayish spots on the pancreas and kidneys. The histologic changes are characterized by neuronal and myelin degeneration with mononuclear cell infiltration and perivascular cuffing. Degeneration of the parenchyma and marked congestion are prominent in the visceral organs. The causal agent, found to be a virus, produced pock lesions on chorioallantoic membranes of developing chick embryos and failed to aagglutinate chicken RBCs. Antisera against Newcastle disease virus and avian encephalomyelitis virus did not neutralize the isolated virus. The virus produced typical signs in experimentally inoculated pigeons.     

Streptococcus gallolyticus infections in racing pigeons, a literature review

S. gallolyticus, formerly known as S. bovis is known since 1988 as a facultative pathogen of racing pigeons. Important clinical signs include acute mortality, inability to fly, lameness, weight loss and slimy green diarrhea. A pathognomonic sign at post mortem examination is the presence of well circumscribed areas of necrosis in the pectoral muscle. Furthermore tenosynovitis of the supracoracoid muscle and arthritis of the knee, shoulder and hock can be observed. In one study S. gallolyticus septicaemia was diagnosed in 10% of necropsied pigeons. Since S. gallolyticus was also isolated from nearly 40% of clinical healthy pigeons it is regarded as a facultative pathogen. Various biotypes, serotypes and culture supernatant phenotypes can be distinguished. Supernatant phenotypes are identified on the basis of the presence of either a T1, T2 or T3 protein triplet and the presence or absence of an extracellular A protein. S. gallolyticus strains with A protein are highly virulent, while strains with only T3 or T2 protein are of moderately or low virulence respectively. Fimbriae are only seen in highly virulent and some of the moderately virulent strains. Possible virulence factors include survival in macrophages, adhesion to cells and toxin production. Infection with serotype 1 and 2 induces some degree of protection against re-infection with serotype 1, which offers perspectives for the development of a vaccine. Experimentally ampicillin, doxycycline and erythromycin have shown therapeutic effects. For the treatment of clinical cases the use of ampicillin is advocated, together with hygienic measures, such as the use of grid floors and avoiding overcrowding.     

Prevalence of pigeon circovirus infections in feral pigeons in Ljubljana, Slovenia

Pigeon circovirus (PiCV) was detected by real-time PCR in cloacal swabs, pharyngeal swabs, and serum samples taken from 74 feral pigeons (Columba livia var. domestica) that were caught at various locations in the city of Ljubljana, Slovenia. PiCV infections were detected in the majority of the tested birds. The highest (74.3%) detection rate was observed in the cloacal swabs and the lowest (31.1%) in serum samples. PiCV DNA was more readily detected in the cloacal swabs, pharyngeal swabs, and serum samples of birds younger than 1 yr. Molecular analysis of partial open reading frame V1 sequences showed that PiCV strains detected in feral pigeons share high nucleotide and amino acid sequence identities with PiCV strains detected in ornamental, racing, meat, and feral pigeons.     

Viral intestinal infections of animals and man

The extensive use of negative staining techniques and electron microscopy in diagnostic centers has resulted in a dramatic increase in the number of reported viral enteric infections in man and animals in the last 10 yr. Enteric infection due to adenoviruses, astroviruses, coronaviruses, paramyxoviruses, parvoviruses, picornaviruses (caliciviruses), rotaviruses as well as some unidentified viral particles are described. The brief literature review on each of these virus families is supplemented with clinical cases submitted to the Texas Veterinary Medical Diagnostic Laboratory. Comparative aspects of viral infections between different animal species as well as man are discussed wherever possible.     

Viral infections and bovine mastitis: a review

This review deals with the role of viruses in the aetiology of bovine mastitis. Bovine herpesvirus 1, bovine herpesvirus 4, foot-and-mouth disease virus, and parainfluenza 3 virus have been isolated from milk from cows with clinical mastitis. Intramammary inoculations of bovine herpesvirus 1 or parainfluenza 3 virus-induced clinical mastitis, while an intramammary inoculation of foot-and-mouth disease virus resulted in necrosis of the mammary gland. Subclinical mastitis has been induced after a simultaneous intramammary and intranasal inoculation of lactating cows with bovine herpesvirus 4. Bovine leukaemia virus has been detected in mammary tissue of cows with subclinical mastitis, but whether this virus was able to induce bovine mastitis has not been reported. Bovine herpesvirus 2, vaccinia, cowpox, pseudocowpox, vesicular stomatitis, foot-and-mouth disease viruses, and bovine papillomaviruses can play an indirect role in the aetiology of bovine mastitis. These viruses can induce teat lesions, for instance in the ductus papillaris, which result in a reduction of the natural defence mechanisms of the udder and indirectly in bovine mastitis due to bacterial pathogens. Bovine herpesvirus 1, bovine viral diarrhoea virus, bovine immunodeficiency virus, and bovine leukaemia virus infections may play an indirect role in bovine mastitis, due to their immunosuppressive properties. But, more research is warranted to underline their indirect role in bovine mastitis. We conclude that viral infections can play a direct or indirect role in the aetiology of bovine mastitis; therefore, their importance in the aetiology of bovine mastitis and their economical impact needs further attention.     

Viral infections shared between water buffaloes and small ruminants in Switzerland

Importation of exotic animals that may harbor infectious agents poses risks for native species with potentially severe impacts on animal health and animal production. Although the Asian water buffalo (Bubalus bubalis) population in Europe is steadily increasing, its susceptibility to viral infections and its role for interspecies transmission is largely unknown. To identify viral infections that are shared between exotic water buffaloes and native small ruminants, we collected blood samples from 3 Swiss farms on which water buffaloes were kept either without, or together with, sheep or goats. These samples were analyzed by next-generation sequencing (NGS) as well as by selected conventional tests, including PCR, ELISA, and in some cases a virus neutralization test. By NGS, a novel virus of the genus Gemykrogvirus (GyKV; Genomoviridae) was first detected in the buffaloes on one farm, and subsequently confirmed by PCR, and was also detected in the co-housed sheep. In contrast, this virus was not detected in buffaloes on the farms without sheep. Moreover, conventional methods identified a number of viral infections that were not shared between the exotic and the native animals, and provided evidence for potential roles of water buffaloes in the epidemiology of ruminant pestiviruses, especially bovine viral diarrhea virus, bluetongue virus, and possibly bovine alphaherpesvirus 2. Our results clearly indicate that water buffaloes are susceptible to interspecies viral transmission and may act as intermediate hosts, or even as reservoirs, for these viruses.     

Paramyxovirus type 1 infections of racing pigeons: 1 characterisation of isolated viruses

Viruses isolated from field outbreaks of disease in racing pigeons in continental Europe and Great Britain were shown to be identical by serological tests using conventional chicken antisera and mouse monoclonal antibodies. The pigeon viruses showed high levels of cross-reaction to Newcastle disease virus (NDV) in haemagglutination inhibition tests and Madin-Darby bovine kidney cells infected with pigeon virus isolates bound three out of nine mouse monoclonal antibodies prepared against NDV Ulster 2C. These results confirm their classification in the paramyxovirus type 1 serotype of avian paramyxoviruses. However, the pigeon viruses could be distinguished from more classical paramyxovirus type 1 viruses by the significantly different titres obtained in haemagglutination inhibition tests, the failure of mouse monoclonal antibodies directed against the HN1 epitope of NDV Ulster 2C to inhibit their haemagglutinating activity and a unique binding pattern seen with the nine mouse monoclonal antibodies.     

Avian paramyxovirus type 1 infections of racing pigeons: 4 laboratory assessment of vaccination

The immune response and protection from challenge afforded to adult pigeons by four different vaccination schedules were assessed. Intravenous challenge with a field pigeon isolate was done four weeks after the second of two doses of vaccine given four weeks apart. Little difference in protection was seen between two 0.25 ml and two 0.5 ml doses of oil emulsion vaccine, although the latter produced a slightly higher immune response. In both cases one of 10 challenged pigeons became sick and died. One dose of Newcastle disease virus B1 live vaccine followed four weeks later by 0.5 ml oil emulsion vaccine gave a comparable immune response to two 0.25 ml doses of oil emulsion but only six birds survived challenge. Two doses of Newcastle disease virus B1 vaccine gave a poor immune response and little protection from challenge; all 10 birds became sick and eight died. Assessment of the onset of protection following one dose of either 0.5 ml oil emulsion vaccine or Newcastle disease virus B1 indicated some partial protection in the latter group as early as five days after vaccination. Both groups showed protection at 10 days but by 21 days, although protection was sustained in the oil emulsion group, birds receiving live vaccine were fully susceptible. Measurement of the duration of protection in pigeons given two 0.5 ml doses of oil emulsion vaccine indicated that protection had begun to wane by 40 weeks after the first dose.     

Chlamydial infections in feral pigeons in Europe: Review of data and focus on public health implications

Feral pigeons (Columba livia domestica), which thrive in most European towns and cities, are commonly infected with the zoonotic bacterium Chlamydophila psittaci, the agent of psittacosis (also known as ornithosis) in humans. A number of surveys carried out over the last thirty years across Europe have detected high seropositivity values and high percentages of infection in feral pigeon populations. Overall, when considering data from 11 European countries, seropositivity values to C. psittaci in the sampled populations ranged from 19.4% to 95.6%. In most surveys, the complement fixation test was used, and antibodies were detected in 19.4-66.3% of the samples, with a median of 46.1%. Indirect immunofluorescence and ELISA tests were employed less frequently, but led to the detection of higher percentages of seropositivity (23.7-67.7% and 35.9-95.6%, respectively). Attempts to grow C. psittaci in cell culture or embryonated chicken eggs were successful in 2-42.3% and 0-57.1% of samples, respectively, antigen detection methods were positive in 2.3-40% of samples, while conventional PCR and real-time PCR using different genomic targets detected the organism in 3.4-50% of samples. Twenty-five C. psittaci isolates from pigeons were typed as ompA genotype B (n=14), E (n=10) and E/B (n=1). The huge increase of feral pigeon populations in Europe is a major cause of concern for the detrimental effect of pigeon droppings on environmental hygiene, in addition to the extensive damage due to the fouling of buildings and monuments. The most important pathogenic organism transmissible from feral pigeons to humans is C. psittaci, with 101 cases of disease reported in the literature. Exposure to C. psittaci-contaminated dust, direct contact with pigeons through handling and, to a lesser extent, through pigeon feeding have been identified as hazardous exposures in more than half of the human cases, while loose or transient contacts with feral pigeons have been mentioned in about 40% of the cases. Education initiatives as to the communication of a health risk resulting from contact with pigeons and pigeon excreta should primarily be targeted at individuals who may be exposed to C. psittaci-contaminated dust, such as demolition/construction workers. Recommendations to this category of workers include wearing protective clothes with hoods, boots, gloves and air filter face masks when removing pigeon faeces from roofs, garrets and buildings, especially if working indoors. Monitoring for C. psittaci infections in these workers over time should also be considered. Children should be warned not to handle sick or dead pigeons, and immunocompromised individuals should be advised to carefully limit their contact to feral pigeons. Culling of pigeons by shooting or poisoning is both unethical and ineffective as the place of the killed birds in the population is quickly filled by new juveniles or immigrating birds from neighbouring areas. Pigeon-deterring systems, such as nets and plastic or metal spikes applied to buildings and monuments will prevent their fouling, and the administration of contraceptive drugs may allow size regulation of the pigeon populations. Nevertheless, the measure that will ultimately lead to permanent reduction and will establish healthy sustainable populations is the restriction of indiscriminate feeding by pigeon lovers. The erection of dovecotes and artificial breeding facilities should be considered for providing shelter and a balanced diet to the birds, as well as a chance of interaction for pigeon lovers in a hygienically controlled environment.     

Viral infections of the respiratory tract of calves: Local immunity

Local immunity is the first defence mechanism against viral respiratory infections in young calves. The great variety of different viruses which may infect the very young animal makes it necessary to develop effective local defences early in life. The best approach appears to be to increase the subjects' defences by using immunoadjuvants and interferon inducers. With this end in view we should increase our knowledge of the immune system of the calf respiratory tract, particularly with respect to specific immunoglobulins, and cells which mediate the immune response.

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Kurzfassung Die örtliche Immunität ist der erste Abwehrmechanismus gegen virale Erkrankungen der Atemwege beim jungen Kalb. Da sich diese sehr jungen Tiere mit den unterschiedlichsten Viren infizieren können, ist ein frühzeitiger Aufbau einer wirksamen örtlichen Abwehr unerlässlich; dieses Problem liesse sich vielleicht durch eine Steigerung der Abwehrkräfte bei den Tieren mit Immunitatsadjuvanten und Induktoren von Interferonbildung bewältigen. Die bisher vorliegenden Angaben über das Immunsystem der Atemwege beim Kalb (spezifische Immunglobuline, Immunzellen) müssen zu diesem Zweck noch vertieft werden.

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Resume L'immunité locale est le premier mécanisme de défense contre les affections réspiratoires virales du jeune veau. La grande diversité des virus pouvant infecter ces sujets très jeunes rend indispensable l'établissement précoce de défenses locales éfficaces; l'augmentation des défenses des sujets par l'emploi d'adjuvants de l'immunite et d'inducteurs d'interféron semble être le moyen d'aborder ce problème. Les données que nous possédons sur le système immunitaire de l'appareil réspiratoire du veau (immunoglobulines specifiques, cellules effectrices de l'immunité) doivent, dans ce but, être approfondies.

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Riassunto L'immunita locale e il primo meccanismo di difesa del giovane vitello contro le affezioni virali delle vie respiratorie. La grande diversità dei virus in grado di infettare soggetti molto giovani rende necessaria l'instaurazione precoce di difese locali efficaci; la soluzione migliore dovrebbe consistere nel potenziamento delle difese dei soggetti mediante adiuvanti dell'immunità e induttori di interferon. A tal fine e necessario approfondire i dati in nostro possesso sul sistema immunitario dell'apparato respiratorio del vitello (Immunoglobuline specifiche, immunociti).

     

The efficacy of different oral dosage forms of furazolidone for E. coli infections in carrier pigeons

The clinical efficiacy of furazolidon for treatment of E. coli-induced gastro-intestinal infections in racing pigeons was investigated. 36 adult pigeons were treated with 2 different oral modes of application (capsule/drinking water) with a daily therapeutic dosage of 12.5 mg furazolidon/pigeon. The pigeons used for this study (Columba livia f. domestica) originated from conventional breeders and were housed in 3 different groups (control-, capsule- and powder-group) in different stables. After infection with an E. coli-strain (O150:H8) that proved to be pathogenic for pigeons, the animals developed clinical signs of disease within 2 days. After onset of disease the treatment with furazolidon for 5 days started. This phase was followed by an adspectory phase for 6 days. The negative identification of the E. coli O150:H8 was determined as main parameter for the clinical efficiacy of the treatment with furazolidon. This parameter showed a highly significant (p = 0.0001) difference between both groups treated with furazolidon and the control group. In both groups treated with furazolidon the E. coli strain could not be isolated after the end of the treatment. An improvement of clinical signs was seen 24 hours after treatment via capsule and 48 hours after treatment via drinking water formulation. The time difference might be caused by the high concentration of furazolidon in the capsules due to the single daily application. Considering the inaccurate dosing via drinking water that results from the varying drinking water intake in pigeons, the application by capsule should be prefered. Both furazolidon preparations proved to be effective in treating gastro-intestinal E. coli-infections in racing pigeons in a dosage of 12.5 mg/pigeon for 5 days, however, best results were obtained by application via capsule.     

Lindane toxicity in pigeons

A flock of Birmingham Rolles pigeons were fed a commercial whole grain pigeon feed contaminated with 2 100 ppm lindane. Soon after ingestion of the feed, symptoms including diarrhea, vomition, anorexia, depression and sudden death, consistent with a feed related organochlorine toxicity were seen. The rapeseed component of the pigeon feed contained seed which had been treated with a lindane seed dressing. Chemical analysis, history and clinical findings support a diagnosis of acute lindane toxicosis which caused sudden death in 47% of the pigeon flock.     

养鸽方略

信鸽是极具灵性的动物．养信鸽更是一门博大精深的学问。本文笔者就养鸽数年的经验和心得与广大鸽友分享，相信会对鸽坛新人有所帮助。若有不当之处．还请广大鸽友批评指正。