Experimental infections with fowl pox in chickens

Seven groups of chickens were challenged with a field isolate of fowl pox virus at 18 weeks old. The birds in the groups that had been vaccinated 3 weeks previously with fowl pox vaccinates showed no signs of disease. Birds which had not been vaccinated against fowl pox developed upper respiratory disease after challenge, and some birds had diphtheritic tracheitis and laryngitis which appeared identical to that commonly seen under field conditions. Seven days after challenge, fowl pox virus was recovered from the tracheas of unvaccinated birds, but not from the vaccinated ones.

Intercurrent Mycoplasma gallisepticum infection appeared to extend slightly the period of respiratory disease but was not essential for development of the diphtheritic lesion.     

Atypical distribution of fowl pox lesions in broilers

An unusual cutaneous fowl pox outbreak occurred in 8-wk-old broilers in California. Rounded and longitudinal, proliferative scratch-associated lesions were found only in feathered areas of the body. Both sides of the hip, the lower abdomen, pericloacal area, and lateral lower neck area were involved. The head, legs, feet, and toes did not have lesions. Birds in only one section of one of five houses were affected. Fifteen percent condemnations occurred in birds from the affected house due to the skin lesions. A diagnosis of fowl pox was achieved by histopathology, viral isolation, and direct electron microscopy. The unusual distribution of pox lesions was assumed to be associated with skin scratches. There was no evidence that mosquitoes or other types of insects were involved in this outbreak. To the knowledge of the authors, this is the first report of this kind of unusual fowl pox in the United States.     

Avian pox in blue-fronted Amazon parrots

During a 1-month period at a quarantine station, an epornitic of avian pox occurred in blue-fronted Amazon parrots (Amazona aestiva). Clinical signs included conjunctivitis, blepharitis, and varying degrees of anorexia and respiratory distress. Lesions included periocular ulcerations and scabs and necrotic plaques in the oral cavity. Histologically, the lesions consisted of epithelial hyperplasia, secondary inflammatory changes, and eosinophilic inclusions which, by electron microscopy, were shown to contain poxvirus. When chicken embryos were inoculated with material from eyelid scabs and pharyngeal plaques, lesions of avian pox developed on the chorioallantoic membrane. The death rate of infected birds was high because of secondary bacterial and fungal infections, but uncomplicated cases were usually self-limiting. Periocular lesions also developed in 2 other species of psittacine birds housed in the same facility.     

Sheep pox: experimental studies with a west african isolate

Under conditions of a maximum security laboratory, four cross-bred sheep were inoculated intradermally only or intradermally and intratracheally with a West African isolate of sheep pox virus. All sheep had increased temperature and depression by the fourth or fifth day after infection. Nasal and lacrimal discharge and coughing occurred in all sheep but were more severe in sheep receiving the virus via the tracheal route. From the fifth day after infection, numerous papular erythematous skin lesions developed at the inoculation sites. These were 3-7 mm in diameter and gradually became nodular. Some of these lesions healed and others coalesced to form tumorlike masses. In one sheep, euthanized 14 days after intradermal and intratracheal inoculation, nodular lesions were found in the skin around the eyes, nostrils, oral and perianal regions, the mucosa of the rumen and throughout the lungs. Histologically, skin nodules were characterized by ischemic necrosis, vasculitis, microvesicualtion, eosinophilic cytoplasmic inclusions in the dermal epithelial cells and vacuolar nuclear degeneration. The pulmonary lesion was that of proliferative alveolitis with occasional cytoplasmic inclusions in the alveolar cells and macrophages. Ultrastructurally, large cuboidal virus particles were found both in the skin lesion and inoculated tissue cultures. The sheep pox virus structure was easily distinguished from contagious ecthyma virus, a parapoxvirus which causes sporadic disease in Canada. Serum neutralizing antibodies developed in all the sheep by 14 days postinfection.

The clinical and pathological characteristics of experimental sheep pox produced with this West African isolate were similar to those caused by Neethling virus of lumpy skin disease in cattle.

     

Transmission studies involving a wet fowl pox isolate

An isolate of fowl pox (FP) virus from a case of "wet" pox in commercial white leghorn (WL) pullets was used to expose WL cockerels via the comb-scratch (CS), eye-drop (ED), or laryngeal-swab (LS) route. Seven days postinoculation (PI), the groups challenged via CS had scabby proliferative pox lesions at the challenge site, the groups challenged via LS had slight dyspnea and rales, and 20% of the cockerels challenged via ED had mild conjunctivitis and lacrimation. By termination of the trial on day 21 PI, the CS-challenged groups had developed pronounced pox lesions. The LS-challenged groups showed severe dyspnea and rales with pronounced raised plaque-like lesions at the opening to the trachea and extending into the upper quarter of the trachea with heavy yellowish caseous exudate partly occluding the glottis. The ED-challenged groups had severe lacrimation and conjunctivitis and small pox lesions on the face, comb, and wattles; 12 of 18 had proliferative lesions on the oral mucosa in the area of the larynx. Forty-five percent of the LS-challenged groups died of suffocation. Pox virus was re-isolated from tissues in all treatment groups. Wet pox transmission appears to be possible via the LS and ED routes.     

Molecular detection of avian pox virus from nodular skin and mucosal fibrinonecrotic lesions of Iranian backyard poultry

In recent years, some outbreaks of skin lesions suspected to be avian pox were observed in the backyard poultry in different parts of western areas in Iran. Consequently, 328 backyard poultries with suspected signs of avian pox virus infection were sampled. All birds showed nodular lesions on unfeathered head skin and/or fibronecrotic lesions on mucus membrane of the oral cavity and upper respiratory tract. For histopathological analysis, the sections of tissue samples from cutaneous lesions of examined birds were stained with H&E method. For PCR, after DNA extraction a 578-bp fragment of avian pox virus from 4b core protein gene was amplified. Results showed 217 and 265 out of 328 (66.1 and 80.7 %, respectively) samples were positive for avian pox virus on histopathological and PCR examination, respectively. In this study, the samples that had intracytoplasmic inclusion bodies on pathologic examination were PCR positive. This study revealed that PCR is a valuable tool for identification of an avian pox virus and that the frequency of pox infection in backyard poultry in western areas of Iran is high.     

Characterization of avipoxviruses from wild birds in Norway

Avipoxviruses from different geographic regions of the world have been characterized to study their genetic and biological properties, but so far, no such work has been performed on Norwegian isolates. Lesions suggestive of avian pox, found on a Norwegian wild sparrow (Passer domesticus) and wood pigeon (Palumbus palumbus), were obtained in 1972 and 1996, respectively. Histologically, these lesions were demonstrated to be characteristic of poxvirus infections and the poxvirus was observed using an electron microscope. The resulting viruses were propagated in chicken embryo fibroblast cells. Restriction fragment length polymorphism of genomes from 2 Norwegian isolates and fowl pox vaccine strain, generated by BamHI, revealed a high degree of heterogeneity among the isolates. The profiles of avipoxviruses isolated from wild birds were clearly distinct from each other and also to the fowl poxvirus strain. Furthermore, chickens experimentally infected with pigeon poxvirus had higher antibody titers and extensive lesions compared to other isolates. This may suggest that pigeon poxvirus is more virulent than the other isolates.     

Experimental Eimeria bovis infection in calves: a histopathological study.

Eight male holstein calves, four to six weeks of age, were infected with 100,000 sporulated oocysts of a culture containing Eimeria bovis. The calves were injected with steroids on days 13, 14 and 15 and killed on days 16, 18, 19, 20, 21, 22, 24 and 26 postinfection. The lesions caused by experimental E. bovis infection in the small and large intestines are characterized by a diphtheritic typhilitis and colitis. Severe lesions were also seen in the last metre of the ileum in a calf killed 19 days after infection. Most of the damage of the intestinal mucosa is caused by the sexual stages. There is destruction and loss of epithelial cells with subsequent exposure of lamina propria and formation of diphtheritic membranes.     

Canary pox causing high mortality in an aviary

In an aviary housing 200 six-month-old canaries, 165 became ill and 145 died over a 6-week period from a disease initially characterized by lethargy, ruffled feathers, open-mouth breathing, and death in 2 to 3 days. Proliferative "pox-like" lesions around the eyes and mouth were not seen until the 4th week. At necropsy, initially affected birds had cloudy air sacs and patchy pneumonia. Histologically, the lungs had proliferative necrotizing bronchitis. Birds necropsied later had proliferative skin lesions and intracytoplasmic inclusions typical of poxvirus in the epidermis and airway epithelium. A virus was isolated from an organ pool of lung, air sac, liver, and skin of affected birds and was identified by electron microscopy as poxvirus.     

Epidemic of infectious laryngotracheitis in Italy: characterization of virus isolates by PCR-restriction fragment length polymorphism and sequence analysis

Between May 2007 and October 2008, 34 outbreaks of mild to moderate forms of infectious laryngotracheitis (ILT) occurred in commercial broiler flocks in Italy. Affected birds showed watery eyes, conjunctivitis, nasal discharge, reduction of feed and water consumption, and gasping with expectoration of blood-stained mucus. The mortality rate was < 10%. Gross lesions consisted of conjunctivitis, excess of mucus, blood, or presence of diphtheritic membranes in trachea. A real-time PCR assay was performed to confirm the presence of ILT virus (ILTV) DNA in tracheal tissue homogenates. Twenty-three ILTV isolates were propagated on the chorion-allantoic membrane of embryonated chicken eggs showing typical plaques. PCR combined with restriction fragment length polymorphism and gene sequencing of isolates showed a high genetic correlation between field strains and chicken embryo origin vaccines.     

Outbreak of cutaneous form of poxvirus on a commercial turkey farm caused by the species fowlpox

The present report documents the occurrence of a poxvirus infection in commercial meat turkeys. The affected farm had six flocks, with a total of 11,680 birds at different ages; birds from two of these flocks were affected. The clinical picture was characterized by severe epithelial lesions and proliferations on the head and neck regions as reported for the cutaneous form of poxvirus infection. Except for these lesions, no adverse clinical signs or gross pathologic lesions were observed. Only a low number of birds was affected (n = 20) and no increase of mortality could be seen. Bacteriologic investigations from the lesions revealed multiresistant Staphylococcus aureus. Eosinophilic inclusions (Bollinger bodies) in histologic examinations in the cytoplasm of keratinocytes were noticeable. Typical pox virions were demonstrated by electron microscopy, and poxvirus was isolated on the chorioallantoic membrane of specific-pathogen-free chicken eggs. Further identification of the poxvirus species was carried out by PCR and sequencing, revealing an infection with the species fowlpox. Layers in vicinity of the turkey farm that also were affected by fowlpox were considered as potential source of infection. Although it is assumed that avian poxviruses are strongly species specific, the present case report reinforces the changing picture of poxvirus infections in turkeys. Furthermore, it supports the assumption of previous data that fowlpox virus has to be seen as recently emerging pathogen in turkeys.     

A case control study of fowl pox in southeastern Ontario

An outbreak of fowl pox, which occurred in south-eastern Ontario between July 1988 and April 1989, was investigated in the spring of 1989 to determine factors associated with the spread of the disease. Clinical fowl pox was confirmed on five farms (cases). Twenty-seven farms, out of 35 egg producers with quota from Durham region to Northumberland county, provided information as controls. Bivariate analyses were performed on mail survey data using Fisher's exact test and odds ratios. Although the tests of hypotheses lacked statistical power because of the small number of case farms, and barns, a number of significant associations were found. At the farm level, fowl pox infection was associated with pullets purchased from a particular pullet grower. At the barn level, fowl pox infection was associated with pullets from a particular grower, mixing different groups of pullets, and a trend towards having birds early in the laying period, and higher numbers of birds placed. Fowl pox-infected barns had higher mortality and lower egg production postoutbreak. The results may indicate that the virus enters the laying barn at, or near, the time new birds are placed. Better communication among producers, catch-and-fill crews, and others associated with the egg industry, as well as more complete records of dates, sources, and persons involved with pullet placements, are recommended.     

Prevalence and clinical signs of avipoxvirus infection in falcons from the Middle East

The prevalence, cutaneous manifestations and concurrent clinical signs of avipoxvirus infection in 3706 falcons in two Middle Eastern countries are reported. Diagnosis was based on evidence of typical 'dry' skin lesions on featherless parts of the body and microscopic detection of Bollinger bodies in epithelial cells. Avipoxvirus was isolated from one representative case. Overall prevalence of cutaneous changes due to avipoxvirus infection did not differ significantly between Kuwait (2.7%) and Dubai (2.3%), although pox lesions were more prevalent on the feet of birds from Kuwait (67.4% vs. 50%) and more common on the eyelids of birds from Dubai (45.6% vs. 30.4%). Foot lesions were always present in birds with multiple infection sites. Some birds from Dubai had severe infection associated with weight loss, anorexia, lethargy, vomiting, central nervous system involvement and ultimately death.     

Postural and neurological deficits in broiler chicks after cervical vaccination with live vaccine.

A disease characterized by paresis and paralysis was seen in 7-9-day-old broiler chicks after vaccination in the neck area at day-of-age with a live virus vaccine containing viruses of Marek's disease, fowl pox, and infectious bursal disease. Affected birds presented with variable signs of ataxia, lateral recumbency, leg paralysis, and twisting or S-shaped flexure of the neck. Gross lesions noted at necropsy included swelling and edema of the subcutaneous tissues and muscles of the neck at the injection site area. A heavy mononuclear inflammatory cell infiltration was seen in the subcutaneous tissues, connective tissues, and muscles of the neck at the injection site. In some cases, the inflammatory process extended along fascial planes to involve the epidural spaces surrounding the spinal cord. Fatty changes with possible demyelination of nerve fibers were noted in some sections of the spinal cord adjacent to the inflammatory lesions. Clusters of poxviruses were found within some inflammatory lesions on transmission electron photomicrographs.     

山羊痘的病理形态学观察

对发生在贵州省的山羊痘进行了病理形态学观察.山羊痘以全身皮肤、呼吸道及消化道粘膜出现痘疹为特征.皮肤疹最初为红斑,红斑肿胀隆起形成结节状丘疹,然后丘疹发生凝固性坏死,脱落而形成痂皮.组织学检查早期皮肤病变可见充血,水肿和多量的巨噬细胞和中性白细胞浸润,随着病变的发展可见更多的巨噬细胞,淋巴细胞,浆细胞和一些体积较大的所谓"山羊痘细胞"出现.在真皮的病变细胞和痘细胞中可见嗜酸性胞浆内包涵体.引起水肿和坏死的血管炎常伴有血栓和梗死.上皮的变化包括棘细胞增生,空泡变性,不全角化,过度角化和坏死等.其他器官的病变也有相似的细胞浸润和血管炎变化.但发生在上呼吸道及上消化道时常出现溃疡.透射电镜观察在感染的皮肤和肺上皮细胞的胞浆内发现有大量不同成熟阶段的典型的山羊痘病毒颗粒.受感染的细胞除可见胞浆内散在的病毒颗粒或形成病毒包涵体外,通常可见细胞水肿、线粒体肿胀、内质网和高尔基复合体扩张.     

Health status of northern bobwhite quail (Colinus virginianus) in eastern Kansas

The health status of wild northern bobwhite quail (Colinus virginianus) from Lyon County, Kansas, was evaluated by conducting comprehensive health assessments on 25 birds. Gross lesions indicative of avian pox, ulcerative enteritis, and quail bronchitis were not present. Serologic tests for antibodies to Salmonella pullorum, Salmonella gallinarum, Pasteurella multocida, Mycoplasma gallisepticum, Mycoplasma synoviae, and avian adenoviruses were all negative. Intestinal coccidia (Eimeria spp.) were found in 36% of the birds. Only three species of helminth parasites were found: Dispharynx nasuta in two birds, Cyrnea colini in one bird, and larval Physaloptera sp. in four birds. Arthropod parasites (ticks, lice, mites, and/or chiggers) were present on 96% of the birds examined. Compared with wild bobwhite populations in the southeastern United States, the diversity, prevalence, and intensities of microbial and parasitic agents were low.     

贵州省首次暴发山羊痘的诊断研究

山羊痘于 2 0 0 2年 1 0月在贵州省首次流行并被确诊。本次疫病以皮肤、呼吸道及消化道粘膜发生痘疹为主要特征 ;取病料经绒毛尿囊膜接种鸡胚传代 ,F2 绒毛尿囊膜明显增厚 ,在接种部位形成明显的痘斑。经病理组织学检查 ,患病皮肤在光学显微镜下可见细胞浆内出现嗜酸性包涵体。电子显微镜观察到典型的痘病毒粒子 ,细菌学检查阴性。为此 ,这次暴发流行的疫病确诊为山羊痘     

绵羊痘的诊断

绵羊痘是由绵羊痘病毒引起绵羊的疾病,其特征为发热、全身皮肤痘疹,内脏(特别是肺脏)黏膜结节,是危害养羊业最为严重的传染病之一。该病经常引起绵羊的大批感染或死亡,病死率可达50%以上,羔羊可达100%,不仅给养羊业带来巨大的经济损失,还严重阻碍了养羊业的发展。文章针对2011年1月份新疆某地区部分养羊户饲养的卡拉库尔羊发生的羊痘疫情进行了流行病学调查、临床症状、病理变化观察和实验室诊断,结果确诊为绵羊痘。     

小尾寒羊绵羊痘病例的诊断

旨在对甘肃某羊场小尾寒羊疑似绵羊痘进行确诊,并深入探讨其病理变化特点。对临诊疑似患绵羊痘的小尾寒羊进行了羊痘间接ELISA抗体检测和PCR检测确诊,并对6只病羊进行病理剖检、病理组织学和超微结构研究。结果如下：羊痘间接ELISA抗体检测显示6例病羊样品均为阳性;同时,对2例病羊样品进行PCR检测,均扩增出绵羊痘病毒（SPV）585 bp的目的基因片段,表明本次小尾寒羊所患疫病为绵羊痘。病理剖检显示,病羊皮肤无毛或少毛处充血,局部有红斑和坏死,尾部常有感染化脓形成溃疡;消化道黏膜,尤其舌和瘤胃黏膜有大小不等痘疹与坏死病灶,局部甚至形成糜烂或溃疡。肺膈叶以及肝、脾等常有痘疹和坏死病灶。病理组织学观察显示,肺痘疹病灶主要呈现渗出-增生结节和坏死-增生结节变化,病灶内血管、细支气管等周围常有大量绵羊痘细胞,胞质内有嗜酸性包涵体;病变消化道黏膜局部,上皮细胞程度不等增生、水泡变性,固有层及黏膜下层充血、水肿,有大量绵羊痘细胞,其细胞质内包涵体明显。肝、脾、肾也有程度不等坏死-增生结节变化。肺超微结构观察显示,肺泡上皮细胞肿大,细胞核浓缩、染色质聚集,线粒体程度不等肿胀、嵴断裂、空泡化,可见细胞质内包涵体。研究证明,除局部皮肤病变外,消化道黏膜和肺等实质器官的痘疹病变是患绵羊痘小尾寒羊具代表性的病理变化,尤其痘疹病灶中大量绵羊痘细胞的出现具有证病性意义。