Isolation of Mycoplasma synoviae from infectious synovitis of chickens

This report describes the first isolations of Mycoplasma synoviae from the synovial sheaths and joints of commercial chickens affected with synovitis in Australia. Over 4 years 3 separate outbreaks were investigated in which up to 20% of birds exhibited clinical signs of poor growth and "hot foot" syndrome (swollen inflamed footpads). Once an outbreak occurred, chronic infection of the farm usually ensued. Grossly the hocks and footpads were swollen by a purulent exudate and associated inflammatory changes with histological features of a severe acute synovitis. Seroconversion of the flocks occurred at the time of the development of lesions. M. synoviae specific antibodies were demonstrated by ELISA in the joint fluid of affected birds. It is concluded that the cases described are similar to avian infectious synovitis syndrome caused by M. synoviae previously described overseas.     

Non-infective factors in the aetiology of synovitis in chickens

A study was conducted to elucidate the relative susceptibility of broiler breed birds to synovitis and the relative resistance of laying breed birds to this disease. It was shown that difference in structure and chemical composition of fibrous connective tissue can be associated with this difference in susceptibility. A loose structure of fibrous connective tissue (common in broiler breed birds) appears to predispose to synovitis, whereas a compact structure (common in laying breed birds) can be associated with resistance to synovitis. The most fundamental approach to the synovitis problem would be the breeding of broiler breed birds with a compact structure of fibrous connective tissue. However, this approach does not seem to offer favourable prospects in the near future. For the present, synovitis resistance in broiler parents can be enhanced by practising a management scheme aiming at activation of the birds.     

The isolation of Mycoplasms synoviae from chickens with infectious synovitis and air-sacculitis in the Republic of South Africa.

Mycoplasma synoviae was isolated from the trachea of chickens showing either typical infectious synovitis lesions or air-sacculitis. M. synoviae was identified by means of the direct plate fluorescent antibody technique and its growth-dependence on nicotine-amide-adenine dinucleotide. This is the first documented report on the isolation and identification of M. synoviae in the Republic of South Africa.     

Studies on the pathogenesis of chicken infectious anaemia virus infection in six-week-old SPF chickens

The pathogenesis of chicken infectious anaemia virus (CAV) infection was studied in 6-week-old and one-day-old SPF chickens inoculated intramuscularly with graded doses of Cux-1 strain (10(6)-10(2) TCID50/chicken). Viraemia, virus shedding, development of virus neutralizing (VN) antibodies and CAV distribution in the thymus were studied by virus isolation, polymerase chain reaction (PCR), immunocytochemistry (IP) and in situ hybridization until postinfection day (PID) 28. In 6-week-old chickens infected with high doses of CAV, viraemia and VN antibodies could be detected 4 PID and onward without virus shedding or contact transmission to sentinel birds. However, virus shedding and contact transmission were demonstrated in one-day-old infected chickens. In the 6-week-old groups infected with lower doses, VN antibodies developed by PID 14, transient viraemia and virus shedding were detected. The thymus cortex of all 1-day-old inoculated chickens stained with VP3-specific mAb. Cells with positive in situ hybridization signal were fewer and scattered throughout the thymus tissue of the one-day-old inoculated chickens as compared to IP-positive cells. These results suggest that early immune response induced by high doses of CAV in 6-week-old chickens curtails viral replication and prevents virus shedding.     

蛋鸡传染性鼻炎的防控

鸡传染性鼻炎是由副鸡嗜血杆菌引起的一种急性上呼吸道疾病,主要表现为单侧或双侧颜面肿胀,鼻腔有浆液性或粘液性分泌物,并伴有结膜炎和鼻炎,可导致育成鸡生长发育受阻,产蛋鸡产蛋量下降10%~40%,死亡率增加,给养殖业带来严重损失。一病原学及流行特点副鸡嗜血杆菌为两极浓染的革兰氏阴性菌,呈球杆菌或小杆菌形态,两端钝圆,无鞭毛,不能运动,不形成芽胞。主要感染鸡,病鸡和带菌鸡是主要传染源。     

Age resistance in chickens against infectious bursal disease

The day old broiler chickens possessing IBD precipitating maternal antibody when exposed either to IBD contaminated environment or challenged intrabursally with virulent virus at weekly intervals indicated 100% susceptibility around 4–5 weeks of age. However, chickens lacking maternal antibody upon intrabursal challenge were found susceptible by 2 weeks of age.     

Dexamethasone reduces infectious bursal disease mortality in chickens

Very virulent infectious bursal disease virus (vvIBDV) causes high mortality in chickens but measures to reduce the mortality have not been explored. Chickens (8–9 weeks) were treated with 3 agents before and during vvIBDV inoculation. Dexamethasone treatment reduced the mortality of infected chickens (40.7% vs. 3.7%; p < 0.001), but treatment with aspirin or vitamin E plus selenium did not affect the mortality. The bursa of Fabricius appeared to have shrunk in both dead and surviving chickens (p < 0.01). The results indicate that dexamethasone can reduce mortality in vvIBDV-infected chickens and may provide therapeutic clues for saving individual birds infected by the virus.     

Survey of infectious coryza of chickens in Indonesia.

A survey of infectious coryza of chickens was performed in West Jawa of Indonesia between 1987 to 1988 by the detection of hemagglutination-inhibition (HI) antibody against Haemophilus paragallinarum (Hpg) in non-vaccinated healthy laying (12 farms, 196 chickens) and native (8 farms, 197 chickens) chickens. HI antibodies against Hpg were detected not only in the native chickens but also in the laying chickens, regardless of the district, and were observed in 70% (14/20) of farms and 19% (73/393) of chickens. HI antibodies against serotype A were detected from 11 farms (55%) and 11% (45/393) in chickens. Those against serotype C were detected from 5 farms (25%) and 8% (30/393) in chickens. Three Hpg strains were isolated from different chickens affected with infectious coryza. Two of them were identified as type A and the other as type C by the rapid plate agglutination test. These results demonstrated that the outbreaks of infectious coryza caused by serotype A and C strains had occurred in Indonesia.     

鸡传染性喉气管炎的防治

传染性喉气管炎(ILT)是由A型疱疹病毒引起的鸡的一种急性呼吸道传染病。1936年由Beaudette首次证明其病原是一种滤过性病毒。目前此病在许多国家广泛流行,是危害养鸡业的重要疾病,近几年来,在我国一些养鸡集中的地区,ILT引起产蛋鸡产蛋下降和鸡群的高死亡率,产蛋率一般下降10%～50%,死亡率一般在5%～70%之间,给养鸡业带来巨大经济损失,现将实践中对该病的诊断、治疗经验及防制要点总结如下。1流行特点鸡是ILT感染的主要自然宿主,各种日龄的鸡均可感染,以4～10月龄的成年鸡最为严重,对产蛋高峰期的鸡特别易感且危害大;从鸡品种来看,以褐…     

Immunogenicity of infectious bursal disease viruses in chickens.

Cross-protective properties of infectious bursal disease viruses (IBDVs) were studied. Viruses represented different subtypes of serotype 1, including recently isolated viruses (variants), and a serotype 2 virus. Chickens were vaccinated at 3 weeks of age with inactivated vaccines containing 10(5), 10(6), 10(7), or 10(8) mean tissue-culture infectious dose of a given virus and challenged 2 weeks later using either 10(2) or 10(3.5) mean embryo infectious dose (EID50) of either a standard virus or a variant serotype 1 virus. Protection was evaluated at 5 and 10 days post-challenge, based on gross and microscopic lesions, body weight, and bursa/body-weight ratios. The serotype 2 virus did not confer protection on birds challenged with the serotype 1 viruses. Vaccines made of variant viruses at the low doses protected chickens challenged with the high or low doses of either the standard or the variant viruses. Vaccines made of the standard or variant strains at low doses protected against high or low challenge doses of the standard strain. Vaccines made of the high dose of any of the standard strains protected chickens against the variant virus when the low challenge dose (10(2) EID50) was used, but not when the high challenge dose (10(3.5) EID50) was used. The lowest dose of the standard viruses vaccines required to confer protection against the variant virus varied depending on the strain. Results indicated that protection depended on the strain and dose of both the vaccine and challenge viruses and that the variant strains and standard strains share a common protective antigen(s).