Disinfecting poultry production premises.

Hygiene and sanitation play a major role in any effective disease control programme for poultry production premises. One of the important requirements to facilitate hygiene and sanitation is adoption of the 'all-in/all-out' method (i.e. all the birds within a single establishment should be of the same age group), together with the restriction of each enterprise to a single type or species of bird. Poultry premises and buildings should comply with requirements for isolation from the environment and strict observance of principles of hygiene and disease prevention (e.g. restrictions on movement of staff, equipment and vehicles). A poultry site must be prepared methodically for the entry of each new batch (removal of birds, litter and manure; vector and rodent control; dry and wet cleaning; disinfection; fumigation). Attention should be paid to the terminal sanitation of houses and equipment after depopulation (physical and chemical cleaning, pressure washing, disinfection, fumigation). Particular care should be exercised in the performance of sanitary procedures after a disease outbreak. Immediate disposal of dead and diseased birds is an important and effective tool in preventing the dissemination of any disease. Disposal methods include the use of burial pits, tanks, burial in trenches, burning, rendering and composting. Regular visual inspection, together with routine testing by microbiological monitoring methods, is very effective in checking the efficacy of cleaning and disinfection.

Application of disinfectants in poultry hatcheries.

Veterinary control and routine sanitary procedures in commercial poultry hatcheries should include the following: choice of a suitable geographical location to ensure an isolated site; proper hatchery design with separation of major operations; one-way flow of work within the hatchery; adequate ventilation of each room; routine cleaning and disinfection; formaldehyde fumigation or alternative method for disinfection of eggs, equipment and incubators; a routine programme for monitoring microbial contamination levels within the hatchery.

Polymyxin B: pharmacokinetics of single doses given intravenously and intramuscularly to turkeys, and minimal inhibitory concentrations for Escherichia coli and Pasteurella multocida.

The 50% and 90% minimal inhibitory concentrations (MIC50 and MIC90) of polymyxin B for avian Escherichia coli and Pasteurella multocida isolates were determined by the agar plate dilution method. Polymyxin B at approximate MIC level in serum was bactericidal for E. coli in 2 to 4 hours. Aqueous polymyxin B sulfate was administered by a single bolus intravenous injection into turkeys at 10,000 IU/kg, and by a single bolus intramuscular injection at 5,000, 10,000 or 20,000 IU/kg. Effective serum drug concentrations after intramuscular injection (MIC50 levels or greater) were maintained for E. coli for 7.0 hr (10,000 IU/kg) and 11.5 hr (20,000 IU/kg), and for P. multocida for 3.0 hr (10,000 IU/kg) and 4.1 hr (20,000 IU/kg). Pharmacokinetic parameters were calculated by non-compartmental methods. Elimination time half-lives, mean residence time, clearance, and apparent volume of distribution at steady state (Vdss) were all much higher for i.m. injection of 20,000 IU/kg than for i.m. injection of 10,000 IU/kg. We postulate that there exists a minimal tissue-interaction threshold concentration (MTC) at which polymyxin B can enter previously unavailable compartments or bind to previously refractory tissue components. Bioavailability of polymyxin B injected i.m. was 0.904 for the 10,000 IU/kg dose and 0.675 for the 20,000 IU/kg dose. Dosage intervals necessary to produce minimal steady state concentrations (Cssmin) equal to the MIC were calculated. Certain aspects of the use of the parameter Vdss, and limitations on the use of dosage interval calculations for polymyxin B, are discussed. One week after i.m. injection of polymyxin B at 10,000 IU/kg, high tissue drug levels were present, especially in bound form in liver. Following single injections, no toxic effects on turkeys were observed.

Adherence-associated characteristics and pathogenicity of Escherichia coli from avian colibacillosis.

Escherichia coli isolates from avian colibacillosis were examined for adherence-associated characteristics and post-colonisation pathogenicity. The adherence-associated characteristics studied included expression of pili, ability to partition with a hydrophobic phase, and ability to bind to Biosilon plastic polar-surfaced microcarriers. None of the adherence-associated characteristics correlated absolutely with post-colonisation pathogenicity, and thus in vitro tests for these adherence-associated characteristics cannot be used to predict whether any given E. coli avian colibacillosis isolate will exhibit post-colonisation pathogenicity. The isolation of strain BT7 from avian colibacillosis, a piliated E. coli strain which binds to Biosilon polar-surfaced plastic microcarriers, but is not pathogenic, is reported.

Vaccination of young turkeys against fowl cholera.

Turkey poults vaccinated at one day of age with commercial inactivated Pasteurella multocida (PM) bacterin responded with low titres of antibody (ab) as measured by ELISA, but had an acceptable degree of resistance when challenged with the X-73 strain of PM until 13 weeks of age. Turkeys vaccinated at 3 and/or 6 weeks of age responded with higher ab titres and were resistant to virulent challenge with PM. Turkey poults vaccinated at 3 and/or 6 weeks of age with a commercial live PM vaccine had a poor immune response and low resistance to virulent challenge. When live PM vaccine was given to turkey poults previously vaccinated with an oil-emulsion PM bacterin, the turkey poults were highly resistant to virulent challenge, although the booster vaccination did not always induce a significant increase in the ab titres. The ELISA test used did not appear to be adequate for evaluation of the degree of protection induced in turkey flocks vaccinated at a very young age.

Newcastle disease in ostriches (Struthio camelus): field case and experimental infection.

An outbreak of Newcastle disease (ND) in ostriches is described. In a flock aged 5 to 9 months of age 13 out of 46 ostriches died, whereas a neighbouring flock of 11-month-old birds remained unaffected. The main clinical signs were nervous. Hemagglutination inhibition (HI) titres reached log(2) 8. The virus was isolated from the brain only. Experimental infection of five, 3-month-old ostriches with virulent ND virus caused the death of three birds within 5 to 10 d. Another had to be killed after showing typical signs. HI titres after 5 days exceeded log(2) 5. The virus could be reisolated from different organs.

Pox in ostriches.

Clinical signs suggesting pox were observed in a flock of ostrich chicks (Struthio camelus), 10 to 60 days old. The disease was confirmed by isolation of the agent from affected ostriches and reproduction of typical pox lesions in turkeys. Further infection of young ostriches was prevented by vaccination with fowl pox vaccine.

Death in broiler breeders due to salpingitis: possible role of zearalenone.

High mortality occurred in a flock of 24,000 broiler breeders. During the 40 weeks of the laying period the mortality was approximately 40% in two houses and 20% in two other houses. Peak egg production in the severely affected houses reached 51% and 56% while the two other houses achieved 66% and 76%. Fertility was not affected and the progeny appeared normal in all respects. In the affected birds ascitic fluid was found in the abdomen while cysts and a large amount of fibrinous material were present in the oviduct. The histopathological examination showed caseous cysts in the epithelium with chronic inflammation of the genital tract (salpingitis and peritonitis). Examination of feed extracts with a radioreceptor assay indicated a high degree of oestrogenic activity. Examination by thin layer and high pressure liquid chromatography indicated that zearalenone - a naturally occurring oestrogenic mycotoxin produced by Fusarium spp -was present in concentrations of up to 5 microg/g of feed.

Immunoelectrophoresis of avian viral proteins in a phosphate-buffered system.

Avian influenza and hemorrhagic enteritis viral preparations were immunoelectrophoresed in a phosphate-buffered system. Excellent separation and resolution of viral proteins were achieved. Reasons are given why this method might be preferred over the conventional method employing a veronal (barbital)-buffered system.

Antigenic and biological characterisation of avian paramyxovirus type I isolates from pigeons--an international collaborative study.

During 1981-1983 a disease of pigeons (Columba livia), characterised predominantly by nervous signs, spread across Europe. In the present study 57 viruses isolated from pigeons from 15 countries (12 European, Japan, Israel and Sudan) were characterised. All were shown to be avian paramyxoviruses of the A/PMV-1 serotype. Monoclonal antibody binding tests showed 53 of the viruses to be identical. The virus from Sudan was similar to these viruses but showed distinguishable variation. One vaccinal virus from France and two virulent viruses from Czechoslovakia were unrelated to the other pigeon A/PMV-1 isolates.

Apramycin: minimal inhibitory concentrations for avian Escherichia coli and serum levels after intramuscular injection in turkeys.

The minimal inhibitory concentrations (MIC) of apramycin, a unique aminocyclitol antibiotic, for 100 Escherichia coli isolates recovered from clinical cases of avian colibacillosis were determined using the agar dilution method. All isolates were inhibited at apramycin concentration of 8.0 micrograms/ml; 90 and 50% of the isolates were inhibited at 6.6 and 3.4 micrograms/ml, respectively. A commercial injectable product containing 200 mg apramycin/ml was administered intramuscularly (i.m.) to groups of 6- and 12-week-old turkeys at 10, 15 and 20 mg/kg. Apramycin was quickly absorbed from the i.m. injection site. Mean peak serum drug concentrations were reached 1 h after treatment and were 19.5, 27.5 and 36.0 micrograms/ml, respectively. The serum elimination half-life (t 1/2) of the drug ranged between 1.75 h for the 10 mg/kg dose and 2.5 h for the 20 mg/kg dose. Very low concentrations of the drug were found 24 h after treatment. Duration of serum apramycin concentrations in relation to the MIC, dose, and age of birds was determined.

Continuous subcutaneous insulin infusion. Improved blood glucose in pregnant diabetics.

The effect of continuous subcutaneous insulin infusion (c.s.i.i.) on the control of blood-glucose concentration and outcome of pregnancy was assessed in two pregnant diabetics (class B and class C White classification) who were poorly controlled with conventional insulin therapy. The insulin pump was carried in a holster and enabled the patients to ambulate freely. The patients were able to refill the syringe, to augment the infusion rate at mealtime and to change the implantation site of the needle weekly, and thus, were able to leave the hospital. Daily glucose profiles were assessed 1-3 times a week, and the infusion rate was readjusted accordingly. Twenty-four hours glucose profiles were obtained from both patients during inpatient conventional insulin regimens, and then, during c.s.i.i. which was maintained for 41 and 145 days, respectively. Mean 24 hours glucose concentrations were reduced from 156 to 113 mg/100 ml, mean fasting glucose from 152 to 106 mg/100 ml, and mean diurnal variation (maximal excursion) from 75 to 65 mg/100 ml. The favourable results achieved with the c.s.i.i. enabled both patients to reach the 18th week of gestation and to deliver healthy non-macrosomic infants, who had uneventful and morbid-free neonatal periods. Since the c.s.i.i. supplies insulin in a more physiological manner than twice daily regimens, better control of blood sugar and body fuel metabolism may be achieved. By extending the therapy to the early stages of pregnancy, or if possible to pre-conceptional period, reduced perinatal mortality and morbidity may be anticipated.

Spray vaccination of chickens with an experimental vaccine against Newcastle disease.

Chickens, of various age groups, were vaccinated against Newcastle disease by spray vaccination with an experimental vaccine, designated V5K7E1. Aerosol spraying of 3-days-old chicks having a high titre of maternal antibodies failed to induce any obvious stimulation of haemagglutination-inhibiting antibodies. The chicks, when challenged 2 and 3 weeks after vaccination, were fully protected, but protection was inadequate when they were challenged 4 to 7 weeks after vaccination. Spray vaccination of 1-day-old specific-pathogen-free chicks resulted in the presence of antibodies at 7, 14 and 21 days. Subsequently the levels of antibodies declined progressively. The chicks resisted challenge up to 42 days after vaccination. Maternally immune chicks spray - vaccinated for the first time at 14 days showed a significant increase in antibodies and remained healthy when challenged at 10 weeks of age. Booster spray vaccination at 21 days of age subsequent to primary spray vaccination at 3 days of age, induced an anamnestic rise in antibody titre that persisted at protective levels for at least 66 days. Similarly, spray vaccination at 28 days, following administration of vaccine in the drinking water at 14 days, gave rise to high antibody titres which persisted for at least 70 days. In field trials, spray vaccination at the age of 3 days or 14 days provoked little or no apparent respiratory disturbance and was followed by an average mortality of 0.9% and 1.4% respectively.

Development of a new vaccine against turkey meningo-encephalitis using a virus passaged through the Japanese quail (Coturnix coturnix japonica).

Turkey meningo-encephalitis virus could be adapted to the Japanese quail by intra-cerebral inoculation. After 4 passages the virus was found to be less pathogenic for the turkey. Further attenuation could be achieved by growing the virus in Japanese quail kidney cell cultures for 11 passages. This attenuated virus was used for the preparation of a live vaccine against turkey meningo-encephalitis. The safety and efficacy of the vaccine was shown in laboratory and field experiments.

Turkey meningo-encephalitis: pathogenic and immunological aspects of the infection.

The distribution of turkey meningo-encephalitis virus in infected birds and the development of immunity were studied. The turkey meningo-encephalitis virus was present in the blood as early as 24 h after experimental inoculation, and persisted for 5-8 d. Antibodies could be detected about the 5th d. A good correlation was found between haemagglutinin-inhibiting and virus-neutralizing antibodies. The virus could not be reisolated from any blood or organ sample collected after the 14th d and no sign of latent infection or carrier state could be found. The infection did not spread from the inoculated turkeys to control un inoculated birds in close contact. The possible existence of a natural reservoir and an arthropod vector of this virus is discussed.