[Properties of local velogenic strains of Newcastle disease virus in poultry]. / Prouchvaniia vurkhu niakoi svoistva na mestni velogenni shtamove na virusa na psevdochumata po ptitsite.

Studies were carried out on four strains of the Newcastle disease virus, isolated in Bulgaria and referred, as typed by the routinely used methods, to the velogenic group. The strains proved to be hemagglutinin - thermostable. Two of the local virus strains (Rosa and Toutrakan) belonged to the velogenic-neurotropic pathogenic type, and two (Bregovo and Haskovo) - to the velogenic - viscerotropic pathogenic one. All four strains were slowly eluated from chicken erythrocytes. Full immunologic similarity was established between these strains by means of the live vaccines used in this country for the specific prevention of Newcastle disease, produced with the lentogenic strains Hitchner B1 and La Sota and the mesogenic Komarov.

[Clinical and pharmacological studies of technical tylosin phosphate from Pharmachem in poultry diseases]. / Kliniko-farmakologichni prouchvaniia na tekhnicheskiia tilozinov fosfat "Farmakhim" pri niakoi zaboliavaniia po ptitsite.

Investigations on the healing anbd prophylactic effectiveness of the technical tylosine phosphate "Pharmachim" with 50 IU/mg activity (pharmazin T-50) in some bird diseases were carried out. It was established that a dose of 20 g/kg fodder pharmazin T-50 applied 2 days pre- and 3 days post chicken Mycoplasma gallisepticum infection protects the chickens completely from respiratory mycoplasmosis. In order to attain a sure healing and prophylactic effect in hen spirohetosis control 10 g/kg fodder applied 2 days or on the 24th to 48th day after Borrelia anserina invasion are completely sufficient. It must be noted, moreover, that pharmazin T-50 application has not a negative effect on the build up of post-vaccinal immunity following the same illness. The good results obtained by pharmazin T-50 allow it to replace successfully the remaining medicinal preparations (some of which much more expensive) applied in the control of spirohetosis and respiratory mycoplasmosis of birds.

[Atypical course of cholera in poultry]. / Prouchvane na atipichno protichashta kholera po ptitsite.

Atypically developing chicken septicemia was studied at 3 farms in Bulgaria. In one of the observed centers of chicken septicemia infection no pathologic anatomical changes were evident while in the other two centers of infection serofibrinose and serofibrinose vitelline peritonitis, as well as pleurisy were present. In the bacteriological investigation carried out on 2969 samples 233 strains of chicken septicemia were isolated. Identification of 84 of them by the aid of the specific bacteriophage P. multocida 115 and of sugar and alcohol fermantation revealed that they can be classified as P. multocida. They are lyzated by a phage but do not reproduce it. Chicken septicemia cultures are virulent for white mice. In intramuscular injections of pullets these cultures prove not virulent, but their intravenous application kills the pullets in 5--10 days and the initial strain is isolated from all inner organs. The biological test on pullets is suitable for determining chicken septicemia culture virulence.

[Production and titration of a vaccine against the infectious encephalomyelitis of poultry]. / Poluchavane i titrirane na vaksina sreshtu zarazen entsefalomielit po ptitsite.

A vaccine was produced against infectious encephalomyelitis of day-old chicks infected cerebrally with strain Calnek 1143. It is a brain suspension from killed birds that have shown disease symptoms, treated with penicillin and streptomycin and stored at -20 degrees C. Experiments were carried out to titrate the vaccine through determining the minimum infective dose for day-old chicks treated with 0.1 cm3 each of it, orally, as obtained from tenfold dilutions. It was found that birds do not manifest clinically the disease, however, with birds killed 20--25 days following infection there have been characteristic histologic changes speaking of infectious encephalomyelitis. The minimum infective dose of the various batches of vaccine have been found to range from 10(-3) to 10(-5)/cm3. Applied under the conditions of the practice the vaccine has proved harmless, contributing to eradication of the disease on the infected farms.

[Role of the housefly in the epizootology of pseudoplague in birds]. / Znachenie na domashnata mukha v epizootologiiata na psevodochumata po ptitisite.

It has been demonstrated that Musca domestica L. could harbour the Newcastle disease virus. It has been isolated from the surface of the flies body 96 hours after these had been in contact with it, and from their digestive tract--after 240 hours. It has also been found that virus excretion in infected flies continues for 96 hours. It is believed that Musca domestica L. flies can participate in the spreading of the ND virus.

[Comparative study of infectious and atypical encephalomyelitis in birds]. / Sravnitelni prouchvaniia na infektsiozniia i atipichniia entsefalomielit po ptitsite

Studied were morphologically a total of 234 birds for infectious encephalomyelitis (IE) and atypic encephalomyelitis (AE) of which 70 were experimentally infected with standard reference strains of IE (Calnek 1143-42 birds, and Van Roeckel 28 birds), 32 were infected with a brain suspension of affected with AE birds, and 110 were spontaneously affected with AE. Those of the birds that were infected with the standard strains of IE as well as with the brain suspension exhibited changes in the central nervous system in the form of a non-suppurative encephalomyelitis, and in the viscera--lymphoidcell proliferations. These alterations proved analogous with those observed in birds spontaneously affected with AE. The changes in CNS in the case of IE were localized in the brain and the spinal cord, while the lesions in the case of AE were found chiefly in the brain. In AE there were perivascular lymphoidcell were groupings along the peripheral nerves. It was concluded that the histologic changes established may well serve to differentiate IE from AE in Marek's disease, the transitional paralysis, the Newcastle disease, and the alimentary encephalomalacia.

[Possible synergic action of some drug combinations against Mycoplasma gallisepticum]. / V'zmozhnosti za sinergichno deistvie na niakoi lekarstveni kombinatsii spriamo Mycoplasma gallisepticum

Yamamoto and Adler's method (1956), making use of the modified medium of Edward, was employed to determine the minimal concentrations of gentamicin (GMC), erytrhomycin (ERM), oleandomycin (OMC) spectinomycin (SPM), tetracycline (TC), tylosin (TLS), and chloramphenicol (CA), all of them showing bactericidal effects on Mycoplasma gallisepticum-S6, applied alone or in combination. In vitro studies showed that relatively most effective were TLS, GMC, and SPM, when used alone. Combining the antibiotics by two in the most cases led to a pronounced synergic effect. Comparatively most effective were the combinations of TLS+ERM; TLS+TC; CA+TC; CA+OMC; TLS+CA; TLS+OMC; SPM+TC; and SPM+CA. Lowest absolute concentrations of the individual components showed the combinations of TLS+GMC; TLS+TC; TLS+ERM; TLS+CA; TLS+SPM; TLS+OMC; SPM+TC; and SPM+CA.