[Immunobiological and antigenic studies of Babesia ovis strains in Bulgaria]. / Imunobiologichni i antigenni prouchvaniia na shtamove Babesia ovis v Bulgariia.

A comparative study was carried out on the immunologic and antigenic properties of 8 strains of Babesia ovis isolated in 5 districts of the country. The immunologic capacity was tested through challenging with each of the strains in group of 4 weaned lambs that were preliminary vaccinated with one of the strains - Veliko Turnovo. Two nonvaccinated animals were included in each group, serving as controls. The strength of immunity was checked by both the temperature and the parasitic reaction as well as through the hematocrit and hemoglobin levels of the challenged lambs. With the exception of one spleen - ectomized animal in each group the vaccinated weaned lambs showed solid immunity against both the homogeneous and heterologic strains. The same result was confirmed also with an analogous biologic experiment with a total of 19870 sheep in 28 enzootic foci in the same 5 districts and in 2 other districts of the country. Cross serologic investigations by means of the complement - fixation test, the agar gel precipitation reaction and IRPA with homologous and heterologous antisera revealed identic or close antigenic properties in the tested strains. In is concluded that the Veliko Turnovo strain can be used to prepare a vaccine for the immunoprophylaxis of babesiasis in sheep in the investigated districts. In is also stated that the serologic reactions, and, more specifically, IRPA can be employed in the antigenic study and differentiation of individual Babesia ovis strains.

[Superinfection in heterakiasis]. / Vurkhu superinvaziiata pri kheterakidozata.

Experiments including single, two-fold and triple superinvasions with 100 invasive heterakidic eggs each on 2 day- and 4 month-old chickens were carried out (beginning of the experiment). Single superinvasions were effected on the 12th, 18th and 30th day, two-fold superinvasions -- on the 12th and 18th, 12th and 30th, 18th and 30th day, while triple superinvasions took place on the 12th, 18th and 30th day. It was established that the superinvasions of 20 day-old chickens reduce 3.6 times the survival of heterakids. The reduction was most pronounced in chickens superinvaded on the 18th day. A certain areactivity was observed in 4 month-old superinvaded chickens: the number of surviving heterakids was 1.4 times greater in superinvaded chickens than in the control. A significant shortening of heterakid length was established in younger experimental chickens as compared to the control, as well as an enhanced pathogenic effect of the helminths. Deviations of this kind were not evident in older chickens.

[Relationship between the viability and pathogenicity of Heterskis gallinarum and the intensity of invasion and age of the infested chickens]. / Prezhiviaemost i patogennost na Heterakis gallinarum v zavisimost ot intenzivnostta na invaziiata i vuzrastta na invaziranite pileta

It has been found that the survival rate of Heterakis worms in chickens aged from one to seven months is directly dependent on the number of Heterakis eggs that have gained access in them only in the case of lower numbers of infective eggs (10 and 50). At comparatively larger numbers of eggs (500 and 2500) the survival rate has been highest at the 3- and 4-month-old chickens, and the morphologic changes in this age group are most pronouncedly expressed. Investigations have shown that the greatest survival rate corresponds to the weakest increase in the leukocyte count and the amount of the gamma-globulins in the 3- and 4-month-old chickens. In the one- and 2-month-old ones the Heterakis infection has caused a strong increase in the leukocyte count, and in those aged 5-7 month-old there has been also an increase in the gamma-globulins. The biochemical indices and the morphologic changes have not in all cases been directly dependent on the age of the infected birds, the number of the infective eggs given, and the number of the Heterakis helminths that have survived. Heterakis injection caused by a greater number of eggs is present by worms of a smaller size. Chickens infected at the age of more than five months have worms among which the female samples are considerably more than the male ones as compared with the respective numbers found in one- to 4-month-old birds.

[Effect of some trace elements on Heterakis gallinarum invasion]. / Vliianie na niakoi mikroelementi vurkhu invaziiata s Heterakis gallinarum

It was found that sodium chloride at the rate of 0.5 per cent in the mixtures lowers by 25 times the survival of the Heterakis helminths in birds, prevents the manifestation of verminous typhlitis, alters the ratio between the female and the male worms in favour of the latter, contributes to the increase in body weight and rises the level of the total protein in the blood serum, and changes the protein spectrum raising the level of globulins. Positive results at a lower size were established in feeding cobaltinitrite and soduim selenite to birds. Last ranked the effects produced with the offer of zinc sulfate. The admixture of sodium chloride at the rate of 0.5 per cent of birds is suggested both from the standpoint of Heterakis control and prophylaxis and from the point of view of pathogenesis.

[Test of the effectiveness of tylan on spirochetosis in chickens]. / Izpitvane efektivnostta na tilana sreshtu spirokhetoza po kokoshkite

The water-soluble preparation Tylan in conc. 1:2000 in the drinking water for three consecutive days was used successfully against spirochetosis in birds both experimently and in the field practice, as a therapeutic and prophylactic means. 175 (92 per cent) out of 190 affected birds in a spontaneous breakout of spirochetosis recovered. It was found experimentally that Tylan does not interfere with immunogenesis. This made it possible for the authors to vaccinate 10,000 chickens from flocks with manifested spirochetosis along with giving Tylan as a therapeutic and prophylactic agent. Spirochetosis ceased and was no more observed up to the time of slaughter i. e., six months following vaccination. If there are no ticks on the spirochetosis-affected farms it is possible to bring to an end the disease through the therapeutic and prophylactic use of Tylan together with disinfection with 1 per cent sodium hydroxide, no vaccination being needed.

[Recuperative processes in experimental Heterakis infections in chickens]. / V'rkhu v'zstanovitelnite protsesi pri eksperimentala kheterakidoza u pileta

Studied were the recuperation processes in birds with Heterakis infection induced with the administration of 300 infective Heterakis eggs per bird, followed by phenotiazin worming at various intervals. It was found that the reconvalescence period sets in sooner and more effectively with the earlier removal of helminths, but not later than the 35th day after infection. The erythrocyte and leukocyte counts were found to come back to normal soonest, while the weight gain, the amount of hemoglobin, the percentage of pseudoeosinophiles and the gamma-globulins were normalized less quickly, and the total protein and the percent of lymphocytes were not normalized at all. Following Heterakis infection there set in changes in the organism which remain even when worming is carried out as early as the first days after the infection. Thirty-five days after the infection with Heterakis such changes were close to those which could not be involved in the reminiscence processes. On the sixtieth day of the infection process recuperation was impossible, and worming did not result in the removal of the helminths in connection with development of chronic typhlitis. It is suggested to undertake worming at intervals not longer than thirty days.