Szerologiai vizsgalatok a csirkeanaemia-virus elterjedtsegere tyukallomanyainkban.
1996
Nemeth I. | Dren Cs. | Farkas T.
Avian infectious anaemia caused by chicken anaemia virus (CAV) is a serious problem in all major chicken-producing countries of the world. In young susceptible chicks, CAV causes impaired growth, severe anaemia with atrophy of the bone marrow marked lymphocytic depletion with atrophy of the lymphoid organs and petechial or ecchymotic haemorrhages throughout the body. Owing to its immunosuppressive effect, CAV depresses vaccinal immunity, considerably aggravates several diseases of young chickens, and also increases susceptibility to concurrent or secondary bacterial, viral and fungal infections. Thus, CAV-infection may occasionally result in considerable economical losses of the poultry husbandry. A serological survey on the prevalence of CAV infection was performed by using the indirect immunofluorescence (IF) test and the virus neutralization (VN) test in commercial chicken populations of Hungary. By the indirect IF test, a total of 846 serum samples from 13 meat-type parent flocks of two breeds were investigated between 10 and 62 weeks of age. All flocks were found to be positive for anti-CAV antibodies, and the rates of antibody-positive birds among flocks ranged from 40 to 93.3 percent and averaged 73.2 percent (Table 1). From nine 1-day- to 9-week-old progeny broiler flocks, 96 serum samples were tested (Table 2). In the 3 flocks sampled at the hatchery 75 to 100 percent (average 86.4) of the tested 22 birds were antibody-positive. Out of the 6 flocks, tested between 4 to 9 weeks of age, 3 were antibody-negative at 4 and 5 weeks of age, whereas in the remaining three 6- to 9-week-old flocks, the rates of antibody-positive birds were between 10 to 20 percent (average 13.5). In two egg-laying parent flocks of two different breeds, 54.5 and 71.7 percent of the tested 79 and 46 birds were found to be positive for anti-CAV antibodies at 14 and 35 weeks old, respectively (Table 1). By the VN test, a total of 670 serum samples from 9 meat-type parent flocks of two breeds aged between 11 and 37 weeks were investigated (Table 3). The rate of antibody-positivity in flocks was always over 80 percent and averaged 90.9. From 7 progeny broiler flocks, 261 serum samples were tested between one day and 7 weeks of age, and the rates of seropositivity in flocks were between 93.3 to 100 percent and averaged 96.9 (Table 4). In an egg-laying parent flock, 89.2 percent of the tested 102 birds had neutralizing antibody to CAV at 35 weeks old (Table 3). It was concluded that CAV is widespread in Hungarian commercial chicken populations. Though, according to simultaneous examination of 195 flock sera, the VN test revealed 11.3 more antibody-positive birds (Table 5), the indirect IF test was found suitable for serological surveys at flock(s) level, provided serum samples from sufficient number of chicks were tested.
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