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The experiments were carried out on 285 cows from 10 herds from different regions of Poland. Extensity of the H. bovis invasion in each herd varied from 10 to 86%. The highest extensity appeared in herds from eastern and north-eastern Poland and the lowest in herds from southern and central regions of the country. Seroconversion of Hypoderma bovis antibodies was calculated for animals in which warbles were detected by clinical examination. The highest serum densities were observed in herds in March, April and May. The results of these investigations demonstrated that the best term for collecting blood samples to examine cattle for hypodermosis is the winter-spring season.

The aim of these investigations was to prepare the antigen and control sera for the ELISA. Positive control sera were obtained from 163 cows showing clinical symptoms of H. bovis infection and negative control sera from 60 cows free from the infection. The antigen for the ELISA was obtained from H. bovis L1 larvae. Three basic fraction were isolated from whole excreted/secreted antigen by elution from gel and by preparative isoelectrofocusing. Using the Western-Blotting method it was demonstrated that Hy A (22-24 kDa and pI 4-5) had the best antigenic property. As can be seen from these investigations the developed ELISA kit for the detection of H. bovis antibodies in cows is highly specific and sensitive.

The aim of investigations was to determine the stability of ELISA components preserved under different conditions. The following components for the ELISA were used: the secreted/excreted antigen prepared from H. bovis L1 larvae, its fraction containing hypodermine A, conjugat, positive and negative control sera. Freezing at -20 degrees C, lyophilization and preservation at 4 degrees C were applied. Seven kits for the ELISA containing components preserved using described methods, were prepared. The identical packets of sera were examined by the ELISA directly after preparation of the kits (day '0'), and next, at 3-4 week intervals for 9 months. The experiments showed that the best method of conservation of ELISA components for the detection of H. bovis antibodies was lyophilization. The kits prepared in this way did not lose their characteristics for 9 months and their specificity and sensitivity were close 100%.