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Sera from 100,400 cattle on 2850 farms in England, Scotland and Wales were tested for the presence of antibodies to Hypoderma species between the end of November 1995 and the end of February 1996. Twelve animals were resampled because the initial results were equivocal but only one of them was confirmed as seropositive. This animal was a bull imported from Belgium which had been treated with an approved warble fly treatment within 24 hours of arrival at its destination in Great Britain. No seropositive animals were confirmed within the native British cattle population. Statistical analysis of these data indicates that the probable maximum number of infested cattle herds in Great Britain is 112. To detect the disease by direct clinical observation would require more than 500 herds to be infested, indicating that the serological testing of this number of cattle and farms is more than four times as sensitive as clinical observation for the detection of hypodermosis.

Sera from 152,434 cattle held on 6175 farms in England and Wales were tested for the presence of antibodies to Hypoderma bovis during the 10 weeks starting on February 6, 1989. Thirty-nine positive animals (25.6 animals/100,000 tested) were identified on 21 of the farms (0.34 per cent). In comparison, the survey in 1988 examined 74,502 cattle on 3087 farms and found 29 positive animals (38.9/100,000 tested) on 18 farms (0.58 per cent).

Sera from 74,502 cattle from 3087 farms in England and Wales were tested for the presence of antibodies against Hypoderma bovis in the spring of 1988. Twenty-nine positive sera were identified on 18 premises and these animals were treated; an examination of 6030 sera taken from 108 neighbouring herds identified another 17 seropositive animals on 10 farms in Devon, Cornwall, Lancashire, Shropshire and Powys, indicating that these counties still harbour populations of warble fly.