ONCHOCERCA GUTTUROSA IN Danish cattle. Prevalence, geographic distribution and host-vector relationships.

1. Onchocerca gutturosa is reported in Danish cattle for the first time. Microfilariae were found in 38 (9.4%) of 406 cows that were 2 years or older. 2. Microfilariae were not randomly distributed throughout the skin but were concentrated in the umbilical area. 3. No difference in prevalence was observed between breeds of cattle. 4. Most of the infected cows had grazed on fields close to streams that contained Simulium ornatum, the vector of O. gutturosa. 5. Differences in preferred biting sites of S. ornatum from cow to cow were correlated with the arrangement of hair.