Lice and mite infestations of cattle in Iceland
The aim of the present study was to survey lice and mite species infesting cattle in Iceland and to evaluate their prevalence on farms, prevalence and site preferences on the animals and correlation with dermatological symptoms. The survey included two separate investigations, a combing study including 50 calves and 50 dairy cows, and a study of skin samples including 27 bullocks and 28 dairy cows. The animals came from farms in Southwest Iceland. In the combing study five preselected areas on each animal were combed. Two lice species were found, the chewing louse Bovicola bovis and the sucking louse Solenopotes capillatus. Lice were found at 7 of 10 farms. B. bovis was found at 50% and S. capillatus at 40% of the farms and both species occurred at 20% of the farms. Lice were found on 40% of the calves and 4% of the cows. B. bovis was found on 28% of the calves and 2% of the cows. S. capillatus was detected on 16% of the calves and 2% of the cows. B. bovis was most prevalent on back and rump, less prevalent on the head, neck and tail and was not detected on the front leg. S. capillatus was most prevalent on the neck, then head and front leg, and was least prevalent on the posterior back and rump and on the tail. Minor dermatological signs were seen on two cows and three calves. In the study of skin samples, samples were taken from five preselected sites of the animals. In this study the hair follicle mite Demodex bovis was found in the skin of the neck of one bullock (1.8%). No macroscopic skin disorders were observed on the samples.
Effects of various infestation levels of cattle lice (Mallophaga: Trichodectidae and Anoplura: Haematopinidae) on feed efficiency and weight gains of beef heifers.
Heifers with a heavy infestation of cattle lice (10 or more per 6.452 cm2 [1 in2] of Bovicola bovis (L.), Linognathus vituli (L.), and Solenopotes capillatus Enderlein) gained significantly less weight (0.09 kg [0.21 lb]/day) than heifers treated with stirofos or trichlorfon. No significant weight gain differences were found between heifers with a light to moderate or moderate to heavy infestation and treated heifers. Feed efficiency was not significantly affected by the three lice infestation levels evaluated in these trials.
Sheep scab outbreaks in Great Britain between 1973 and 1992: spatial and temporal patterns.
In January 1973, the mange mite Psoroptes ovis was found in a sheep flock in Lancashire, UK after a 20 year period of eradication. Over the next 20 years, a total of 1480 flock outbreaks were reported, until June 1992 when the control of sheep scab was deregulated. The spatial and temporal patterns of the number of outbreaks in each month over this period were analysed using time series methods, a geographical information system (GIS) and second order approaches to the exploration of space-time interaction (K-function analysis). The monthly time series displays clear evidence of seasonal cyclicity, with most outbreaks being reported in the winter months. After removal of the summer compulsory dip in 1988 however, there is evidence of a change in the seasonal pattern, with more cases being reported in the autumn months. There is also evidence of a contribution from a sinusoidal wave with a period of 8 years, which roughly corresponds to the major changes in the national control policy. The spatial pattern also appears to expand and contract on a roughly 4 year cycle, again reflecting the oscillating periods of success and failure. Examination of the spatial and temporal pattern revealed strong evidence of space-time clustering (p < 0.001) and a major contribution to the pattern from very local (< 12 km) spread within 5 months of an arbitrary outbreak.