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Title: Contributions to the epidemiology of Louping-ill
Author: Turnbull, Duncan McDiarmid
ISNI:       0000 0004 2672 8155
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1979
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Part 1. The ecology of Ixocles trianguliceps Birulav 1895- Ixodes trianguliceps and its small mammal hosts have previously been proposed as serving an occult reservoir role in the cycling of Loupine-ill virus. The tick was collected from three host species: C. glareolus, M. agrestis and A. sylvaticus. The main study area was at Balerno, Ididlothian where it was the only species of 'tick recovered. Regular collections were made from July 1974 until August 1976. C. glareolus had the greatest frequency of parasitised hosts and the heaviest burdens; the males were more heavily burdened than the. females. Such sex preference was not found for the other hosts. Larvae infest the hosts throughout the year, burdens being maximal in June and minimal in July, a second, much lower, peak occurs in October. Females are active from early spring and nymphs from late spring until autumn. The ear pinna is the area of the body most heavily infested by larvae and nymphs, particularly the inner surface with voles and the outer surface with the mouse. While larvae are overdispersed on all three species of host, nymphs and females are overdispersed on glareolus only, and this host alone of the three maintains the instars in appropriate numbers and proportions to qualify it as an independent maintenance host. While C. glareolus could maintain the tick population, M. agrestis and A. sylvaticus could not and may even be deleterious to the tick population. Larvae have a pre-feeding diapause while attached to the host from December until February. There is no evidence that larvae are active during winter as reported by other workers. Diapause is abandoned when infested hosts are brought into the laboratory and engbrý6memt to repletion is slower on all three hosts than it is during the rest of the year. At any time of the year larvae take longer to feed on A. s1vaticus than on the voles. only 9% of field captured larvae completed development and it is proposed that the majority of engorged larvae enter a pre-developmental diapause. Similar conclusions are reached for nymphs and females. For larvae and nymphs which develop at constant temperature without manifest dispause delays the relationship between incubation temperature and developmental velocity is linear and direct, Part 2. Prevalence of Louping-ill in northern Scottish cattle., In a survey of cattle in the northern counties and inner islands of the west coast of Scotland, 4529 sera were tested for immunoglobulin G to Louping-ill, using antigen derived from Louping-ill strain 31 The incidence of antisera in herds increases from the west of the country to the east. In a stable herd structure there is a significantt steady increase in antibody with age. It is suggested, that cattle are useful indicators of Louping-ill, but their role in maintenance of the disease remains an unknown factor.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available