Studies on louping-ill virus (Flavivirus group) in wild red grouse (Lagopus lagopus scoticus)

Abstract

SUMMARYStudies were made to find evidence of louping-ill virus infection in free-living red grouse and relate this to their breeding success. In areas where ticks were abundant 61 (84 %) adult grouse had antibody to the virus compared with 1 (10 %) in areas where ticks were relatively scarce. Of 162 chicks tested 25 were shown to be viraemic. Infected chicks were of significantly less weight than comparably aged uninfected birds and the probability that they died was much greater than that of uninfected birds. It is concluded that the relatively poor breeding success in areas of high tick numbers was principally due to infection with louping-ill virus.

Antigenic Variation among Members of the Tick-borne Encephalitis Complex

“…In addition, the disease is now established in southern areas of Germany and has been reported in virtually every European country. Although no cases of TBE have been reported in the U.K., a similar animal disease has been prevalent there for several years and isolates have been obtained from several wild and domestic animals and birds (Reid et al, 1978;Bannatyne et al, 1980). The TBE group of viruses, in common with other flaviviruses, appears to contain a major envelope glycoprotein (E) on which reside the biological properties associated with the virion particle (Heinz et al, 1981).…”

Investigating the loss of recruitment potential in red grouse (Lagopus lagopus scoticus): the relative importance of hen mortality, food supply, tick infestation and louping-ill

“…Prevalence in sheep with grouse present can vary between 16 and 45.6 % (Gilbert et al 2000) and on grouse chicks in Scotland between 0 and 36 % (Reid et al 1978). The effect of acaricide treatment on LIV is difficult to determine in this study because LIV prevalence in grouse chicks was only 3 % (2/67) on moor 1 and zero on moor 2 (Moseley et al 2007).…”

“…Samples were centrifuged and the plasma separated and frozen within 6 h of collection before being transported to the Moredun Research Institute and stored at −70°C. Plasma was used to determine seroprevalence for louping-ill virus using a haemagglutination-inhibiting antibody (HIA) test to detect antibodies to LIV in chicks and hens (Reid et al 1978). Where sufficient sample remained (n = 67), a real-time reverse transcriptase PCR test (Marriott et al 2006;Moseley et al 2007) was conducted to detect the LIV virus directly.…”

“…Tick transmitted LIV can be a major cause of mortality for sheep and red grouse (Reid 1975;Reid et al 1978). Prevalence in sheep with grouse present can vary between 16 and 45.6 % (Gilbert et al 2000) and on grouse chicks in Scotland between 0 and 36 % (Reid et al 1978).…”

“…Clinical signs of this disease were present about 5 days post infection (Buxton and Reid 1975), and it has been shown to cause up to 78 % mortality in birds inoculated with the virus in the laboratory (Reid 1975) with high mortality indicated in the wild (Reid et al 1978). In Scottish uplands, tick infestations of red grouse chicks (aged 1-40 days) increased between 1985 and 2003 from an average of 2.6-12.71 ticks per chick (Kirby et al 2004).…”