Clinical findings in two cases of atypical scrapie in sheep: a case report

Abstract

Background: Atypical scrapie is a recently recognised form of transmissible spongiform encephalopathy of sheep that differs from classical scrapie in its neuropathological and biochemical features. Most cases are detected in apparently healthy sheep and information on the clinical presentation is limited.

Atypical/Nor98 scrapie: properties of the agent, genetics, and epidemiology

“…When the same isolates are deglycosylated with PNGase before Western blot analysis, the profile shows three bands referred to as bands A, B, and C migrating at around 23, 18, and 11 kDa. This contrasts with the pattern observed in the classical isolate where the three band pattern (27,23, and 19 kDa respectively) is transformed into a mono-band migrating at around 19 kDa after deglycosylation.…”

“…In a German comparison of the epidemiology of classical scrapie and atypical scrapie, secondary cases were detected in seven flocks, two of these flocks had more than 500 animals and five of the flocks had more than 1 500 animals, but it is not clear how many animals were actually examined in these flocks, in the same study only single cases were detected in 81 of the flocks [27]. Two cases were reported from a flock with 650 sheep in the UK [23]. There is also one report on two cases detected in a small Irish flock [32].…”

“…The case in the Falkland Islands displayed poor body condition and an abnormal behaviour with persistent biting at its leg and had shown collapsing episodes when it tried to run [14]. The two cases reported in the UK [23] were also ataxic and showed delayed repositioning of the hind limbs. It was noted that both displayed signs suggestive of a cerebellar disease but the signs were not identical (hypermetria in the first case, ataxia, fine head tremor, and abnormal menace response in the second case).…”

“…When cases are detected through active surveillance the data available on clinical signs, or absence of such, is many times restricted to what might have been observed by the farmer. There are a limited number of cases described to be detected through clinical suspicion where, more detailed information from veterinary clinical examinations is available [23].…”

“…Pruritus has not been reported in the atypical/Nor98 scrapie cases, but one of the cases detected on clinical suspicion in the UK showed a positive scratch response [23].…”