TSE Monitoring in Wildlife Epidemiology, Transmission, Diagnosis, Genetics and Control

Abstract

Among the transmissible spongiform encephalopathies (TSEs), chronic wasting disease (CWD) in cervids is now the rising concern within Europe. CWD will be outlined in this chapter gathering its epidemiology, transmission, diagnosis, genetics, and control. Prion diseases are fatal neurodegenerative diseases characterized by the accumulation of an abnormal isoform of the prion protein (PrP c), usually designated by PrP sc or prion. CWD is a prion disease of natural transmission affecting cervids detected mainly in North America. The first European case was detected in Norway, in 2016, in a wild reindeer; until April 2018, a total of 23 cases were described. The definite diagnosis is postmortem, performed in target areas of the brain and lymph nodes. Samples are first screened using a rapid test and, if positive, confirmed by immunohistochemistry and Western immunoblotting. It is not possible to establish a culling plan based on the genotype, once affected animals appear with all genotypes. However, some polymorphisms seem to result in longer incubation periods or confer a reduced risk. The control is not easy in captive cervids and even more in the wildlife; some recommendations have been proposed in order to understand the danger and impact of CWD on animal and public health.

Wildlife Population Monitoring

“…In captive cervids the prevalence is higher and may reach 79% or more of affected animals on the herd. In young animals, this number could be even higher [66,97]. The annual incidence may be higher than 50% in white-tailed deer and mule deer [95].…”

“…Wild-type inbred strains of mice (e.g., RIII, C57BL, and VM) were important for the identification and characterization of different types of scrapie prions [126][127][128][129][130][131], but CWD transmission to wild-type mice presented only few results [29]. In order to optimize time and resources as well as the results obtained, when performing studies of scrapie prions, transgenic (Tg) mice for ovine or cervid prion protein gene were developed [115,117,118,[132][133][134].…”

Estimating sequence diversity of prion protein gene (PRNP) in Portuguese populations of two cervid species: red deer and fallow deer

“…Prions can convert PrP C into PrP sc , leading to accumulation of aggregated PrP sc in the central nervous system and ultimately causing the animal's death [1]. TSEs can affect several mammalians species including Humans [2] but show a predominance in ruminants: scrapie in sheep and goats [3] bovine spongiform encephalopathy (BSE) in bovids [4] and chronic wasting disease (CWD) in cervids [5].…”