A-Z Index × Submit A-Z Index × Submit A-Z Index Search Dropdown × Submit Facebook Twitter LinkedIn Syndicate Emerging Infectious Disease journal ISSN: 1080-6059 Disclaimer: Early release articles are not considered as final versions. Any changes will be reflected in the online version in the month the article is officially released.
We report 6 cases of camel prion disease in dromedaries in Tunisia, confirming widespread occurrence in North Africa. Affected animals showed neurologic signs and scrape prion protein accumulation in brain and lymphoid tissues. These findings highlight the importance of active surveillance and investigation of the epidemiology, transmission, and public health implications.
In 2018, a novel animal prion disease was identified in Algeria, termed camel prion disease (CPrD), affecting a previously unreported host species, the dromedary camel ( Camelus dromedarius ) ( 1 ). After identification of CPrD in Algeria, an epidemiologic surveillance network was set up in Tunisia to monitor neurologic diseases in dromedaries. We describe results of investigations of suspected cases and report the detection of 6 CPrD cases.
Tunisia hosts ≈57,000 dromedaries, 75% of them in the south. Accordingly, investigations focused on Tataouine, the southernmost governorate. Over 3 years, we identified 8 dromedary camels showing neurologic and behavioral signs consistent with CPrD ( 1 ), raising suspicion of prion disease ( Table ).
Figure 1 . Detection and characterization of the PrP res of scrapie prion protein (PrP Sc ) from brain tissues of dromedary camels, Tunisia, 2019–2021. A) PrP res detected using TeSeE Western...
In addition to a histopathologic examination for spongiform changes, we examined all brains for the presence of the scrapie isoform of prion protein (PrP Sc ) by using Western blot (WB) and immunohistochemistry (IHC) ( Appendix ). We performed WB analyses by using the TeSeE western blot kit (Bio-Rad Laboratories, https://www.bio-rad.com ) and the ISS (Istituto Superiore di Sanità) discriminatory WB method, validated for the animal prion diseases surveillance in Europe. Six animals tested positive, revealing the presence of the pathognomonic protease-resistant PrP Sc (PrP res ), characterized by the classical 3-band pattern in the 18–30 kDa range, in all available brain regions ( Appendix Table 1), providing evidence of the involvement of several brain areas ( Table ; Figure 1 , panels A, B). Conversely, 2 animals tested negative.
After confirmation of PrP Sc , we conducted in-depth analysis of the 6 positive cases to investigate PrP res features, including protease cleavage site, presence of additional fragments, and glycosylation pattern. We treated samples with high concentrations of proteinase K to clearly define the cleavage site and probed them with a panel of monoclonal antibodies spanning the PrP sequence ( Appendix Table 2, Figure 1).
PrP res from dromedary isolates displayed a higher apparent molecular weight of the unglycosylated band than the scrapie control, and we detected no additional C-terminal or internal fragments ( Figure 1 , panel C; Appendix Figure 1). PrP res exhibited lower overall glycosylation levels compared with scrapie, mainly in cortical areas relative to subcortical regions ( Figure 1 , panel D; Appendix Figure 2). The PrP res characteristics of the cases, including the electrophoretic profile, molecular weight and glycoprofile, are consistent with those previously reported in C...