Camel Prion Disease, Tataouine, Tunisia, 2019–2021 CDC Dispatch August 2026
Volume 32, Number 8—August 2026 Dispatch
Camel Prion Disease, Tataouine, Tunisia, 2019–2021
The Study Conclusions Suggested Citation Figures Figure 1 Figure 2 Figure 3 Tables Table Downloads Appendix RIS [TXT - 2 KB] Article Metrics Metric Details Abdelkader Amara1, Michele Angelo Di Bari1, Kéfia Elmehatli, Rosalia Bruno, Rihab Andolsi, Barbara Chiappini, Ilaria Vanni, Elena Esposito, Geraldina Riccardi, Obaid Allah Ben Abid, Stefano Marcon, Atef Malek, Boubaker Ben Smida, Haykel Kessa, Walid Chandoul, Mariem Handous, Roukaya Khorchani, Romolo Nonno, Malek Zrelli, Umberto Agrimi, Gabriele Vaccari, and Laura PirisinuComments to Author Author affiliation: Université Mannouba Tunisie, École Nationale de Médecine Vétérinaire, Sidi Thabet, Tunisia (A. Amara, R. Andolsi, A. Malek); Istituto Superiore di Sanità, Rome, Italy (M.A. Di Bari, R. Bruno, B. Chiappini, I. Vanni, E. Esposito, G. Riccardi, O.A. Ben Abid, S. Marcon, R. Nonno, U. Agrimi, G. Vaccari, L. Pirisinu); Arrondissement de Production Animale de Siliana, Siliana, Tunisia (K. Emehatli); Regional Delegation for Agricultural Development in Tataouine, Tataouine, Tunisia (B. Ben Smida); Arrondissement de Production Animale de Sousse, Sousse, Tunisia (H. Kessa); Regional Delegation for Agriculture in Medenine, Medenine, Tunisia (W. Chandoul); Institut Pasteur de Tunisie, Tunis, Tunisia (M. Handous); Direction Générale des Services Vétérinaires, Ministère de l’Agriculture, Tunisia (R. Khorchani) Ministry of Agriculture, Tunis (M. Zrelli) Suggested citation for this article
Abstract
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.
The Study 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).
Detection and characterization of the PrPres of scrapie prion protein (PrPSc) from brain tissues of dromedary camels, Tunisia, 2019–2021. A) PrPres detected using TeSeE Western blot kit (Bio-Rad Laboratories, https://www.bio-rad.com). Membrane probed with the Sha31 monoclonal antibody. Loading order (left to right): ovine scrapie control, Tunisian camel prion disease–positive cases (animal no. P81/9–65) and Tunisian camel prion disease–negative samples (animal nos. P81/64 and P81/15). All samples, except for P81/64 and P81/15, were diluted 1:4 prior to electrophoresis and loaded at 3.75 mg tissue equivalent per lane. The negative samples were loaded at 15 mg tissue equivalent per lane. Approximate molecular weights (expressed in kDa) are reported at top of blot. B) Representative Western blot analysis of different available brain regions from selected positive cases. Brain tissues analyzed using the ISS (Istituto Superiore di Sanità) discriminatory Western blot protocol. Case identifiers indicated below each blot. Corresponding brain regions labeled at the top: a, striatum; b, frontal cortex; c, prefrontal cortex; d, capsule; e, occipital cortex; f, parietal cortex; g, cerebellar peduncle; h, cerebellum; i, temporal cortex; j, basal ganglia; k, thalamus; l, hippocampus; m, midbrain; n, medulla oblongata; o, hypothalamus; p, pons; q, scrapie. All membranes probed with the 12B2 antibody, except for P81/17, which was probed with L42. Tissue equivalents loaded per lane: 2 mg for P81/9 and 0.5 mg for P81/13, P81/16, and P81/17. Molecular weights (in kDa) are indicated on the left of blot. C) Representative replica blots showing the epitope mapping analysis of PrPres from brain homogenates of positive dromedary camel cases. A preliminary assessment of dromedary PrPres reactivity with a panel of monoclonal antibodies was performed to identify suitable diagnostic tools for camel prion disease and to characterize PrPres. Within each antibody group, the antibody with the best sensitivity toward dromedary PrPSc was chosen for epitope mapping (Appendix Table 2, Figure 1). In addition, the SAF32 antibody, which targets the octarepeat region, was included to enable comparison with scrapie, in which this epitope is partially lost. The brain areas analyzed for each sample were as follows: P81/9, prefrontal cortex; P81/13, frontal cortex; P81/14, thalamus; P81/16, parietal cortex; P81/17, prefrontal cortex; P81/65, not identifiable; scrapie, medulla oblongata. A scrapie-affected sheep sample was included as control in last lane of each blot. Molecular weights (expressed in kDa) reported on the left of blot. Membranes were probed with monoclonal antibodies indicated below each blot. D) Relative proportions of diglycosylated, monoglycosylated, and unglycosylated PrPres bands in each available brain region of animal P81/13. Scrapie is shown on the right for comparison. Quantifications were performed on membrane probed with 12B2 antibody. Ctrl, control; PrPres, proteinase K-resistant core. Figure 1. Detection and characterization of the PrPres of scrapie prion protein (PrPSc) from brain tissues of dromedary camels, Tunisia, 2019–2021. A) PrPresdetected 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 (PrPSc) 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.comExternal Link) 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 PrPSc (PrPres), 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 PrPSc, we conducted in-depth analysis of the 6 positive cases to investigate PrPres 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).
PrPres 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). PrPres exhibited lower overall glycosylation levels compared with scrapie, mainly in cortical areas relative to subcortical regions (Figure 1, panel D; Appendix Figure 2). The PrPres characteristics of the cases, including the electrophoretic profile, molecular weight and glycoprofile, are consistent with those previously reported in CPrD cases in Algeria (1).
We initially performed histopathologic and immunohistochemical analyses on the medulla oblongata and cerebellum, the primary target regions for animal TSE surveillance. We subsequently extended the analyses to other areas of the brains available (Appendix Table 1).
Histopathologic and immunohistochemical analyses of medulla oblungata and cerebellum of dromedary camels, Tunisia, 2019–2021. Images show the analyses performed on medulla oblongata (A, E, C, G) and cerebellum (B, F, D, H) of 2 representative animals (P81/65 and P81/17). Hematoxylin and eosin staining of the obex (A, C) and cerebellar cortex (B, D) revealed spongiform changes in the nucleus of the solitary tract (A, arrows) and in the molecular layer of cerebellar cortex (B, arrows) of P81/65, but no such alterations were observed in P81/17 (C, D). Conversely, immunohistochemistry revealed scrapie prion protein deposition in both animals (E–H), affecting the nucleus of solitary tract (E, G) and cerebellar cortex (F and H). Brown color indicates PrPSc deposition. Brain sections from P81/17 showed partial loss of tissue integrity. Scale bars indicate 20 μm. GL, granular layer; ML, molecular layer; PC, Purkinje cells. Figure 2. Histopathologic and immunohistochemical analyses of medulla oblungata and cerebellum of dromedary camels, Tunisia, 2019–2021. Images show the analyses performed on medulla oblongata (A, E, C, G) and cerebellum (B, F,... Histopathologic examination revealed spongiform changes in only 2 animals (P81/16 and P81/65), in both obex (mainly in the dorsal vagal nucleus and the nucleus of the solitary tract) and cerebellar cortex (molecular layer), whereas we observed no lesions in the other animals (Table; Figure 2, panels A–D). Immunohistochemistry performed on the medulla oblongata and cerebellum demonstrated the presence of PrPSc in all samples except P81/15 and P81/64. In the obex, we observed intense PrPSc immunoreactivity in the dorsal vagal nucleus, the nucleus of the solitary tract (Figure 2, panels E, G), the hypoglossal and olivary nuclei, and the reticular formation. In the cerebellum, we detected extensive PrPSc immunolabeling throughout all layers of the cerebellar cortex (Figure 2, panels F, H) and in the white matter.
Histopathologic and immunohistochemical analyses of brain tissues and lymph nodes of camel prion disease–affected dromedary camels, Tunisia, 2019–2021. A) Examination of all available cerebral cortices (Appendix Table 3) showed mild spongiform changes exclusively in the temporal and occipital cortex of sample P81/16. B) Scrapie prion protein (PrPSc) immunostaining found in prefrontal cortex of sample P81/13. C) Magnification of the prefrontal cortex (dashed box in panel B) showing the involvement of the I and V–VI layers. D) Intraglial (inset) and intraneuronal PrPSc depositions observed in the thalamus in animal P81/9. E–I) PrPSc deposition patterns observed in camel prion disease–affected brain tissues: intraneuronal (E, arrows), perineuronal (F, arrows), glial associated (G, arrows), perivascular (H, arrows), punctate (I, arrows) and diffuse (I, asterisk) in the neuropil. J) Dense intra-astrocytic PrPSc deposition (arrows) observed in the medulla oblongata. K–L) PrPSc deposition, observed in primary and secondary follicles of lymph nodes, appear as a reticular network within the center of lymphoid follicles, accompanied by fine to coarse cytoplasmic granules in nonlymphoid cells. Representative immunostaining (arrows) of mandibular lymph node from animal P81/65 (K) and prescapular lymph node from animal P81/17 (L) highlights intense granular PrPSc depositions in tingible body macrophages within germinal centers. Brown indicates PrPSc deposition in brain sections; red indicates PrPSc deposition in lymph nodes. Scale bars indicate 50 µm in panels A and D, 100 µm in panel B, 250 µm in panel C, and 20 µm in panels E–L. Figure 3. Histopathologic and immunohistochemical analyses of brain tissues and lymph nodes of camel prion disease–affected dromedary camels, Tunisia, 2019–2021. A) Examination of all available cerebral cortices (AppendixTable 3) showed... We extended histopathological and IHC analyses to other brain regions available for each case (Appendix Table 3). We observed mild spongiform changes exclusively in the cortices of animal P81/16 (Figure 3, panel A) and scattered vacuoles in the basal ganglia of P81/13 and P81/14.
IHC confirmed the diagnosis established from the medulla and cerebellum, identifying the same 6 CPrD-positive animals. In the cortex, PrPSc deposition was predominantly localized to layers I, V, and VI (Figure 3, panels B, C). The basal ganglia and thalamus (Figure 3, panel D) showed marked PrPSc accumulation in gray and white matter. We identified multiple PrPSc deposition patterns, including punctate and diffuse, intraneuronal, perineuronal, stellate, and perivascular (Figure 3, panels E–I). Of note, in the medulla oblongata, we observed a dense intra-astrocytic PrPSc deposition that filled the entire cytoplasm (Figure 3, panel J). IHC revealed PrPSc deposits in the primary and secondary follicles of all available lymph nodes, with variable immunostaining intensity (Table; Figure 3, panels K, L).
We conducted sequencing analysis of the entire PrP coding sequence. The analysis revealed that the 7 dromedary camels shared the same genetic background, being homozygous for the wild-type prion protein allele (Table).
Conclusions
In this study, we report the detection of CPrD in dromedary camels in Tunisia, providing further evidence for the geographic distribution of the disease and supporting the hypothesis of its broader presence in North Africa. Analyses were concordant across methods; 6 of 8 suspected camels tested positive, confirming that standard tools (e.g., kits, WB, IHC, monoclonal antibodies) reliably detect PrPSc in CPrD and provide effective methods for diagnosis and surveillance.
The detection of PrPSc in all available lymph nodes, together with the relatively young age of some camels, supports the hypothesis that CPrD is a transmissible prion disease. As in scrapie and chronic wasting disease, lymphoid involvement may enable extraneural propagation and serve as a source of environmental contamination (2–5), raising concerns about prion shedding and persistence.
Despite the typically long incubation periods of prion diseases, several affected camels were relatively young, showing clinical signs at 3 years of age, when sexual maturity is only just reached (3–5 years). That finding might reflect early-life or high-dose exposure, given that extensive environmental contamination can shorten incubation (6,7). Similar patterns are reported in scrapie and chronic wasting disease, where vertical and early-life transmission contribute to infection in young animals (4,8–14).
The recent detection of sheep scrapie in the same area of Tunisia as CPrD (15) raises the question of possible links, although no similarities have yet been shown. Bioassays will be crucial to clarify strain relationships and whether environmental factors might facilitate cross-species transmission or adaptation.
Taken together, the data from Algeria and Tunisia suggest that CPrD may be endemic in certain areas. Despite the limited number of reported cases so far, the absence of active surveillance programs in those countries, unlike in Europe for scrapie and bovine spongiform encephalopathy (BSE), raises the possibility of a higher number of undetected cases. Given frequent cross-border movements and the extensive pastoral systems in which camels roam widely, contact between herds in Tunisia and herds in Algeria is frequent and has possible implications for disease circulation.
CPrD may substantially affect camel health and production, given that dromedaries are long-lived animals with extended reproductive and productive roles and are vital to pastoralist communities in arid regions. Its detection in areas where camels are central to food production underscores the need to understand its epidemiology, transmission, and long-term impact.
The emergence of a new animal prion disease also raises public health concerns. Although only BSE has shown zoonotic potential, its history highlights the necessity of monitoring all animal prion diseases. Long incubation and absence of early clinical markers complicate risk assessment, as exemplified by the decade-long delay between cattle BSE and the variant Creutzfeldt–Jakob disease epidemic in humans (2).
Given the potential implications for animal and human health and the possible socioeconomic impact in regions where dromedaries play a key role, ongoing surveillance and in-depth characterization of CPrD are essential to enhance our comprehension of its epidemiology, host range, and zoonotic potential.
Dr. Amara is emeritus professor of histology and pathological anatomy at the National School of Veterinary Medicine of Sidi Thabet in Sidi Thabet, Tunisia. He is also vice president of the Expert Committee on Animal Health at the National Center for Veterinary Surveillance in Tunisia. His primary research interests include prion diseases in ruminants and dromedaries.
Acknowledgments We would like to thank Baaissa Babelhadj, who first described CPrD, for providing us with the samples from the dromedaries in Algeria. This contribution was essential because it enabled a direct comparison with the cases in Tunisia included in our study.
This study was supported by the Istituto Superiore di Sanità, Independent Research Program (grant no. ISS20-97e1d82bda5a) and by the La Sapienza University of Rome and Istituto Superiore di Sanità, Italy–Africa PhD Program (grant no. 5165/2023).
References
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***> “The detection of PrPSc in all available lymph nodes, together with the relatively young age of some camels, supports the hypothesis that CPrD is a transmissible prion disease. As in scrapie and chronic wasting disease, lymphoid involvement may enable extraneural propagation and serve as a source of environmental contamination (2–5), raising concerns about prion shedding and persistence.” <***
Proceedings of the Prion 2025 - Advancing the understanding and treatment of prion diseases
ISBN: 978-65-80968-48-0
Identification of Camel Prion Disease in Tunisia: evidence of an emerging prion disease in North Africa
Amara, Abdelkader 1Bari, Michele Angelo Di 2Andolsi, Rihab 1Elmhatli, Kéfia 3Malek, Atef 1Bruno, Rosalia 4Chiappini, Barbara 5Vanni, Ilaria 6Esposito, Elena 5Riccardi, Geraldina 5Smida, Boubaker Ben 7Kessa, Haykel 8Chandoul, Walid 9Zrelli, Malek 10Abid, Obaid Allah Ben 5Marcon, Stefano 5Nonno, Romolo 5Agrimi, Umberto 5Vaccari, Gabriele 6Pirisinu, Laura 6 Vol 1, 2025 - 329818
Abstract Prion 2025
Abstract
Introduction: Camel prion disease (CPrD), a recently identified prion disease in dromedary camels from Algeria, has raised concerns regarding its potential spread in North Africa and possible implications for animal and public health.
Objectives: This study aimed to assess the presence of CPrD in Tunisia by investigating clinically suspect dromedary camels and characterizing the pathological and biochemical features of the disease.
Methods: Brain and lymph nodes from eight dromedary camels showing neurological and behavioral signs were sampled from the Tataouine and Sousse governorates. Samples were analysed by Western blot, immunohistochemistry, and histopathology techniques. PrP gene sequencing was also performed.
Results and Discussion: PrPSc accumulation was detected in six out of eight animals, with positivity confirmed in brain and, when available, lymph nodes. They showed molecular and neuropathological features closely resembling Algerian CPrD, clearly distinct from classical scrapie and BSE. All genotyped animals were homozygous for the wild-type PRNP allele. The detection of PrPSc in lymphoid organs, together with the relatively young age of some affected individuals, suggests the possibility of a contagious nature and early-life exposure.
Conclusion: This study provides the first identification of CPrD in Tunisia and underscores the importance of ongoing surveillance and the need to better understand the epidemiology, transmission dynamics, and zoonotic potential of this emerging prion disease.
Funding: This work was supported by grants: Bando Ricerca Indipendente ISS 2020-2022 (ID ISS20-97e1d82bda5a) by Istituto Superiore di Sanità; Bando “Dottorati di Ricerca Italia-Africa 2023” (DB04-id: 5165) by Università La Sapienza di Roma and Istituto Superiore di Sanità.
Identification of Camel Prion Disease in Tunisia: evidence of an emerging prion disease in North Africa
The detection of PrPSc in lymphoid organs, together with the relatively young age of some affected individuals, suggests the possibility of a contagious nature and early-life exposure.
***> USA Report, Scrapie, CWD, BSE, TSE, Cattle, Sheep, Pigs, Cervid, Humans, Zoonotic, 2026
April 2026
Tuesday, June 9, 2026
Hazard identification for the risks to terrestrial animal health from the import of hay and straw, BSE, CWD, Scrapie, TSE, Prion
Chronic wasting disease prions in cervids and wild pigs in North America Preliminary Outbreak Assessment DEFRA 26 January 2026 Department for Environment, Food and Rural Affairs
Preliminary Outbreak Assessment
Chronic wasting disease prions in cervids and wild pigs in North America
26 January 2026
Disease report
Chronic wasting disease (CWD) is a fatal neurodegenerative disease of cervids, such as deer, elk, moose and reindeer. It is caused by prions – infectious proteins that cause normal cellular prion proteins to misfold (CIDRAP, 2025). The disease is widespread in captive and free-ranging cervids in North America (Figure 1). For the first time, CWD prions have also been detected in the tissues of wild pigs (Sus scrofa) caught in CWD-affected areas of the USA (Soto et al. 2025). This discovery emerged from a study designed to investigate potential interactions between wild pigs and CWD prions, as wild pigs often coexist with cervids, which can shed prions into the environment. The following assessment discusses the epidemiology of CWD in North America and the detection of CWD prions in wild pigs. It also considers the potential implications for Great Britain.
Conclusion
CWD has continued to spread among captive and free-ranging cervids in North America since it was first detected in the 1960s. The finding of CWD prions in wild pigs in the USA suggests they could contribute towards transmission of the disease, influencing its epidemiology, geographic distribution and interspecies spread. However, further research is needed to confirm this. CWD has never been reported in Great Britain and the current risk of CWD prions being introduced into Great Britain’s wild pig or cervid population ranges from very low to negligible.
Readers are reminded to be vigilant for signs of CWD. Information on how to spot the disease can be found here. Suspected cases must be reported immediately to the Defra Rural Services Helpline on 03000 200 301. In Wales, call 0300 303 8268. In Scotland, contact your local Field Services Office. Failure to do so is an offence. We will continue to monitor the situation.
Authors • Lawrence Finn • Dr. Lauren Perrin • John Spiropoulos • Dr. Helen RobertsDepartment for Environment, Food and Rural Affairs
References
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Detection of Prions in Wild Pigs (Sus scrofa) from Areas with Reported Chronic Wasting Disease Cases, United State Volume 31, Number 1—January 2025
Chronic Wasting Disease CWD TSE Prion, Economical, Environmental, Zoonotic, Risk Factors 2026
Cervid CWD TSE PrP Transmission to Humans, has it already happened and being masked as sporadic CJD, What if? July 2026 Review
Terry S. Singeltary Sr.
