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Clinical Examination Protocol to Detect Atypical and Classical Scrapie in Sheep
Published on: January 19, 2014
Microscopic and PCR findings in sheep after experimental infection with Ehrlichia phagocytophila
García-Pérez1, Mandaluniz, Barral
1Instituto Vasco de Investigación y Desarrollo Agrario (NEIKER). Berreaga 1. 48160 (Bizkaia), Derio, Spain
Abstract:
Methods available for the diagnosis of Ehrlichia phagocytophila infection are limited and of low sensitivity. Since polymerase chain reaction (PCR) is a highly sensitive and specific method for the detection of infectious agents in animals, it was considered useful to develop a PCR method specific for this agent. An experimental protocol in which blood from 10 different flocks was inoculated into 10 naive 1 month-old lambs was carried out. Progress of the infection was monitored during 3 weeks by daily rectal temperature and blood samples. Eight lambs showed hyperthermia, presence of E. phagocytophila in blood, and lower growth rate while the other two never showed the agent in their blood or any clinical signs. This experimental infection, essentially designed to provide infected samples, also showed that flocks from areas previously thought to be free of E. phagocytophila were actually infected. PCR on blood samples allowed detection of the infection earlier than in case of microscopic examination. This was related to an increased sensitivity (87-91%). PCR yielded positive results on samples with as few as 1.08 infected neutrophils/µl (about 0.1%).
Insights
A new polymerase chain reaction (PCR) test offers a highly sensitive method for detecting Ehrlichia phagocytophila infection in animals. This advanced diagnostic tool improves upon existing methods, enabling earlier and more accurate identification of the pathogen.
Area of Science:
- Veterinary Microbiology
- Infectious Diseases
- Molecular Diagnostics
Background:
- Current diagnostic methods for Ehrlichia phagocytophila infection lack sensitivity and specificity.
- There is a need for improved diagnostic tools to accurately detect this important animal pathogen.
Purpose of the Study:
- To develop and evaluate a highly sensitive and specific polymerase chain reaction (PCR) method for the detection of Ehrlichia phagocytophila.
- To compare the efficacy of PCR with traditional diagnostic techniques.
Main Methods:
- An experimental infection model was established using lambs inoculated with E. phagocytophila.
- Blood samples were collected regularly and analyzed using both microscopic examination and the newly developed PCR assay.
- Clinical signs, including rectal temperature and growth rate, were monitored throughout the study.
Main Results:
- The PCR method demonstrated significantly higher sensitivity (87-91%) compared to microscopic examination, allowing for earlier detection of infection.
- PCR successfully identified E. phagocytophila in blood samples with as few as 1.08 infected neutrophils/µl.
- The experimental infection confirmed the presence of E. phagocytophila in flocks previously considered free of the agent.
Conclusions:
- The developed PCR assay is a sensitive and specific tool for the early diagnosis of Ehrlichia phagocytophila infection in animals.
- This molecular diagnostic approach offers a substantial improvement over conventional methods, aiding in disease surveillance and management.
- The study highlights the utility of PCR in identifying infections in areas not previously recognized as endemic.
