The use of a Psoroptes ovis serodiagnostic test for the analysis of a natural outbreak of sheep scab

Particle and Fibre Toxicology

John F Huntley²  Alasdair J Nisbet²  Fiona Kenyon²  David Frew²  Francesca Nunn²  Giles Innocent¹  Stewart TG Burgess² 

[1] Biomathematics & Statistics Scotland, JCMB, King's Buildings, Edinburgh, EH9 3JZ. Scotland. UK;Moredun Research Institute, Pentlands Science Park, Bush Loan, Edinburgh. Midlothian. EH26 0PZ. Scotland. UK

关键词: Sheep scab;    Psoroptes ovis;    ELISA;    Diagnostic;    Ectoparasite;   

Others  :  1233657
DOI  :  10.1186/1756-3305-5-7

 received in 2011-09-15, accepted in 2012-01-10,  发布年份 2012

【 摘 要 】

Background

Sheep scab is a highly contagious disease of sheep caused by the ectoparasitic mite Psoroptes ovis. The disease is endemic in the UK and has significant economic impact through its effects on performance and welfare. Diagnosis of sheep scab is achieved through observation of clinical signs e.g. itching, pruritis and wool loss and ultimately through the detection of mites in skin scrapings. Early stages of infestation are often difficult to diagnose and sub-clinical animals can be a major factor in disease spread. The development of a diagnostic assay would enable farmers and veterinarians to detect disease at an early stage, reducing the risk of developing clinical disease and limiting spread.

Methods

Serum samples were obtained from an outbreak of sheep scab within an experimental flock (n = 480 (3 samples each from 160 sheep)) allowing the assessment, by ELISA of sheep scab specific antibody prior to infestation, mid-outbreak (combined with clinical assessment) and post-treatment.

Results

Analysis of pre-infestation samples demonstrated low levels of potential false positives (3.8%). Of the 27 animals with clinical or behavioural signs of disease 25 tested positive at the mid-outbreak sampling period, however, the remaining 2 sheep tested positive at the subsequent sampling period. Clinical assessment revealed the absence of clinical or behavioural signs of disease in 132 sheep, whilst analysis of mid-outbreak samples showed that 105 of these clinically negative animals were serologically positive, representing potential sub-clinical infestations.

Conclusions

This study demonstrates that this ELISA test can effectively diagnose sheep scab in a natural outbreak of disease, and more importantly, highlights its ability to detect sub-clinically infested animals. This ELISA, employing a single recombinant antigen, represents a major step forward in the diagnosis of sheep scab and may prove to be critical in any future control program.

【 授权许可】

   
2012 Burgess et al; licensee BioMed Central Ltd.

【 图 表 】

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