In the event cases are observed that meet the SE Outbreak Definition, samples should be collected from all affected animals for laboratory diagnosis. Recent, acute cases are the best subjects for virus isolation, antigen detection, or RT-PCR.
Live affected animals:
· ocular and nasal swabs (essential)If available, perform a Clearview tests on site. Be sure to conserve sufficient swab sample for confirmatory tests such as RT-PCR, immunocapture ELISA or AGID.
· scrapings of oral lesions
· prescapular lymph node aspirates (optional)
Herd or in contact animals:
· serumSacrificed or deceased animals:
· 10 gm samples of fresh spleen, mesenteric lymph node and tonsil eyelids in formalinComments:
· 10 gm blocks of spleen, lymph node and tonsil in formalin and ethanol
For most viral diseases, pathogens are most easily detected in the acute phase just at the onset of symptoms. This is particularly true for rinderpest and every effort should be made to sample animals in the phase after the onset of fever and before the onset of diarrhoea. Usually, tearing and oral erosions appear during this 48 hour period. Thus, the herder can be asked to point out animals that just started tearing within the last 24 hours but have not started to show signs diarrhoea, if diarrhoea is a feature of the outbreak.
If the SE outbreak is not associated with mortality, sampling will have to focus on ocular and nasal swabs, scrapings of oral lesions and seum. Lymph node aspirates can also be collected, but offer no particular advantage over good ocular swabs. If a high index of suspicion exists that the SE outbreak is rinderpest, the appraisal team can request the herders to sacrifice an animal or offer to buy a sick animal for post mortem. However, even full payment may be refused.
As a general rule, serum should be collected from the entire herd.
In the event that moribund cases or recently deceased cattle are present, an autopsy should be completed and tissue samples should be collected. Fresh and formalin fixed tissues should be collected. Definitive diagnosis can be made on tissue samples collected in formal using simple immunohistochemical techniques. Samples collected up to 24 or 48 hours post mortem are diagnostic. Eyelids have been shown to be the most useful sample for immunohistochemistry and are also easy to collect (Brown among others, 1996).