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The animal will later develop foul- smelling diarrhoea, containing blood and pieces of dead gut tissue. Dyspnoea, tachypnoea and coughing may be present. Pregnant animals may abort.
The animal will later develop foul- smelling diarrhoea, containing blood and pieces of dead gut tissue. Dyspnoea, tachypnoea and coughing may be present. Pregnant animals may abort.
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== Pathology ==
The carcass is usually dehydrated, and soiled with faeces. The peri-orbital and perinasal areas are usually encrusted with muco-purulent discharges. The erosions and ulcerations in the mouth and throat are usually prominent, as is the presence of the secondary broncho-pneumonia. The underlying primary viral pneumonia may be less obvious but is manifested by areas of level red consolidation (Rowland et al., 1969). 'Zebra striping' in the colon may also be seen, and lympadenopathy.
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The most important histopathological indicator of PPRV is the presence of multi-nucleated giant cells containing intra-nuclear and intra-cytoplasmic inclusions. Multi-nucleated giant cells (syncytia) are most readily detected in the lungs, but also occur in bronchial, alveolar and ileal epithelium.
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Antibodies are strongly induced by infection, and become detectable from the diarrheic stage onwards. The prescribed test for international trade (that which is accepted as a basis for the veterinary certification of animals as having evidence of presence or absence of antibodies) is virus neutralisation (VNT; OIE, 2000). Since there is cross-neutralisation between antibodies to PPR and RPV, a positive VNT result to PPR virus needs to be compared to the titre obtained with RPV. The OIE considers that a serum is considered to be positive for PPR when the neutralisation titre is at least two-fold higher for PPR than for rinderpest. Virus neutralisation tests involve use of live virus and cell cultures, and therefore require well-equipped laboratories and biosecurity to prevent escape of virus. VNT is therefore mainly restricted to laboratories with sufficient expertise and through-put of samples to justify the investment involved. The tests are sensitive and specific, and enable differentiation of antibodies to rinderpest virus, should these occur as a result of use of RP vaccine in small ruminants or exposure to the type 1 lineage of RPV. Haemagglutination inhibition tests for antibody have also been described with good correlation with VNT (Raj et al., 2000). After countries have been declared free of rinderpest infection, it may be sufficient to use more simple antibody detection methods that do not require differentiation of RPV infection of small ruminants.
Antibodies are strongly induced by infection, and become detectable from the diarrheic stage onwards. The prescribed test for international trade (that which is accepted as a basis for the veterinary certification of animals as having evidence of presence or absence of antibodies) is virus neutralisation (VNT; OIE, 2000). Since there is cross-neutralisation between antibodies to PPR and RPV, a positive VNT result to PPR virus needs to be compared to the titre obtained with RPV. The OIE considers that a serum is considered to be positive for PPR when the neutralisation titre is at least two-fold higher for PPR than for rinderpest. Virus neutralisation tests involve use of live virus and cell cultures, and therefore require well-equipped laboratories and biosecurity to prevent escape of virus. VNT is therefore mainly restricted to laboratories with sufficient expertise and through-put of samples to justify the investment involved. The tests are sensitive and specific, and enable differentiation of antibodies to rinderpest virus, should these occur as a result of use of RP vaccine in small ruminants or exposure to the type 1 lineage of RPV. Haemagglutination inhibition tests for antibody have also been described with good correlation with VNT (Raj et al., 2000). After countries have been declared free of rinderpest infection, it may be sufficient to use more simple antibody detection methods that do not require differentiation of RPV infection of small ruminants.
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