Diagnosis
A presumptive diagnosis of the acute forms of PPR can be made from the epidemiology, clinical signs, and lesions but subacute form may require laboratory diagnosis.
Samples and specimens
- For virus isolation or viral antigen detection, from live animals during early stages of fever until the beginning of the erosions, ocular or nasal swabs, scrapings of early oral lesions, blood with heparin or EDTA "buffy coat". From deceased animals portions of the spleen, lymph nodes, and lungs collected within 2 hours of death. The specimens should be chilled on ice, but not frozen, and examined as soon as possible.
- For serology collect serum from acutely ill and recovered animals.
- For histopathology slices of lymph node, spleen, tonsils, and mucosal lesions are collected in 10 % formalin saline for.
- The virus is isolated by inoculation of buffy coat, swab material, or 10% tissue suspention onto lamb or kid kidney, CPEs develops after 4 days which are indistinguishable from that of RP virus. CPEs specificity is confirmed serologically by comparative titration against antisera to homologous and heterologous antisera, the homologous titre usually being much higher than the heterologous. The isolates can be examined with cELISA based on monoclonal antibodies and specific cDNA probes.
- Specific viral antigens in 30% tissue suspentions or in undiluted swap material of suspected cases is detected by hyperimmune sera to RP or PPR viruses by AGID and counter immunoelectrophoresis "CIEP". Antigen can also be detected by immunohistochemical staining of tissues "immunoperoxidase staining" and dot-ELISA.
- In survivors, a four-fold or greater increase in neutralizing antibodies in paired serum samples confirms the presumptive diagnosis. Seroconvertion in paired serum samples is mainly used only for disease serviullance.
- Confirmation by the experimental transimission of the disease requires strict isolation facilities and can done by i.v inoculation of 5 ml blood from suspected animal at the height of the disease into susceptible goat, sheep, and cattle. PPR usually causes severe disease in goats, miler disease in sheep and subclinical infection in cattle.
Differential diagnosis
PPR should be differentiated clinically from RP, bluetongue, contagious caprine pleuropneumonia "CCPP", contagious ecthyma, foot and mouth disease, sheep and goat pox, Nairobi sheep disease, heartwater, bacterial and parasitic diarrhea, and viral and parasitic pneumonia.