Download Peste des petits ruminants - South African Veterinary Council

Peste des petits ruminants - a disease foreign to South Africa, but spreading southwards
in Africa
Dr Sunelle Strydom (BVSc)
Sub-directorate of Epidemiology, Directorate Animal Health, Department of Agriculture, Forestry
and Fisheries
Email: [email protected]
Intoduction
Peste des petits ruminants (PPR), also known as "goat plague" or Rinderpest of small ruminants,
is a highly contagious transboundary viral disease of goats, sheep and some captive wild
ruminants. This disease is of increasing importance in Africa where there is heavy reliance on
subsistence farming for food supply. During 2009 PPR outbreaks were reported in Tanzania,
leaving only one country, Mozambique, between a PPR affected country and South Africa.
There is therefore a serious risk that PPR may spread to South Africa, especially by the illegal
smuggling of small ruminants.
Clinical signs
Outbreaks tend to be associated with direct contact of immuno-naïve animals with animals from
PPR endemic areas. Transmission of the PPR virus is mainly by aerosols, but fomites may be
another means by which infection spreads. The PPR virus does, however, not survive for long
outside the host. The PPR virus is excreted in all secretions and excretions of incubating and
sick animals. Since PPR infected animals excrete the PPR virus before showing clinical signs of
the disease, it can be spread by movement of infected animals. All animals in a flock may be
affected during a PPR outbreak, with a resultant mortality rate of 20 to 90%.
The incubation period of PPR is 2 to 10 days, followed by:
 Pyrexia, depression and anorexia;
 Oculonasal discharges;
 Crusting around the nose resulting in the blocking of nostrils and respiratory distress;
 Matting together of the eyelids;
 Hyperaemic ocular and oral mucous membranes;
 Multifocal pin-point necrosis of the epithelium of the gingiva, dental pad, palate, lips, inner
aspects of the cheeks, and the upper surface of the tongue;
 Profuse salivation with a foul smell exuding from the mouths of infected animals;
 Diarrhoea characterised by faeces that are initially soft, becoming watery, foul-smelling,
containing blood streaks and pieces of sloughed necrotic gut tissue;
 Bronchopneumonia;
 The formation of small nodular skin lesions on the outside of the lips and around the muzzle
during the later stages of the disease;
 Abortions; and
 Death within 7 to 10 days or recovery after a period of convalescence.
Post mortem findings
The lesions are very similar to those that were observed in cattle affected with rinderpest (prior to
the global eradication of rinderpest during May and June 2011):
 Extensive erosions lesions, extending from the oral cavity to the retirculo-rumen junction;
 Necrotic or haemorrhagic enteritis with zebra stripes located in the colon;
 Apical pneumonia;
 Pleuritis and hydrothorax may be present; and
 Congested spleen with/without necrotic lesions.
Diagnosis
Diagnostic tests:
The diagnostic tests include viral isolation and polymerase chain reaction (PCR).
Samples from live animals:
Swabs of the conjunctival discharges and nasal- and oral mucous membranes are
recommended. Whole blood may also be collected in anticoagulant during the early stages of the
disease.
Samples at post mortem:
Aseptical collection of lymph nodes, especially the mesenteric and bronchial lymph nodes; lungs;
spleen and intestinal mucosae, from 2 to 3 animals. These samples must be chilled on ice and
transported under refrigeration.
Samples may also be collected in 10% formalin for immunofluorescence or immunochemical
testing.
Differential diagnoses
 Contagious caprine pleuropneumonia;
 Bluetongue;
 Pasteurellosis;
 Contagious ecthyma;
 Foot-and-mouth disease;
 Heartwater;
 Coccidiosis; and
 Mineral poisoning.
Conclusion
PPR is a controlled animal disease in terms of the Animal Diseases Act, 1984 (Act No 35 of
1984), and the incidence or suspected incidence of PPR must be immediately reported to
the nearest state veterinarian. PPR is frequently confused with other diseases that cause
respiratory problems and mortality in small ruminants and hence it is essential that PPR
be added to the differential diagnostic lists for these respiratory conditions, in order to
facilitate early detection and control in the event of introduction of PPR into South Africa.
References
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11. Pictures: Peter Roeder