Peste des petits ruminants - an emerging plague?

Rinderpest, arguably the most feared livestock disease of previous decades, is currently a reality to farmers in a few isolated areas only. But perhaps more worrying for farmers in many parts of Asia and Africa, is the reality of another highly contagious viral disease - peste des petits ruminants (PPR), which affects goats and sheep, gives similar signs to rinderpest and is becoming more widespread. Rinderpest now remains a persistent plague in only a few small areas and, with international commitment, could soon be eliminated completely. And, with the breadth of experience that has accumulated through the eradication efforts of this major disease, it is possible that eventually PPR may also be brought to its knees.

From rinderpest to PPR

credit: Peter Roeder, FAO

Specific recognition of PPR has proved difficult in many countries, especially when the disease is first introduced. It is characterized by a sudden decline in the animal, fever, discharges from the eyes and nose, sores in the mouth, laboured breathing, diarrhoea and death. It is important to discriminate between PPR and rinderpest, because rinderpest has sometimes also been recognised to affect sheep in the Indian subcontinent with signs similar to PPR. Peste des petits ruminants is an important disease in its own right but correct identification is essential particularly as any outbreak of rinderpest, at this stage of the eradication programme, represents an international emergency.

PPR was once thought to be only an African problem: it has not been recognized in southern Africa, nor in most of northern Africa, but infection has been identified in many of the African countries between these regions where it has been, and continues to be, a serious problem. It is also present in much of the Middle East but it is in Pakistan, Afghanistan, Nepal, Bhutan, Bangladesh and India that it is currently causing alarming losses and there is a grave risk that it could spread into the central Asian countries.

"It's becoming very clear that if you are undertaking any development of livestock production involving small ruminants in Asia and much of Africa, that PPR has be taken extremely seriously. Livestock have to be protected against it," states Peter Roeder, Animal Health Officer responsible for viral diseases at FAO and the Secretary of the Global Rinderpest Eradication Programme. This is particularly the experience of Bangladesh where PPR is currently jeopardizing a goat development project, which had been very successful. Development projects based on sheep in Afghanistan and Jordan have also been seriously affected.

Positive progress

Unfortunately, unlike the situation with rinderpest, coordinated eradication of PPR is not a likely prospect in the immediate future but progressive control of the disease is possible. Vaccination, combined with common-sense actions such as safeguarding flocks and herds against inadvertent introduction of the disease, are able to provide good control, particularly as a vaccine is available to provide life-long immunity. The turnover rate of small ruminant populations is, however, much faster than that of larger livestock, which means that vaccination has to be used more intensively and more frequently. But, if this can be achieved within a programme of progressive control, losses could be minimized and certain areas should be able to be freed from PPR. In the meantime, further support is to be provided by FAO to help authorities understand PPR and to be able to differentiate it from a variety of diseases that cause similar respiratory problems and mortality of small ruminants, including pneumonic pasteurellosis and contagious caprine pleuropneumonia (CCPP).

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