Development of marker vaccines, companion diagnostic tests and improvement of epidemiological knowledge to facilitate control of rinderpest and peste des petits ruminants viruses

RP is extremely contagious and probably the most-lethal disease of cattle and buffalo with a case-fatality rate of up to 90% (21). All species of the Order Artiodactyla are affected although cattle, buffalo and large wild ruminants are the most sensitive. Due to the severity of the disease economic losses can be catastrophic and this endangers food security and the livelihoods of thousands of farmers. As a consequence there is an ongoing campaign to achieve global eradication of the disease. The control of RP has a long history with many international collaborative interventions and these have succeeded in making important advances towards RP eradication from the world (report of the GREP Consultant meeting, 2002). The current RP eradication campaign is mainly funded by the EU with logistical support provided by the FAO and OIE. In Africa, considerable efforts were made by the Pan African Rinderpest Campaign (PARC) which ended in 1999. Owing to its success, it was followed up by continuing surveillance activities under the same authority within the Pan African Programme for the Control of Epizooties (PACE). As a consequence of these international efforts RPV has been brought close to extinction, with only limited foci remaining in Eastern Africa centred in the Somali ecosystem. Global eradication of RP is achievable in the foreseeable future if these efforts are continued and the year 2010 is the date targeted by GREP to declare the world free from RP. To meet this objective, the OIE exhorted all countries concerned to adopt a time-bound programme leading to verification of RP eradication. This has become known as the OIE Pathway to "Freedom from Rinderpest". The final step requires that no antibody to RPV should be detected in susceptible animals following at least two years of intensive surveillance. The rationale behind this international rule is the inability, when using the current vaccine, to differentiate by serological tests vaccinated animals from those infected with wild type viruses. However, should there be a localised outbreak of the disease due to the re-introduction of RP virus, an emergency vaccination campaign in cattle and buffalo in the previously free zone would be required. This could be more easily managed if marker vaccines were available. PPR is the other major Morbillivirus disease of livestock in Africa. It is highly transmissible and affects mainly sheep and goats. As our knowledge of the epidemiology of PPR improves it is apparent that the disease is not limited to West Africa where it was first described and its presence has now been recognised in many of the sub-Saharan countries, from the Atlantic Ocean to the Red Sea. It is also present in most countries of the Middle East and South and West Asia, including Turkey from where it constitutes a high risk for Europe. Due to the severe economic impact of PPR on small ruminant production, many countries have started to control the disease by vaccination using the homologous live attenuated vaccine developed under two previous EU funded projects (7, see annex, A2, A3). This live vaccine has progressively replaced the use of the RP vaccine for the control of PPR in small ruminants. This important shift allows countries free of RP to ban the use of RP vaccine, while still maintaining the ability to carry out PPR vaccination, and thus fulfil the OIE requirements for RP-free status.