Progress towards eradication of peste des petits ruminants

Globally, the number of outbreaks of peste des petits ruminants (PPR) fell by two-thirds in recent years, raising hopes for meeting the goal of global eradication by 2030.

Just over 1,200 global PPR outbreaks were recorded in 2019 compared to more than 3,500 in 2015 according to data from the Food and Agriculture Organization of the United Nations (FAO) and partners.

The decrease in PPR outbreaks is attributed to the impact of vaccination campaigns in more than 50 countries. The campaigns were led and funded by countries with support from FAO and partners. In just 12 of these countries, over 300 million goats and sheep were vaccinated between 2015 and 2018.

Two regions have been the worst hit by PPR, and reported the majority of outbreaks between 2015-2019 – Asia (over 75%) and Africa (over 24%), although the disease may also be underreported. Nearly half of all outbreaks in this period occurred in only five countries (Benin, Afghanistan, Iran, Kuwait and Turkey), highlighting the need for strengthening prevention and control mechanisms.

More than 70 countries, mostly in Asia, Africa and Middle East, have reported PPR since it was first identified in Côte d’Ivoire in the 1940s. At its worst, the disease threatens to infect up to 80 percent of the world’s 2.5 billion small ruminants if not controlled, putting enormous pressure on some of the world’s most vulnerable people.

Although it was first considered as a rinderpest-like disease of small domestic ruminants, in the recent past, PPR has also infected camels, cattle, water buffalo and a range of wildlife species – from the African buffalo to the saiga antelope in Asia.

In 2015, the international community set the goal of eradicating PPR by 2030, and, since then, FAO and the World Organisation for Animal Health (OIE) have developed and implemented a Global PPR Control and Eradication Strategy.

As of May 2020 (latest data available), 58 countries and one region in Namibia have been recognized as free of PPR. In addition, 21 countries, which have had no new cases for five consecutive years, can prepare their documentation for validation by OIE for a PPR-free status.

To reach PPR-free status, countries go through a thorough four-stage process (assessment, control, eradication, and post-eradication) supported by FAO and OIE.

Vaccination is essential for PPR prevention and control based on experience from the successful global eradication of rinderpest in 2011 by FAO, OIE and their partners, and the availability of effective PPR vaccines.

FAO and OIE recommend that PPR vaccination should be rolled out during two successive years, followed by vaccination of newborn animals during one or two successive years.

Shortage of vaccines, livestock movement, and mostly logistical challenges in carrying out vaccinations continue to remain the main obstacles for PPR prevention and control. The cost of one vaccine dose represents around one-eighth of the cost of vaccine delivery.

While thermotolerant technology is available, none of the existing vaccines are thermotolerant, and most PPR endemic countries are in tropical or subtropical regions with limited cold-chain resources for vaccine storage and transport. Current existing vaccines also do not differentiate between infected and vaccinated animals.

The PPR vaccine stock/bank established by FAO, OIE, and other partners have improved the quality assurance and supply of vaccines. However, to achieve PPR eradication, the funding gap for vaccination campaigns and other program activities must be filled.

The first phase of the global PPR programme set a target of vaccinating 1.5 billion small ruminants by the end of 2021. As of mid-2020, around half of this target had been achieved, with the COVID-19 pandemic having significantly disrupted animal health services, including PPR vaccinations and outbreak reporting, last year. These disruptions continue in 2021.

FAO also stresses the need for prevention and control measures to be coordinated between neighbouring countries to restrict transboundary movement of disease. Strengthening surveillance and post-vaccination sero-monitoring at country level is also essential.

Article: Zhao, H., Njeumi, F., Parida, S., Benfield, C. T. O. (2021). Progress towards Eradication of Peste des Petits Ruminants through Vaccination. Viruses 13(1) 59, doi: 10.3390/v13010059

See also: FAO and PPR