Peste des Petits Ruminants

Abstract

Bluetongue virus (BTV) continues to surprise the scientific community and requires constant adaptation of previous assumed knowledge. This chapter deals with various aspects of the biology and potential control of BTV infection with particular reference to evolving trends in vaccines and vaccination strategies that might be used to control this economically important disease. Bluetongue vaccines are divided into nonreplicating and replicating vaccines. Inactivated, whole-virus and live attenuated virus vaccines are the only nonreplicating and replicating BT vaccines available in the market. Following infection with BTV, antibodies against all structural and nonstructural viral proteins can be detected in the serum of ruminants. Neutralizing antibodies are the immune correlate believed to protect previously infected animals against reinfection with a BTV strain of the homologous serotype. The basis of protective immunity of livestock to BTV infection is increasingly defined, including the protective immunogens of BTV. Peste des petits ruminants (PPR) is a highly contagious viral disease of small ruminants. It is caused by a virus, the peste des petits ruminants virus (PPRV) that belongs to the genus Morbillivirus within the family Paramyxoviridae. The main characteristic of the pathogenesis of PPRV infection, as for all other morbilliviruses, is the profound but transient immunosuppression induced by the virus in its host with the consequence of increased susceptibility to opportunistic infections and increased mortality. To assess the results of a vaccination campaign, the PPR-GCES includes a postvaccination evaluation (PVE) tool. This is a guide, based on performance indicators, describing methods to assess the immunity of small ruminant populations and to measure changes in the level of PPR outbreaks and/or small ruminant productivity. The success of a vaccination program depends upon many factors such as: the vaccine quality, the effectiveness of the vaccine delivery system, and the targeted population coverage.