Peste des petits ruminants experimental infection in adult goats

Peste des petits ruminants (PPR) is a contagious viral disease of small ruminant, causing significant economic losses with high mortality especially in young population, more in goat than in sheep. Adult animals are considered more resistant to express clinical signs of the disease, probably because of previous contact with the virus or vaccination. If there is resistance, adult animals can be vectors for young which are the main victims. It is not known if the disease is introduced into a naïve country and how the virus will behave in young and adult populations in terms of morbidity and mortality. Some authors claim that vaccination may last for 3 years but no one does the challenge test to determine the duration of immunity in animals. Hence, studies on the disease pathogeny focused only on young animals from highly sensitive breeds. These considerations prompted us to carry out this study, and PPR pathogenesis was evaluated by experimental infection of local North Africa adult goats, comparatively to alpine goats. Evaluation was based on expressed symptoms and lesions in addition to virus secretion and serology. The experiment showed that adult alpine goats are almost as sensitive as young, expressing typical signs of the disease that may conduct to mortality. Young local goats also showed respiratory symptoms followed by diarrhea while adult local goats express mild respiratory signs but allowing virus secretion and diffusion. This finding is important to take in consideration for the disease surveillance and eradication strategy.