Role of Wild Small Ruminants in the Epidemiology of Peste Des Petits Ruminants

Abstract

Peste des petits ruminants virus (PPRV) causes one of the most contagious and highly infectious respiratory diseases in sheep and goats known as peste des petits ruminants (PPR). Reports of outbreaks of PPR in captive and wild small ruminants have extended the known spectrum of susceptible species to include antelopes. Phylogenetic analysis of nucleoprotein and fusion genes indicates that all PPRVs isolated from wild ungulate outbreaks belong to lineage IV. While it is clear that a number of wildlife species are susceptible to infection, the role of wildlife in the epidemiology of PPR remains uncertain. The available information about the occurrence of disease in free-ranging wildlife is mainly derived from surveys based on serological evidence. Data on the genetic nature of circulating PPRV strains are scarce. Given the scope of PPR in wild ungulates that are widespread in many countries, current disease surveillance efforts are inadequate and warrant additional investment. This is crucial because domestic and wild ruminants mingle together at several points, allowing inter-species transmission of PPRV. There is no reason to believe that PPRV circulates in wild animals and acts as a potential source of virus for domestic species. Irrespective of the possibility of wild small ruminants as the reservoir of PPRV, concerns about the role of susceptible species of antelopes need to be addressed, due to the fact that the disease can pose a serious threat to the survival of endangered species of wild ruminants on the one hand and could act as a constraint to the global eradication of PPR on the other hand. In this review, knowledge gained through research or surveillance on the sustainability of PPRV in wild ruminants is discussed.

Seroprevalence and risk factors for peste des petits ruminants and selected differential diagnosis in sheep and goats in Tanzania

“…Although it is probable that PPR transmits between domestic and wild animals [32,69,70], our results do not support the hypothesis of wildlife as an important risk factor for exposure for domestic animals in an endemic setting. For the closely related rinderpest virus, the well-accepted hypothesis was that infection in wildlife was not self-sustaining, but rather a case of spillover from domestic animals [71,72]. The same hypothesis has been suggested for PPRV [32,73], and our results seem to be in agreement with this.…”

Future research to underpin successful peste des petits ruminants virus (PPRV) eradication

“…Infection of wild sheep/goats [28][29][30] and other wild and domestic ruminants (cattle, buffalo, gazelle and wildebeest) have been reported [31][32][33][34], as well as camels [35] and recently even dogs [36]. If confirmed and shown to be relevant from a transmission perspective, such observations would be very important due to the continued existence of transhumance and pastoralism amongst sheep and goat herders.…”

The Opportunity To Eradicate Peste des Petits Ruminants

“…The number of possible outbreaks recorded is low and there is no evidence of persistence in camel populations to date. PPR infection and disease have been confirmed in a number of wild artiodactyl species (12). Available evidence indicates that PPR does not persist in wildlife populations and that exposure to infected sheep and goats precedes outbreaks in wildlife (as demonstrated with RP) (13).…”

“…No clinical disease has been recorded in wildlife in Africa. Wildlife populations have not been noted to sustain infection or act as a source of infection for domestic animals (14). It is of course scientifically impossible to prove an absolute negative.…”