Current factors behind the spread
Over the past few years, the key factors behind the speed of the geographic spread of the disease are related to:
the growing world population of small ruminants,
the uncontrolled migration of people accompanied by their small livestock,
Their flight from socio-political insecurity (massive displacement of refugees to escape armed conflict), economic insecurity (rural exodus to escape poverty), and climate insecurity (recurrent drought, catastrophic flooding) increases the risk of PPR spreading to disease-free regions and countries.
and the mobility of animals due to livestock practices and trade.
The movement of animals over long distances and beyond national frontiers dictated by traditional pastoral and transhumance livestock practices facilitates encounters between healthy and infected animals and contributes to the spread of the virus.
Fundamental :
However, the primary factor behind the spread of PPR is the intensification of animal movements to meet an increasing demand for animal protein.
The demographic and economic development of mega-cities and consequent increase in demand for meat induce the ever increasing trade of live animals, which are moved from rural production areas to urban consumption zones. Trade flows are particularly important during religious holiday periods in Islamic countries. Small ruminants often cross borders, sometimes illegally, without undergoing any health controls.
Depending on the epidemiological status of the country of origin, which most often is enzootic, the risk of the South-South spread of PPR through the introduction of infected animals must be considered from both a health and economic perspective even if small ruminants do not have an impact on international markets in the same way as cattle.
An understanding of the spread of PPR is required to develop effective epidemiological surveillance and control strategies. Sound knowledge of animal mobility networks (trade networks and migration routes) on local, national, regional and inter-regional levels, along with molecular epidemiological data obtained through phylogenetic analyses of different PPRV lineage strains, are required.
