 Their mobility is often  source of conflict with farmers of the crossed areas , and engender the spread of diseases such as Rift Valley Fever.
<fluency>  Their mobility is often  source of conflict with farmers of the crossed areas , and engender the spread of diseases such as Rift Valley Fever.
 Their mobility is often a source of conflict with farmers of the crossed areas , and engender the spread of diseases such as Rift Valley Fever.