Trans-border Transmission of Rabies Between South Africa, Zimbabwe and Mozambique Resulted in the Re-emergence of Rabies in Northern South Africa

Abstract

Despite the effectiveness and the availability of vaccines for animal and human use, the largely populated rural areas of South Africa are still haunted by rabies. In these areas the dog is the main vector species transmitting rabies to humans. In one such rural area, the Limpopo province in northern South Africa, canine rabies has been under control for the past two decades. However, in 2005 an unexpected and drastic increase of dog rabies cases in this area was observed. Laboratory confirmed cases increased from 5 cases in 2004 to 35 cases in 2005 and 100 cases in 2006 and this increase was paralleled by human rabies outbreak during 2005/2006. In order to determine the origin of this outbreak, a panel of 60 rabies viruses obtained from South Africa, Zimbabwe and Mozambique were genetically characterised by sequencing an 850 bp amplicon spanning the cytoplasmic domain of the glycoprotein gene and the non-coding G-L intergenic region of each of these viruses. Through phylogenetic analysis of the nucleotide sequence data, it was demonstrated that the virus variant associated with the recent outbreak in Limpopo was genetically related to rabies viruses from southern Zimbabwe indicating that this lineage could have been introduced from Zimbabwe. Furthermore the results showed that common rabies cycles exist among South Africa, Zimbabwe and Mozambique highlighting the transboundary transmission of rabies in southern Africa. The porous nature of the African borders enables translocation of infected animals across national borders. The re-emergence of dog rabies in Limpopo highlighted the importance of continuous and sustained animal vaccination programs and further underlined the importance of multinational collaboration in the control of animal movement across national borders.