Molecular Detection of Rabies Lyssaviruses from Dogs in Southeastern Nigeria: Evidence of TransboundaryTransmission of Rabies in West Africa.

Ukamaka U Eze,Chika I Nwosuh,Boniface M Anene,Claude T Sabeta,Ernest C Ngoepe,Romanus C Ezeokonkwo

doi:10.3390/v12020134

Abstract

Despite being the first country to register confirmed cases of Mokola and Lagos bat lyssaviruses (two very distant lyssaviruses), knowledge gaps, particularly on the molecular epidemiology of lyssaviruses, still exist in Nigeria. A total of 278 specimens were collected from dogs in southeastern Nigeria between October 2015 and July 2016, and 23 (8.3%) of these tested positive for lyssaviruses with the direct fluorescent antibody test (DFA). The lyssaviruses were genetically characterized by amplifying the highly conserved nucleoprotein (N) gene of the rabies lyssaviruses (RABVs) of the viral genome. Phylogenetic analyses of the nucleotide sequences showed that all the RABV sequences in this study were of the Africa-2 lineage. Our results demonstrated that transboundary transmission of rabies lyssavirus is a key event, given that one of the RABV sequences (MN196576) clustered with rabies variants from neighboring Niger Republic. Furthermore, three RABVs from dogs from Anambra State clustered separately forming a novel and distinct group. Our results demonstrated that transboundary transmission of RABLVs is a key driver in the spread of rabies in West Africa. In order for the successful control of this zoonotic disease, a multinational stepwise surveillance and elimination of rabies in Africa by 2030 is probably the solution for regional elimination.

Highlights

Rabies is one of the oldest but deadliest zoonotic diseases known to man, and has a case fatality rate approaching 100% once clinical symptoms are apparent
Apart from rabies lyssaviruses (RABVs), which is mainly dog-mediated through bites and scratches, there are other lyssaviruses that were identified in the country in the late 1950s, namely Lagos bat lyssavirus (LBLV)
This study was undertaken with a view to detecting and genetically characterizing RABVs circulating among dogs in Southeastern Nigeria from the dog markets and other rabies-suspect dogs presented at the Veterinary Clinic

Summary

Introduction

Rabies is one of the oldest but deadliest zoonotic diseases known to man, and has a case fatality rate approaching 100% once clinical symptoms are apparent. The boundaries within the West African countries are porous (as in most parts of the African continent) and allow all sorts of activities such as smuggling, human, drug, and illicit arms trafficking, nomadism, and dog trading, which may promote rabies virus transmission [9,10]. The illegal trade of dogs within and across West African countries is a contributory factor to the transboundary movement of the disease, a phenomenonnot only unique to Africa [11,12,13,14,15,16,17]. In the sub-Saharan African region, three genetically distinct rabies lyssavirus lineages (Africa 1, 2, and 3) were identified, each spanning a different region [18]. A rabies lyssavirus strain in Liberia was found to cluster with other rabies viruses in the China lineage 2, confirming transcontinental transmission of the disease [20]

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