Factors influencing canine rabies vaccination among dog-owning households in Nigeria

Rabies perpetuates in Nigeria despite initiatives like the Regional Disease Surveillance System Enhancement Project, with evidence indicating suboptimal canine vaccination rates as a contributing factor. To inform effective planning of mass dog vaccination campaigns, it is crucial to understand the factors associated with variation in canine vaccination rates. We conducted a cross-sectional study in 2022 to understand factors associated with canine vaccination. We used stratified random sampling of the streets and dog-owning households to survey 4162 households from three states and the Federal Capital Territory (FCT). We then built a joint probabilistic model to understand factors associated with dog vaccination and non-vaccination. First, we modelled rabies knowledge as a latent variable indirectly measured with several targeted survey questions. This method allowed a respondent's unobserved understanding of rabies to be estimated using their responses to a collection of survey questions that targeted different aspects of rabies epidemiology and took various possible response distributions (i.e., ordinal, categorical, binary). Second, we modelled factors influencing pet owners' decisions to vaccinate their dogs against rabies and barriers to dog vaccination among dog owners whose dogs were not vaccinated against rabies. Posterior distributions revealed that the probability of dog vaccination was positively associated with the owner's latent knowledge of rabies, civil servant service employment, residence in the FCT, ownership of a single dog, providing care to dogs, and a preference for contemporary treatment following a dog bite. Conversely, non-vaccination was positively associated with private employment, residing in Anambra and Enugu states, owning multiple dogs, allowing dogs to search for leftovers, and a preference for traditional treatment after a dog bite. Cost was the primary barrier against vaccination for dog owners in Anambra and Enugu, while mistrust posed a major challenge for those in the FCT. Owners in areas with veterinary establishments cited cost as a barrier, while those without a veterinary establishment cited access as the primary barrier. Our study underscores the need to enhance rabies knowledge, tailor vaccination campaigns to specific demographics, address financial and access barriers, and combat hesitancy to improve rabies vaccination rates in Nigeria

Detection of Some Lyssaviruses from Fruigivorous and Insectivorous Bats in Nigeria

We report the first evidence of Shimoni bat virus (SHBV) and the detection of Lagos bat virus (LBV)and Mokola virus (MOKV) in bats from Nigeria. In total, 356 bats representing 7 genera and 8 species, collected in 8 locations of northern Nigeria. None of the 356 bat brains screened by direct fluorescent antibody (DFAT) test were positive for <i>lyssavirus</i> antigens. Of the 76 sera screened by modified rapid fluorescent focus inhibition test (RFFIT) 24 (31.6%) had  neutralizing activity; 22(29.0%) neutralized LBV, 6(7.9%) neutralized MOKV and 18(23.7%) neutralized SHBV). Lyssaviruses may be circulating in bats or other wild animals in Nigeria

Development and characterization of novel chimeric monoclonal antibodies for broad spectrum neutralization of rabies virus.

Current post-exposure prophylaxis for rabies virus infection has several limitations in terms of supply, cost, safety, and efficacy. Attempts to replace human or equine rabies immune globulins (HRIG or ERIG) have been made by several companies and institutes. We developed potent monoclonal antibodies to neutralize a broad spectrum of rabies viruses by screening hybridomas received from the U.S. Centers for Disease Control and Prevention (CDC). Two kinds of chimeric human antibodies (chimeric #7 and #17) were constructed by cloning the variable regions from selected hybridomas and the constant region of a human antibody. Two antibodies were bound to antigenic site III and I/IV, respectively, and were able to neutralize 51 field isolates of rabies virus that were isolated at different times and places such as Asia, Africa, North America, South America, and Australia. These two antibodies neutralize rabies viruses with high efficacy in an in vivo test using Syrian hamster and mouse models and show low risk for adverse immunogenicity

A broad-spectrum and highly potent human monoclonal antibody cocktail for rabies prophylaxis

Post-exposure prophylaxis (PEP) is highly effective in preventing disease progression of rabies when used in timely and appropriate manner. The key treatment for PEP is infiltration of rabies immune globulin (RIG) into lesion site after bite exposure, besides wound care and vaccination. Unfortunately, however, RIG is expensive and its supply is limited. Currently, several anti-rabies virus monoclonal antibody (mAb) products are under development as alternatives to RIG, and two recently received regulatory approval in India. In this study, fully human mAbs that recognize different rabies virus glycoprotein conformational antigenic site (II and III) were created from peripheral blood mononuclear cells of heathy vaccinated subjects. These mAbs neutralized a diverse range of lyssavirus types. As at least two anti-rabies virus mAbs are recommended for use in human PEP to ensure broad coverage against diverse lyssaviruses and to minimize possible escape variants, two most potent mAbs, NP-19-9 and 11B6, were selected to be used as cocktail treatment. These two mAbs were broadly reactive to different types of lyssaviruses isolates, and were shown to have no interference with each other. These results suggest that NP-19-9 and 11B6 are potent candidates to be used for PEP, suggesting further studies involving clinical studies in human.</jats:p

The results of primary screening with six rabies viruses using RFFIT.

The results of primary screening with six rabies viruses using RFFIT.</p

Interference test with CVS-11 rabies virus strain by the RFFIT.

Interference test with CVS-11 rabies virus strain by the RFFIT.</p

Binding affinity test between mAbs and ERA G protein expression cells.

NP-19-9 and 11B6 have binding capacity to the ERA G protein expression cells.</p

Inhibitory effect of anti-rabies virus mAbs on ERA G-protein-induced membrane fusion assay.

Cells were treated with TPCK-trypsin and were subject to low pH condition. Syncytia formation is apparent for the control group (up, IgG and Control) whereas when treated with NP-19-9 or 11B6, syncytia formation is drastically decreased.</p

Efficacy of mAbs after rabies virus infection.

Ten mice were tested and were injected with 100MICLD50 rabies virus before mAb administration. The graph demonstrates either NP-19-9 or 11B6 alone and cocktail administration all effectively protect tested mice from rabies virus infection.</p