Pattern of infection, vaccination response and risk of transmission of rabies from dog slaughter and consumption in rural Ghana: implications for control

Rabies is one of the highly documented zoonotic diseases throughout history, with a highly notable clinical presentation and 100% fatality rate. Cultural practices such as dog slaughter for meat consumption is common in some parts of Ghana, however, little is known about its role in rabies transmission. This thesis analysed dog bite surveillance data and tested field-derived samples for virus and antibodies. In the first part surveillance data on dog-bites, rabies records from Ashanti regional laboratory, investigations and hospital visitations were analysed between 2009 through 2019 from the Ashanti region of Ghana. We determined a time-course series of bite investigations and linked laboratory outcomes to bite-exposed victims. A total of 442 bite incidents were reported, out of which Kumasi metropolis recorded the highest of 83% (367/442). Within the Kumasi metropolis, Oforikrom (n = 68, 15.4%) and Manhyia (n = 66, 14.9%) sub-metros contributed most to the overall number of recorded dog bite events. A smaller proportion of dog-bite victims visited hospitals within the same district of the bite incident (n = 156, 37%) while 266 (63%) visited a healthcare facility outside the district of the bite-incident. Among the latter, the Manhyia government hospital known to be the international vaccination centre in Ashanti region was the most visited (n = 105, 39.5%), suggesting vaccine availability may account for increased visitation. An average of two days used for a bite-incident report and 14 days to culminate final observation was acceptable to give enough time for exposure investigation and post exposure prophylaxis if required although reporting on same day would have been the best option. The WHO recommends as a public health measure, a 10 to 14-day quarantine and observation period for suspected rabid dogs that bite people, after which surviving dogs without clinical signs are considered negative and discontinuation of post exposure prophylaxis. Secondly, we tested 144 brain tissues from apparently healthy dogs slaughtered for human consumption for the presence of rabies viruses using a Lyssavirus-specific real-time reverse transcription polymerase chain reaction (RT-PCR). Positive samples were confirmed by virus genome sequencing. We also administered questionnaires to 541 dog owners from three regions in Ghana and evaluated factors that could influence dog meat consumption. We interacted with butchers and observed slaughtering and meat preparation procedures. Three out of 144 (2.1%) brain tissues from apparently healthy dogs tested positive for rabies virus ribonucleic acid (RNA). Two of the viruses with complete genomes were distinct from one another, but both belonged to the Africa 2 lineage. Thirdly, we qualitatively examined 819 dog sera for rabies vaccine antibody titres from three rural areas of Ghana using a commercially available Rabies Virus IgG antibody (Dog) ELISA. We interviewed 541 dog owners from Adidome, Agogo and Bolgatanga in Ghana and assessed factors that could affect rabies seropositivity. Antibodies were tested under the assumption that rabies is not survived by dogs and seropositive dogs were vaccinated obtaining a prevalence of 3.2% (26/819) rabies vaccine antibody titre. Adidome and Agogo from the southern and middle parts of the country exhibited 6.4% (14/219) and 3.3% (10/300) seropositivity respectively, whilst Bolgatanga from the northern sector recorded only 0.7% (2/300). Logistic regression analysis shows dogs from Bolgatanga in the northern sector of Ghana were less likely to test positive for rabies vaccine antibodies and statistically significant [cOR= 0.10, 95% CI (0.02-0.44), p-value 0.002]. Older dogs ≥3 years were more likely to test positive for Antirabies antibodies, however, this was only statistically significant for the crude odds ratio [cOR= 6.09, 95% CI (2.00-18.51), p-value 0.001; aOR=2.61, 95% CI (0.76-9.02), p-value 0.129]. Vaccinated dogs were significantly associated with positive serological outcome [cOR= 5.53, 95% CI (2.43-12.59), p-value <0.0001; aOR=2.57, 95% CI (1.01-6.51), p-value 0.047]. This study shows extremely low (3.2%) rabies vaccine antibody prevalence in the study areas, an indication of high rabies susceptibility, worsening in rural northern Ghana.