Factors of maintenance of rabies transmission in dogs, in Kinshasa, Democratic Republic of the Congo

Rabies kills every year 61 000 humans in the world, mainly in Asia and Africa. In Democratic Republic of the Congo (DRC), dog rabies is endemic. Despite mandatory vaccination of dogs since 1938, disease control remains ineffective. Accordingly, this research aimed to investigate the risk factors of rabies transmission between dogs and to establish a risk map by combining the dog density, dog roaming behaviour and vaccination coverage. The method used to estimate the three factors was a household survey conducted in 22 study sites of Mont-Ngafula, Ngaliema and Lemba communes in Kinshasa. In addition to household survey, (i) a subgroup of owned dogs (n=16) was tracked during 24 hours using GPS collars in order to characterize the dog roaming behavior, (ii) the ownerless dog proportion was estimated by the street count method , and (iii) the serological evaluation of the immunization status of a subgroup of 132 reported vaccinated dogs. The survey included 6122 households. In total, 504 dog-owning households with 922 dogs were recorded, corresponding to 9% of all households. The mean age of dogs was 2.5 years and 60% of dogs belonged to local breeds. Dog density was estimated to 49 dogs/km2. Between 2 to 100% (mean 60%) of owned dogs were intermittently or continuously free roaming in study sites. The mean distance covered by tracked dogs within 24 hours was 0.718 km (0.046-2.341 km) and each dog had a chance to come in contact with 30 free-roaming dogs. The proportion of ownerless dogs was less than 2%. The vaccination coverage was 53% (24-81% among study sites). The coverage significantly increased with age and was higher in pure and cross breed dogs. Associated costs and low age were reported as main reasons for not vaccinating. 73% of the 132 tested dogs displayed protective anti-rabies antibody titers (≥0.5 IU/ml) irrespective of time span since vaccination. By combining the dog density, the percentage of free-roaming dogs and the vaccination coverage, the risk map indicated a high risk of rabies transmission in 41% (9/22) of the study sites. Our study shows that the risk of rabies transmission varies locally in urban settings in Kinshasa. Dog-keeping practices and vaccination coverage correlate with the socioeconomic status of households and thereby influence the risk level of dog rabies transmission. The establishment of a low scale risk map provides a tool for local risk assessment and targeting areas and/or action aiming at rabies control.