Development of a Non-Meat-Based, Mass Producible and Effective Bait for Oral Vaccination of Dogs against Rabies in Goa State, India.

Introduction: To achieve the global goal of canine-mediated human rabies elimination by 2030 there is an urgent need to scale-up mass dog vaccination activities in regions with large dog populations that are difficult to access; a common situation in much of India. Oral rabies vaccination may enable the vaccination of free-roaming dogs that are inaccessible to parenteral vaccination, and is considered a promising complementary measure to parenteral mass dog vaccination campaigns. WHO and OIE have published detailed minimum requirements for rabies vaccines and baits to be used for this purpose, requiring that baits must not only be well-accepted by the target population but must also efficiently release the vaccine in the oral cavity. For oral rabies vaccination approaches to be successful, it is necessary to develop baits which have a high uptake by the target population, are culturally accepted and amenable to mass production. The aim of this study was to compare the interest and uptake rates of meat-based and an egg-based prototype bait constructs by free roaming dogs in Goa, India. Methods: Three teams randomly distributed two prototype baits; an egg-flavoured bait and a commercial meat dog food (gravy) flavoured bait. The outcomes of consumption were recorded and compared between baits and dog variables. Results: A total of 209 egg-bait and 195 gravy-bait distributions were recorded and analysed. No difference (p = 0.99) was found in the percentage of dogs interested in the baits when offered. However, significantly more dogs consumed the egg-bait than the gravy-bait; 77.5% versus 68.7% (p = 0.04). The release of the blue-dyed water inside the sachet in the oral cavity of the animals was significant higher in the dogs consuming an egg-bait compared to the gravy-bait (73.4% versus 56.7%, p = 0.001). Conclusions: The egg-based bait had a high uptake amongst free roaming dogs and also enabled efficient release of the vaccine in the oral cavity, whilst also avoiding culturally relevant materials of bovine or porcine meat products.

Evaluation of an Immunochromatographic Assay as a Canine Rabies Surveillance Tool in Goa, India.

Rabies is a fatal zoonotic disease transmitted by the bite of a rabid animal. More than 95% of the human rabies cases in India are attributed to exposure to rabid dogs. This study evaluated the utility of a lateral flow immunochromatographic assay (LFA) (Anigen Rapid Rabies Ag Test Kit, Bionote, Hwaseong-si, Korea) for rapid post mortem diagnosis of rabies in dogs. Brain tissue was collected from 202 animals that were screened through the Government of Goa rabies surveillance system. The brain tissue samples were obtained from 188 dogs, nine cats, three bovines, one jackal and one monkey. In addition, 10 dogs that died due to trauma from road accidents were included as negative controls for the study. The diagnostic performance of LFA was evaluated using results from direct fluorescence antibody test (dFT); the current gold standard post mortem test for rabies infection. Three samples were removed from the analysis as they were autolysed and not fit for testing by dFT. Of the 209 samples tested, 117 tested positive by LFA and 92 tested negative, while 121 tested positive by dFT and 88 tested negative. Estimates of LFA sensitivity and specificity were 0.96 (95% CI 0.91-0.99) and 0.99 (95% CI 0.94-1.00), respectively. The LFA is a simple and low-cost assay that aids in the rapid diagnosis of rabies in the field without the need for expensive laboratory equipment or technical expertise. This study found that Bionote LFA has potential as a screening tool in rabies endemic countries.

Reproducibility of the mark-resight method to assess vaccination coverage in free-roaming dogs.

The mark-resight methodology is a widely used tool to assess both population size and vaccination coverage of free-roaming dogs. Evaluating coverage is often critical to determine the progress and impact of vaccination interventions. The aim of this study was to assess the reproducibility of the mark-resight method during a rabies vaccination campaign. A total of 90 areas in Goa, India, were surveyed on two occasions following a vaccination campaign, during which vaccinated dogs were marked. The estimated vaccination coverage for both confined and free-roaming dogs in the study area after a first round of vaccination was 68.9% (95% CI, 66.7-71.0%). The number of dogs counted in each survey, as well as the proportion of marked dogs, were the main outcomes recorded. Linear and mixed-effects models were used to evaluate the effect of survey order, surveyor, time of day, days between surveys, and weather on the outcomes between repeated surveys. Fewer dogs were likely to be counted in afternoon surveys compared to morning surveys (19.2% fewer dogs, 95%CI 7.5-31.9%) and a 17.2% (95%CI 3.6-32.7%) higher proportion of marked dogs was associated with the repeated survey compared to the first survey. Increased variation of the marked percentage between surveys was associated with using different surveyors (8.3%, 95%CI 0.4-16.2). This study demonstrated that external or personnel factors can influence the number of dogs counted and the estimated vaccination coverage of individual survey areas. Regular staff training, to ensure equal effort and quality of survey techniques between surveyors, could help standardise survey outcomes.