Boké Prefecture is in the western zone of Lower Guinea, between 10˚30' and 11˚45' North latitude and 13˚45' and 15˚00' West longitude. According to the General Population and Housing Census, it covers an area of 11,055 km² and has a population of 481,007, corresponding to a density of 43 inhabitants per km². Boké is situated approximately 250 km from the capital, Conakry. The field survey was conducted from October 2024 to December 2024.

Five of the six administrative districts of Boké urban commune were selected by simple random draw. Within each selected district, vaccinated dog-owning households were identified with the assistance of local veterinary officers who maintained records of vaccination activities. This sampling approach was therefore random at the district level and purposive at the household level. To minimise clustering bias, only one dog per household was eligible for inclusion. Prior to blood sample collection, structured interviews were conducted with these dog owners. The dogs included in the study were household-owned dogs from the urban municipality of Boké. Owner consent was obtained prior to any blood sampling.

The required sample size was calculated using Cochran’s formula [12] for proportions: n₀ = Z²pq/e², where Z = 1.96 (95% confidence level), p = 0.50 (expected seroconversion prevalence, maximum variance assumption), q = 1 – p = 0.50, and e = 0.1170 (absolute margin of error, corresponding to a relative precision of 23.40% of p). Substituting these values: n₀ = (1.96)² × 0.50 × 0.50/(0.1170)² ≈ 70. A total of 70 dogs were therefore targeted for inclusion.

The serological assessment of anti-rabies antibody titers was performed via the IDEXX Canine Anti-Rabies Ab ELISA Kit following the manufacturer’s instructions. Blood samples were collected by venipuncture under simple manual restraint, without anesthesia, in accordance with standard veterinary practice. Serum samples were diluted 1:10 in the provided buffer solution and then added to the wells of ELISA plates, along with positive and negative controls. The plate was incubated at 37˚C for two hours to allow the binding of specific antibodies to rabies antigens. After incubation, the wells were washed to remove unbound components, and the conjugated antibody was added, followed by a second incubation. After a second wash, the TMB substrate was added to reveal the enzymatic reaction. The reaction was stopped with the provided stop solution, and the absorbance was measured at 450 nm via an ELISA plate reader.

Vaccination status, vaccine brand, and date of last vaccination were verified from vaccination cards (77% of dogs) or district veterinary officer logbooks (23%); no animal was included based solely on unverifiable owner recall. Absorbance values were converted to IU/mL using the IDEXX proprietary calculation spreadsheet according to the manufacturer’s instructions. Samples below the assay’s lower limit of quantification (<0.125 IU/mL) were assigned to this limiting value and classified as non-seroconverted. The protective threshold of ≥0.5 IU/mL was applied in accordance with WHO/WOAH recommendations.

Survey data were analyzed via R and GraphPad Prism. Descriptive statistics (means, medians, and standard deviations) were calculated to characterize the distribution of the antibody titers. Data normality was assessed via the Shapiro-Wilk test. Nonparametric tests were applied: the Mann-Whitney test for comparisons between two independent groups and the Kruskal-Wallis test for comparisons among multiple groups. Correlation analysis was also conducted to evaluate the associations between adherence to the vaccination schedule and antibody levels. The significance threshold was set at p < 0.05.

Serological results were interpreted according to the following antibody titer thresholds: titers between 0.125 - 0.2 IU/mL were considered indicative of no seroconversion; titers between 0.2 - 0.5 IU/mL were classified as insufficiently seroconverted, requiring a booster vaccination; and titers between 0.5 - 4 IU/mL were considered indicative of adequate seroconversion, corresponding to a protective level against rabies. All comparisons between subgroups were conducted as unadjusted (univariable) analyses.

The distribution of consenting respondents by socioprofessional category indicates that laborers, traders, and farmers were the most represented groups in this study, accounting for 20%, 20%, and 17% of participants, respectively, followed by civil servants (14%). With respect to educational level, secondary education was the most represented level (31%), whereas primary education accounted for only 13%. Furthermore, 93% of the dog owners who had benefited from vaccination campaigns provided consent for inclusion in this study (Figure 1).

The distribution of the study dogs by breed revealed that 96% were local breeds, whereas only 4% were exotic breeds. Half of the dogs (50%) were adults aged 2 - 7 years, followed by young dogs aged 3 months to 2 years (46%). Dogs older than 7 years were less represented (4%). Furthermore, 53% of dogs lived in complete freedom, whereas caged and mixed housing systems represented 20% and 27%, respectively (Figure 2).

The level of knowledge regarding rabies among the dog owners was assessed. The results revealed that 69% of the consenting participants had previously heard of rabies, whereas 31% had never heard of the disease (Figure 3(a)). Among those aware of rabies, 27% were unfamiliar with the disease’s clinical manifestations, whereas 18% and 16% recognized signs of agitation and nervousness, respectively.

Figure 1. Distribution of consenting respondents: by socioprofessional category (a), educational level (b), and participation in vaccination campaigns (c).

Figure 2. Distribution of dogs by breed (a), proportion of study dogs by age group (b), and housing type of study dogs (c).

Figure 3. Dog owners’ knowledge of rabies: awareness of rabies (a); reported rabies-associated clinical signs (b); knowledge of rabies prevention measures (c); types of anti-rabies vaccines used (d).

Overall, 79% of the participants were aware of preventive strategies, whereas 21% had no knowledge of such measures. Nobivac was the most frequently used vaccine, reported by 61% of the respondents, whereas Rabisin was less commonly used (39%) (Figure 3).

The seroconversion status of dogs was assessed. Among the sampled dogs, 87% exhibited protective antibody levels (≥0.5 IU/mL), whereas 10% and 3% had insufficient and undetectable antibody levels, respectively. Overall, 97% of the dogs seroconverted, whereas 3% had no detectable antibodies (Table 1).

The influence of vaccine type on the immune response was assessed by comparing antibody titers between dogs vaccinated with Nobivac and those receiving Rabisin via the Mann-Whitney U test (Figure 4). A significant difference was observed between the two groups (p < 0.05). The median antibody titer was greater in dogs

Table 1. Seroconversion levels in vaccinated dogs.

Figure 4. Antibody titers according to vaccine type, dog age, and housing type.

vaccinated with Nobivac (0.6 IU/mL) than in those vaccinated with Rabisin (0.5 IU/mL). Additionally, the effect of dog age on the immune response was evaluated: analysis revealed a significant difference in antibody levels according to age (p < 0.05). Dogs aged 2 - 7 years presented higher median antibody titers (0.6 IU/mL) than dogs aged 3 months to 2 years (0.5 IU/mL) and those older than 7 years (0.2 IU/mL). Furthermore, housing type had no statistically significant effect on the vaccination response (p > 0.05).

A comparison was conducted between recently vaccinated dogs and those vaccinated over one year prior via the Mann-Whitney U test (Table 2). The results revealed a statistically significant difference in antibody levels based on the time elapsed since vaccination (p < 0.05). Dogs vaccinated more than one year ago presented significantly lower antibody titers (median = 0.5 IU/mL) than dogs vaccinated within the past year (median = 0.6 IU/mL).

Table 2. Comparison of antibody titers according to time since vaccination (Test U Mann-Whitney; U = 261; r = 0.49).

Biserial correlation analysis revealed a significant negative correlation between time postvaccination and antibody titers (Rpb = −0.51; t = −4.85; p < 0.001) (Table 3). This relationship indicates that antibody levels gradually decrease over time following vaccination.

Table 3. Correlations between antibody titers and time postvaccination (point-biserial correlation).