Rabies vaccinations at the rural-urban divide: successes and barriers to dog rabies vaccination programs from a rural and urban campaign in Zambia

Abstract

Introduction: Dog vaccination against rabies is considered one of the most effective strategies at preventing human deaths from rabies and is a key strategy for eliminating dog-mediated human rabies deaths. Traditional vaccination approaches in Zambia rarely collect operational data to assess coverage and inform subsequent campaigns.

Methods: Following mass vaccination campaigns in rural (Itezhi tezhi) and urban (Lusaka) communities, we evaluated vaccination coverage achieved during the campaigns and characterized and estimated the dog population in these communities.

Results: Herd immunity (i.e., 70% vaccination coverage) was not achieved in the Lusaka campaign, likely due to challenges in pre-campaign community sensitization and distance to vaccination sites in the central point campaign approach. Dog population density showed a strong exponential association with human density (R² = 0.89). Extrapolating this relationship nationally, there are an estimated 3.2 million dogs in Zambia (human-to-dog ratio 5.8:1) with 86% residing in rural communities at a very low density of less than 6 dogs per square kilometer.

Discussion: As most dogs were found to reside at very low densities, unique challenges to large-scale dog vaccination approaches may impact Zambia, due to high logistical costs associated with these settings. Prioritizing vaccinations in higher-density free-roaming dog populations could maximize effectiveness in resource-limited settings. Private veterinary services were commonly utilized among surveyed dog owners in urbanized communities in Lusaka, suggesting that they are an important collaborator for achieving rabies herd immunity. With improved knowledge of dog population and ownership characteristics, Zambia is well-prepared to design more effective vaccination campaigns as the rabies elimination program expands.

Keywords: dog vaccination programs; dog-mediated human rabies elimination; dog-mediated rabies; rabies; rabies vaccination.

Figure 1

Vaccination zones, central point vaccination locations, and total number of vaccinations administered—Lusaka, Zambia, 2022. Grey polygons indicate regions targeted by the campaign (i.e., vaccination zones), red dots indicate central point vaccination locations, and size of the red dots corresponds to the number of vaccinations administered.

Figure 2

Vaccination coverage adjusted for distance from central point vaccination location—Lusaka, Zambia, 2022.

Figure 3

Vaccination zones, vaccinations administered, and estimated vaccination coverage in Itezhi tezhi district, Zambia, 2021. Black dots represent locations where vaccinations were administered.

Figure 4

Association between willingness to walk to a central point vaccination location and vaccination coverage–Lusaka, Zambia, 2022. The blue line represents household survey respondents self-reported willingness to walk to a central point vaccination location. The dotted blue lines represent 95% confidence intervals. The red line represents adjusted willingness to walk distances. The pink dots represent household survey-derived vaccination coverage.

Figure 5

Estimated distribution of dogs across the provinces of Zambia. (A) Central Province, (B) Copperbelt Province, (C) Eastern Province, (D) Luapula Province, (E) Lusaka Province, (F) Muchinga Province, (G) North Western Province, (H) Northern Province, (I) Southern Province, (J) Western Province.

Figure 6

Total daily vaccinations by central point vaccination location (bars, left y-axis) and mean hourly rate of vaccination (lines, right y-axis)—Lusaka, Zambia, 2022.

Figure 7

Dog ownership, roaming status, and human to dog ratios derived from two post-vaccination evaluations in Itezhi tezhi (2021) and Lusaka (2022) by type of community. (A) Dog ownership and roaming characteristics. (B) Dog ownership and roaming characteristics by community type. (C) Tukey box and whisker plot of human to dog ratios by community type. CD = community dog; OFRD = owned free-roaming dog; OCD = owned confined dog; R = rural; P = peri-urban; U = urban.

Figure 8

Dog vaccinations reported among household survey respondents by location of vaccination receipt and dog confinement status—Lusaka, Zambia, 2022. Abbreviations: MFL = Ministry of Fisheries and Livestock. Private represents dogs who were reportedly vaccinated in the past year through private veterinary services. MFL represents dogs who were reportedly vaccinated through the MFL-sponsored campaign.

Figure 9

Association between dog population density and human population density across the Itezhi tezhi and Lusaka vaccination zones. (A) Free roaming dog population density. (B) Total dog population density. Grey box highlights human population densities for which no dog population studies were conducted.