Healthcare demand in response to rabies elimination campaigns in Latin America

Author summary Several global health organizations have prioritized investment for global elimination of human death from canine rabies. Cost-effective deployment requires understanding complex connections between rabies risk and healthcare seeking behavior. During 1995-2005, there was a rapid decline in dog and human rabies cases in several Latin American countries following concerted investment in mass dog vaccinations and human post-exposure vaccination. Using data from this period, we econometrically estimate relationships between dog vaccinations, dog rabies cases, human exposure reports, human post-exposure prophylaxis (PEP) use, and human rabies deaths. We estimate quantitatively how dog vaccinations indirectly reduce human rabies deaths, mediated through dog rabies cases, dog bite reporting, and PEP use. We find that reported human exposures decline as dog rabies cases decline, but these declines are offset by increases in reported exposures per dog rabies case, which may be driven by increased rabies awareness through anti-rabies campaigns. Furthermore, while PEP demand declines as dog rabies cases decline, increases in income and public health expenditures concurrently increase demand for PEP. These findings provide better understanding of the underlying factors driving PEP demand and exposure (under)reporting to inform cost-effective policy design to reduce unnecessary PEP prescription and false negatives leading to human death. The World Health Organization, the World Organization for Animal Health, and the Food and Agriculture Organization have resolved to eliminate human rabies deaths due to dog bites by 2030, and the Vaccine Alliance (Gavi) has added human rabies vaccines to their investments for 2021-2025. Implementing these goals cost-effectively and sustainably requires understanding the complex connections between dog rabies vaccination and human risk and response. The objective of this paper is to estimate how dog rabies vaccinations affect human rabies deaths, mediated through dog rabies cases, dog bite reporting, and post-exposure human rabies vaccination. To approach this objective, we apply multivariate regression analysis over five rabies-related outcomes: (a) dog vaccinations, (b) dog rabies cases, (c) reported human exposures, (d) human post-exposure prophylaxis (PEP) use, and (e) human rabies cases. Analysis uses aggregate annual data over 1995-2005 for seven Latin American countries that experienced dramatic declines in canine and human rabies. Among other results, we estimate the following. (i) A 10% increase in dog vaccinations decreases dog rabies cases by 2.3%. (ii) Reported exposures decline as concurrent dog rabies cases decline, but these declines are more than offset by increases in reported exposures per dog rabies case, which may result from higher rabies awareness due to anti-rabies campaigns. (iii) A 10% increase in PEP use decreases human deaths by 7%, but a 10% increase in dog vaccination induces a 2.8% decrease in PEP use. The net effect is that a 10% increase in dog vaccination reduces human deaths by 12.4% overall, although marginal effectiveness declines as dog rabies incidence declines. (iv) Increases in income and public health expenditures increase PEP demand. The findings highlight the importance of mass dog vaccination, heightened awareness, treatment access, and clinical algorithms to reduce both false negatives leading to death and false positives leading to costly unnecessary PEP prescriptions.