Rabies exposures, post-exposure prophylaxis and deaths in a region of endemic canine rabies

Abstract

Background: Thousands of human deaths from rabies occur annually despite the availability of effective vaccines following exposure, and for disease control in the animal reservoir. Our aim was to assess risk factors associated with exposure and to determine why human deaths from endemic canine rabies still occur.

Methods and findings: Contact tracing was used to gather data on rabies exposures, post-exposure prophylaxis (PEP) delivered and deaths in two rural districts in northwestern Tanzania from 2002 to 2006. Data on risk factors and the propensity to seek and complete courses of PEP was collected using questionnaires. Exposures varied from 6-141/100,000 per year. Risk of exposure to rabies was greater in an area with agropastoralist communities (and larger domestic dog populations) than an area with pastoralist communities. Children were at greater risk than adults of being exposed to rabies and of developing clinical signs. PEP dramatically reduced the risk of developing rabies (odds ratio [OR] 17.33, 95% confidence interval [CI] 6.39-60.83) and when PEP was not delivered the risks were higher in the pastoralist than the agro-pastoralist area (OR 6.12, 95% CI 2.60-14.58). Low socioeconomic class and distance to medical facilities lengthened delays before PEP delivery. Over 20% of rabies-exposed individuals did not seek medical treatment and were not documented in official records and <65% received PEP. Animal bite injury records were an accurate indicator of rabies exposure incidence.

Conclusions: Insufficient knowledge about rabies dangers and prevention, particularly prompt PEP, but also wound management, was the main cause of rabies deaths. Education, particularly in poor and marginalized communities, but also for medical and veterinary workers, would prevent future deaths.

Figure 1. Age distribution of rabies-exposed individuals.

The age distribution of suspected rabies bite victims (dark gray, n = 642) compared to the population as a whole in Serengeti and Ngorongoro districts (light gray, n = 307,099).

Figure 2. Correlation between the monthly number of exposures by suspected rabid animals and the corresponding number of animal-bite injury records during that month.

Records of patients from Serengeti and Ngorongoro districts.

Figure 3. Factors affecting delays to delivery of PEP following exposure.

(A) Distribution of delays till first dose of PEP. (B) Delivery delays by distance from district hospital and (C) by socioeconomic status.

Figure 4. Means of obtaining funds to pay for PEP for rabies exposed individuals of high and low socioeconomic status.