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Original Research |

Cost-Effectiveness of Canine Vaccination to Prevent Human Rabies in Rural Tanzania

Meagan C. Fitzpatrick, MPhil; Katie Hampson, PhD; Sarah Cleaveland, PhD, VetMB; Imam Mzimbiri, BVM; Felix Lankester, DVM; Tiziana Lembo, PhD; Lauren A. Meyers, PhD; A. David Paltiel, PhD; and Alison P. Galvani, PhD
[+] Article and Author Information

From Yale School of Public Health and Yale University, New Haven, Connecticut; Boyd Orr Centre for Population and Ecosystem Health, Institute of Biodiversity, Animal Health and Comparative Medicine, and College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom; Serengeti Health Initiative, Lincoln Park Zoo, Chicago, Illinois; Paul G. Allen School for Global Animal Health, Washington State University, Pullman, Washington; The University of Texas at Austin, Austin, Texas; and Santa Fe Institute, Santa Fe, New Mexico.

Acknowledgments: The authors thank Dr. Jamie Childs for insightful conversation about the rabies system and Mr. Israel Silaa and Mr. Kaneja Ibrahim Mangaru of the Serengeti Health Initiative for informative discussions about campaign logistics. They also thank Angelika Hofmann for editorial assistance. The authors thank the Ministries of Health and Social Welfare, Ministry of Livestock and Fisheries Development in Tanzania, Tanzania National Parks, Tanzania Wildlife Research Institute, Ngorongoro Conservation Area Authority, the Tanzanian Commission for Science and Technology, and National Institute for Medical Research for permissions and collaboration, as well as colleagues from the Serengeti Viral Transmission Dynamics team, medical officers, field officers, paravets, and village officers in Serengeti and Ngorongoro.

Financial Support: By the National Institute of General Medical Sciences (U01 GM087719, Models of Infectious Disease Agent Study) and the Miriam Burnett Trust (Ms. Fitzpatrick and Dr. Galvani). Ms. Fitzpatrick also received support from the National Institute of Allergy and Infectious Diseases, Multidisciplinary Parasitology Training Program (T32AI007404), and Lindsay Fellowship for Research in Africa. Support for Dr. Hampson was provided by the Wellcome Trust. Dr. Paltiel received support from the National Institute on Drug Abuse (R01 DA015612). Vaccination campaigns were conducted and field data were generated with the support of the National Science Foundation and National Institutes of Health (DEB0225453 and DEB0513994), the Wellcome Trust, and Lincoln Park Zoo.

Potential Conflicts of Interest: Disclosures can be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=M13-0542.

Reproducible Research Statement: Study protocol: Not available. Statistical code: Available from Dr. Fitzpatrick (e-mail, meagan.fitzpatrick@yale.edu). Data set: Epidemiologic data from Dr. Hampson (e-mail, katie.hampson@glasgow.ac.uk), campaign information from Dr. Lankester (e-mail, lankesterf@vetmed.wsu.edu), and economic data from Dr. Cleaveland (e-mail, sarah.cleaveland@glasgow.ac.uk).

Requests for Single Reprints: Meagan C. Fitzpatrick, MPhil, Yale School of Public Health, 60 College Street, New Haven, CT 06520; e-mail, meagan.fitzpatrick@yale.edu.

Current Author Addresses: Ms. Fitzpatrick and Drs. Paltiel and Galvani: Yale School of Public Health, 60 College Street, New Haven, CT 06520.

Drs. Hampson, Cleaveland, and Lembo: Graham Kerr Building, University of Glasgow, Glasgow G12 8QQ, UK.

Dr. Mzimbiri: PO Box 395, Usa River, Arusha, Tanzania.

Mr. Lankester: Paul G. Allen School for Global Animal Health, PO Box 647090, Washington State University, Pullman, WA 99164.

Dr. Meyers: 1 University Station C0930, Austin, TX 78712.

Author Contributions: Conception and design: M.C. Fitzpatrick, S. Cleaveland, A.D. Paltiel, A.P. Galvani.

Analysis and interpretation of the data: M.C. Fitzpatrick, K. Hampson, S. Cleaveland, F. Lankester, A.D. Paltiel, A.P. Galvani.

Drafting of the article: M.C. Fitzpatrick, K. Hampson, S. Cleaveland, L.A. Meyers, A.P. Galvani.

Critical revision of the article for important intellectual content: S. Cleaveland, F. Lankester, A.D. Paltiel, A.P. Galvani.

Final approval of the article: M.C. Fitzpatrick, K. Hampson, S. Cleaveland, T. Lembo, L.A. Meyers, A.D. Paltiel, A.P. Galvani.

Provision of study materials or patients: F. Lankester.

Statistical expertise: M.C. Fitzpatrick, A.P. Galvani.

Obtaining of funding: K. Hampson, S. Cleaveland, L.A. Meyers, A.D. Paltiel, A.P. Galvani.

Administrative, technical, or logistic support: S. Cleaveland, I. Mzimbiri, T. Lembo, A.P. Galvani.

Collection and assembly of data: M.C. Fitzpatrick, K. Hampson, S. Cleaveland, I. Mzimbiri, F. Lankester, T. Lembo.


Ann Intern Med. 2014;160(2):91-100. doi:10.7326/M13-0542
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Background: The annual mortality rate of human rabies in rural Africa is 3.6 deaths per 100 000 persons. Rabies can be prevented with prompt postexposure prophylaxis, but this is costly and often inaccessible in rural Africa. Because 99% of human exposures occur through rabid dogs, canine vaccination also prevents transmission of rabies to humans.

Objective: To evaluate the cost-effectiveness of rabies control through annual canine vaccination campaigns in rural sub-Saharan Africa.

Design: We model transmission dynamics in dogs and wildlife and assess empirical uncertainty in the biological variables to make probability-based evaluations of cost-effectiveness.

Data Sources: Epidemiologic variables from a contact-tracing study and literature and cost data from ongoing vaccination campaigns.

Target Population: Two districts of rural Tanzania: Ngorongoro and Serengeti.

Time Horizon: 10 years.

Perspective: Health policymaker.

Intervention: Vaccination coverage ranging from 0% to 95% in increments of 5%.

Outcome Measures: Life-years for health outcomes and 2010 U.S. dollars for economic outcomes.

Results of Base-Case Analysis: Annual canine vaccination campaigns were very cost-effective in both districts compared with no canine vaccination. In Serengeti, annual campaigns with as much as 70% coverage were cost-saving.

Results of Sensitivity Analysis: Across a wide range of variable assumptions and levels of societal willingness to pay for life-years, the optimal vaccination coverage for Serengeti was 70%. In Ngorongoro, although optimal coverage depended on willingness to pay, vaccination campaigns were always cost-effective and life-saving and therefore preferred.

Limitation: Canine vaccination was very cost-effective in both districts, but there was greater uncertainty about the optimal coverage in Ngorongoro.

Conclusion: Annual canine rabies vaccination campaigns conferred extraordinary value and dramatically reduced the health burden of rabies.

Primary Funding Source: National Institutes of Health.

Figures

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Figure 1.

Rabies transmission model.

Our dynamic compartmental model is stratified by host type. Rabid dogs are linked to human deaths through a probability tree of human health outcomes. The equations governing the movement between classes are given in Table 1 of Supplement 2. PEP = postexposure prophylaxis.

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Figure 2.

Cumulative rabies cases after 10 y of annual canine vaccination campaigns at increasing vaccination coverage.

Cases are undiscounted.

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Figure 3.

Component and total costs of rabies control with increasing canine vaccination coverage.

All costs are cumulative over 10 y. PEP = postexposure prophylaxis.

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Figure 4.

Cost of vaccination coverage and life-years saved.

Points indicate increasing canine vaccination coverage. Smaller points indicate dominated strategies, which achieve fewer health benefits than other strategies of equal or lesser cost. Costs and life-years saved are cumulative over 10 y. Note that the 2 districts are represented on different scales.

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Figure 5.

Cost-effectiveness acceptability curves.

Curves show the probability that a given canine vaccination coverage is optimal (that is, providing the largest net health benefit at a given willingness-to-pay threshold). At willingness-to-pay thresholds of $1430 and $4290 per life-year, the World Health Organization thresholds for “very cost-effective” and “cost-effective” interventions in Tanzania, optimal annual coverage ranges between 70% and 90% in both districts. These thresholds are indicated by solid vertical lines.

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