Hierarchical epidemiology of rabies: the spread and persistence of infectious diseases in complex landscapes
Background: Rabies is a fatal disease that can infect all mammals, but is primarily spread by domestic dogs. Following a bite, rabies can be prevented through prompt administration of post-exposure prophylaxis. This involves a course of vaccinations administered over several weeks, together with immunoglobulins for high-risk exposures. A major challenge in low-income countries is ensuring these vaccines are available and affordable to bite victims. The risk of exposure can be reduced and rabies can be controlled at source through mass dog vaccination. Rabies has been eliminated in industrialized countries through mass dog vaccination, however in most low-income countries there has been little investment in dog vaccination and rabies continues to kill thousands of people every year. In 2010, the Tanzanian government and the World Health Organization secured funding from the Bill and Melinda Gates Foundation for a large-scale rabies control programme across southern Tanzania, as part of a multi-country initiative. The overarching aim was to eliminate human rabies deaths through establishing annual mass dog vaccination campaigns across the region and improving the provision of post-exposure prophylaxis to bite victims. In Tanzania this project operates across 28 districts, including Pemba Island and covers a 150,000km2 catchment area serving around 10 million inhabitants. For more information:
Integrated surveillance for rabies: Surveillance is critical for managing preventative health services and controlling infectious diseases. Surveillance involves the routine collection, analysis and dissemination of data to guide health policy and practice. But paper-based surveillance is slow and often incomplete, therefore does not allow effective monitoring or timely responses. Surveillance for zoonotic diseases (spread from animals to humans) requires intersectoral collaboration between the health and veterinary sectors. For rabies, health workers need to report animal bites to veterinary officers to trigger outbreak investigations, and vets need to alert medical authorities to exposure risks from animal cases. Our mobile phone-based surveillance system for rabies supports around 300 health workers and veterinary officers to record information needed to monitor the progress of rabies control and prevention efforts in Southern Tanzania. It is worth stressing the wider potential here: when it comes to diseases that spread from animals to people, such as anthrax and ebola, you need veterinary and health workers to co-operate. In a similar way, controlling diseases spread by mosquitoes, such as malaria and zika, depends on the joint efforts of environmental and health workers. A dedicated e-surveillance website for this work can be accessed here:
Progress so far: We have just reached the end of a five-year trial of this system in southern Tanzania. It has involved over 300 health and veterinary workers submitting over 30,000 records across an area that is home to several million people. It has supported a WHO-funded rabies control programme in which the government has been aiming to vaccinate at least 70% of dogs in the 2,000-plus villages across the region every year since 2011. This is part of a global push to eliminate human deaths from rabies by 2030. Our results have been very encouraging. Patients reporting to clinics with dog bites have halved over the past five years, and rabies has disappeared entirely from Pemba, an island with a population of over 400,000. Admittedly, it is much easier to eliminate rabies from an island with a small dog population, but the trajectories across the pilot area are promising, too. Dr Chibonda used to see bite patients almost every day, but now sees just one or two a month; and where previously he didn’t even know the veterinary officer in his community, now they call one another and even carry out joint outbreak investigations.
Prospects: The system may not solve the problem of chronic u