"World Rabies Day" is September 28th. Copyright: CC, Global Alliance for Rabies Control
Rabies: a contagious and fatal viral disease of dogs and other mammals, transmissible through the saliva to humans and causing madness and convulsions. Rabies is fatal once symptoms appear.
Latin America is doing far better at managing, controlling and ultimately eliminating rabies from the region. Africa is failing to make the same gains and a rethink is required: can the lessons learned in Latin America be applied or adapted to Africa?
At the biennial RSTMH meeting “Challenges in Disease Elimination” held in Cambridge [September 12-16th, 2016], Katie Hampson [University of Glasgow] described the Pan American Health Organisation (PAHO)'s surveillance & management framework operating in Mexico and Brazil, and devised to support the elimination of rabies in 25 PAHO countries. She also described the work of Tanzanian colleagues who have developed a “pragmatic approach to surveillance” for the African setting where resources are constrained.
Current situation of rabies control in Latin America vs Africa
The short answer is that in Latin America, PAHO, which exists to “strengthen national and local health systems and improve the health of the peoples of the Americas”, has concentrated on vaccinating the dog population against rabies and interrupting transmission. African countries have no similar regional support structure for their health ministries and rely on post-exposure prophylaxis (PEP) of humans bitten by dogs, to achieve a form of control of rabies. PEP vaccination only saves lives if the bitten person has timely access to a well-stocked clinic, and the money to pay for the shots. In remote and rural areas, this can lead to grim choices: which child do you treat if you only have money for one? We heard at the RSTMH of an African mother with several children bitten by the “family dog”, who having travelled a great distance to reach the vaccine, was then faced with that very choice.
Growing Success in Latin America
Latin America’s approach has achieved the magnificent result of a 99% reduction in dog-rabies cases, down to 150 cases per year. Human cases from dog-mediated rabies have declined by 95%.
They have done this largely through campaigns of dog vaccination, and monitoring the level of disease in dogs, post-mortem. Diagnostic tests are excellent but only work on dead animals, requiring a brain sample. Collecting samples from dead dogs is a sensitive issue, since the dogs roaming freely in the villages are not wild but are indeed “owned”. Usually they are obtained from suspect dogs that have been killed after biting a person.
Campaign teams have to work closely with communities and be able to demonstrate real benefits arising from the program. If you don’t do this, don’t gain the support of local people, then they won't bring their dogs for vaccination nor allow sampling of dead dogs. Bite victims receive PEP.
Moving to the End-Game in Latin America: zero human deaths from dog-mediated rabies by 2030.
The framework for eliminating rabies, developed by PAHO and the researchers in Glasgow, Mexico and Brazil, is based on 3 elements: a robust classification system identifying risk of incursion of infected dogs, the surveillance dB for SIRVERA (Regional Rabies Surveillance System in the Americas) and direct management of cases.
How does the framework function? Each state in a country submits confirmed cases of dog-rabies and a 5 year pattern is built-up, classifying the results into 5 groups ranging from endemic through to absent. The pattern is used to identify the risk of incursion of infected dogs into each state (or country). A country might have many states classified as “absent” but if a state shares a border with an endemic state: its classified as absent-vulnerable, ie it’s at risk. In Mexico, which has been very successful overall, Chiapas state (endemic) and Yucata (declining to intermittent level) are therefore sources of incursion for neighbouring states, and vaccination efforts are now focussed on them. In Brazil, the rabies foci are the poorest states such as Maranhão.
The plan is to build this framework into the SIRVERA database so programme managers in the other 23 countries can make use of it.
Lessons Learned from Latin America applicable to Africa?
Can we take the lessons learnt in Latin America and now apply them equally well to an African country? Many african countries do not have the resources to vaccinate dogs on the same scale as PAHO-Latin America (60% coverage cf to 6% in Africa) nor able to sample enough dogs to be certain estimates of dog-rabies are valid (case detection).
Realizing this, Tanzanian researchers believe they have found a way of improving case detection by focusing on dogs that have bitten a human being, using the human bite victims as sentinels. It’s a “pragmatic approach to surveillance”.
The approach emerged as part of a large-scale WHO rabies control program in Tanzania based on dog vaccination, in which surveillance data was reported from health & veterinary clinics via mobile phones.
Preliminary data shows that on average there is 0.4 persons bitten per rabid dog and that 70% of bite victims seek care. Dogs that bite will obviously divide into those with and without disease. The researchers created a system which enables healthcare workers (HCW) in clinics to interview the human victim and, it would appear, identify with 98% accuracy which dogs were provoked to bite and which bit because they were infected. They also believe that there is a ready source of dead dogs to use in clinical confirmation since the data suggests that 60% of rabid dogs died or were killed by the bite victim, & that lab-based diagnostic kits could be applied in the field at these clinics.
Focussing on bite victims and the dogs involved, the researchers believe, will improve sampling & case detection in dogs, and improve monitoring of the effectiveness of PEP in human rabies victims. They are now planning to use phone networks to facilitate contact with bite victims
Not only does this system improve case detection, but it builds collaboration between HCWs and veterinary workers and could form the basis for control of emerging zoonotic diseases.
Post-Script: Problems of the end-game
Elimination in the public health sense means getting disease levels to a point where the disease is not self-sustaining. In the case of dog-mediated rabies, if we could achieve 70% dog vaccination, we would control & eliminate dog rabies across Africa and Asia even in wildlife-rich areas, saving the lives annually of nearly 55 000 humans and countless dogs. Most human cases occur in children aged below 15 years.
It was clear from the tone and title of the conference that this is an exciting and interesting time as several neglected tropical diseases apart from rabies are now moving beyond control into the elimination phase. But time and again notes of caution were raised by delegates and speakers around what’s needed in the end-game to get to the “Last man standing”:
- Improved surveillance and case detection methods
- Dedicate resources to surveillance
- Handle any outbreaks without delay (using PEP and ring vaccination)
- Public & politicians need to be kept onside …just think about polio in Nigeria
- Donor Fatigue: governments and donors see disease levels falling and tend to think the “job’s done” too soon and redeploy the resources elsewhere
- Resources will still be needed for disabled survivors
So when can you say you have beaten rabies?
Current wisdom, based on simulation models, says that you need to have two years clear of reported cases of rabies in people, after you have stopped vaccinations (of dogs). The problem will be in having confidence in the processes that identify and then manage the cases being reported (“case detection”) and there is some dispute about the OIE/WHO guidance in this area. Which is where the end-game framework described by Katie Hampson will prove its worth.
In the News
Further reading from CABI's Global Health database
- Sri Lanka takes action towards a target of zero rabies death by 2020. WHO South East Asia Journal of Public Health 2016
- Government response to the discovery of a rabies virus reservoir species on a previously designated rabies-free island, Taiwan, 1999-2014. Zoonoses and Public Health 2016
- Estimating the global burden of endemic canine rabies. PLOS Neglected Tropical Diseases 2015
- On dogs, people, and a rabies epidemic: results from a sociocultural study in Bali, Indonesia. Infectious Diseases of Poverty 2015
- Concomitant administration of GonaConTM and rabies vaccine in female dogs (Canis familiaris) in Mexico. Vaccine 2013