Rabies

Guest blog: Multi-disciplinary interactions under the Mexican sun – reflections from the ISVEE conference

Guest blog by Tiziana Lembo and Liliana Salvador with contributions from Rowland Kao and Louise Matthews.

What is the role of scientific conference? Is it to present our research and expound upon our scientific philosophies? Is it to hear people talking about the interesting research that they are developing? Or is it to meet old friends and make new ones while also traveling to interesting places? All of these aims and more were fulfilled when a group of us left umbrellas and raincoats behind to travel to sunny and warm Mérida, Mexico, for two stimulating weeks of ISVEE 14 (International Society for Veterinary Epidemiology and Economics) conference and workshops. The sun, heat, margaritas, “Jarana” tunes and dances, and the colourful decorations of the “Día de Muertos” created an ideal atmosphere for productive and enlightening scientific interactions.

Dia de muertos

The beginning of ISVEE 14 coincided with the “Dia de Muertos” (Day of the Dead), an ancient Mexican celebration to remember ancestors, family members and friends who have died. Traditionally, altars (“ofrendas”) are built that are laden with decorations, and favourite foods and beverages of teh departed. Above an altar dedicated to the famous Mexican painter Frida Kahlo de Rivera at La Casa Azul in Mexico City, where Frida Kahlo lived and worked most of her life (photo: Tiziana Lembo)

Every three years, ISVEE provides opportunities for academics from a range of different disciplines, policy-makers and stakeholders from the private sector to come together to share their expertise in innovative research, technological developments, and policy health agendas. By blending a wide range of disciplines to address health issues of global importance, the Boyd Orr Centre has a major role to play in all these discussions. What were our contributions to the ISVEE agenda this year?

 

Let’s start with our research on the very topical bovine Tuberculosis (bTB), caused by Mycobacterium bovis. Rowland Kao discussed a subject that is very close to his heart – the transformative role of Whole-Genome-Sequencing (WGS) in elucidating complex transmission dynamics and disease maintenance patterns in multi-host systems. He provided examples of how the approach has been used by the Glasgow team and collaborators to expose the role of wildlife in the maintenance and transmission of bTB to cattle in different parts of the world, including Great Britain, the United States, and New Zealand. He contrasted currently available data with optimal data and listed some of the key features of an ideal dataset for WGS approaches, most importantly dense, representative sampling across all important hosts; representative samples across populations, but also the way that evolutionary analyses and model-based epidemiological approaches complement each other in interpreting these data.

 

Joseph Crisp and Liliana Salvador provided examples of the use of WGS to tackle bTB in New Zealand and US wildlife and cattle populations. Joe showed that the evolutionary substitution rates of M. bovis in his study populations, including cattle, possums and other wildlife are higher than previously thought and that non-cattle reservoirs were heavily involved in the maintenance of M. bovis in the sampled population. Liliana focused on bTB transmission amongst elk, deer and cattle in Michigan, US, and demonstrated that elk is the only one of these species with spatial and temporal clustering of M. bovis. In addition, for the available data, she showed that there is no evidence of transmission between elk and cattle and that cross-species transmission in Michigan is likely due to deer.

 

Liliana also presented her work on surveillance of bTB in Low Risk Areas (LRAs) in England. She showed that larger herds and herds that receive a high number of animals from high-risk areas are most exposed to infection. She also demonstrated that in LRAs there is no clear advantage of testing herds for bTB more frequently, since it would give no increase in the number of detected breakdowns, but the number of false positive would rise considerably. However, adopting risk-based surveillance, where herds that are at higher risk of infection are targeted, can improve the efficiency of the testing regime by increasing the number of identified cases and reducing the number of herds tested.

 

An entire session of the conference was dedicated to foot-and-mouth disease (FMD) with a focus on the latest research efforts in Africa, Asia and Latin America. The work of the Boyd Orr Centre on endemic FMD in Tanzania featured prominently. Findings from micro-econometric studies investigating impacts of FMD outbreaks on individual livestock-owning communities were presented by Tom Marsh, a collaborator from Washington State University. These analyses have revealed that FMD outbreaks in cattle cause reductions in milk production, traction capacity and income from livestock sales, and that households would spend more on child education if they were not affected by milk losses due to FMD. Tiziana Lembo’s talk focused on epidemiological studies investigating temporal and spatial FMD virus dynamics in East Africa to devise appropriate control strategies. She showed that four different serotypes (A, O, SAT 1 and SAT 2) are responsible for FMD outbreaks in cattle in northern Tanzania, and that there is a pattern of serotypic dominance over time across Tanzania and Kenya, which allows us to predict the timing of epidemics of specific serotypes. The implications are that livestock vaccination could target given serotypes ahead of expected outbreaks, using monovalent vaccines, which are much more readily available than polyvalent vaccines needed to cover all of the wide range of serotypes circulating in these areas.

 

In her talk, Louise Matthews tackled the question of whether farmers would adopt a new diagnostic test for early detection of sheep scab at the subclinical stage. The advantages of using the test are that it would allow farmers to detect and treat the disease before clinical signs, reducing production losses, and also reducing transmission to other sheep and flocks. However, the farmers would need to pay for the test and may be reluctant to do so if they believe their flock to be at low risk of infection or if their neighbour is using the test, therefore not posing a transmission risk. These advantages and disadvantages can be assessed using a game theory framework that predicts whether farmers will adopt the test and how that uptake depends on test cost. The outcome was uptake of the test when farmers are at high risk (i.e. when they had experienced clinical sheep scab in the previous year), leading in the long term to a reduction in the proportion of infected farms by around 50%.

 

Harriet Auty, a collaborator from Scotland’s Rural College, presented research on human African trypanosomiasis caused by Trypanosoma brucei rhodesiense in Tanzania. She talked about the relative importance of different wildlife species in the reservoir community for human trypanosomiasis in multi-host populations of the Serengeti National Park. She showed that species such as bushbuck, reedbuck and impala, which are frequently infected with T. brucei, might play an important role in the reservoir community, even though they are not regular food sources for the tsetse vector. Conversely, elephant or giraffe are frequently fed on but rarely infected, indicating they may play a role in dampening transmission, and suggesting how changes in wild species composition could impact on human disease risk.

 

As always, ISVEE also provided a forum for conference delegates to update and strengthen their skills in a number of methods and topics through workshops run by academic colleagues from around the world. For instance, Tiziana Lembo benefited from training and discussions in data management and analyses in R organised by the Swedish National Veterinary Institute, as well as in the use of economics for animal health decision-making coordinated by the Royal Veterinary College and collaborators.

Back to the rain and grey skies now, we have many memories and knowledge to treasure from the land of revolution, music and art.

Zapata

Street mural depicting Emiliano Zapata in Tepoztlan, State of Morelos, Mexico during the Mexican Revolution. Zapata remains an iconic figure in Mexico to this day (Photo: Tiziana Lembo).

 

 

 

 

 

 

 

 

 

ode to life.png

An ode to life (“Viva la Vida”) by the Mexican painter Frida Kahlo de Rivera, La Casa Azul, Mexico City (Photo: Tiziana Lembo).

The research presented and our attendance were funded by: BBSRC / DFID / Scottish Government (Combating Infectious Diseases of Livestock for International Development initiative), MSD Animal Health, and Scottish Universities Life Sciences Alliance (Tiziana Lembo); BBSRC/DFID (Zoonoses in Emerging Livestock Systems) and EPIC (The Scottish Centre of Expertise in Animal Disease Outbreaks); Defra, NSF/BBSRC

Guest post by Sarah Cleaveland: World Rabies Day, 2013

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The World Rabies Day team: (L to R) Kirstyn Brunker, Barb Mable, Will Harvey (hiding), Gran Hopcraft, Captain Sarah Cleaveland, Taya Forde and Christina Ahlstrom

An impromptu team from the Boyd Orr Centre gathered in Aberfoyle to take part in the Trossachs 10 km run to mark World Rabies Day on 28th September.  World Rabies Day is a UN day that was initiated in 2007 by the Global Alliance for Rabies Control with the aim of raising awareness about the impact of rabies around the world, and to catalyse programmes to control and eliminate this deadly but preventable disease (www.rabiesalliance.org).  Scientists from the Boyd Orr Centre have led research that provides convincing evidence that eliminating canine rabies is a feasible objective that can save many thousands of lives, at highly cost-effective levels of investment.  The Boyd Orr rabies team is also closely involved in international partnerships and networks that are working to initiate and coordinate national and regional rabies elimination programmes in Africa and Asia.

Events relating to World Rabies Day are now held in more than 100 countries around the world and range from dog vaccination campaigns, educational events, fund-raising activities, and international webinars.  While the global rabies problem is unlikely to be high among the day-to-day concerns of many in the UK – our rabies T-shirts were met with rather bemused enquiries from the polite residents of Aberfoyle – there are many reasons why we also have a vested interest in controlling dog rabies overseas.  First, many of us travel to countries where dog rabies is still endemic (most countries in Asia and Africa), and encounters with dogs are not uncommon.  In one study of backpackers travelling to southeast Asia, ~4% experienced an exposure (lick or bite of an unknown dog) that could result in rabies, and few people who were exposed were able to receive the course of vaccination and immunoglobulin as promptly as needed. Second, with the recent changes in quarantine regulations for pets from non-EU countries, increasing numbers of dogs are being brought into the UK from countries where canine rabies is widespread.  Dogs in these countries that are kept as pets, with a history of vaccination, are unlikely to pose a risk in terms of introducing rabies into the UK.  But there are concerns about street dogs and rescue dogs that are increasingly being adopted by travellers for re-homing in the UK.  The history of these dogs is likely to be more uncertain than that of pet dogs, and, even when the required vaccination and blood testing schedules are met, there remains a risk that a proportion of dogs could be incubating rabies when entering the UK.  While the risk is very small, the consequences of this could be devastating and extremely costly.

So, while dog rabies may have seemed like a distant problem to those of us running through the beautiful environs of the Queen Elizabeth Forest Park in the Trossachs, there are good reasons for us all to care about rabies and to invest in a world that is free of dog rabies – not only to prevent the thousands of terrifying and needless deaths that occur every year among the most disadvantaged people in the world, but also protect us, as travellers, and to reduce the risk of rabies entering the UK.

Some further references

Hampson, K., Dushoff, J., Cleaveland, S., Haydon, D.T., Kaare, M., Packer, C., and Dobson, A.  (2009).Transmission dynamics and prospects for the elimination of canine rabies. PLoS Biology. 7: (3). e53 doi:10.1371/journal.pbio.100005.3.

Hampson K., Dobson A., Kaare, M., Dushoff J., Magoto M., Sindoya E. and Cleaveland S. (2008) Rabies exposures, post-exposure prophylaxis and deaths in a region of endemic canine rabies: a contact-tracing study. PLoS Neglected Diseases, 2(11): e339. doi:10.1371/journal.pntd.0000339

Lembo T., Hampson K., Kaare M., Ernest E., Knobel D., Kazwala R., Haydon D. and Cleaveland S. (2010) The feasibility of eliminating canine rabies in Africa: dispelling doubts with data. PLoS Neglected Tropical Diseases 4: e626.

Piyaphanee W. et al. (2010)  Rabies exposure risk among foreign backpackers in Southeast Asia. Am. J. Trop. Med. Hyg, 82: 1168–1171.

Shaw M. et al. (2009) Rabies Postexposure Management of Travelers Presenting to Travel Health Clinics in Auckland and Hamilton, New Zealand.  Journal of Travel Medicine, 16: 13–17

Guest blog by Katie Hampson: Elimination of infectious diseases – why the last mile is the hardest – and editing a special issue is worth the effort.

fox rabiesThe latest issue of Philosophical Transactions B on the topic of the elimination of infectious diseases has just come out. I had the pleasure of editing this issue, together with Petra Klepac and Jess Metcalf, thanks to impetus from Angela McLean!

Disease elimination is a topic close to my heart. It’s the ultimate goal for those of us in the Boyd Orr Centre who research rabies. Whilst global elimination of canine rabies is a long way off, the possibility has recently become a tantalizing prospect. One reason for this is the incredible progress in vaccinating dogs to eliminate rabies from the Americas, reported by Vigilato and colleagues in this issue. At this rate, their target of 2015 for continent-wide elimination might just be reached.

Only two diseases in history have been eradicated globally: millions of cases of smallpox used to occur annually and one third of those infected died from the disease. But in 1979 a global health triumph was realized when the disease was wiped out. Rinderpest, a disease of cattle responsible for famines and economic hardships across Africa and Asia was recently declared eradicated in 2011.

In both these cases reliable, heat-stable vaccines proved vital. And for both diseases surveillance strategies during the final stages of elimination relied on determined foot soldiers to hunt down the last remaining cases. While modern technology is driving forward many innovations in global health, there is apparently no replacement for having people in the right places.

One of the best things about being involved in this special issue, was the opportunity to interview a hero integral to the smallpox story: DA Henderson who headed the international effort to eradicate smallpox. Although with the imminent and early arrival of twins on the horizon, my questions had to be fielded from afar. Needless to say, his interview was fascinating, though the most illuminating and entertaining insights were definitely not going into print! Suffice to say, dogged determination, cunning and luck all contributed.

The last stands for both smallpox and rinderpest were remote regions of the world, subject to civil strife and conflict. Reaching these places to vaccinate people or cattle was difficult and dangerous and is a recurring obstacle during the endgame when the target of elimination is in sight.

Another endgame obstacle covered in this issue was vaccine refusal; when parents refuse vaccinations for their children because of religious, political or personal beliefs about the (unfounded) dangers of vaccines. Unvaccinated children can end up becoming a reservoir for infection, another topic that felt close to home. Earlier this year, while I was ferrying newborn twins to the doctors for their measles jabs, an epidemic was spreading across England and Wales.

The media pitch being used to ramp up vaccinations to stem this epidemic impressed me. Not only was there a serious attempt to explain herd immunity, but campaigners argued that by not getting kids vaccinated parents were selfishly endangering the most vulnerable: seriously ill children with suppressed immune systems (e.g. cancer suffers) unable to fend of the disease. Definitely a persuasive and heart rending argument.

Image courtesy of the Pan-American Health Organisation.

Image courtesy of the Pan-American Health Organisation.

For anyone else considering editing a special issue I’d say that it is definitely hard work, but it can also be hugely inspiring. Contributing authors represented a diverse range of perspectives, including those really at the frontline of disease control. And the messages conveyed were so positive, from progress towards the elimination of Dracunculiasis (a decidedly gruesome infection) without the use of a drug or a vaccine, to an optimistic outlook for malaria elimination, which has seemed so insurmountable in the past. Even eliminating disease from wildlife was shown to be possible. How? By chucking out chicken heads from airplanes.  Strategic aerial delivery programmes distributed oral rabies vaccine baits over more than 1.9 million square kilometers to rid Western Europe of fox rabies. That such an extraordinary feat can be achieved, definitely gives hope to those of us thinking about how to vaccinate dogs.

Katie Hampson