Animal-to-human diseases: From panic to planning–new recommendations for policymakers

Greatest Burden of Zoonoses Falls on One Billion Poor Livestock Keepers

Map by ILRI, published in an ILRI report to the UK Department for International Development (DFID): Mapping of Poverty and Likely Zoonoses Hotspots, 2012.

The UK’s Institute for Development Studies (IDS) has published a 4-page Rapid Response Briefing titled ’Zoonoses: From panic to planning’.

Veterinary epidemiologist Delia Grace, who is based at the International Livestock Research Institute (ILRI), along with other members of a Dynamic Drivers of Disease in Africa Consortium, based at the STEPS Centre at IDS, c0-authored the document.

The briefing recommends that policymakers take a ‘One-Health’ approach to managing zoonotic diseases.

‘Over two thirds of all human infectious diseases have their origins in animals. The rate at which these zoonotic diseases have appeared in people has increased over the past 40 years, with at least 43 newly identified outbreaks since 2004. In 2012, outbreaks included Ebola in Uganda . . . , yellow fever in the Democratic Republic of Congo and Rift Valley fever (RVF) in Mauritania.

‘Zoonotic diseases have a huge impact – and a disproportionate one on the poorest people in the poorest countries. In low-income countries, 20% of human sickness and death is due to zoonoses. Poor people suffer further when development implications are not factored into disease planning and response strategies.

‘A new, integrated “One Health” approach to zoonoses that moves away from top-down disease-focused intervention is urgently needed. With this, we can put people first by factoring development implications into disease preparation and response strategies – and so move from panic to planning.

Read the Rapid Response Briefing: Zoonoses: From panic to planning, published Jan 2013 by the Dynamic Drivers of Disease in Africa Consortium and funded by the UK Department for International Development (DFID).

About the Dynamic Drivers of Disease in Africa
The Dynamic Drivers of Disease in Africa is a consortium of 30 researchers from 19 institutions in Africa, Europe and America. It conducts a major program to advance understanding of the connections between disease and environment in Africa. Its focus is animal-to-human disease transmission and its objective is to help move people out of poverty and promote social justice.

Over the past few decades, more than 60 per cent of emerging infectious diseases affecting humans have had their origin in wildlife or livestock. As well as presenting a threat of global disease outbreak, these zoonotic diseases are quietly devastating lives and livelihoods. At present, zoonoses are poorly understood and under-measured — and therefore under-prioritized in national and international health systems. There is great need for evidence and knowledge to inform effective, integrated One Health approaches to disease control. This Consortium is working to provide this evidence and knowledge.

Natural and social scientists in the Consortium are working to provide this evidence and knowledge for four zoonotic diseases, each affected in different ways by ecosystem changes and having different impacts on people’s health, wellbeing and livelihoods:

  • Henipavirus infection in Ghana
  • Rift Valley fever in Kenya
  • Lassa fever in Sierra Leone
  • Trypanosomiasis in Zambia and Zimbabwe

Of the 30 scientists working in the consortium, 4 are from ILRI: In addition to Delia Grace, these include Bernard Bett, a Kenyan veterinary epidemiologist with research interests in the transmission patterns of infectious diseases as well as the technical effectiveness of disease control measures; Steve Kemp, a British molecular geneticist particularly interested in the mechanisms of innate resistance to disease in livestock and mouse models, and Tom Randolph, an American agricultural economist whose research interests have included animal and human health issues and assessments of the impacts of disease control programs.

Delia Grace leads a program on Prevention and Control of Agriculture-associated Diseases, which is one of four components of a CGIAR Research Program on Agriculture for Nutrition and Health. Tom Randolph directs the CGIAR Research Program on Livestock and Fish. Steve Kemp is acting director of ILRI’s Biotechnology Theme.

 

 

Zoonoses: The lethal gifts of livestock–Part 3 of ILRI ‘livestock live talk’ by Delia Grace

View this ILRI slide presentation, which is a ‘slidecast’ that includes an audio file of a ‘livestock live talk’ given by veterinary epidemiologist Delia Grace at ILRI’s Nairobi headquarters on 31 Oct 2012.

The following remarks are a transcript of the third part of a presentation made on 31 Oct 2012  by Delia Grace, who works at the International Livestock Research Institute (ILRI), in Nairobi. Grace, a Irish veterinary epidemiologist, leads ILRI’s research on food safety in informal markets in developing countries and on ‘zoonoses’—diseases shared by animals and people. Grace also leads a component on agriculturally related diseases of a new multi-centre CGIAR Research Program on Agriculture for Health and Nutrition, which is headed by John McDermott, former deputy director general-research at ILRI, who is now based at ILRI’s sister CGIAR institute the International Food Policy Research Institute (IFPRI), in Washington, DC, USA. Grace is also a partner in another multi-institutional initiative, called Dynamic Drivers of Disease in Africa.

A prolific writer of scientific publications and a scientist of particularly wide research interests, Grace began her ‘big-picture’ talk on zoonoses—on why, and if, they are ‘the lethal gifts of livestock’—with an overview of human health and disease at the beginning of the 21st century. Go here to read part one:  The riders of the apocalypse do not ride alone: Plagues need war, famine, destruction–and (often) livestock, ILRI News Blog, 4 Nov 2012, and here to read part two: Mapping the perfect storms: Where poverty, livestock and disease meet in terrible triage, ILRI News Blog, 6 Nov 2012.

Here we begin the third and final part of this ILRI ‘livestock live talk’ presentation by Delia Grace on ‘The lethal gifts of livestock’.

‘So we’ve talked a bit about the big picture: human health and disease in the 21st century and why livestock matter. I’ve presented some of the findings on these studies, trying to get some evidence—the evidence decision-makers want, in a format they can use, in a way that motivates them to invest money.

Zoonoses: The Lethal Gifts of Livestock: From mapping to managing slide

Zoonoses: The Lethal Gifts of Livestock: From mapping to managing, by Delia Grace, ILRI ‘livestock live talk’ seminar, 31 Oct 2012.

‘But now, finally, I want to talk a bit about how we move from mapping to managing.

‘Mapping is good but there is always the “paralysis by analysis” with such organizations, And it’s true; I was originally trained as a vet and it’s like we spend all our time on diagnosis and we don’t do any therapy; we never get round to actual treatment. I think too much of the work we’ve done so far has been assessing, trying to know more and more, and not saying, “OK, we know enough; let’s go and do something; let’s show that we can do something; and let’s try and make a difference.

‘So in this last section I’m going to talk about how we are planning to move from mapping and measuring to managing. This takes me to the new CGIAR Research Program ‘Agriculture for Nutrition and Health’, which just started in January, like the CGIAR Research Program on Livestock and Fish, which you may be more familiar with.

‘This brings together a lot of CGIAR centres to focus for the first time on the links between agriculture and human health. It’s led by the International Food Policy Research Institute (IFPRI) and has four components. Three of these components focus on human nutrition—human nutrition is a big problem and it’s probably where the donors are most interest at the moment. But one component focuses on disease, and that’s the component that’s led by ILRI.

Zoonoses: The Lethal Gifts of Livestock: Agriculture-associated diseases slide

Zoonoses: The Lethal Gifts of Livestock: Agriculture-associated diseases, by Delia Grace, ILRI ‘livestock live talk’ seminar, 31 Oct 2012.

‘So “agriculture-associated disease” works at that intersection, the intersection between human health, animal health and agro-ecosystems and value chains. We sometimes talk about “one-health”, this new integrated movement. We like to think of three healths: people, animals and the planet—three healths that are interdependent. And if they’re managed separately, they won’t be managed best.

‘The aim of this component on disease is to have key development implementors as well as the enablers to have the evidence, motivation and capacity. So we need somehow to generate evidence, motivation and capacity, motivation probably being the tricky one, to reduce the burden of disease through agricultural-based interventions and innovations. And that’s key, because of course this whole area of innovation and human health is a very crowded, busy map. We need to identify where agricultural research and agricultural-based interventions can make a difference.

‘So what do we focus on? We focus on big five areas, which we call research activities. Two of them are under food safety, the first being risk management in these informal food markets, where most poor people buy and sell; the second being mycotoxins, which are a fungal toxin in staple crops. And then under “zoonoses”, we have three major focuses: the first being emerging infectious disease, the second neglected zoonoses, and the third “eco-health/one-health”, which is a kind of capacity-building paradigm.

‘Cross-cutting disease and appearing in all of them is a focus on gender and equity. Gender is quite important in disease because it’s both a biological and a social determinant of exposure and vulnerability to disease Equity likewise—poverty, age, other issues can very much affect susceptibility and vulnerability. The second is capacity building; this is key to change and we mean capacity building at all levels, from decision-makers to the science community to the actual farmers and value chain actors. Of course, we won’t be doing that directly; that’s not our comparative advantage. But we can develop pilot tools and new approached that can then be taken up by the development sector. And, third, communication and influence.

How do we get these messages out? How do we move from outputs to outcomes? And how do we show how those outcomes can contribute to impact?

‘There are some key assumptions or hypotheses. These are based on five to ten years’ work. At the same time, they’re not written in stone; they’re things we need to generate more evidence about. And many people would disagree with some or all of these.

‘So, first of all is that the informal food markets are the most important for poor buyers and consumers and will be—no ‘supermarketization’ here–and will be into the next few decades, at least in the countries we care about, where there are the most poor people.

Current food safety regulation is ineffective and unfair; we know it; we know it can even be paradoxical; we know it can make things worse. It’s kind of like the Somalia story—once you’ve got rid of the government, you’ve removed the first constraint to export. We find in many cases, these food safety regulations brought in to make things better make things worse. The way forward we believe is through risk- and incentive-based approaches.

‘The second main areas and the second main hypothesis is that these rapidly intensifying and urbanizing livestock systems are something the planet has never experienced before at this level and this rate, and it really does have the potential to bring about something very nasty. We talked at the beginning of great societal dislocations, of the Neolithic transition, of these massive plagues that wiped out ninety per cent of the population. I’m not saying it’s a fact, it may not even be probable, but it’s certainly something that cannot be ignored.

‘And at the moment, we are woefully ignorant of the disease dynamics and drivers and emergence of what’s going on in these new, novel, never-before seen systems, especially around South Asia, Southeast Asia and parts of the peri-urban areas of African cities. Here we think innovative surveillance—I showed you the surveillance we’ve got, 920,000 dead, 80,000 reported—so here we need innovative surveillance and whole-chain interventions. These are product-driven, demand-driven, rapidly emerging value chains and we need to work with the chain, not just work here and there in a piecemeal approach, as we have done in the past.

‘Our third big area are the cold spots. We sometimes emphasize the hotspots. These are places that are bubbling up, rapidly changing, doing strange things, lots of innovation going on, lots of possibility for thing to pop out of the cooking pot. But then we also have the cold spots, the neglected zoonoses, the pastoral areas, where you still have hundreds of millions of people cut off from markets, cut off from these emerging rapid opportunities, getting poorer and poorer, digging themselves deeper into poverty. And for these people, they’re the ones who are bearing the burden of these neglected zoonoses.

‘Take cysticercosis; you don’t have cysticercosis anymore in Vietnam, where you’ve got rapidly growing, highly innovative pig keepers. You get it in places in Uganda, where pigs are still scavenging and people don’t use latrines. So these people are still suffering from neglected zoonoses that have been eradicated everywhere anyone has got enough money and will power, and they’re symptoms of poverty, really; they’re symptoms of the whole complex. This is not a place for silver bullet approaches; this is a place for integrated approaches—taking a community wide, a gender approach, an equity approach—that deals with all the symptoms and not just the disease.

‘So those are our assumptions and how those assumptions affect what we’re going to be working on as we try and see how agriculture can do its little bit to help manage these diseases.

‘I’m going to give you a few examples before we finish and close for questions.

Zoonoses: The Lethal Gifts of Livestock: Highlight 1 slide

Zoonoses: The Lethal Gifts of Livestock: Highlight 1, by Delia Grace, ILRI ‘livestock live talk’ seminar, 31 Oct 2012.

So here is one highlight. One thing we’re doing this year is conducting rapid integrated assessments of food safety, zoonoses and nutrition in five high-potential CGIAR Research Program on Livestock and Fish value chains. This Livestock and Fish program has made the decision to focus on nine value chains in the whole world and really transform them, bring all of research with development partners to really change these value chains to move millions of people out of poverty. And these value chains are pre-selected as being one of these hotspots I’ve been talking about—rapidly changing, rapidly intensifying, lots going on. The Livestock and Fish program cares about production; they care about increasing productivity. They’re not necessarily thinking about the externalities of this, that they might unleash new diseases on the world, or make lots and lots of people sick by giving them more and more pork that is full of salmonella and trichomonas and things like that. So we see an added value of food safety working with those value chains, not just those in the Livestock and Fish program but in all the CGIAR research program value chains. And also, in many of these areas, food safety is not a standalone concern but if we can piggyback it on lots of other activities, then we can make it go further. Just a quick example—well, no I won’t. But ask me about pigs in Uganda sometime; it’s rather scary.

Zoonoses: The Lethal Gifts of Livestock: Highlight 2 slide

Zoonoses: The Lethal Gifts of Livestock: Highlight 2, by Delia Grace, ILRI ‘livestock live talk’ seminar, 31 Oct 2012.

‘The second highlight I mentioned before and I won’t go into it now but how this mapping and measuring we’re doing of the hotspots is already starting to inform donor agendas and we also want to be part of that funding, if we can be, to help manage what we have measured and mapped.

Zoonoses: The Lethal Gifts of Livestock: Highlight 3 slide

Zoonoses: The Lethal Gifts of Livestock: Highlight 3, by Delia Grace, ILRI ‘livestock live talk’ seminar, 31 Oct 2012.

‘And the third highlight is how these integrated approaches have started making a difference. And these highlights are things the whole of the CGIAR Research Program on Agriculture for Health and Nutrition has done during the year:
(1) Publishing special editions on urban zoonoses.
(2) Starting a new project on how the pathogens flow in Nairobi, from the abattoir to the dumps to the slums to the hospitals to the ILRI campus, and back and forth.
(3) Eco-health, one-health—we set up and are supporting two new centres in Southeast Asia and we’re looking at the barriers and bridges for governments doing things differently.
(4) Rift Valley fever—how does climate change and irrigation cause disease to jump around? We think it does; we want to know how.
(5) Pathogen hunting, here in our biotechnology facilities there’s a big pathogen hunting facility and now bio-repository. What are the implications of these new diseases getting into new systems?
(6) We’re integrating; instead of doing everything separately, we’re putting human and livestock disease surveys. We’re doing that in Kenya, Laos, Vietnam, China. There are some maps from Laos.
(7) Developing and testing new diagnostics; one thing main here has been for cysticercosis.

‘So in conclusion, here are my take-home messages. This is what I’d like people to think about.

‘First, here and now, the burden—the human sicknesses and deaths caused by neglected zoonoses—is much, much higher than that caused by emerging diseases. And most are very manageable. Moreover, the pareto law applies of the vital few and the trivial many. So these are places we can and must act to alleviate human misery.

‘Second, emerging infectious diseases are not so scary by themselves. But when you get a great societal dislocation, then they can be civilization-altering. And are we farming on the brink of chaos? We don’t know. It’s important that we find out, because this is one of the big questions for humanity’s future. Moreover, if societal dislocation is the missing ingredient X that nobody is talking about, we need to think about that, not just the disease.

‘And my final point is that agricultural research has an important role in integrative approaches to improve human health, animal health and the health of the planet.

Zoonoses: The Lethal Gifts of Livestock: Bibliography slide

Zoonoses: The Lethal Gifts of Livestock: bibliography slide, by Delia Grace, ILRI ‘livestock live talk’ seminar, 31 Oct 2012.

‘And here I just list some of the various chapters and papers that this presentation was based upon and where you can get more information if you are scared or skeptical or anything like that.

‘I’d like to acknowledge the mapping and spillover work, which is funded by the UK Department for International Development (DFID) and done with partners from different institutions, and the team leading the component on Agriculture-Associated Diseases of the CGIAR Research Program on Agriculture for Nutrition and Health, whose work I’m representing across food safety, mycotoxins, emerging infectious diseases, zoonoses and eco-health, and the many people who have supported us. And with that, I’ll hand it over to questions and to Tezira Lore to moderate.’

Notes
This ends the third and final part of the seminar by Delia Grace.

Part one of this seminar is here: The riders of the apocalypse do not ride alone: Plagues need war, famine, destruction–and (often) livestock, ILRI News Blog, 4 Nov 2012. Part two is here: Mapping the perfect storms: Where poverty, livestock and disease meet in terrible triage, ILRI News Blog, 6 Nov 2012.

View the slide presentation, which is a ‘slidecast’ that includes an audio file of the presentation by Grace: Zoonoses: The lethal gifts of livestock, an ILRI ‘livestock live talk’ by Delia Grace at ILRI’s Nairobi headquarters on 31 Oct 2012.

Read the invitation to this ILRI ‘livestock live talk’, and sign up here for our RSS feed on ILR’s Clippings Blog to see future invites to this new monthly seminar series.

 

Mapping the perfect storms: Where poverty, livestock and disease meet in terrible triage

The following remarks are a transcript of the second part of a presentation made last week by Delia Grace, who works at the International Livestock Research Institute (ILRI), in Nairobi. Grace, a Irish veterinary epidemiologist, leads ILRI’s research on food safety in informal markets in developing countries and on ‘zoonoses’—diseases shared by animals and people. Grace also leads a component on agriculturally related diseases of a new multi-centre CGIAR Research Program on Agriculture for Health and Nutrition, which is headed by John McDermott, former deputy director general-research at ILRI, who is now based at ILRI’s sister CGIAR institute the International Food Policy Research Institute (IFPRI), in Washington, DC, USA. Grace is also a partner in another multi-institutional initiative, called Dynamic Drivers of Disease in Africa.

A prolific writer of scientific publications and a scientist of particularly wide research interests, Grace began her ‘big-picture’ talk on zoonoses—on why, and if, they are ‘the lethal gifts of livestock’—with an overview of human health and disease at the beginning of the 21st century. Go here to read part one:  The riders of the apocalypse do not ride alone: Plagues need war, famine, destruction–and (often) livestock, ILRI News Blog, 4 Nov 2012.

Here we begin part two of this ILRI ‘livestock live talk’ presentation by Delia Grace on ‘The lethal gifts of livestock’.

Getting a handle on why zoonotic diseases matter, to whom and how much
‘So, we’ve discussed the links between livestock and disease and why livestock play such an important role in human disease. The next question we have to ask is to try and put some details on this, to put some parameters on it. So, if disease matters, and if animals have a big role in disease, what disease matters? How much? To whom? What does it cost? And what can we do about it?

‘In thinking through this, we tend to think at ILRI of different categories, which help us get more of a handle on some of the details. So we talk about the neglected zoonoses; these are the diseases like TB, brucellosis, cystercicosis—diseases that have been eradicated anywhere people have money and care, but persist—hang on—in poor countries. We talk about emerging infectious diseases—the BSEs, the SARS, the bird flus, Rift Valley fever, blue tongue—diseases that are changing their patterns and becoming more important. Then the food-borne diseases are the other big category. This is the single-most important. If you’re interested in human health and human death, food-borne diseases are the single-most important category. And finally, there are the other health risks in agro-ecosystems: How we farm and what this means for our health and nutrition.

Let the mapping begin
‘I now want to talk about some recent work we did on mapping poverty, zoonoses and emerging livestock systems in order to get a better handle on some of these questions about why it matters, who it matters to, how much it matters, and what we should or could do about it.

‘I’m going to present some work that was commissioned by DFID [the UK Department for International Development]. These were two systematic reviews that DFID asked us to do. The aim of these was to present data and expert knowledge on poverty and zoonoses hotspots in order to prioritize areas, to target areas, where prevention of zoonotic diseases can bring the greatest benefits to poor people.

‘This study took us down some interesting paths and some interesting conclusions. I’m going to talk about them in a little bit of detail.

‘So, the methods. What we wanted to do was to update global maps of poor livestock keepers. The first ever global map of poor livestock keepers was produced by ILRI around 10 or 15 years ago, again commissioned by DFID. This, I would say, was a landmark map. We also wanted to map rapidly emerging livestock systems. And here we drew a lot again on ILRI’s expertise, especially Mario Herrero’s group, which have been doing a lot of big-picture work on changes in livestock systems—what’s happening, where it’s happening and why it’s driving change. We also wanted to update one of the most iconic maps for people in the zoonoses community, and this is the map by Kate Jones on emerging infectious diseases that appeared in Nature about ten years ago (and everywhere else since).

‘We wanted to identify which were the most important zoonoses for poor people. You’d think that we’d know that, but what we find is that we have a dozen definitions and none of them agree. And then, finally, we wanted to develop the first global mapping of where zoonoses, poverty and emerging [livestock] systems come together to make hotspots, for maximum investments, for maximum bang for the buck.

Where are the poor livestock keepers?

Density of poor livestock keepers (updated 2012)

Update in 2012 by ILRI’s Delia Grace of map by ILRI’s Phil Thornton showing density of poor livestock keepers (map credit: ILRI/Philip Thornton).

‘Here is the updated map of poor livestock keepers. I think you can see by looking at it that it’s focal. The dark areas represent high density. South Asia jumps out at us. And in Africa we see the ‘magic 7’, from the coastal regions of West Africa to Nigeria and up through the highlands of Ethiopia and right down the Rift Valley through Uganda and northern Tanzania and right down to Malawi.

‘So what can we say in our updating of poor livestock keepers?

One billion poor livestock keepers depend on 19 billion livestock. Most of the livestock in the world are owned by poor people: 24 billion in total in the world and 19 billion in poor countries. That’s a lot of opportunities for disease to spill over, 19 billion animals.

What’s more, the ‘parietal law’, the law of ‘the vital few and the trivial many’, applies. Just 4 countries have 44 per cent of poor livestock keepers. All countries are not equal.

‘Livestock matter a lot: 75% of rural people, and 25% of urban people, depend on livestock. Now ‘depend’ is one of those weasel words that we keep being asked to shine more light on. We don’t know enough—it’s amazing how little we know despite how important this is—but our best guess for now is that when we say ‘depend’ we mean that livestock contribute between 2 and 33% of household income and 6 to 36% of protein. It’s not trivial.

Where are the fast-evolving livestock production systems?

Change in poultry production
Change in pig production
2012 maps showing changes in poultry and pig production between 2000 and 2030 (map credit ILRI/Delia Grace).

‘The second map we updated was these emerging livestock systems. As we suspected, most emergence is happening in the monogastrics, the pigs and the poultry. And of course this has been known since the landmark papers on the livestock revolution. Our maps confirm this; we’re getting a lot of change in pigs and poultry, and again it’s focal; you can see that it’s not uniform.

‘So in summary, where are we getting massive, rapidly changing systems? Big changes in numbers? Big changes in baselines? Where do we have people who don’t have a lot of experience doing this sort of farming now doing it in a big way? (Once you get naïveté along with massive intensification, you get problems.)

Poultry in several places on all continents, bovines in South and East Asia, and pigs in sub-Saharan Africa. These are the rapidly emerging livestock systems.

Where are the emerging infectious diseases?
‘Next, we updated the emerging infectious diseases map. This was a study that was originally done by Jones et al. based on all emerging diseases from 1940 to 2004. What we wanted to do was to focus just on zoonotic diseases (the 75% of all human disease that are zoonotic) and also to update it with data from 2004 to 2012.

Emerging Zoonotic Diseases Events 1940-2012

Map by IOZ, published in an ILRI report to DFID; Mapping of Poverty and Likely Zoonoses Hotspots 2012.

‘All of these dots represent new, potentially scary, diseases. The bigger the dot, the more the outbreaks. The new diseases are the blue circles; they are the ones that happened in the last ten years. The brown are the old; those are the ones that happened in the 70 years before. Again you can see a pattern here, but it’s not the same pattern we saw in the other map.

‘What we see is that western USA and western Europe are the hotspots for disease emergence. There’s a reporting bias in here, but we believe that this is not just reporting bias but actually represents emerging events. Interestingly, the blue events, the new events, are more common in South America and Southeast Asia, as intensification takes off in these regions and start to look more like intensive [livestock] systems of the West.

Multiple disease burdens are ‘where it’s at’
‘So, what are the high-priority zoonoses? We were interested in multiple [disease] burdens. One of the things we believe leads to bad management of zoonoses is that it’s done sectorally; it falls between lots of chairs. The World Health Organisation thinks about the human burden. The United Nations Food and Agriculture Organization thinks about the animal burden. Other people think about the wildlife burden. But people too rarely get together and think about the multiple burden.

What isn’t measured isn’t managed. And we think that one great step forward is just having people think about multiple burdens. So our listing, our criteria, consists of looking at the burdens across human health, animal health and ecosystems health.

‘From lots of listings, we assessed 56 zoonoses and found that together they caused a lot of problems. But the ones that were most important tended to have a wildlife interface, had a major impact on livestock and were amenable to on-farm agricultural interventions.

Top zoonoses calculated by ILRI's Delia Grace in 2012

Slide of ‘top zoonoses’ from ‘livestock live talk’ presentation, ‘Zoonoses: The Lethal Gifts of Livestock’, made by Delia Grace on 31 Oct 2012.

‘Just to give you some idea of the numbers, there are about 600 zoonoses and we looked at the top 50. Of that top 50, this is the human death caused by the top 13 and that by the next 43. Again, I think you can see it’s a case of the vital few and the trivial many. If you’ve got scarce resources and care about human death, you invest in the top 13, not in the bottom 43.

And here it is just broken out by individual zoonoses, and even in that top 13, you can see that there’s a difference between big killers and little killers. And sometime the ones we hear most about—and worry most about—are the ones that kill least.

‘The first thing we did then was to go to official reporting systems to try to find out where these zoonoses were and how these linked to the other things we were mapping. There are several reporting systems. There’s one by OIE [World Organisation for Animal Health], which is ‘notifiable’, that is, every OIE member has to report all their animals that die of notifiable diseases (you’d think that was easy enough). There’s also one run by FAO, and there’s Pro Med, there’s GEWS, and there’s Health Map, which is an aggregator.  That a picture of Health Map, and it’s a pretty exciting innovation. A ‘bot’ trawls the web and captures all the information on diseases.

When we put all of these [official disease reporting systems] together, what we found was that they were completely useless. They told us almost nothing about the burden of diseases. They told us about exciting things, interesting things. When a kid in Buenos Aires got bitten by a rabid dog, that showed up here. But when we were interested in what is sickening and killing billions and millions of people, it was just hopeless.

‘Just to give you an example, Africa has about 250 million tropical [aggregated] livestock units; we know that around 25 million of them die prematurely every year. We estimate around half of those deaths are due to notifiable diseases. There are over 60 notifiable diseases and pretty much everything falls into these. And what’s reported? Say 10 million dead, 80,000 reported.

This isn’t just under-reporting; this is a reporting system that is not very helpful!

‘So we couldn’t use the official reports. And it’s a huge weakness. People go along blindly and mechanically collecting this data, sending it in to OIE, doing complicated analyses showing all the different effects and impacts of these diseases, but they fail to take into account that they’re only looking at the 80,000 that are reported, and not the 920,000 that are not reported. It’s sort of an exercise in futility.

‘So what we did instead was a systematic literature review. We found that the only way we could get some sort of handle on where these zoonoses are was just to keep looking through the literature, pulling it out—grey, white, published, local language—and get as many surveys as we could and geographically map them and see what they are doing. In fact, we got over a thousand studies, which was enough to get some sort of a spatial understanding.

Greatest Burden of Zoonoses Falls on One Billion Poor Livestock Keepers

Map by ILRI, published in an ILRI report to DFID: Mapping of Poverty and Likely Zoonoses Hotspots, 2012.

‘This is what we came up with. Where you see a dot is where 1 or more people or animals in 100 are affected by 1 or more diseases per year. At least a 1%, at least 1 in 100 are sickened or killed. The dark colour shows where the poor livestock keepers are. Again, you can see the ‘7’ in Africa, whereby the zoonoses are linked to the poor livestock keepers. You can see quite a bit in South Asia and some in Southeast Asia.

‘There is a definite link between livestock keeping and poverty, which is what we suspected, but here again there is a lot of under reporting.

An unlucky 13 zoonoses sicken 2.4 billion people and kill 2.2 million people and they affect more than 1 in 7 livestock each year. These numbers are not trivial. These are large numbers, large numbers of sickness and death.

Our zoonotic problems are big problems

Multiple burdens of zoonoses calculated by ILRI's Delia Grace in 2012

Slide of ‘multiple burdens of zoonoses’ from ‘livestock live talk’ presentation, ‘Zoonoses: The Lethal Gifts of Livestock’, made by Delia Grace on 31 Oct 2012.

‘As I said, we focused on multiple burdens of  zoonoses, and here are some. I won’t read through them in detail, but again, going across all of these surveys, the numbers are frighteningly high. Round about 10% of animals have brucellosis, which is a serious disease in people, causing ungulant fever, infertility in men; it can cause psychosis and depression. And it’s transmitted in milk. If you don’t boil your milk, 1 in 10 animals has brucellosis. Ten per cent of animals in Africa have tryps [African animal trypanosomiasis], reducing their productivity by 15%. With 250 million livestock units, say they’re worth USD500 each, and you reduce their productivity by 15%—we’re talking large numbers here. TB, cysticercosis, bacterial food-borne disease, all of these came up.

‘The bad news is that it’s there and it’s a big problem in animals as well as people. The good news, of course, is that this provides incentive-based ways of tackling some of these zoonoses. Because if you can manage your animal zoonoses and boost your productivity by 10 or 20%, there’s a strong incentive for you to do it. What we’ve found with these studies (and we’ve been doing a lot of them over the years), is that too often the human health attitude is that people should do this because it’s good. You should do it to protect your own health. You should do it to protect the consumer’s health. That is one of the weakest motivations of all. How many things do we not do even though we know they’re good for our health? And how many fewer things do we do if they’re not good for our health but they’re good for someone else’s health?

Give people incentives, not rules, to better manage disease
‘What we find in these informal markets, where regulation is a joke and you have a hundred vets in a country and a hundred million animals, there’s no point in regulations or officials telling people “You should do this because it’s good for you”. It has to be incentive-based. People have to see a real benefit from changing their behaviour, either in their pocket or in their social status. And it doesn’t have to be money. We found people will change their behaviour just as much if they can get a social kick out of it. If instead of being a low-status person they get to be a high-status person, they’ll change their behaviour.

‘So, in summary what did we find? There are definite [zoonotic] hotspots, which is good, because that’s what the donor wanted  because that’s where the donor wants to invest. This is also a nice example of how science can generate evidence that is asked for by a donor and then influences donor behaviour, so it’s a virtuous cycle.

Where the ‘perfect storms’ lie
‘Poor livestock keepers? South Asia is the biggest. Emerging livestock systems? Again, South Asia. Zoonotic emerging infectious diseases? Western Europe and USA. Zoonoses? South Asia and central and eastern Africa.

If we are to name six countries where all of these come together, where you get the ‘perfect storm’ conditions, they are India, Bangladesh and Pakistan in Asia; Ethiopia, Nigeria and Congo in Africa.

‘So we’ve talked a bit about the big picture, human health and disease in the 21st century and why livestock matter. I’ve presented some of these findings of our mapping studies trying to get some evidence: the evidence that decision-makers want in a format they can use, in a way that motivates them to invest money.

‘But now, finally, I want to talk a bit about how we move from mapping to managing. . . .’

Notes
This ends part two of the seminar by Delia Grace. Look on this ILRI News Blog for part three in a couple of days’ time.

Part one of this seminar is here: The riders of the apocalypse do not ride alone: Plagues need war, famine, destruction–and (often) livestock, ILRI News Blog, 4 Nov 2012.

View the slide presentation, which is a ‘slidecast’ that includes an audio file of the presentation by Grace: Zoonoses: The lethal gifts of livestock, an ILRI ‘livestock live talk’ by Delia Grace at ILRI’s Nairobi headquarters on 31 Oct 2012.

Read the invitation to this ILRI ‘livestock live talk’, and sign up here for our RSS feed on ILR’s Clippings Blog to see future invites to this new monthly seminar series.

The riders of the apocalypse do not ride alone: Plagues need war, famine, destruction–and (often) livestock

Albrecht Dürer

a presentation made last week by Delia Grace, who works at the International Livestock Research Institute (ILRI), in Nairobi. Grace, a Irish veterinary epidemiologist, leads ILRI’s research on food safety in informal markets in developing countries and on ‘zoonoses’—diseases shared by animals and people. Grace also leads a component on agriculturally related diseases of a new multi-centre CGIAR Research Program on Agriculture for Health and Nutrition, which is headed by John McDermott, former deputy director general-research at ILRI, who is now based at ILRI’s sister CGIAR institute the International Food Policy Research Institute (IFPRI), in Washington, DC, USA. Grace is also a partner in another multi-institutional initiative, called Dynamic Drivers of Disease in Africa.

A prolific writer of scientific publications and a scientist of particularly wide research interests, Grace began her ‘big-picture’ talk on zoonoses—on why, and if, they are ‘the lethal gifts of livestock’—with an overview of human health and disease at the beginning of the 21st century.

'livestock live talk' 31 Oct 2012: Delia Grace listens to a question

Regarding diseases, it’s not the past we have to worry about, says ILRI scientist Delia Grace; it’s the diseases we’re picking up and the lifestyle choices we’re making (picture credit: ILRI/Susan MacMillan).

‘At the moment we are 7 billion people and by 2050, we’ll probably be 9 billion.

To date, farming is not doing a very good job of feeding us or looking after our health. We have 1 billion people who are hungry, 2 billion people who suffer from ‘hidden hunger’, or micronutrient deficiencies (iron, vitamins, minerals), and we 1.5 billion people who are overweight or obese. All in some ways functions of a dysfunctional agricultural system.

‘Not only does agriculture have an important role in nutrition, it also has an important role in health. And that’s going to be the main topic of my presentation.

‘But a few facts here just to get us in the mood.

‘Of our 7 billion people, 55 million die each year; 18 million die of infection. That’s preventable—there’s no reason now why anyone should die of an infectious disease. But to put that in perspective, there are lots of other preventable things that also kill people: 1.2 million people die each year in road traffic accidents, 170,000 from fatal agricultural accidents and 22,000 (and rising) from extreme weather events.

‘Of those people who die each year . . . two-thirds live in middle-income countries and most of those people die of lifestyle-associated diseases (cardio-vascular/chronic). About a sixth of those who die each year die in high-income countries, and most of them die from being just too old—they die from things like Alzheimer’s and stroke and cardiac disease, things that often come at the end of a life. And then there are the one-sixth who die in low-income countries, and what they die of are the ‘preventables’, mainly infectious diseases.

So, where do these infectious diseases come from? When we look at diseases as a whole, we can see that most are ‘earned’. The wages of sin may be death but the wages of lifestyle choice is disease.

‘The major causes of disease on this planet are the choices we make or the choices that are forced upon us: degenerative diseases, cardiac diseases, diabetes, stroke, cancer. Allergies and asthmas, which are probably reflections of a lifestyle that was not the way we were evolved to live. Those diseases are not the focus of this discussion.

‘What we are focusing on are the “souvenirs”, the diseases we pick up from other sources. And those sources are pretty much animals. Around 60 per cent of all human diseases are shared with animals, and of the new and emerging diseases, 75 per cent are “zoonotic”, that is, they come from animals. What’s more, of the 18 million people who die of infectious diseases each year, two of the biggest killers are zoonotic, or jumped from animals to people.

‘One thing that distinguishes the “souvenir” diseases is that many of these are diseases that kill people when they are young or in the prime of their life, when they have a future ahead of them.

We’re all going to die—that’s one thing that’s fairly inevitable. If we want to spend scarce resources doing something about making our planet more healthy and productive, it makes sense to invest in the souvenirs, the diseases we’ve acquired rather than these end-of-life diseases, about which nothing much can be done.

‘In fact, some economists argue it’s cheaper to let people die once they’ve reached a certain age than it is to invest in trying to make them better, because they’re not going to contribute much more to society.

The diseases that don’t matter so much we call the ‘legacies’. These are the diseases that have always been with us, the diseases that humans brought with them in their evolution from non-human primates. It’s interesting to see that these diseases (e.g., staph, lice, typhoid) are pretty much conquered. So it’s not the past we have to worry about; it’s what we’re picking up and the choices we’re making.

'livestock live talk' 31 Oct 2012: Richard Bishop asks Delia Grace a question

ILRI scientist Richard Bishop asks Delia Grace a question following her ‘livestock live talk’ on 31 Oct 2012 in Nairobi on the subject of ‘Zoonoses: The lethal gifts of livestock’ (photo credit: ILRI/Susan MacMillan).

‘So, how do these diseases get from animals into people, these 60 per cent of diseases that we share with animals? “Spillover” is the word. Here we see what we call an epidemiological or sylvatic cycle. That’s a little pathogen living in a kind of equilibrium with its wild host. By the usual evolutionary rules, once these pathogens have been living a long time with their hosts, they tend to co-evolve so that they get a little less malignant. Otherwise, if the pathogen kills all its hosts, it’s not good for its long-term survival. So what you tend to get are complex pristine ecosystems with lots of hosts and lots of pathogens, all in an evolutionary race but all staying in a relative status quo.

‘Once you bring in humans, you can get spillover. Once humans start coming into these pristine ecosystems and start messing with them—start killing lots of animals or butchering game meat or doing other things that happen when people invade pristine ecosystems—some of these pathogens can spill over into humans. What tends to happen when they first spill over is that they’re not adapted to humans: they kill them and that’s it. That’s what we tend to see with the ebola and marburg viruses; you’ve heard about these in Uganda. They spill over, they kill, that’s it. But if they get lots and lots of opportunities to spill over to people, evolution starts kicking in, too, and they now have got a new host, a new lease, so they’re going to start being able to be transmitted more readily, from human to human.

‘The other thing that can happen in these sylvatic cycles is the spillover can occur into livestock. This can be expected. Humans have contacts with wild animals, but livestock have many more. So we often see that livestock can act as a sort of bridge to bring these wild animal diseases into people. And that’s what we see with diseases such as the Nipah virus, diseases such as avian influenza and Rift Valley fever. The host is out there somewhere in the wild; often we don’t know where it is. It’s shocking to say: we still aren’t sure where the host for Rift Valley fever is, we just don’t know. But we know it gets into livestock, and from livestock it gets into people. People can be a dead-end host—the virus can get in, sicken and kill and that’s it—or the virus can gradually start adapting to humans.

‘Some of the factors that can help this transition are increasing the densities, increasing the contacts, increasing the amount of pathogen in the environment, but also other things like habitat change, biodiversity, vector density, host density.

I would argue—this is a little bit provocative and not everyone would agree—that spillovers happen all of the time and most of the time just aren’t any big deal. A lot of the present effort to control emerging infectious diseases is perhaps not well directed because we’re dealing with problems that are intrinsically self-limiting. However, when you look back at history, in order for a spillover to become a disaster—in order for a spillover to become a pandemic, a civilization-altering disease—you need something else. I think this missing ingredient is great societal dislocation.

‘And that’s what history shows. The first big transition was the Neolithic transition. I’m going to come back to that because it’s important. Other examples, from the 13th to the 15th centuries, Europe went through a little Ice Age—we talk about climate change making it hotter today; then, it got colder. People got hungry, people, starved, people moved; you got Black Death and it killed one in three.

‘When they opened up the New World and when people came to the Americas, something like 90 per cent of the population died in the Americas, from smallpox, from measles. This is what we call ‘virgin soil’ epidemics; people who had no immunity; why? because they hadn’t hung out with livestock for long enough, according to some people, so people just died in droves.

‘But it wasn’t just a disease—it was the collapse of their society, the collapse of a highly advanced, highly stable, highly functioning society. It was destroyed from the outside and the disease came in.

The riders of the Apocalypse do not ride alone. Plague by itself needs war, needs famine, needs destruction.

‘We saw the same in the First World War, with the trenches and that massive societal misery, which led to Spanish flu and 40 million dying, and colonialization and urbanization in Africa in the early 20th century leading to HIV.

Disease spillover + societal dislocation = pandemic

Slide from ‘livestock live talk’ by Delia Grace on 31 Oct 2012 (slide by ILRI/Delia Grace).

 

‘Some argue and some spend millions of dollars hearing that we are about to enter a new time of unprecedented societal dislocation. As we get massive population increases, massive climate change, massive global destruction, we’re in for another big plague.

‘Let’s look at the first epidemiological transition, just to take us back to history and to show how domestication leads to disease. The first [animal we domesticated] was the dog [15,000–30,000 BC], and some would argue that the dog domesticated us, and the last was the goose (1,500 BC), and anyone who has been chased around a farm by a goose knows that they are as yet imperfectly domesticated!

But between the dog and the goose, there’s been a long range of domestication and the animals brought disease with them, diseases we tend to think of as human diseases; measles, mumps, diptheria, flu, smallpox, they all jumped from animals, many of them from livestock.

Disease and livestock domestication

Slide from ‘livestock live talk’ by Delia Grace on 31 Oct 2012 (slide by ILRI/Delia Grace).

 

‘And of course this is a dynamic: once they jumped in they can jump back; other diseases jumped from people to livestock, and once they were in the livestock, they came back again.

‘So that was the link between livestock and disease and why livestock play such an important role in human disease.

‘The next question we have to answer is to try and put some details on this, try and put some parameters on it. If disease matters, and if animals play a big role in disease, what disease matters? how much? to whom? what does it cost? what can we do about it? . . .’

This ends part one of this ILRI ‘livestock live talk’ presentation by Delia Grace on ‘The lethal gifts of livestock’. Check back here tomorrow for part two.

Read the invitation to this ILRI ‘livestock live talk’, and sign up here for our RSS feed on ILR’s Clippings Blog to see future invites to this new monthly seminar series.

View the slide presentation: Zoonoses: The lethal gifts of livestock, an ILRI ‘livestock live talk’ by Delia Grace at ILRI’s Nairobi headquarters on 31 Oct 2012.