In 2012, the Dynamic Drivers of Disease in Africa Consortium embarked upon an ambitious programme of research to investigate the links between the environment and those diseases, called 'zoonoses', that can transmit from animals to people.
Zoonoses can kill people and animals. Even when they don’t kill, their effects can devastate poor people's lives and hamper development efforts. They can also cross countries and continents with alarming speed.
Yet poorly understood, and consequently underdiagnosed, most zoonoses remain under-prioritised in national and international health systems.
We wanted to understand the complex relationships between disease, ecosystems and poverty - and in particular how wider global patterns such as climate and land-use change affect how diseases emerge and spread.
Led by the ESRC STEPS Centre (Institute of Development Studies/University of Sussex), the Consortium brought together social and natural scientists from 21 research institutes and government bodies in Africa, Europe and the US in a unique multidisciplinary endeavour.
Over the past four years we have published and presented widely. We encourage you to explore our academic and other outputs, all accessible via our Consortium website.
Here, though we want to take the opportunity to show how our research is making a difference, right now, in the real world.
WITH THE Ebola epidemic in recent memory, bats –believed by many to have been the source of the Ebola outbreak – have become widely vilified. Though the origin of the 2014/15 crisis remains unclear, these night-time flying mammals are nevertheless known to carry and transmit many dangerous viruses – and the straw-coloured fruit bat (Eidolon helvum), which occurs in vast numbers in Ghana, is known to carry Henipaviruses. These can cause illness and death in people and domestic animals.
However bats also play an important role in many ecosystems. For example, they are an important pollinator. It's therefore essential to conserve bat populations while at the same time minimising the
possibility of bat-borne disease spread.
A BALANCING ACT
Our Ghana team wanted to assess community perceptions of bats. Their aim: to understand how these influence human-bat interactions – and therefore the risk of people acquiring diseases from the animals. Although Henipavirus infection has to date not been recorded among people in Ghana, this is most likely because it has never been looked for.
A ‘citizen science’ approach, in which the team asked the public to report locations of bat colonies, showed bats occurring in far greater numbers and far closer to people than previously thought – showing a much higher nationwide risk of transmission of bat-borne diseases than initially thought.
Eighty-six towns and villages were reported to have bat roosts, with the roosts occurring across all regions and ecological zones. Only 10 of these were previously known. Most roosts are in the heart of towns or close to where people live, for example in hospital and school compounds, markets places and bus stations. Commonly they are in trees within the compound of houses where people relax or prepare food.
Participatory work undertaken with a wide variety of stakeholders was used to find out how people felt towards the animals they live so closely alongside.
Unsurprisingly perhaps, people's feelings were found to be closely linked with the benefits obtained from the bats. Economic benefits from, for example, hunting or tourism, were especially important.
People’s proximity to roosting sites and their religious and cultural beliefs were also significant though. Some people had very negative attitudes towards bats, describing how the animals defecate and urinate on clothes, cars and other property, as well as their unpleasant noise, ‘hideous’ looks and ‘foul’ smell.
Overall, the findings illuminated the variety and extent of human-bat interactions – and from this the team could identify the groups of people most at risk of bat-borne disease. These are:
• Fruit farmers
• People living or working close to the bat roosts.
Policymakers and public health officials can now use this information to develop effective strategies and target public health messages. This will ensure that people can interact safely with bats without exposing themselves to risks of disease transmission – or, importantly, compromising bat conservation.
· Download this impact story (pdf)
Consortium partners for the Ghana case study were: in Ghana, University of Ghana and Wildlife Division of the Forestry Commission; and in the UK, ESRC STEPS Centre (IDS/University of Sussex), Institute of Zoology and University of Cambridge.
RIFT VALLEY fever (RVF) is a disease with the potential to wipe out household livelihoods, devastate communities and severely damage national economies. It is a disease of sheep, goats, cattle and camels, and is caused by a virus carried by mosquitoes. It can also be transmitted to people through the body fluids of infected animals.
In livestock, it causes abortions, stillbirths and the early death of young animals, and so severely affects livestock production, including herd viability. In people, it mainly causes a flu-like illness, though in rare cases it can be severe, even resulting in death.
RVF is common in East Africa, where it is regularly found at low levels within communities. There are also periodic epidemic outbreaks.
RVF has major impacts on poverty and wellbeing. Pastoralists in particular are affected as they are dependent on their animals for their food and income. RVF is also a trade-sensitive disease as livestock trade bans usually follow an outbreak. The 2006/7 RVF epidemic was estimated to have cost the Kenyan economy US$32 million.
RELIABLE RISK MAPS
When our researchers in Kenya started work, epidemic patterns of RVF, and in particular its association with El Niño weather patterns, had been well documented. However, there was little knowledge on other disease drivers.
Importantly, there were no reliable guidelines, tools or procedures that could be used to guide emergency response measures in the event of an outbreak or warnings of one.
In the past, inertia arising from failure to recognise risk and act accordingly was in part responsible for the huge losses associated with outbreaks. Insufficient capacity offered by decision makers to mount preventative and response measures was also an issue.
The multidisciplinary team consulted with decision makers throughout the research process. The result: practical tools to prepare for potential emergency as well as for application in times of expected or actual emergency.
In particular, known disease hotspots were geo-referenced and analysed with detailed data on precipitation, rainfall, soil types, land use and vegetation to produce RVF risk maps. These maps have replaced existing ones which were, to a large extent, insufficiently detailed.
In late 2015, as meteorological forecasts warned of an El Niño occurrence, the maps were an essential component of the Kenyan government’s strategy of disease monitoring and containment.
Looking ahead, the risk maps have the potential to be used as a trade negotiation tool too, as they can identify ‘clean’ areas where livestock trade can take place with limited risk of spreading the disease. This could spell an end to blanket trade bans with their disastrous consequences for livelihoods.
In addition, combined with data which define communities' various vulnerabilities, the maps can be used to determine how best to respond to an outbreak.
· Download this impact story (pdf)
ENDEMIC RVF AND IRRIGATION
While epidemic occurrences of RVF have huge, known impacts and can make global headlines, the extent of its low-level but persistent occurrence within particular areas has been less well understood and little investigated.
This endemic transmission of RVF was known to be common in rural areas near rivers in Kenya. But its impact and the identification of the potential drivers of it, such as land-use change, had not been identified.
Our team found that knowledge of how people acquire RVF was poor, with people in irrigated areas showing considerably less knowledge of the disease than those in pastoral areas. This has significant risk implications as far greater numbers of people in riverine and irrigated areas tested positive for RVF than in pastoral ones.
The density of mosquitoes was also found to be relatively high in irrigated areas, most likely because large masses of standing water make good breeding grounds for the insects.
In addition, the analysis of land-use changes showed that the conversion of rangeland into crop land through irrigation has led to extensive habitat degradation and reduced biodiversity.
The team is now using this information to develop an RVF dynamics model integrating the epidemiological processes involved in disease transmission and socio-economic factors for estimating impacts. This can then be used to bring the impacts of endemic infections to light and – importantly – to identify intervention measures.
· Download this impact story (pdf)
Consortium partners for the Kenya case study were: International Livestock Research Institute (ILRI), Kenya Directorate of Veterinary Services, Kenya Medical Research Institute (KEMRI) and University of Nairobi.
THE MULTIMAMMATE RODENT...
in Sierra Leone
IN PARTS of West Africa, Lassa fever is endemic. In Sierra Leone, it adds significantly to the health burdens, poverty and vulnerabilities faced by people.
Transmission is known to be usually via Mastomys natalensis, a common rodent in the region. However, until recently there had been little research into the disease. That which existed chiefly consisted of laboratory-based studies as the Lassa virus is considered one of the world’s most dangerous organisms and a potential bioweapon.
Our Sierra Leone team wanted to take a more holistic approach, understanding the disease’s social and environmental drivers. This work found unexpected relevance when the 2014/15 Ebola epidemic swept through Sierra Leone, Guinea and Liberia.
THE VALUE OF LOCAL KNOWLEDGE
Lassa fever is one of a group of illnesses known as viral haemorrhagic fevers. Severe cases cause internal bleeding and often lead to death. Estimates of its incidence in West Africa vary widely, from 100,000 to 13 million infections, and 5,000 to 67,000 deaths, each year.
When the Ebola epidemic hit in 2014, many aspects of our research had to stop. Movement restrictions were imposed, and laboratory and clinic facilities were turned over to Ebola work.
However, much of the learning about the social dynamics, and in particular local understandings, of Lassa fever which had already been undertaken was found to be applicable to Ebola. Ebola has similar symptoms to Lassa fever, and like Lassa fever also has an animal host which mediates virus transmission.
As the public health response to the Ebola epidemic in West Africa faltered for a variety of reasons, our team worked with partners in both the UK and Sierra Leone to form the Ebola Response Anthropology Platform (ERAP), funded by Wellcome/UK Department for International Development (DFID). This became a focal point for anthropological advice in the UK and internationally. It delivered real-time evidence-based advice to organisations such as DFID, the UK Ministry of Defence, the World Health Organization (WHO), the UN Mission for Ebola Emergency Response (UNMEER) and many others.
ERAP members provided valuable insight into the social dimensions of:
• identifying and diagnosing cases,
• managing death and funerals,
• caring for the sick,
• clinical trials and research, and
• communications and community engagement.
The website energised US, European and West African networks and was accessed by more than 16,000 users. ERAP had a major influence on UK Government strategy.
The initiative achieved unprecedented recognition of the relevance of anthropological research for responses to infectious diseases – as well as illustrating how learning can have impact in the most surprising and unforeseen of ways.
· Download this impact story (pdf)
Consortium partners for the Sierra Leone case study were: in Sierra Leone, Njala University and Kenema Government Hospital; in the UK, ESRC STEPS Centre (IDS/University of Sussex, University of Cambridge and University College London; and in the USA, Tulane University.
• Final image: UNMEER/Martine Perrett
THE TSETSE FLY...
in Zimbabwe and Zambia
THE TSETSE fly is a major problem in Zimbabwe and Zambia. The fly can transmit a parasite that in people causes sleeping sickness (human trypanosomiasis), a disease that is fatal if not properly treated. Yet the seriousness of the problem is largely hidden. Local people sometimes fail to report outbreaks, very often because sleeping sickness is easily confused with malaria and sometimes attributed to witchcraft.
In addition, tsetse can carry a related parasite that causes the disease nagana (animal trypanosomiasis) in animals. Nagana causes severe production losses in livestock and is a major concern for the millions of poor farmers who depend upon their animals for their livelihoods.
TALKING TO LOCALS
Our Zimbabwe team wanted to investigate whether tsetse were present and, if so, where the fly was distributed along the Zambezi Valley. A lack of official knowledge had in recent years been a major obstacle to tackling the tsetse problem.
Government researchers had carried out tsetse surveys but the traps were only occasionally monitored and often they were found damaged or vandalised. The trap cloth in particular would be stolen to be made into clothes.
The result was that the ministries of health and agriculture found no evidence of tsetse at their study sites and no longer considered tsetse a problem in settled areas and control operations were suspended.
Our researchers found more survey success by interesting Valley inhabitants in the research and encouraging them to participate. In this way, and through group-based participatory mapping activities, six sites were identified as potentially harbouring the fly. Traps were deployed in these sites and the villagers committed to protect them.
The findings were surprising – and at odds with those of government surveillance. The message was clear: acting on their own, government researchers cannot learn about tsetse distribution.
Our research had enabled villagers and their traditional authorities to learn about tsetse research and to have a role in it. With a new vested interest in the research came a new attitude and a new cooperation.
One traditional leader told our researchers: “We are now researchers here and eyes for government as far as tsetse survey is concerned. From now on, traps for survey work are safe, because these are for our benefit.”
And the exercise provided a wake-up call to government. As one senior government official admitted: “We now know we have a problem in our yard and must do something to deal with the fly.”
· Download this impact story (pdf)
SAFE AREAS TO SETTLE
Our multidisciplinary research has some real practical policy implications too. The findings showed not only that tsetse persist, but that the fly is increasingly confined to low-lying areas, waterways and thick bushes. These patches have water, pastures and wildlife – an ideal combination for the tsetse.
Trypanosomiasis transmission, it seems, occurs when people encroach into these fly-ridden patches. Sometimes too, though, wildlife emerge from these areas, bringing the fly with them. In this way, even goats and cattle in settled areas can become infected.
Previously, in order to reduce tsetse populations, huge swathes of tsetse habitat have been targeted. Our work suggests localised control campaigns may be more appropriate.
By focusing on the high-risk patches, government can ensure the problem is dealt with effectively, allowing safe settlement to take place in the cleared areas. This could be a major contribution to poverty alleviation in Zimbabwe, where land for settlement and farming is in short supply.
This more targeted approach would not only be more effective than mass eradication efforts, it could also save government money – as well as serving to safeguard human lives and Zimbabwe’s US$24 million cattle industry.
· Download this impact story (pdf)
Consortium partners for the Zimbabwe case study were: in Zimbabwe, University of Zimbabwe and Ministry of Agriculture, Mechanisation and Irrigation Development; and in the UK, ESRC STEPS Centre (IDS/University of Sussex), Lancaster University, University of Edinburgh and University of Southampton.
COMMUNITIES IN FLUX
OUR ZAMBIA team wanted to find out how dramatic changes in land use in the mid-Luangwa Valley in Zambia’s Eastern Province have affected tsetse and trypanosomiasis.
The area has historically been known for its abundant tsetse population and, accordingly, few cattle have been kept there. Residents grew crops and hunted for bushmeat, but people mostly lived and farmed on the plateau over 50km away.
However, the past three decades have seen Zambia’s population more than double, driving a huge increase in the demand for land for cultivation and livestock rearing.
Investigating the migration pattern in the area, our team identified a mobile population setting up new homesteads, often in response to declining soil fertility. Google Earth images show a mosaic of new fields in the woodland. Cotton, a key component of the cash economy, was found to be grown by 85% of households.
Our team also found that tsetse densities are low, reflecting loss of their preferred woodland habitat and, possibly, the use of pesticides on cotton fields. Still, blood sampling showed that nagana was present in just under a quarter of cattle.
A clear picture of local concerns emerged during focus group discussions. In particular, the communities’ relationships with wildlife were seen to be complex and often unsatisfactory. While wildlife remain a source of illegal bushmeat, they also cause crop damage and endanger lives, and benefits to households from wildlife tourism often fail to mitigate these downsides for those living on the boundaries of the National Park.
Our research established a new baseline for monitoring the tsetse population, nagana in livestock and the risk of sleeping sickness in people.
Importantly, it also enabled communities to make their views heard. The feedback sessions acted as a vehicle for discussing with local people the diseases they face, as well as those emerging, for example cysticercosis, a disease diagnosed in pigs in that area for the first time by our team and which causes epilepsy and seizures in people.
The household interviews highlighted the poverty of the people in these shifting settlements. Their health and that of the animals they depend on is precarious.
Resources are limited and the best option for local populations to access health, veterinary and other services can be to set up farming groups which can club together to buy drugs or ask for support. This was an option explored during our feedback workshops.
The relationships and trust built during the research between the researchers and local people, their chiefs, teachers, human and animal health workers and agricultural extension agents are now set to act as a focus for future disease surveillance, community education and empowerment.
· Download this impact story (pdf)
MODELLING FOR PUBLIC HEALTH
Disease modelling is invaluable for informing public health messages and interventions. But the sleeping sickness disease system is complex, making modelling it particularly challenging.
Many wild animals and all domestic ones are capable of carrying the trypanosomiasis parasite and the risk of being bitten by an infected tsetse fly is not distributed evenly across the Luangwa Valley. The behaviour of individuals varies according to their livelihoods and their position in the household, and this in turn influences their risk of infection.
Our researchers though have successfully developed a mathematical model to represent this complex disease system by incorporating human, livestock and tsetse populations alongside important behavioural, ecological and physical characteristics.
It was informed by a range of multidisciplinary activities including a household and livestock census, focus groups, transect walks, a tsetse survey and mapping work used to find out about people’s daily routines.
Information on people's activities such as collecting water and firewood, washing clothes by streams, grazing livestock and checking beehives all provided insights into which parts of daily routines and livelihood activities are most risky, and which people are most at risk from disease, for example by gender, age group or livelihood.
In this way, an ‘agent-based model’ – a method for simulating disease transmission in a complex system with separately acting ‘agents’ – was created in which the agents included people, livestock and tsetse.
The resulting model predicted one or two human infections in a six-month period, an accurate representation of the real situation.
This model has valuable practical application. It can be used to study the impact of changes in human or livestock populations on disease transmission. In turn, it can be used to guide disease prevention strategies.
In particular, it can be used to test the conditions in which livestock can become the primary disease ‘reservoir’ (i.e. harbour the disease-causing parasite) if wildlife populations decline further than they already have.
The model can now help guide policy formulation at the national level and provide guidance through veterinary officers on managing animal health to local communities. It can also inform development policies so that risk to local people can be minimised and environmental sustainability enhanced.
· Download this impact story (pdf)
Consortium partners for the Zambia case study were: in Zambia, University of Zambia and Ministry of Fisheries and Livestock; and in the UK, ESRC STEPS Centre (IDS/University of Sussex), Lancaster University, University of Edinburgh and University of Southampton.
DISEASE OUTBREAKS: IS IT POSSIBLE TO PREPARE?
Humans are fundamentally shaping the face of our planet. Climate change, land-use change, urbanisation and more are likely to affect human health in many ways.
A scenarios approaches may be one way to shed light on the complex processes at play in determining disease risk – and so prepare for the possibility of large-scale outbreaks of zoonotic disease that human-wrought changes to the planet may bring.
Scenarios modelling can:
• Identify possible futures
• Start discussion about a desirable future
• Help decision-makers and communities take action to create more resilient societies.
ONE HEALTH FOR THE REAL WORLD
The Dynamic Drivers of Disease in Africa Consortium embraced a One Health approach.
One Health recognises that only by considering animal and environmental health alongside human health can better and more effective poverty and public health interventions emerge.
For our research, this meant epidemiologists, GIS mappers, veterinarians, social anthropologists, ecologists, economists and other experts working alongside each other. And beyond that it meant, wherever possible, integrating their findings to enable a truly holistic evidence base to emerge.
To explore further what One Health for the real world means, explore the presentations, videos, blogs and media coverage from our two-day high-level symposium of the same name.
The Dynamic Drivers of Disease in Africa Consortium was funded with support from the Ecosystem Services for Poverty Alleviation (ESPA) programme. ESPA is a global development research programme funded by the UK Government, supported by the Natural Environment Research Council, Department for International Development and the Economic and Social Research Council. ESPA aims to provide new world-class research evidence demonstrating how ecosystem services can reduce poverty and enhance wellbeing for the world’s poor.
The Dynamic Drivers of Disease in Africa Consortium was led by the ESRC STEPS Centre (IDS/University of Sussex).
Other partners were: UK: Institute of Zoology, Lancaster University, University of Cambridge, University College London, University of Edinburgh and University of Southampton. Ghana: University of Ghana and Wildlife Division of the Forestry Commission. Kenya: Department of Veterinary Services, International Livestock Research Institute, Kenya Medical Research Institute and University of Nairobi. Sierra Leone: Kenema Government Hospital and Njala University. Zambia: Ministry of Fisheries and Livestock and University of Zambia. Zimbabwe: Ministry of Agriculture, Mechanization and Irrigation Development and University of Zimbabwe. Sweden: Stockholm Resilience Centre. USA: Tulane University.