Recently, I visited Ghana as part of the Dynamic Drivers of Disease in Africa Consortium which is focused on zoonoses, animal diseases which can be passed on to humans. During the trip, other partners in the Consortium and I conducted some planning and fieldwork, including participatory mapping, the work being led by the Ghana team.
The Consortium as a whole is considering four zoonoses in five countries. In Ghana, we are looking into Henipavirus infection which is found in bats and can potentially cause fatal disease in people. We are especially interested in the effects of ecosystem services and how land-use change may be affecting the likelihood of virus spillover. This could happen due to bat roosting and feeding patterns changing and affecting direct and indirect interactions with people and their livestock. Our project is interdisciplinary so we are looking at many different areas, including tagging bats to see their movement patterns, counting bats and taking blood samples to analyse.
The aim of the trip was to trial some social science methods we have been using in Sierra Leone to look at Lassa fever. Our social science work will focus on several key areas, including:
- how people perceive bats and their relationship with ecology and disease
- how people experience and seek treatment for fevers
- how people interact with different ecosystem services across seasons as part of their livelihoods, and
- what activities bring people into contact with bats and how this affects their risk of disease.
Participatory mapping was chosen to look into some of these issues and this worked really well in Sierra Leone, allowing us to produce a landscape map of crops and other areas (and what seasons different work was done in), in order to find out where people saw Mastomys (the rodent vector for Lassa fever virus) and also construct a participatory epidemiological map showing where in the village people who had been sick lived and how this related to the crops in the area and the number of rodents seen. When interrogated this gave us further information to investigate further. For example the map showed schoolboys to be a risk group for fever and, when questioned, villagers talked of boys hunting cats and rats, giving one possible explanation for this and further areas to investigate. This work will also help prepare the team for future interviews and surveys by providing areas to explore in these.
Additionally, the participatory mapping in Sierra Leone has been planned to interlink with the other disciplines. For example, the seasonal movements of men and women gained from the mapping can be compared with the epidemiological data on prevalence of disease. This can be triangulated with fevers identified in the participatory work as well as looking at the village-made epidemiological map and comparing it to the blood sample data.
So, we were keen to try out these methods in Ghana and see if they could be applied to another disease and location. To do this, we drove for seven hours to one of the case study sites – our plan being to try out participatory landscape mapping, epidemiological mapping and matrix scoring.
The landscape mapping of the village and farming areas went well and there was a dynamic and animated discussion amongst many villagers marking out where things in the village are. The roads were drawn first so the houses could then be plotted more accurately. There were mainly men in the group, but the team will go back and undertake a separate exercise with female villagers, so we can ensure both genders are represented.
There were though additional challenges to the work in Ghana due to the more elusive reservoir animal – the bat. In Sierra Leone, people could detail where rodents (the focus animals there) lived and ate, whereas in Ghana, people rarely saw bats, and not up close unless they were hunting them. The main indication of bats was the evidence of their presence they left behind rather than sightings.
Bats also created further work in another sense. As they visit many locations we have decided to extend the case study sites to the human population at the different bat roosts, and also another site within 60km of each roost, along the bat feeding route so comparisons can be made. These sites will be identified using data from the other disciplines who are tracking bat movements.
The very low known disease prevalence meant that studying fevers was also more of a challenge in Ghana than it had been in Sierra Leone. However, changes have been made to work around this issue. The fieldwork identified that people suffer from fevers more between May and July and so the team will go back to discuss fevers and attempt an epidemiological map in July, to assist recall for the fevers. Alternatively, we may discuss this during interviews with villagers and a map made from the information gained. The team will also conduct a survey. Human blood samples will be taken by other team members from different disciplines and the social science team will, to a large extent, ensure that they sample the same people for the survey so that the data is comparable.
Lastly, the matrix scoring provided us with some useful information. This work showed that people could clearly identify different types of bats and information about them but they could only identify two different types of fever, neither with clear diagnostic links.
All the information gained from the fieldwork was put into the social science fieldwork plans for the project and will be useful for comparisons with the other disciplines in Ghana and the other countries involved in the project, Kenya, Zambia, Zimbabwe and, of course, Sierra Leone.
by Catherine Holley, Research Officer, Dynamic Drivers of Disease in Africa and HEART Research Officer
Images: ‘Participatory mapping’ and ‘Matrix scoring’ . Credit: Catherine Holley.