key: cord-0836888-3pn04u32
authors: Gaddy, Hampton Gray
title: Using local knowledge in emerging infectious disease research
date: 2020-06-13
journal: Soc Sci Med
DOI: 10.1016/j.socscimed.2020.113107
sha: 3c13e61370089eeeee0009518f288ea4ab6f3155
doc_id: 836888
cord_uid: 3pn04u32

Emerging infectious diseases (EIDs) are a growing global health threat. The best research protocol to date on predicting and preventing infectious disease emergence states that urgent research must commence to identify unknown human and animal pathogens. This short communication proposes that the ethnobiological knowledge of indigenous and impoverished communities can be a source of information about some of those unknown pathogens. I present the ecological and anthropological theory behind this proposal, as well as a few case studies that serve as a limited proof of concept. This paper also serves as a call to arms for the medical anthropology community. It gives a brief primer on the EID crisis and how anthropology research may be vital to limiting its havoc on global health. Local knowledge is not likely to play a major role in EID research initiatives, but the use of the incorporation of EID awareness into standard medical anthropological practice would have myriad benefits, even if no EIDs were discovered this way.

Emerging infectious diseases (EIDs) present a major threat to global health.

They are communicable human diseases that have recently grown in their geographic and/or host range. For example, West Never fever, Lyme disease, and methicillinresistant Staphylococcus aureus (MRSA) are EIDs that have that spread geographically in recent decades. EIDs that have recently jumped the species barrier from infecting non-humans to infecting humans are called zoonoses, and they include Ebola virus disease, HIV/AIDS, and COVID-19. Zoonoses comprise about 75% of all EIDs that have emerged in recent years, and they are especially feared for the toll they could take on global health over time (World Health Organization, 2014) .

That toll is expected to grow. The 20 th century paradigm of host-pathogen interaction suggests that species barriers should be very difficult for pathogens to overcome, but the Stockholm Paradigm, a new but well-substantiated understanding of pathogens, challenges this. It proposes that species barriers tend to be much lower than previously thought and will tend to fall significantly in the face of anthropogenic environmental change (Brooks et al., 2014 (Brooks et al., , 2019 . For example, climate change is already associated with many recent vector-borne disease outbreaks (Reisen, 2015) , since the 1980s, EIDs have been discovered at a rate of more than three per year (Woolhouse & Gaunt, 2007) , and that rate has been increasing since the 1940s (Jones et al., 2008) . As such, researchers from various disciplines view EIDs as a growing crisis-one that requires interdisciplinary research, especially in order to limit infectious disease emergence (Parkes et al., 2005; Goodwin et al., 2012; Brooks et al., 2019) .

This paper aims to contribute to that research agenda.

The main research protocol for preventing infectious disease emergence is DAMA (documentation-assessment-monitoring-action). It proposes an integrated research initiative to isolate and categorize unknown pathogens ('documentation'), identify which are most likely to become EIDs ('assessment'), develop surveillance networks for those pathogens ('monitoring'), and take proactive steps to minimize human exposure to them ('action') (Brooks et al., 2014 (Brooks et al., , 2019 . DAMA is still very much on its first phase of implementation. The largest research program that has studied zoonosis emergence was PREDICT, a ten-year effort funded by the U.S. Agency for International Development (USAID) and launched in 2009. It focused on isolating pathogens from animals in likely hotspots of zoonotic emergence, i.e. low-income areas of Africa and Asia (Kelly et al., 2017) . As yet, that seems to be the only tested strategy for 'documentation.' This paper suggests that utilizing local knowledge may also be a useful strategy for documenting potential EIDs.

Local knowledge refers to "the knowledge that people in a given community have developed over time, and continue to develop. It is based on experience; often tested over centuries of use; adapted to the local culture and environment; embedded in community practices, institutions, relationships and rituals; held by individuals or communities; and dynamic and changing" (Food and Agriculture Organization, 2004).

The concept of 'local knowledge' significantly overlaps with those of 'traditional knowledge,' 'indigenous knowledge, 'traditional ecological knowledge,' and 'situated knowledge,' each of which tends to be used in different social sciences. This paper primarily uses the term 'local knowledge,' as it is the broadest of these concepts.

However, I primarily use it to refer to the experience-and community-based knowledge of indigenous people and vulnerable communities in low-income countries. Borrowing from the idea of local knowledge as 'situated knowledge' (e.g. Haraway, 1988; Nazarea, 1999; Tschakert et al., 2016) , I refer to these communities as 'locally-situated communities.'

Local knowledge is already used as a source of empirical knowledge to different extents by different disciplines. Traditional ecological knowledge is a bountiful source of pharmaceutical drugs, as well as knowledge about ecology, environmental health, and the health of indigenous communities (e.g. Alves & Rosa, 2007; Finn et al., 2017) .

Moreover, the study of local disease knowledge is well-established within medical anthropology.

In this paper, I propose that local knowledge is also a useful source of information about potential EIDs that are unknown to science. Local knowledge can be a problematic source of information. However, it likely contains relevant information about human diseases, animal diseases, and zoonoses that has not yet been empirically documented. I will discuss this possibility with reference to theoretical considerations and some limited case studies.

There are theoretical reasons to suspect that local knowledge could be useful for identifying potential EIDs. As already mentioned, ethnobiological systems can surpass empirical knowledge of certain subjects. Those subjects are generally distant from the purview of empirical knowledge gathering systems, e.g. geographically remote or in lowincome settings, and they are often salient to local life. Human and animal diseases that exist in locally-situated communities fit both of those criteria.

useful information about diseases of which the scientific community was already aware.

A study of local knowledge in Ghana about Buruli ulcers, a poorly understood, necrotic infection caused by Mycobacterium ulcerans, revealed information that is likely useful for understanding the etiology and life cycle of the disease (Tschakert et al., 2016) .

Similarly, local knowledge in Malaysia and Latin America has been helpful in identifying neglected hideouts of the animal vectors that transmit dengue fever (Dickin et al., 2014) and Chagas disease (Abad-Franch et al., 2011) , respectively. Given that such communities have independent knowledge of diseases already known to science, it is likely that they have knowledge of diseases not known to science. This is not a valid inference if science is assumed to have a complete understanding of disease, but this is not the case. Accurate estimates of global pathogen diversity are very difficult to obtain, but only a small fraction of potential pathogens have been empirically documented (Pedrós-Alió & Manrubia, 2016).

Moreover, there are ecological reasons why locally-situated communities are more likely to be in contact with animal diseases. Such communities often live in highly biodiverse environments. Cultural diversity correlates with biodiversity on a global scale (Gorenflo et al., 2012) , and it is likely that this principle applies to pathogen diversity as well (Guernier et al., 2004) . Therefore, locally-situated populations are arguably in closer proximity to a higher density of animal disease than any other population just because of their geography-not to mention because of any economic or subsistencedriven needs for such communities to interact with animals.

It is also likely that locally-situated communities face relatively high rates of zoonotic infection. Sharing an ecosystem with a great diversity of pathogens increases the risk of disease transmission almost in and of itself, given that risk of zoonotic infection is a function of ecological connectivity (Brooks et al., 2019) . Additionally, ecological degradation is a risk factor for zoonosis (Ostfeld, 2009; Bonds et al., 2012) , and locally-situated communities are generally the most likely to live in degrading ecosystems. The ecosystems in which such communities live are among the most likely to face damaging anthropogenic pollution, e.g. due to poor regulation and the presence of pollution-prone industries (Hoover et al., 2012; Sapkota & Bastola, 2017) . Such communities are also least able to mitigate the effects of climate change in their environments. For Arctic communities, this is especially true because warming is happening faster there than any other region of the planet (Dai et al., 2019) . Therefore, locally-situated communities can be expected to be in especially frequent proximity to human diseases, animal diseases, and zoonoses that are unknown to the scientific community.

One can expect those communities to have knowledge of at least some of those diseases. Zoonoses, as novel diseases, should always have a high degree of salience within communities. Regarding the salience of animal diseases, indigenous communities, in particular, rely heavily on the animals in their environment for subsistence. Furthermore, many such groups have a high degree of psychological connection with the other organisms around them (Salmón, 2000) . Animal diseases can be practically, economically, and spiritually relevant to indigenous and low-income communities. There is the problem that pathogens themselves are too small to be observed without formal training, and the same may apply to certain symptoms of human and animal diseases. Ethnobiological theory recognizes that the size of natural features limits the perceptual salience of those features (Hunn, 1999) . Despite that, locally-situated communities do, in fact, tend to have extensive knowledge about animal disease. Therefore, since there is likely a high density of potential EIDs in those communities and those communities have likely noticed many of those diseases, their local knowledge can be expected to be a useful source of novel knowledge about potential EIDs.

History also tells us that this is likely the case. The most salient human and animal diseases were likely known first by ancient populations, who, of course, did not have modern methods for collecting knowledge (see Hoeppli, 1956 ).

There are, of course, problems with using local knowledge as a source of information about EIDs. Translating local knowledge into empirically relevant information can be difficult at times. For example, this would be a problem if one encounters a locally described disease for which there is no biomedical name.

Understanding the local description of the disease may prove challenging, especially as doing so may require anthropological and/or linguistic analysis (Kleinman, 1980) . Then, empirically confirming the existence and nature of that disease may prove challenging, especially if the disease is an alleged zoonosis. I recognize that interdisciplinary integration is often difficult and costly, but the recruitment of anthropologists, linguists, and local guides can mitigate all of these challenges. Furthermore, if there is a paradigm shift towards viewing local knowledge as a valued source of disease surveillance, the opportunity costs of collecting and using it may fall. Incorporating an awareness of EIDs into medical anthropology has benefits even if no EIDs are discovered this way. In particular, I think that an awareness of EIDs can produce a more dynamic understanding of health progress and security. For example, the current COVID-19 pandemic has shown that although traditional statistics like infant mortality rates and life expectancy are usually good markers of health progress, the fundamental mark of a strong health system is its ability to respond to an emerging threat. Recognition of the fact that EID outbreaks are likely to become more common may lend new importance to the study of resilience in health systems. That said, I think that the limited case studies that follow show that there is some real promise to discover EIDs by using local knowledge.

The literature on local knowledge and potential EIDs is scarce. I will discuss three useful but limited case studies below. However, it does not seem that any anthropological or ethnobiological studies have been conducted with the explicit aim of learning about diseases unknown to science. This is not that surprising. Anthropology is the discipline that has studied indigenous medicine and disease to the greatest extent. However, until recent decades, medical anthropology had focused more on the ritual and psychology of local medical systems than any biological or epidemiological knowledge that could be gained from studying them (Waldstein & Adams, 2006) . There is now a slowly growing recognition within health science literature that non-scientist stakeholders can be vital in the production of empirical knowledge (e.g. Catley et al., 2012; Quinlan & Quinlan, 2016; Den Broeder et al., 2018) . But, I found no studies of local health knowledge that engaged with the possibility that locally-situated communities might know of human infectious diseases, animal diseases, or zoonoses that are still unknown to science.

Most studies did not actually seem to account for that possibility in their design. I suspect that this disregard for local disease knowledge is partly because of the popular but incorrect perceptions that infectious disease emergence is an uncommon and unpredictable event (Brooks et al. 2019) . That thought presumably leads researchers to assume that indigenous knowledge would not be helpful in discovering new diseases.

For those reasons, finding proof of concept for what I propose is difficult. However, I present three somewhat promising case studies.

The first comes from a study of disease knowledge held by Fula-speaking pastoralists in the Far North Region of Cameroon (Moritz et al., 2013) . Locals identified two diseases called haahaande and gawyel, which they said could infect both cattle and humans. The authors of this study dismissed this information, saying that heartwater (the scientific name for haahaande) and blackleg (the scientific name for gawyel) are not zoonotic diseases. Case reports suggest that the local knowledge may have been correct.

Heartwater is a systemic cattle disease caused by Ehrlichia ruminantium; it is characterized by increased vascular permeability that causes fatal respiratory, cardiovascular, and neurological symptoms. There are reports that E. ruminantium can infect humans (Esemu et al., 2011) , in whom it may cause fatal encephalitis (Allsopp, 2005) . Furthermore, E. ruminantium has been shown to infect a wide variety of wild and domestic animals (Peter et al., 2002) , suggesting that it is a plausible zoonotic agent.

Blackleg is a myonecrotic disease caused by species of Clostridium. Moritz et al. (2003) suggested that gawyel could refer to infection by C. chauvoei or the less common C. septicum. C. chauvoei is known to have infected humans in at least two cases-though it is unclear whether those cases were zoonotic (Nagano et al., 2008; Weatherhead & Tweardy, 2012 ). An analysis of C. chauvoei genomes concluded that the species has too little genetic diversity to infect non-ruminants (Rychener et al., 2017) , but recent paradigms of infectious disease emergence suggest that intraspecific genetic diversity is not necessarily requisite for pathogens to colonize new host species (Brooks et al. 2019) . C. septicum is known to infect humans, and some human cases have been presumed to be zoonotic in origin (Barnham, 1998) . However, neither species of Clostridium has been widely recognized as a zoonotic pathogen (e.g. Songer, 2010) . This case study suggests that local knowledge can be a source of information about E. ruminantium and Clostridium zoonosis.

A second case study comes from research on Maa-speaking pastoralists in northern and eastern Tanzania (Mangesho et al., 2017) . These pastoralists also identified blackleg (locally called emburuo) as a zoonosis. Additionally, they identified a respiratory infection called mapafu ya kikohozi ya mbuzi, which they said was contracted from goats, and they identified a fungal infection called ndororo, which they said was contracted by stepping in raw cattle remains or slurry. These two diseases were only mentioned in passing by the authors, as was emburuo, and no attempts were made to identify a biomedical name for them, nor to anthropologically or medically validate their existence.

I mention this case because of how frustrating it is. Ndororo and mapafu ya kikohozi ya mbuzi may refer to diseases that have already been empirically documented, diseases that are not empirically known, or they may be local constructions that do not correspond to any biomedical illness. Ndororo could refer to any number of foot fungi. Mapafu ya kikohozi ya mbuzi could be contagious caprine pleuropneumonia, a respiratory disease known to infect goats in Tanzania, but this disease has never been reported in humans (Iqbal Yatoo et al., 2019) . In the absence of more information, there is no way to judge whether the diseases are novel or even medically real. However, there are countless similarly brief and frustrating references in existing literature, e.g. ente kurwaara omutima and okunvara ckine in Katunguka- Rwakishaya et al. (2004) , eyaliyal in Gradé et al. (2009) , and many diseases in Catley & Mohammed (1995) . I propose that much of this local knowledge may be useful for identifying potential EIDs.

A third case study comes from camel-herding pastoralists in Somalia and Northern Kenya. Surveys of these communities have consistently identified two camel respiratory diseases with distinct symptomatic and epidemiological characteristics (Wako et al., 2016) . One is called hergeb in Somali; it is characterized by frequent outbreaks that cause nasal discharge and mortality among young camels. The other is called dhuguta in Somali; it is characterized by infrequent outbreaks that cause coughing and emaciation. There is no empirical knowledge about these diseases.

Several respiratory pathogens are known to cause disease in camels, including strains of influenza, respirovirus, Mycoplasma sp., Streptococcus sp., small ruminant morbillivirus, and infamously, MERS-CoV. However, none of these have yet been identified as hereb or dhuguta. Furthermore, either might be one of the many other locally known camel respiratory diseases that have been described across Africa, e.g. mhaz in Volpato et al. (2015) , sonbobe in Bekele (1999) , and ah and laxawgal in Catley & Mohammed (1995) . Given the limited scientific knowledge about camel respiratory diseases and the abundance of local knowledge about them, it seems that the local knowledge of pastoralists should certainly be studied further in the future.

Case studies show that local knowledge can be a useful source of new information about human diseases (e.g. Buruli ulcers), animal diseases (e.g. camel respiratory infections), and potential zoonoses (e.g. blackleg and heartwater). This is not surprising, given how sophisticated systems of ethnomedical and ethnoveterinary knowledge have been found to be. This is also not surprising given the apparent proximity of locally-situated communities to animal, pathogen, and zoonosis biodiversity. This review is preliminary, but the theoretical considerations and limited case studies I present suggest that locally-situated knowledge can be an important source of information about potential EIDs. The DAMA protocol is currently our best defense against the growing EID crisis, and the documentation stage, the 'D' in DAMA, should not fail to engage with the documentation of local knowledge. The inclusion of anthropologists in diverse public health disciplines is growing (e.g. Stellmach et al., 2018) , and the study of EIDs is another area in which their expertise is needed.

Community Participation in Chagas Disease Vector Surveillance: Systematic Review

Ehrlichia ruminantium: An emerging human pathogen?

Biodiversity, traditional medicine and public health: Where do they meet?

Clostridium septicum infection and hemolytic uremic syndrome

Studies on the respiratory disease 'sonbobe' in camels in the eastern lowlands of Ethiopia. Tropical animal health and production

Serologic evidence for human ehrlichiosis in Africa

Participatory epidemiology: Approaches, methods, experiences. The Veterinary

Ethnoveterinary knowledge in Sanaag region, Somaliland (Part II): Notes on local methods of treating and preventing livestock disease

Arctic amplification is caused by sea-ice loss under increasing CO2

Citizen science for public health

Mosquitoes & vulnerable spaces: Mapping local knowledge of sites for dengue control in Seremban and Putrajaya Malaysia

Ehrlichia species, probable emerging human pathogens in sub-Saharan Africa: Environmental exacerbation

The value of traditional ecological knowledge for the environmental health sciences and biomedical research

Food and Agriculture Organization

Interdisciplinary approaches to zoonotic disease

Ethnoveterinary knowledge in pastoral Karamoja

Ecology drives the worldwide distribution of Human Diseases

Situated knowledges: The science question in feminism and the privilege of partial perspective

The knowledge of parasites and parasitic infections from ancient times to the 17th century

Indigenous peoples of North America: Environmental exposures and reproductive justice

Size as limiting the recognition of biodiversity in folkbiological classifications: One of four factors governing the cultural recognition of biological taxa

Contagious caprine pleuropneumonia -a comprehensive review

Global trends in emerging infectious diseases

Organisation for Social Science Research in Eastern and Southern Africa (OSSREA)

One Health proof of concept: Bringing a transdisciplinary approach to surveillance for zoonotic viruses at the human-wild animal interface

Patients and healers in the context of culture: An exploration of the borderland between anthropology, medicine, and psychiatry

Exploring local knowledge and perceptions on zoonoses among pastoralists in northern and eastern Tanzania

On not knowing zoonotic diseases: Pastoralists' ethnoveterinary knowledge in the Far North Region of Cameroon

Human fulminant gas gangrene caused by Clostridium chauvoei

Ethnoecology: Situated knowledge/located lives

Biodiversity loss and the rise of zoonotic pathogens

All hands on deck: Transdisciplinary approaches to emerging infectious disease

The vast unknown microbial biosphere

Ehrlichia ruminantium infection (heartwater) in wild animals

Ethnobiology in One Health

Vector-borne diseases

Clostridium chauvoei, an evolutionary dead-end pathogen

Kincentric ecology: Indigenous perceptions of the human-nature relationship

Foreign direct investment, income, and environmental pollution in developing countries: Panel data analysis of Latin America

Clostridia as agents of zoonotic disease

Anthropology in public health emergencies: what is anthropology good for?

Situated knowledge of pathogenic landscapes in Ghana: Understanding the emergence of Buruli ulcer through qualitative analysis

Ethnoveterinary of Sahrawi pastoralists of Western Sahara: Camel diseases and remedies

Indigenous knowledge of pastoralists on respiratory diseases of camels in northern Kenya

The interface between medical anthropology and medical ethnobiology