In 1993, the Four Corners region of the Southwestern United States experienced an unknown virus outbreak that killed its victims within 48 hours. While the Centers for Disease Control (CDC) turned to biomedical science to understand the mysterious virus, the affected Indigenous community turned to their own history. Ultimately, Navajo oral history offered answers that streamlined the research process and correctly identified the source of the virus. What can we learn from this outbreak and how can we integrate traditional knowledge in understanding pathogen spillover events?

Many zoonoses, or diseases which are transmitted to humans from animals, can exist for long periods in animal reservoirs and emerge sporadically as a result of changes in environmental or climate conditions. Identifying the climatic and environmental risk factors associated with these outbreaks is thus critical to their mitigation and prevention. Indigenous communities are well-placed to have knowledge of these risk factors given their long, continuous history occupying specific environments or regions, strong oral tradition, and close relationships with wildlife or livestock. Such communities have long depended upon their understanding of ecological networks in their environment for survival. Indigenous knowledge can enable understanding of the mechanisms and ecosystem-embedded relationships between pathogens, hosts, vectors, and climate. Anthropologists can and should play a key role in identifying and documenting this traditional ecological knowledge. Such documentation necessitates the development of a framework that allows for cultural context and nuanced interpretation of local knowledge to provide valuable insight into emerging global health threats.

The Four Corners Outbreak:

During the spring and summer of 1993, an unknown respiratory illness swept through the Four Corners region of the Southwestern US, claiming 27 lives. Representatives of the Navajo nation met with members of the CDC and local health departments to discuss the crisis. Drawing on Navajo oral history, the representatives reported that disharmony was the cause of the outbreak. They noted two prior occasions in Navajo oral history when a previously unknown disease had emerged that killed community members: 1918 and 1933. In each of these years, unusually wet winters and springs had preceded the disease’s emergence, and in these wet conditions abundant piñon crop growth had led to a larger than normal rodent population which fed on the nuts (Schwarz 1995, 340). Known disease vectors, the mice had been linked to the outbreaks in both of these cases.

In the winter and spring of 1992-1993, the Four Corners region once again saw excess rain and snowfall resulting in an abundance of piñon nuts and vegetation. The Navajo representatives hypothesized that the 1993 virus outbreak was once again linked to the unusually wet conditions, abundant crop growth, and greater number of rodents in the local ecosystem. Biomedical test results would eventually confirm this hypothesis: the CDC trapped rodents (Peromyscus maniculatus) found in case households and tests concluded that the disease was a previously unknown variety of hantavirus. The virus, which is carried by deer mice, may be transmitted directly from rodents to humans via contact with saliva or feces, or through the inhalation of dust infected with the virus (ibid 390). 

This case demonstrates the power of incorporating Indigenous knowledge in understandings of disease ecology. The Navajo nation representatives utilized traditional ecological knowledge and community history to quickly identify the risk factors associated with an otherwise unknown disease outbreak, illustrating the important role that traditional ecological knowledge can serve in elucidating the causal pathways of emerging infectious disease. Within this, it is crucial to consider how the integration of traditional ecological knowledge in public health frameworks may occur given the significant challenges that exist in knowledge translation between different conceptualizations of health and disease. 

The Association of Climate and Zoonoses:

Throughout history, changes in climate have affected the occurrence, distribution, and severity of disease outbreaks. For example, a strong El Niño Southern Oscillation (ENSO) event in 2015-2016 was linked to disease outbreaks across ENSO-connected regions worldwide (Anyamba et al. 2019). In the case of many infectious diseases, climatic factors play crucial roles in the distribution of pathogens via influencing dynamics among host and vector populations. In particular, changes in temperature and precipitation greatly affect the environment in which vector-borne diseases are transmitted. Temperature changes influence the distribution of vector species by making novel environments more hospitable and enabling the invasion of new regions. As just one example, warmer temperatures on the slopes of Mount Kilimanjaro are enabling the distribution of Anopheles arabiensis mosquitoesat higher altitudes, which has increased the transmission of malaria to vulnerable populations (Foque and Reeder 2019). 

Such climatic changes can have a powerful impact on vectoral capacity. For example, vector density is strongly related to rainfall capacity for mosquitoes, which require standing water to breed. Further, insect vectors are typically poikilothermic (cold-blooded); since insects cannot regulate their own body temperature, the ambient temperature dictates the extent to which they amplify and circulate pathogens (ibid). Aedes aegypti mosquitoes, for example, will amplify and transmit dengue viruses only if exposed to temperatures within the range of 20 to 35 degrees Celsius (Carrington et al. 2013). Temperature changes have also been found to impact biting behavior, fecundity, and vector survival (Goindin et al. 2015). Indeed, during the remarkably powerful 2015-2016 ENSO event, the number of reported cases for dengue fever in Brazil was the highest reported from 2000-2017. The ENSO event produced higher-than-normal land surface temperatures and therefore drier habitats. These climatic and environmental changes drew mosquitoes into populated, urban areas containing the open water needed for laying eggs. Furthermore, warmer air may have caused mosquitoes to grow hungrier and reach sexual maturity more quickly, resulting in increased rates of mosquito bites (Anyamba et al. 2019).

Finally, climate factors influence the distribution and behavior of host populations. As in the case of the 1993 Four Corners outbreak, precipitation and temperature can influence the abundance and distribution of vegetation in which host populations live or feed upon. Take, for example, plague (caused by Yersina pestis infection) cycles associated with climate via changes in host population distribution. The Mongolian gerbil, a key pathogen reservoir, typically avoids habitats with dense and high grasses. Researchers found a negative relationship between the abundance of vegetation and gerbil abundance. When taken in the broader ecological context, this provided a link between temperature and plague conditions. Higher temperatures the previous year and increased precipitation in the current year were positively associated with vegetation coverage but negatively associated with gerbil abundance. Decreased gerbil population density was found to increase flea (vector) burden per gerbil, causing a high flea index and potentially increasing plague transmission (Xu et al. 2015). Thus, understanding the relationship between climate and disease outbreak requires detailed understanding of the tropic webs (the relationships between organisms within an ecosystem) involved.

Given that all of these factors may fluctuate in different ways while acting in conjunction to influence patterns of disease, understanding in detail the ecosystem dynamics that link climatic factors with outbreaks is critical to their mitigation and prevention. Detailed documentation and experimental work are needed to study these processes and parameters.

Local Indigenous communities, defined by the World Health Organization as “communities that live within, or are attached to, geographically distinct traditional habitats or ancestral territories, and who identify themselves as being part of a distinct cultural group” (“Indigenous Populations” 2010), are often the longest continuous inhabitants of a given region and arguably know their environment and wildlife the best. Communities that have relied upon their relationship with their ecosystem for hundreds or thousands of years are best placed to elucidate the interconnectedness of weather patterns, host behavior, vegetation changes, and other factors influencing disease. They may even, as the Four Corners region Navajo community did, maintain collective memory of past outbreaks and the warning signs associated with them.  Indeed, Indigenous communities often preserve oral history and traditional knowledge spanning centuries of habitation. They also frequently live in close contact with animals such as livestock, increasing their likelihood of having experienced zoonotic-origin outbreaks before. Correctly documenting, interpreting, and applying this knowledge can expedite the process of identifying and responding to disease outbreaks and can aid outbreak prevention and containment.

Anthropology as a Tool:

Anthropologists are well-equipped to document Indigenous knowledge in a way that is guided by the knowledge-holders themselves and considers the challenges of knowledge translation between different epistemological frameworks of health and disease. In anthropological studies of Indigenous communities, the researcher aims to construct a narrative that illustrates the full extent of the community’s understanding, including translation of terms, ideas, and ways of thinking about disease in the specific cultural context.

However, translations inevitably come with distortion or loss of these contextual and cultural cues. In the case of the Four Corners outbreak, translation did not prove to be a significant barrier because the Navajo elders were fluent in the same language as the researchers and could thus offer their own interpretation of their knowledge. This is not the case for many study populations and thus it is worth considering whether (and how) integration of traditional ecological knowledge into predominant health frameworks may occur.

Knowledge translation, as defined by the Canadian Institutes of Health Research (CIHR), involves the exchange, synthesis, and ethically sound application of knowledge within a complex system of interactions among researchers and users. Indigenous knowledge systems and Western biomedical systems are often presented as two diametrically opposed conceptualizations of health, with Indigenous systems seen as holistic, relational, pluralistic, and narrative-based while Western biomedicine is perceived as empirical, linear, singular, and written (Smylie et al. 2004). Given that knowledge exists within nuanced and complex, culturally-informed frameworks of understanding, translation between disease epistemologies may significantly reduce complex or multilayered understandings to a single dimension or misrepresent them altogether.

Incorporation and translation of traditional ecological knowledge into biomedical frameworks must be directed by knowledge-holders and facilitated by anthropologists to avoid distortions and misrepresentations of knowledge to the fullest extent possible. This endeavor in itself is not without challenges, particularly given the long history of exploitation and appropriation of Indigenous knowledge within colonial power frameworks. Translation may be viewed as a further expression of the power frameworks in which global health interventions occur (Østmo and Law 2018).  A process of knowledge translation must first and foremost recognize the equal validity of Indigenous ways of understanding ecological relationships of health and disease and must be open to the idea that the community knows something that researchers do not. In being driven by knowledge holders, appropriate translation, usage, and benefit-sharing may be facilitated.   

In recent years, there has been a call for increased investment in practices of participatory epidemiology, as analysts have condemned traditional top-down, one-size-fits-all health and development interventions as reinforcing global and often colonial hierarchies of power (Ebata et al. 2020). Proponents of participatory epidemiology assert that researchers should work closely with the target communities of their intervention to understand the unique dynamics, goals, and perceptions of the community in which the intervention is situated. This work emphasizes the need to expressly incorporate the viewpoints, knowledge, and experience of marginalized groups and form an approach in which affected communities participate in creating the solutions to the issues that affect them, reevaluating traditional top-down approaches to epidemiology.  It must be done with consideration to the wider context and power structures in which it takes place, carefully involving all invested parties and making sure that their voices are heard, their interests represented, and their goals honored.

The same must be true for studies aimed at documenting traditional ecological knowledge among Indigenous or marginalized communities. These studies must appropriately credit and benefit all stakeholders and participants, employing a social science framework that addresses bias and power dynamics (Ebata et al. 2020). Any framework used must allow for nuance and a diversity of community voices in the process of recording knowledge. 

With this in mind, a thorough anthropological study of local knowledge can document and highlight detailed knowledge of disease ecologies, enabling more rapid pathogen identification or outbreak prevention and management. I thus offer three case studies hinting at the potential untapped reservoir of knowledge of disease ecology, distribution, and identification.

Indigenous communities often possess detailed understandings of the ecology of diseases affecting their people or livestock. Dwyer and Istomin (2006) documented the knowledge of Komi reindeer herders in northern Russa regarding the etiology of diseases originating in their herd. The authors identified several diseases mentioned by the Komi for which there is no established translation to a disease within Western knowledge. The community mentions yur visem in reindeer, which translates to “head-disease.” The cause of this disease is said to be flies’ eggs, which give rise to maggots. The authors speculate about what species of insect or parasite could cause this, listing such suggestions as Calliphoridae (blowflies), specifically Protophormia terraenovae, which may cause wound myiasis and serious illness in cattle, sheep and reindeer (Dwyer and Istomin 2006, 153). The species has been documented in the Nordic region of Fennoscandia, but with no reports of associated disease. Another illness listed by the Komi herders was löb visem, which translates to “spleen disease.” The authors acknowledge that they could not establish a precise translation for this disease but speculate on such diseases as pasteurellosis or brucellosis. The herders noted that there was an increased risk of löb visem if the antlers were cut or broken, suggesting that the disease enters the body via a wound.  This community demonstrates a strong understanding of disease vectors and factors related to the development of illness in reindeer herds, offering targets for intervention in the chain of transmission. 

Indigenous communities may also act as first reporters for changes in disease distribution or host populations. In the summer of 2004, 17 reindeer died suddenly in a Tsaatan herd in Northwestern Mongolia (Haigh et al. 2008). Post-mortem analysis revealed that the peritoneal fluid and tissues in the abdominal cavity had turned yellow. Other symptoms were described as fever, lethargy, and pale mucous membranes. Biomedical analysis revealed the cause to be the tick-borne disease Anaplasma ovis, making this instance the first report of a natural A. ovis infection in reindeer (ibid 569). The presence in the reindeer population of A. ovis, a disease which typically occurs in tropical and subtropical regions in livestock like sheep, goats, and cattle, indicated a host-species jump – a concerning revelation with implications for zoonosis outbreak risk and management.

Finally, Indigenous communities may be aware of diseases unknown to Western medicine. In a study conducted of Maasai perceptions of illness, Casucci (2015) documents several diseases for which no obvious English translation exists. He dismisses these mentions as likely “teasing” by participants (ibid 95). However, it is worth considering that these diseases may exist but their presence in the region, or existence altogether, remain unknown to Western medicine. In fact, one of the diseases he lists as likely false is emporoto, a name almost identical to the one used for anthrax in the Maa language (documented by Mangesho as emboroto). Thus, in assuming untranslated diseases are automatically false, Casucci may have overlooked at least one disease that impacts the lives of community members. The other diseases listed with no translation, Normawei and Nalapone, might well be worth further study, but no additional information (such as symptoms or a perceived cause) is given. Intriguingly, he also mentions two diseases which are referred to as “Maasai illnesses”. A participant claims that these are “not understood at the sipitali [hospital]” (Casucci 2015, 103). One of these, olkurto, is translated simply as “worms”, and the other as “flies in the chest”. These diseases are well worth further investigation by biomedical researchers with context-specific knowledge translation informed by the involvement of representatives of Indigenous communities themselves in the research process. 

Considerations of Linguistic and Sociocultural Nuance

It is worth considering examples of specific linguistic and sociocultural barriers in Indigenous knowledge translation.  Firstly, literal translations may eliminate important cultural context. For example, in the Maa language, “enkijebe” literally translates to “wind.” However, contextualized it expresses a “wind of God”, implying unknowable or unpredictable misfortune, and thus is implicated in disease causation for carrying pathogens or pollutants (Casucci 2015, 102). Translations of disease etiology must take into account the belief systems and understandings of causality informed by the context. Literal translations may not reflect the complex layers of understanding of disease that intermingle religious, spiritual, or moral beliefs with mechanistic understanding of disease. Further, translation inevitably comes with connotations that may shape how seriously the medical beliefs and systems are taken. For example, documenting a study participant as a “witch doctor” may undermine the degree to which epidemiological researchers take the individual’s knowledge under genuine consideration. [TG10] 

Further, disease classification and taxonomy may vary significantly between cultures; thus, direct translations of disease may be misleading. Interpretation of knowledge may require a more detailed understanding of the sociocultural understanding of disease states and the specific clinical presentation associated with these states. Differences may exist in the divisions of disease categorization: for example, differing clinical presentations of the same disease may be understood as different diseases. Caprara (1998) documents how pisa has been translated from Alladian as “tuberculosis.” However, the symptoms associated with pisa vary from those classically associated with tuberculosis: pisa is primarily seen as a disease of the blood rather than of the lungs. There is a greater focus on blood in Alladian understandings of the disease than in Western medicine and diagnosis of pisa typically occurs when an abnormal situation arises (complications potentially linked to interacting pathologies). This must be accounted for in documentation of Alladian knowledge of disease. Thus, rather than seeking direct connections between nosographic categories, Caprara asserts that understanding the semantic networks linking various pathologies is crucial for understanding the burden of disease within a community.  

Additionally, there may be levels of simultaneous understanding of a misfortune or event. It is important that disease etiology documentation frameworks leave room for “overlapping” understandings of disease. A community may understand both the mechanism of disease and simultaneously have a religious or cultural understanding of why it occurs. In the interpretation of Navajo Nation representatives, the agent of disease transmission was identified as rats. Simultaneously, the “why” of the outbreak (Why now? Why the Navajo community?), was understood to be a breakdown “in the proper relationship between Navajo people and Mother Earth” (Schwarz 1995, 393). Both of these understandings exist simultaneously. Thus, anthropologists must be able to recognize and separate multiple layers of beliefs surrounding causality. In involving community leaders in the research process, Navajo disease etiology could be correctly interpreted and applied to the investigation.

Conclusions:

There must be an acknowledgement of the significant differences in Indigenous and Western biomedical epistemologies of disease and that translation will inevitably involve changes, distortions, or losses of nuance of knowledge that reflects (and can further reinforce) existing power imbalances. Knowledge translation and application driven by knowledge-holders (and, when necessary, facilitated by anthropologists) must be a crucial consideration when integrating traditional ecological knowledge into biomedical understandings of disease ecologies.

Ultimately, the incorporation of traditional Navajo ecological knowledge in the investigation of the 1993 Four Corners hantavirus outbreak demonstrates the great potential of Indigenous knowledge to elucidate disease ecologies. There is a great urgency to identify ecological relationships of pathogens, vectors, and climate. Understanding each factor can offer targets for intervention at specific steps in the chain of transmission to prevent large scale outbreaks. This endeavor becomes even more urgent as climate change and ecological fragmentation are drastically changing our relationship with pathogen hosts and vectors, heightening the risk of future outbreaks (Brooks et al. 2014). We must be proactive in identifying and documenting these disease ecologies. Few individuals or groups are better placed to recognize patterns in zoonotic-origin diseases than Indigenous and pastoral communities. Correctly interpreting this traditional ecological knowledge using anthropological methods may prove key to understanding and preventing zoonotic disease outbreaks.

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Rebecca Lynn Perez is an undergraduate student currently in her final year of a BA in Human Sciences at the University of Oxford. Twitter: @RLynnPerez

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