Do pharmaceuticals displace local knowledge and use of medicinal plants? Estimates from a cross-sectional study in a rural indigenous community, Mexico

Abstract

Researchers examining the relationships between traditional medicine and biomedicine have observed two conflicting tendencies. Some suggest that the use of biomedicine and biomedical concepts displaces the use of traditional medicine and medical beliefs. Other scholars have found that traditional medicine and biomedicine can co-exist, complement, and blend with each other.

In this paper we use an econometric model and quantitative data to test the association between individual knowledge of pharmaceuticals and individual knowledge of medicinal plants. We use data from a survey among 136 household heads living in a rural indigenous community in Oaxaca, Mexico. Data were collected as a part of long term fieldwork conducted between April 2005 and August 2006 and between December 2006 and April 2007. We found a significant positive association between an individual’s knowledge of medicinal plants and the same individual’s knowledge of pharmaceuticals, as well as between her use of medicinal plants and her use of pharmaceuticals. We also found a negative association between the use of medicinal plants and schooling. Our results suggest that, in the study site, individual knowledge of medicinal plants and individual knowledge of pharmaceuticals co-exist in a way which might be interpreted as complementary. We conclude that social organization involved in the use of medicines from both traditional medicine and biomedicine is of particular significance, as our findings suggest that the use of pharmaceuticals alone is not associated with a decline in knowledge/use of medicinal plants.

Introduction

Understanding whether and how traditional medicine [here defined as “the sum total of knowledge, skills and practices based on the theories, beliefs and experiences indigenous to different cultures that are used to maintain health, as well as to prevent, diagnose, improve or treat physical and mental illnesses.”(WHO, 2008)] and biomedicine (here defined as a global, hegemonic medical system based on western scientific principles which includes the use of pharmaceuticals, healthcare professionals and biomedical facilities) complement or compete with one another has direct application in instructing effective policy for improving health care systems in developing countries, which still rely heavily on traditional medicine (WHO, 2008). The relationships between traditional medicine and biomedicine, that develop when different worldviews meet, are an important topic of debate in medical anthropology, medical ethnobotany, and health care development (Calvet-Mir et al., 2008, Etkin et al., 1990, Hoa et al., 2009, Muela et al., 2002, Scrimshaw and Cosminsky, 1980, Vandebroek et al., 2004). At least two conflicting tendencies regarding this relationship have been documented. According to some researchers traditional medicine and biomedicine may be incompatible and the use of biomedicine and biomedical concepts often displaces the use of traditional medicine and medical beliefs (Ackerknecht, 1942, Foster and Anderson, 1978, Ngokwey, 1995, Saethre, 2007). In contrast, other scholars have found that traditional medicine and biomedicine can co-exist, complement and blend with each other (Byg et al., 2010, Etkin et al., 1990, Muela et al., 2002, Scrimshaw and Cosminsky, 1980).

In this paper we examine the relationships between traditional medicine and biomedicine in a rural indigenous community in Oaxaca, Mexico, by focusing on knowledge and use of local medicinal plants (central to what is called traditional medicine) and knowledge and use of commercial pharmaceuticals and supplements (a key aspect of biomedicine, hereafter broadly referred to as pharmaceuticals).

In the remainder of this section, we briefly review recent studies that have found (a) a mutually exclusive relationship between knowledge of traditional medicine and biomedicine and (b) a relationship of co-existence and syncretism between traditional medicine and biomedicine. Following a description of the research site we test the following hypotheses:

• (1) laypeople who hold more knowledge of pharmaceuticals hold less knowledge of medicinal plants and

• (2) laypeople who use more pharmaceuticals use fewer medicinal plants.

Our work provides a methodological improvement insofar as we measured quantitatively both knowledge and use of medicinal plants and pharmaceuticals at the same time and unit of analysis (individual). Moreover, we included several control variables in our model and used an instrumental variable to control for possible reverse causality, omission of important third variables, and random measurement error (Angrist & Krueger, 2001).

Historically, in medical anthropology there was a focus on conflict between biomedicine and traditional medicine (Ackerknecht, 1942, Foster and Anderson, 1978, Ngokwey, 1995, Saethre, 2007). For example, most literature on Australian Aboriginal medicine supports the idea that this medical system is incompatible with biomedicine (Saethre, 2007). Studies analyzing the results of education programs on specific health problems have stressed the role of traditional medicine as a barrier for the introduction of the new biomedical knowledge. Hoa et al. (2009) conducted a survey with 12,143 people living in a rural district in Vietnam to assess their knowledge about tuberculosis (TB). Despite the effort to introduce biomedical information on TB, traditional beliefs about etiology were a strong barrier for knowledge acquisition, and only 15% of the respondents knew that TB is caused by bacteria.

Ethnobotanists have also argued that the increasing use of pharmaceuticals is a major determinant of the decreasing use and loss of knowledge of medicinal plants among indigenous populations (Caniago & Siebert, 1998). Access to and use of biomedical health care may disrupt the dissemination of traditional medicine (Ragupathy, Steven, Maruthakkutti, Velusamy, & Ul-Huda, 2008). Thus, in the conflict between traditional medicine and biomedicine the latter seems to displace the former, at least in some parts of the world.

Despite these assumptions, few studies have collected quantitative data to test the association between both traditional medicine and biomedicine. Vandebroek et al. (2004) measured both knowledge and use of medicinal plants and pharmaceuticals in six communities in the national park Isiboro-Sécure in the Bolivian Amazon. A village’s physical isolation and distance from a primary health care service with a medical doctor were positively associated with knowledge and use of medicinal plants and negatively associated with the use of pharmaceuticals. They also found a negative association between medicinal plants knowledge and the use of pharmaceuticals at the community level. They concluded that where people were exposed and had access to pharmaceuticals and other forms of biomedicine, they were more likely to adopt them and reduce/discontinue the use of medicinal plants.

Some authors have suggested that traditional medicine and biomedicine, although perceived as discrete and separate bodies of knowledge, complement rather than compete with each other. For example, in a study conducted among Tsimane’ Amerindians living in Amazonian Bolivia, Calvet-Mir et al. (2008) asked 39 informants to sort 20 medicinal plants and pharmaceuticals according to their similarities. They found that Tsimane’ recognize these medicines as two discrete groups, suggesting that Tsimane’ conceptualize the two types of medicine as “two independent domains of knowledge” (Calvet-Mir et al., 2008: 9). However, Tsimane’ laypeople use both kinds of medicine when they are sick, and biomedical practitioners and traditional healers both expressed a willingness to work with one another, suggesting that cooperation between traditional medicine and biomedicine is possible. Similarly, Spring (1980) interviewed more than 300 Luvale women in rural Northwest Zambia. While her informants chose between traditional and biomedical options based on their faith in one system or the other, the use of traditional medicine and biomedicine sometimes was exclusive and sometimes was complementary.

In contrast to the theory of discrete domains of knowledge, several authors have suggested that traditional knowledge can integrate and/or be integrated into recently acquired knowledge of biomedicine (see Byg et al., 2010). Muela et al. (2002) investigated local knowledge about malaria in two rural communities in Tanzania. They found that in some cases introduced biomedical information merged with pre-existing local concepts instead of displacing them. For example, in a survey carried out with 220 women, 62% of them shared an interpretation of the disease etiology that is the result of syncretism of traditional medical beliefs and the introduced biomedical model. Thus, even if biomedical health messages are well understood, the meanings given to them may be different from those health workers intended, as they are reinterpreted through the traditional medical beliefs.

Similarly, in a study that focused on the medical pluralism of a Guatemalan plantation, Scrimshaw and Cosminsky (1980) found that folk practitioners frequently combined elements from both traditional medicine and biomedicine in their treatment of patients. These authors stress the adoption and adaptation of elements from both domains of knowledge. In a study conducted in a Hausa-Fulani community in Nigeria, increased access to and use of pharmaceuticals did not replace local disease concepts and the use of medicinal plants (Etkin et al., 1990). Rather, the introduced pharmaceuticals were used by Hausa according to local medical beliefs, a phenomenon that Etkin names “indigenization of pharmaceuticals” (Etkin et al., 1990: 919).

Both the conceptualization of traditional medicines and biomedicines as discrete but complementary domains and the hybridization of the two types of medicines are made possible by and contribute to medical pluralism (i.e. the existence of multiple theories of illness/disease and corresponding therapeutic strategies in a single society). Kleinman (1980) suggested that a society’s healthcare system is not only made up of traditional and biomedical practices, but is also composed of different sectors (i.e. popular, folk and professional) with different therapeutic options. The work we describe in this paper focuses on popular medical knowledge and self-treatment with medicinal plants and pharmaceuticals and as such represents only one of many dimensions of medical pluralism in Mexico.