Plants and animals have been used as medicinal sources since ancient times 1 2 3 4 , and even today animal and plant-based pharmacopeias continue to play an essential role in world health care 5 . The use of biological resources for various therapies has been documented in many different parts of the world – but largely in remote regions, where traditional medicines provide a de facto alternative to "modern" health care systems 6 7 8 9 10 11 12 . Recent studies, however, have highlighted the relevant role also played by traditional medicine in urban areas 13 14 15 16 17 18 19 where health care needs are generally met by mainstream services such as hospitals and allopathic pharmacies 16 .

Although plants and plant-derived materials make up the majority of ingredients used in most traditional medical systems, whole animals, animal parts, and animal-derived products (e.g., urine, fat, etc.) also constitute important elements of the folk pharmacopoeia throughout the world. Indeed, zootherapy (the use of animal products in healing) is an ancient and widespread practice across most cultures 3 20 . Traditional medicine still makes use of animals and products derived from animal organs 1 , and examples of the use of animal-derived remedies can currently be found in many urban, semi-urban, and more remote localities in all parts of the world 9 10 21 22 23 24 25 26 .

Biological remedies are openly commercialized in essentially all of the towns and cities in Brazil, principally in public markets. It is common to find specific places in these markets where plants and animals are sold for medicinal purposes – locations that serve to unite, maintain, and diffuse empirical knowledge from different regions and of different origins 11 13 16 18 19 22 24 25 27 28 29 30 . The on-going search for natural products, as part of a collective social strategy, emphasizes the importance of these traditional centers. However, despite their cultural relevance, few ethnobotanical and ethno-zoological studies have focused on herbal vendors in public and/or open markets 9 31 . Almeida and Albuquerque 22 have pointed out that the information obtained in these markets concerning the exotic and the native flora and fauna may aid in formulating conservation strategies for commercialized natural resources.

In northeastern Brazil, especially in the semi-arid region, animals and plants are widely used in traditional medicine and play a significant role in healing practices there 9 10 16 24 . Zootherapies form an integral part of the local culture, and information about animals and their uses are passed from generation to generation through oral folk lore. Studies on medicinal animals, however, are still scarce when compared to those focusing on medicinal plants. The present work therefore sought to contribute to our knowledge of the medicinal animals used by the inhabitants of the caatinga region in northeastern Brazil. The caatinga is a highly threatened biome covering a vast area of Brazil, and is the source of many little-known natural resources 32 33 . About 15% of the Brazilian population (more than 25 million people 34 lives in the caatinga region and the rural populations there are characterized by extreme poverty 35 . Because of the adverse environmental condition in the region the local populations have developed unique social-environmental structures as well as strong relationships with the natural resources available in the region, including those used for medicinal purposes.

The use of medicinal plants and animals in the semi-arid region has a strong relation with socioeconomic factors, as a large part of the human populations living there do not have access to adequate health services and use phytotherapeutic and zootherapeutic products as easily accessible and low-cost alternatives to medicines sold in commercial pharmacies 11 36 . The gathering and selling of these products is also compatible with popular traditions, and can even generate some income.

In this context, the present study surveyed the medicinal animals sold in public markets in Santa Cruz do Capibaribe, Pernambuco State, in the semi-arid region of northeastern Brazil. The study primarily focused on field surveys to address the following questions: which animal species are used for medicinal purposes? Which animal body parts are used to prepare these remedies? What are the illnesses treated by these remedies? By highlighting the role played by animal-based remedies in Brazil's semi-arid northeastern region we hope to increase awareness about zootherapeutic practices and contribute to the conservation of both cultural and biological diversity.

Animals have been used for medicinal purposes since colonial times in Brazil 11 and they still play a significant role in current folk healing practices. Various publications have shown the importance of zootherapy to traditional communities in various socio-cultural environments in Brazil 11 41 42 43 44 , and the commercialization of the medicinal animals in various Brazilian cities has been documented by numerous authors 16 18 22 24 45 46 .

In Santa Cruz do Capibaribe, as in other cities in Brazil, plants and animals are sold for medicinal purposes in traditional public markets. Table 1 summarizes the names (vernacular and scientific) of medicinal animals, the parts used, ailments treated, and the mode of preparation and/or use. A total of 37 species distributed among 29 families were reported as having medicinal value by the shop owners. The taxonomic group with the largest number of animal species was insects (with 10 species), followed by birds (9), mammals (8), and reptiles (6). Other groups mentioned by the interviewees were fish (2), echinoderms (1), and amphibians (1).

The number of species mentioned in this study was quite expressive, nearing or exceeding the numbers of species sold for medicinal purposes in studies undertaken in other regions of Brazil. Almeida and Albuquerque 22 registered 19 medicinal species in research carried at in Caruaru, Pernambuco; Silva et al. 24 reported the trade of 18 medicinal animals in Recife, Pernambuco, and Costa-Neto 27 and Andrade and Costa-Neto 47 reported the trade of raw materials derived from 16 species in Feira de Santana, Bahia. In the public markets of Maceió, Alagoas State, Freire 48 encountered 17 reptile species commercialized for medicinal purposes (this author worked exclusively with that group). In work carried out in metropolitan areas of northern and northeastern Brazil, Alves and Rosa 16 reported the use and trade of 50 medicinal animal species in Belém (Para State), 61 in São Luís (Maranhão State), 27 in Teresina (Piauí State), and 28 in João Pessoa (Paraiba State). These results indicate that the use of medicinal animals is widespread in probably all urban areas of Brazil.

Most of the animals cited are species native to the caatinga biome (only 6 were domestic), demonstrating the importance of the local fauna to regional zootherapeutic practices. This observation is in agreement with previous studies carried out in Brazil that demonstrated that the diversity of medicinal animals used by human populations is influenced by animal diversity in the regional environment 9 10 16 . A similar situation was observed in an examination of the trade in medicinal plants in Witwatersrand, South Africa, where there was found to be a greater use and trade of species collected in biomes near the public markets and of species common in biomes familiar to the commercial gatherers. These authors concluded that the use and trade of medicinal species tends to be proportional of their availability 49 .

Only two of the medicinal species cited, the sea horse Hippocampus reidi (Ginsburg, 1933) and the star-fish Oreaster reticulates (Linnaeus, 1758), do not occur in the area near Santa Cruz do Capibaribe. The use of an oceanic species in the midst of the semi-arid region indicates existence of trade routes for medicinal animals, a situation previously reported by Alves and Rosa 16 for cities in northern and northeastern Brazil. The existence of trade routes is reinforced by the fact that many of the species registered in this study are known to be commercialized in other cities in the country 22 24 27 48 . The present work also identified two medicinal species (Struthio camelus Linnaeus, 1766 and Nasutitermes macrocephalus (Silvestri, 1903) not previously documented as being used in Brazil. The toasted egg shells of S. camelus are used to treat osteoporosis, and the termite N. macrocephalus is used to treat asthma.

The interviewees indicated that the following animal parts/products are used as folk remedies: honey, bee wax, fat, secretions, leather, urine, eggs, feathers, nests, blood, marrow, horns, suet, manure, hooves, spines (from porcupines), and meat. A considerable number of species (17) have multiple therapeutic uses, and were prescribed to treat various ailments. The fat of the Tupinambis merianae (Duméril & Bibron, 1839), for instance, is indicated for treating four health problems (wounds, sore throats, earaches, perforations). The fat of Crotalus durissus Linnaeus, 1758, is indicated for treating rheumatism, swelling, cancer, bone pain, gastritis, eczema, wounds, and backaches; while the chicken fat of Gallus gallus domesticus (Linnaeus, 1758) was mentioned as being useful for treating renal calculi, headaches, throat inflammations, nasal congestion, fevers, and general swelling. Similar usages have been reported in other traditional medicine systems as, for example, the carapace and tail of the armadillo Dasypus novemcinctus (Linnaeus, 1758) are used to treat diarrhea, tuberculosis, and whooping cough, and to accelerate parturition in Mexico 26 . The fat, skin, and bile ducts of the land monitor Varanus bengalensis (Daudin, 1758) are used for treating piles, rheumatism, burns, and spider and snake bites in India 50 . In Bolivia, products derived from the Agouti paca (Linnaeus, 1766) are used as remedies for general body pain, leishmaniasis, snakebites, rheumatism, heart pain, bone pain, liver pain, fever, and to alleviate pain during childbirth 23 .

Honey bee products and fats (and/or suet) are the most frequently used natural resources, although there have been no reports emphasizing the intensive use of fats and suet as zootherapeutic medicines. This may be due to the fact that the animals used for medicinal purpose are generally vertebrates with significant amounts of fatty tissue that is easy to obtain, store, and transport.

According to the interviewees, zootherapeutic products are used to treat at least 51 different maladies. The most frequently cited treatments are therapies for the respiratory system – and are mainly related to asthma. A similar situation was described by Costa-Neto 27 with regards to the use of medicinal animals in Feira de Santana, Brazil, where animal-based remedies are frequently used to treat respiratory diseases (asthma and bronchitis). Alves and Rosa 51 likewise pointed out that at a minimum of 113 animal species are used in Brazilian traditional medicine for treating asthma. A similar trend in relation to medicinal plants was observed in Pernambuco, where the two most frequent use-categories referred to gastrointestinal and respiratory diseases 52 .

The interviewees described many different ways of preparing and administering animal-based remedies. Hard parts generally were sun-dried, grated, and crushed to a powder, to be administered in teas or eaten during meals. Fats, body secretions, and oils were ingested directly or used as ointments. Zootherapeutic products can be prescribed as single-ingredient drugs or mixed with other ingredients. In mixtures, several to many of the more valuable medicinal animal components are mixed with other more available medicinal animal or plant ingredients in more liberal quantities.

The use of some medicinal animals is associated with popular beliefs locally known as 'simpatias'. These 'simpatias' are often secretive in nature, so that the people receiving the treatment cannot know what that they are taking, otherwise the remedy will not be effective. This popular belief is commonly associated with the use of medicinal animals in Brazil 11 . Other interesting examples recorded in present study are associated with the use of the tail of Euphractus sexcinctus's (Linnaeus, 1758) to cure deafness – by simply scratching the ear with the tail; and the use of a living specimen of Cyanocorax cyanopogon (Wied-Neuwied, 1821) to ingest left-over food from an asthmatic patient, who will then be cured, according to a local belief. This observation is in line with information provided by Alves et al. 11 who pointed out that traditional Brazilian medicine is often associated with local belief systems of simpatias, and these popular beliefs may have different implications depending on the manner in which the animal species are used (either dead or alive) and the community's traditions.

Some of the medicinal species cited by interviewees in Santa Cruz do Capibaribe have also been recorded in more distant regions. The honey of Apis mellifera (Linnaeus, 1758), for example, is indicated for treating coughs in Brazil and is used for the same purpose in Sudan 53 . Lev 1 reported that the honey of Apis mellifera (Linnaeus, 1758) is used in the traditional medicine of Israel as a purgative, and to treat eye inflammations, sore throats, burns, and coughs. Honey from Melipona scutellaris Latreille, 1811, was mentioned as a treatment for cancer, fatigue, sexual problems, coughs, and general weakness. This same product was also reported by Costa-Neto 54 as being used as a tonic by residents of Bahia State, Brazil. In Paraiba State in northeastern Brazil, the fat of Iguana iguana (Linnaeus, 1758) is used for treating wounds in the local traditional of veterinary medicine 55 . Ovis aries (Linnaeus, 1758), a species broadly utilized by the population of Santa Cruz for treating various illnesses, was also previously reported by Costa-Neto and Oliveira 56 , Almeida and Albuquerque 22 and Alves and Rosa 9 10 . These examples confirm the knowledge and use of zootherapeutics in different parts of Brazil and around the world.

The present study also noted that some endangered species of medicinal animals (e.g. H. reidi) are widely traded. As such, the social use of the biodiversity in mega-diverse countries such as Brazil is crucial to considerations of conservation biology, public health policies, sustainable management of natural resources, and biological prospecting 10 – and there is a great need to stimulate local populations, herbalists, and medicinal animal merchants to adopt conservation measures that avoid over-exploitation, so that the use of these species will not lead to their extinction and the permanent loss of access to their medicinal products.

Our studies indicated that 37 medicinal animals were being traded in the public markets of Santa Cruz do Capibaribe, and that the zootherapeutic products extracted from them are used to treat 51 ailments – thus indicating the very rich ethnomedical knowledge of the local population in relation to zootherapy. Zootherapy represents an alternative to official medicinal practices in the semi-arid region of northeastern Brazil, and has also become part of urban popular medicine. The local fauna, folk cultures, and the commercial value of these activities are key factors in maintaining and driving the use and commerce of animal species for therapeutic purposes. The lack of monitoring programs or any sort of regulation of this industry in troublesome, however, and argues for undertaking multidisciplinary studies to investigate the social, cultural, economic, clinical, and environmental aspects of these activities to increase our understanding of the use of these medicinal animals and help establish workable management strategies to conserve these zootherapeutic resources.

The authors declare that they have no competing interests.

RRNA, AV, RRDB and WMSS – Writing of the manuscript, literature survey and interpretation; HNL and MCT- Ethnozoological data, literature survey and interpretation; RRNA and AV – Analysis of taxonomic aspects. All authors read and approved the final manuscript.