The interviews resulted in a rich repertoire of ethnoherpetological information about local snakes. In general, dwellers mentioned a high frequency of encountering venomous snakes. In all communities, the main folk category cited was “surucucu”, being known, beyond the regular one, more three ethnospecies: surucucu de fogo (fire surucucu), surucucu marreca (teal surucucu), and rabo de mucura (mucura’s tail surucucu). Other venomous snakes mentioned were: surucucu caninana, surucucu papagaio, one with the same pattern as Boa constrictor Linnaeus 1758, and jararaca d’água (classified as non-venomous in Cabeça D’Onça).

Encounters with surucucu ethnospecies occur throughout the year. However, up to the date of the interviews, participants highlighted that 2023 was the year with the fewest meetings. Among the participants who answered about the meeting period (N = 70), 48.6% said that venomous snakes appear more often in the Amazon summer (dry season), 21.4% in the Amazon winter (flood season), and 30% regardless of the season. During winter, they specified that the encounter usually occurs over river's flood or ebb.

According to participants, this species looks for dry places; during high tide, it stays on tree branches or close to houses. Data showed that 32.3% of the encounters occurred on family farms and 27.8% occurred in houses. Other encounter sites were pathways (16.5%), plants such as branches, bananas trees or marajá (15.8%), “muri”, grass brought by river water (4.1%), and fishing and chicken coops (1.5% each). In total, at least 25.9% (N = 36) of the dwellers had already killed a surucucu ethnospecies.

Considering the five communities together, at least 33 dwellers had already been bitten by one of these ethnospecies; that is, approximately 28.7% of participants who responded this question (N = 115—Fig. 2). Furthermore, in 53 interviews, dwellers reported one or more acquaintances who had already been bitten in the region, totaling 77 reports of snakebites (Fig. 2). Among the dwellers or the acquaintance, some were bitten more than once. Overall, this species was not considered aggressive by the dwellers, only biting when bumped.

Number of interviews in which residents said they had already been bitten by a snake (dwellers) or knew someone who had (acquaintance). The numbers above the bars indicate the raw number of positive responses, while the percentage refers to the number of positive responses in relation to the number of interviews that addressed this topic

In 22 interviews (two in Água Preta, three in Carapanatuba, ten in Centro, two in Costa and five in Cabeça D’Onça), the participants mentioned deaths due to snakebite. One victim, who was repeatedly mentioned among the different communities, was the husband of a current dweller of Água Preta, a man in his 70 s, who was bitten approximately 2–3 years ago. Indeed, in 54.8% (N = 17) of the reported cases, it was specified that the victim was a child or an elderly person and, in one case, a pregnant woman. For the remaining participants, it was either not possible to determine their age (38.7%), or they were in early adulthood or middle-aged (6.45%).

The main symptoms mentioned in case of snakebites were pain, swelling and redness of the affected area and blood purging from different locations (bite, old scars, and pores such as hair, eyes, mouth, nails, among others). Some reported difficulty walking and sleeping, mental confusion, and short faints. Treatments, in turn, varied among going to the hospital (42.8%; 27/63), home treatments (23.8%; 15/63) and both (25.4%; 16/63); sometimes, treatments were carried out by healers (7.9%; 5/63). In another 4 interviews not included in this percentage, all in Cabeça D’Onça, participants said they could only be cured by God.

The length of hospital stay varied from 9 h to 18 days, with an average hospitalization of 7.5 ± 4.5 days. For the most part, dwellers usually go to the hospital in Santarém. However, in Cabeça D’Onça, some participants said they preferred the hospital in Alenquer, not only due the distance (in this case it is closer), but also because it is less crowded. Regardless of the chosen city, they always spend time commuting—it will depend on the facility to find transportation, the kind of transportation, the climate conditions, among others. There were cases in which patients went to hospital hours later or even in the next day.

They used to say that in the past healing depended greatly on faith. However, currently, this trip to the city would be easier due to the ambulancha, that is, a speedboat available to the community and used only for medical emergencies.

Among the home treatments, we registered the use of phyto and zootherapeutics. As examples of plant-based products, we have the majority of counterpoisons, such as “Pau X”, “Específico Pessoa” (both in their original names) and cat claws (plants of the Rubiacea family). Among these, Pau X was the most mentioned, cited in 22.3% of the interviews. The interviewees also commented on the use of plants to make liquid and greased solutions (such as “parra”, a species of vine from the region) or poultices (with a plant like aningas, a macrophyte of the family Araceae). On the other hand, a frequently cited zootherapy was the injectable use of Amazon River dolphin (Inia geoffrensis (Blainville, 1817)) fat (mentioned in 12.9% of interviews), whether for human or animal treatment. Other treatments of animal origin mentioned were black stone and little cane toad.

The black stone is made from the shin bone of the ox. After a process of preparation in the fire, the piece of bone (the so-called black stone) would have the capacity to suck out the poison from the person, serving both to snake bite as to stingray sting. After use, the stone must be kept in milk. In a similar way is used the little cane toad (a small, white frog). According to the dwellers, the animal must be placed above the wound; as the frog sucks the poison, it turns purple. More than one frog may be needed until all the poison is removed.

In addition to these treatments, participants mentioned ingesting coffee grounds diluted in water; eating raw eggs with mangerioba juice (Senna sp., a shrub from the Lemininosae family); drinking water from the hat (take water from the river with the crown of the hat and drink it); placing a boiled egg on the wound (which acts in a similar way to the cane toad); washing the area with coconut soap and obtaining a Tetanus shot; applying levomenthol-based medicine over the wound (which would be good for all kinds of insect bites); and the classics treatment, such as cutting the bite to remove the venom and making a tourniquet. In an interview, the participants also reported that if the person is bitten twice in a row, the second snake bite would not cause much damage, as one venom cancels out the other.

Overall, no serious sequelae were reported. For those who still have a problem, it usually occurs according to the moon and can range from swelling and itching near the bite, malaise, and pain. The most problematic cases were those of a dweller from Centro do Aritapera who needed surgery because the blood clotted inside his knee and the father of an elderly dweller from Cabeça D’Onça. In the first case, the dweller said that, because the snake had not eaten anything yet, it injected all the venom into his knee, and that's why it became more swollen. In the second, the interviewee reported that the victim’s neighbor, who was drunk on the occasion, carried out the wrong treatment with a plant, resulting in cooking the skin of the victim’s foot and worsening the situation.

There have also been cases of snakebites in animals. Dogs, cattle, horses and chickens are among the bitten ones. For large mammals, it was also recommended the application of the Amazon River Dolphin fat. According to dwellers, this treatment was responsible for healing many cattle. Horses, however, were classified as very weak animal for snake bites, being rare saving one. Dogs, in turn, usually have the tip of the ear cut, to bleed the poison out–in addition to administering counterpoison or dolphin fat.

The participants also mentioned treatment by healers. In total, there were 50 reports about the passage of these “doctors” (term used among the interviewees) in the communities. In 30%, dwellers used their service, whether for themselves, relatives or to their land; in the other 70%, they commented that they knew about the existence of the healers and stated that they passed by but did not take their services. From the reports provided, we could propose a possible genealogical line of the main curators who passed through the region.

All healers appeared to be from the Assis family, except for Neuto, which was more recent, but apparently from another lineage. The Assis family came from Pacoval, a community originated of descendants of enslaved Africans in Brazil historically seeking autonomy and preservation of their culture, known as “quilombo”, in Alenquer–PA. Residents of this community are known for carrying out practices considered exoteric or spiritual. According to reports, Raimundo Assis was the first generation of snakebite healers to pass through the communities, and Didico Assis the most recent. In this middle ground, there is some confusion with the names Francisco Assis and Antônio Assis. It is not known whether it is a lineage of four generations (Raimundo father of Antônio, grandfather of Francisco and great-grandfather of Didico), or if it is a three-generation linage and Antônio and Francisco Assis would actually be the same person. In any case, currently all these members have passed away. There was also a mention of Gorete, possibly alive and a sister in the family.

The treatment provided by them can be performed in three ways: before the bite, after the bite, and on the land. People who undergo this procedure before any accident are called healed and become immune to any snakebite. None of the participants could say exactly what the procedure was like, as it is usually done during childhood. However, putting the stories together, it seems to be kind of a prayer, in which the healer drinks something, spits it out and gives it to the patient to drink and, at the end, ties a string in the patient’s leg. Some also reported the use of candles, either to place in the patient's mouth, head or on the skin. Furthermore, it is recommended that cured people not kill snakes after that.

The treatment after a snake bite involved, above all, the use of Pau X (Fig. 3). During this procedure, patients said the healers clean a needle with alcohol, cut around the bite to get the poison out and give the patient the counterpoison to drink. Last, the healing of the land consists of driving the snakes out of it. According to reports, if the healers healed one quadrant of the land, the snakes went to another in front or behind it; that is, the quantity decreased in one area and increased in another. No one knew exactly how they did that, but they said that if the healer spat on the snake, the animal would remain still in the coiled position.

Bottle of Pau X found at Mercadão 2000, a local grocery store in Santarém, PA. There are no details about the composition on the label; it just says that it is made from medicinal herbs. Photo: the author

Not all interviewees believed in the healing of the land, and some said that healers were deceivers, that they charged too much, or that sometimes took the money and never came back. However, believing or not, there was a consensus that when they went to the region, the number of snakes increased somewhere nearby. However, with the death of the old members, there was a decrease in these practices, due to the distrust in the new healers.

According to those who had already been bitten, the person can feel very thirsty; in these cases, it is recommended to drink only milk. Despite the different types of treatment, warnings of not drinking water after a snakebite accident were common because it can clot the blood. As explained by one participant:

My uncle didn’t want to go to the city. It appeared some wound blisters that he pierced with needles. He got fever; he put ice on and drank cold water… that was what killed him. (interview Mrai, Centro do Aritapera–free translation)

Also, according to three reports in Cabeça D’Onça and one in Costa do Aritapera (by a nurse who worked with different indigenous ethnicities), snakebites cause more damage to pregnant and menstruating women due to blood clotting. Also, this last participant added that, in Marubo and Mayoruna ethnicities, women are forbidden from approaching snakebite victims, as the wound would hurt much more if they were close to a pregnant or menstruating woman.

From the three containers, we collected seven snakes, of which 71.4% (5/7) were venomous; all from Bothrops atrox (Linnaeus, 1758) species. The others were Erythrolamprus poecilogyrus (Wied-Neuwied, 1824) and Eunectes murinus (Linnaeus, 1758). The snakes were deposited by residents who found them in various locations. We had no interference in the process of capturing the animals and did not have awareness or control over the specific circumstance where each animal was found.

We collected three specimens of B. atrox on Costa do Aritapera, one in Carapanatuba and one in Água Preta (Table 1); the non-venomous snakes were all collected in Água Preta. The average SVL for B. atrox collected was 84.3 ± 46.4 cm. The largest specimen collected was a male with 194.2 cm of SVL, and the smallest a female with 50.5 cm SVL. Females have a lower SVL mean than males (F = 71.4 ± 15 cm X M = 93.4 ± 58.2 cm). Males also had a higher mean of HL (4.4 ± 1.8 cm), ID (1.7 ± 1.5 cm), HW (2.6 ± 1.1 cm) and TL (12.9 ± 9.6 cm), while the mean of females for the same measurements were HL = 3.9 ± 0.9 cm; ID = 1.5 ± 0.7 cm; HW = 2.4 ± 0.9 cm; TL = 11.8 ± 1.6.