Importância epidemiológica de cobras-corais (Elapidae: Micrurus) na Amazônia brasileira

Abstract

In the Brazilian Amazonia, knowledge of human envenomation by coral snakes is restricted to a few case reports, some of which are poorly detailed. Most of the information available for Brazil comes from the Northeast and Southeast regions, which are more populous and have the largest number of research centers and accident records. In this context, this thesis investigated the epidemiological importance of coral snakes (Micrurus spp.) in the Amazonian region, exploring over four chapters aspects related to the frequency of accidents, the main involved species, the main symptoms reported in the cases, and which areas are more prone to the emergence of this group and the its bites. In the first chapter we observed a low frequency and incidence in elapidic bites. Pain, edema and paresthesia were the most common symptoms. Systemic symptoms not generally associated with coral snake envenomation, such as coagulopathy and thrombocytopenia, have been reported in Amazonia. Antivenom has been misused, and we recommend carrying out educational programs to prevent such bites and teach both the general public and healthcare professionals the correct treatment for the cases. We also suggest improvement in the coverage of Intensive Care Units in the region. In the second chapter, we found that five species were involved in accidents in the region of Manaus, with Micrurus lemniscatus being responsible for the largest number of cases. There was no difference between the sexes of the snakes that caused the bites, and the patients were mostly male. Most cases were reported in urban areas and in the dry season, and there was a clear geographic segregation between the species. We describe seven cases of envenomation. Paresthesia, pain and edema were the most common local symptoms. The most common systemic manifestations were dyspnea, palpebral ptosis, blurred vision, dysarthria, and difficulty in walking. Envenomations by coral snakes in the Manaus region are clinically serious, but rare and sparsely distributed over time, making the detection of epidemiological and clinical patterns a challenge for public health. In the third chapter, two cases of bites by M. hemprichii involving two patients were reported, in which, due to the confusion in the identification of the snake and risk of aggravation of the case, we discussed the importance of correctly identifying snakes of snakebites in the context of hospital care. In the fourth chapter, we used distribution modeling of coral snake species in Amazonia, together with data from Micrurus cases, to assess possible risk areas in the region. We concluded that the entire biome shows high environmental suitability for the occurrence of coral snakes, and that such suitability explains little about the incidence of bites in the region. This is likely due to the low human density in Amazonia, but also to coral snake characteristics such as cryptic habits. Unlike other medically important snake species, the ecological and epidemiological scenario of coral snake bites precludes detection of important geographic areas of concern and requires a broad and equitable availability of health centers across Amazonia.