Low Health System Performance, Indigenous Status and Antivenom Underdosage Correlate with Spider Envenoming Severity in the Remote Brazilian Amazon

• Type of Material: Article
• Authors: Vanderson Souza Sampaio, Fundação de Medicina Tropical Dr. Heitor Vieira Dourado; André Alexandre Gomes, Fundação de Medicina Tropical Dr. Heitor Vieira Dourado; Iran Mendonça Silva, Fundação de Medicina Tropical Dr. Heitor Vieira Dourado; Jacqueline Sachett, Fundação de Medicina Tropical Dr. Heitor Vieira Dourado; Luiz Carlos Lima Ferreira, Fundação de Medicina Tropical Dr. Heitor Vieira Dourado; Sâmella Oliveira, Fundação de Medicina Tropical Dr. Heitor Vieira Dourado; Meritxell Sabido, Fundação de Medicina Tropical Dr. Heitor Vieira Dourado; Hipócrates Chalkidis, Faculdades Integradas do Tapajós; Maria Graças Vale Barbosa Guerra, Fundação de Medicina Tropical Dr. Heitor Vieira Dourado; Jorge Salinas, Emory University; Fan Hui Wen, Secretaria de Estado da Saúde de São Paulo; Marcus Vinícius Guimarães Lacerda, Fundação de Medicina Tropical Dr. Heitor Vieira Dourado; Wuelton Marcelo Monteiro, Fundação de Medicina Tropical Dr. Heitor Vieira Dourado
• Language: English
• Date: 2016-05-26
• Publisher: Public Library of Science
• Publication Version: Final Published Version
• Copyright Statement: © 2016 Sampaio et al.
• Final Published Version (URL): http://dx.doi.org/10.1371/journal.pone.0156386
• Title of Journal or Parent Work: PLoS ONE
• ISSN: 1932-6203
• Volume: 11
• Issue: 5
• Start Page: e0156386
• End Page: e0156386
• Grant/Funding Information: This study was supported by the PPSUS Public Call (FAPEAM/SUSAM-SES-AM/MS/CNPq number 001/2013). JLS is a fellow from Fogarty Global Health [R25TW009337]. MVGL is a level 1 fellow from CNPq.
• Keywords: Spiders; VENOM; Vomiting; ENVENOMATION; LATRODECTISM; PHONEUTRIA-NIGRIVENTER; LOXOSCELISM; SECONDARY; Health services administration and management; Brazil; HEMOLYTIC-ANEMIA; Edema; Socioeconomic aspects of health; BITE; NECROTIC ARACHNIDISM; Abdominal pain; Rural areas; Multidisciplinary Sciences; BROWN RECLUSE SPIDER
• Research Categories: Health Sciences, Epidemiology; Health Sciences, Public Health; Health Sciences, Health Care Management

Abstract

Background: A better knowledge of the burden and risk factors associated with severity due to spider bites would lead to improved management with a reduction of sequelae usually seen for this neglected health problem, and would ensure proper use of antivenoms in remote localities in the Brazilian Amazon. The aim of this study was to analyze the profile of spider bites reported in the state of Amazonas in the Western Brazilian Amazon, and to investigate potential risk factors associated with severity of envenomation. Methodology/Principal Findings: We used a case-control study in order to identify factors associated with spider bite severity in the Western Brazilian Amazon from 2007 to 2014. Patients evolving to any severity criteria were considered cases and those with non-severe bites were included in the control group. All variables were retrieved from the official Brazilian reporting systems. Socioeconomical and environmental components were also included in a multivariable analysis in order to identify ecological determinants of incidence and severity. A total of 1,181 spider bites were recorded, resulting in an incidence of 4 cases per 100,000 person/year. Most of the spider bites occurred in males (65.8%). Bites mostly occurred in rural areas (59.5%). The most affected age group was between 16 and 45 years old (50.9%). A proportion of 39.7% of the bites were related to work activities. Antivenom was prescribed to 39% of the patients. Envenomings recorded from urban areas [Odds ratio (OR) = 0.40 (95%CI = 0.30-0.71; p<0.001)] and living in a municipality with a mean health system performance index (MHSPI >median [OR = 0.64 (95%CI = 0.39-0.75; p<0.001)] were independently associated with decreased risk of severity. Work related accidents [OR = 2.09 (95%CI = 1.49-2.94; p<0.001)], Indigenous status [OR = 2.15 (95%CI = 1.19-3.86; p = 0.011)] and living in a municipality located >300 km away from the state capital Manaus [OR = 1.90 (95%CI = 1.28-2.40; p<0.001)] were independently associated with a risk of severity. Living in a municipality located >300 km away from the state capital Manaus [OR = 1.53 (95%CI = 1.15-2.02; p = 0.003)] and living in a municipality with a MHSPI <median [OR = 1.91 (95% CI = 1.28-2.47; p = 0.002)] increased the odds of antivenom underdosage. Conclusions: Spider bites is prevalent across the study region with a higher incidence in the rainy season in rural areas. Spider bites can be painful and lead to local manifestations but rarely result in life-threatening envenoming. Major local complications were dermonecrosis and secondary infection in cases diagnosed as Loxosceles bites. Based on the correlations shown here, envenomings occurring in remote rural areas, Indigenous status and living in a municipality located >300 km away from the state capital Manaus could be contributing factors to higher severity of spider envenomings in this area, as well as to antivenom underdosage.