Background: Syphilis is a sexually transmitted infection (STI) transmitted from person to person mainly by sexual intercourse or through vertical transmission during pregnancy. Female sex workers (FSWs) are exposed especially to syphilis infection, and besides all the efforts to control the spread of STIs, syphilis prevalence is still rising, mainly occurring in low-income countries. This study aimed to investigate the syphilis prevalence, demographic characteristics and sexual habits among FSWs in the Amazon region of Brazil. Methods: A cross-sectional study was carried out including 184 FSWs from 3 countryside cities of the state of Pará, Amazon region of Brazil. A venereal disease research laboratory test and an indirect immunoenzyme assay to test antibodies against Treponema pallidum were used for screening syphilis infection, while sexual habits and demographic data information were collected through a semi-structured questionnaire. Data was analyzed comparing groups with/without syphilis. Poisson regression models were used to estimate the reasons of prevalence (RP). Results: The overall prevalence of syphilis was 14.1% (95% CI = 9.8-17.8). FSWs had between 15 and 56 years of age, most were unmarried (65.7%), had attended less than 8 years of formal education (64.1%), had between 10 and 20 partners per week (64.1%), and reported no previous history of STIs (76.1%) and regular use of condom (52.7%). Low level of education attending up to the primary school (RP adjusted = 3.8; 95% CI = 1.4-9.2) and high frequency of anal sex during the past year (RP adjusted = 9.3; 95% CI = 3.5-28.7) were associated with a higher prevalence of syphilis. Conclusions: A high prevalence of syphilis among FSWs in the Brazilian Amazon region was identified, showing that syphilis is more likely to be transmitted in FSW working in low-income areas, which is attributed to the low level of education. Anal intercourse was found as a risk factor associated with syphilis. Health programs focused on risk populations appear as a rational way to control syphilis spread, which is a rising problem in Brazil and in other several countries.

Hepatitis C virus (HCV) infection causes acute and chronic liver disease and may lead to cirrhosis, liver failure or hepatocellular carcinoma. The behavior of illicit drug users (DUs) typically exposes them to risks of viral infection. In the Brazilian Amazon region, a number of studies have identified high rates of drug use among adolescents, and a high prevalence of HBV infection in DUs, disseminated by sexual and parenteral activities. However, the epidemiological scenario of HCV infection in the region is still poorly understood. This study determined the prevalence, genotypes, and risk factors for HCV infection among DUs of the Marajó Archipelago. This cross-sectional study collected samples and epidemiological information from DUs in 11 municipalities. The diagnosis was established by EIA and real-time PCR, and the samples were genotyped by multiplex real time PCR. The data were analyzed by simple and multiple logistical regression. In 466 DUs, 28.3% had anti-HCV antibodies, and 25.5% had HCV-RNA. In 92 injecting drug users, 88.0% had anti-HCV antibodies, and 80.4% had HCV-RNA. Genotypes 1 and 3 were detected, with three cases of mixed infections. The multivariate analysis indicated associations of HCV infection with age (≥ 35 years), tattoos, intravenous drug use, shared use of injection equipment, and the daily and long-term (> 3 years) use of illicit drugs. These findings will contribute to the development of effective measures for the prevention of HCV infection among Brazilian DUs, as well as its general population.

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Background: Previous studies found a high prevalence of pathogens among female sex workers (FSWs) in the Amazon region, and established their parenteral and sexual transmission. This study estimated the prevalence of hepatitis C virus (HCV) infection and associated risk factors, and the frequency of HCV genotypes and resistance-associated substitutions (RASs) in this vulnerable group. Methods: Distinct sampling methods were used to access 412 FSWs in cities and riverside communities in the Amazon region from 2015 to 2018. Three methods for HCV diagnosis were used to determine infection status. HCV genotypes and RASs were identified by sequencing and nucleotide fragment analysis. An association between HCV infection and exposure factors was determined by bivariate and multivariate analysis. Results: In total, 44 (10.7%) FSWs were exposed to HCV, and 32 (7.8%) of them had active infection. Nine socioeconomic characteristics and risky sexual behaviors were associated with HCV exposure, particularly unprotected sex and condom exemption for the clients who paid extra money. Genotype 1 (81.3%) and 3 (18.7%) were detected. The frequency of FSWs with RASs was 23.1% (6/26) for grazoprevir related to the occurrence of substitutions Y56F and S122G. Conclusions: HCV infection among FSWs is highly prevalent and dominated by genotype I. Urgent preventive and treatment measures are required to reduce HCV infection in FSWs and the general population.