Factors associated with sexually transmitted infections in sugarcane cutters: subsidies to caring for*

Objective: to estimate the prevalence of Sexually Transmitted Infections (STIs) and associated factors in sugarcane cutters. Method: a cross-sectional, analytical study with 937 sugarcane cutters from Paraíba and Goiás, states of Brazil, respectively. An outcome variable was the positive results in some rapid tests for HIV, syphilis, hepatitis B and C. Bivariate and multiple analyses were performed to identify the association between these infections and sociodemographic and behavioral variables. Results: all participants were male, most were young adults and had low schooling. Prevalence of STI was estimated at 4.1% (95% CI: 3.0-5.5). According to multiple regression analysis, the variables age over 40 years (OR 5.0; CI 95%: 1.8-14), alcohol consumption (OR 3.9; CI 95%: 1.3-11.9), and illicit drugs (OR 2.9; CI 95%: 1.3-6.3) were factors associated with the STIs investigated. On the other hand, having some religion (OR 0.4; CI 95%: 0.2-0.8), and work in the Midwest Region (OR 0.4; CI 95%: 0.2-0.9) were factors negatively associated with these infections. Conclusion: presence of risk behaviors for STI among sugarcane cutters. Screening for these infections in groups of rural workers is essential for early diagnosis and breaking the chain of transmission.


Introduction
Worldwide, approximately one million people acquire some sexually transmitted infection (STI) each day, with an annual forecast of 357 million new curable infections. There are more than 20 microorganisms causing STIs, among those responsible for asymptomatic infections are hepatitis B virus (HBV), hepatitis C virus (HCV), human immunodeficiency virus (HIV) and the Treponema pallidum, the aetiological agent of syphilis (1) .
The World Health Organization (WHO) has estimated 257 million and 71 million people chronically infected with HBV and HCV in 2015, respectively. These viruses are responsible for more than one million deaths per year and are the cause of acute and chronic liver disease, including cirrhosis and hepatocellular carcinoma (2) .
Brazil is considered a country of low endemicity for viral hepatitis B and C, however, considering its population size, the absolute number of infected individuals is significant. According to the epidemiological bulletin for 2019, 233,027 cases of hepatitis B and 359,673 cases of hepatitis C were reported from 1999 to 2018 (3) .
Globally, about 37.9 million people were living with HIV in 2018, with 1.7 million new infections (4) . In Brazil, the HIV epidemic is of the concentrated type, that is, it new cases of HIV infection were registered (5) .
In 2016, the number of syphilis cases in people aged 15 to 49 was estimated at 6.3 million, with a global prevalence of 0.5% (6) . In Brazil, in recent years, there has been an increase in the number of people infected by T. pallidum. In 2017, the detection rate of acquired syphilis was 59.1 cases/100,000 inhabitants, while in 2018 this rate reached 75.8 cases/100,000 inhabitants, an increase of almost 17 new cases/100,000 inhabitants in just one year (7) . HIV, HBC, HCV, and Sustainable Development Goals (8)(9)(10) .
In general, men are more susceptible to risk behavior and seek health services less when compared to women, especially those men belonging to more vulnerable populations with less education and purchasing power, including those living in rural areas (11) .
Male norms such as competitiveness, strength, power, and self-confidence can interfere with how a man whether commits or not to his own health (12) . Also, beyond gender issues, the operation hours of health facilities often coincide with the working hours of individuals, reducing their opportunities to participate in disease prevention and knowledge activities, and of their health situation and treatment (13) . In this context, screening and treating STIs in men is an important strategy for interrupting the chain of transmission of these infections, particularly among those who possibly have less access to health services, such as male field workers.
Brazil is one of the largest producers of sugarcane and alcohol in the world. Although mechanization of cane cutting is gradually replacing manual cutting, this technology has not yet fully reached some regions such as the Northeast and Midwest (14) . Manual sugarcane cutting is a strenuous job performed by men of low education and income. These individuals work under a productivity regimen and, in order to obtain better wage earnings, they submit themselves to an excessive workload. The seasonal nature of cane harvesting favors the migration of workers to harvesting regions (15) . Studies show several health problems related to sugarcane harvesting, among the most cited are respiratory problems, decreased kidney function, and repetitive strain injury (16)(17)(18) . However, there is no information on sexually transmitted infections in this population of rural, seasonal-migrant males.
In a previous publication, the prevalence of HIV, HBV, HCV and syphilis infections in the cane cutter population and analysis of factors associated with exposure to HBV were presented (19) . However, considering that these infections present common forms of transmission, the objective of the present study was to identify variables During the study period, there were 38 and 9 sugar and alcohol mills in Goiás and Paraíba, respectively (20) .
For the study, we considered the mills that performed predominantly manual harvesting of sugarcane and that were in the harvesting period. In Paraíba, data collection was carried out at the largest plant in the region, and in Goiás at four plants.
The target population of this study was rural workers, manual sugarcane cutters. All individuals Soares JP, Teles SA, Caetano KAA, Amorim TF, Freire MEM, Nogueira JA, Oliveira BR, Leadebal ODCP, Araújo PS, Silva ACO. aged 18 years or older, who performed manual cutting of sugarcane in alcohol and sugar mills in the State of Paraíba and Goiás were included. The minimum sample needed, considering a statistical power of 80% (β=20%), significance level of 5% (α<0.05), accuracy of 0.5%, 1.5 drawing effect, and prevalence for anti-HIV of 0.39% (21) was 895 participants.
In general, cane cutters are distributed in teams of 30 to 50 men to perform the cane cutting. The For the analysis of the interview data and the rapid tests, the statistical STATA program version 13.0 (StataCorp., CollegeStation, TX) was adopted.
The descriptive analysis was performed by frequency distribution, mean and standard deviation. We considered STI outcome the positive results in some of the tests performed. Prevalence was calculated with a 95% confidence interval (95% CI). Chi-squared and Fisher's Exact tests were used to test differences in proportions. To estimate the odds ratio, the variables that presented a p-value < 0.20 were included in a logistic regression model (23) , using the forward procedure  (24) . Those individuals who tested positive for any infection were referred for diagnosis and/or treatment confirmation.

Results
Of the total number of participants (n=937), 301 worked in sugar cane and alcohol mills in Paraíba and 636 in Goiás. The mean age was 35.4 years (SD=9.2 years) and most were under 40. We found that 47.4% declared schooling of fewer than five years. Regarding the place of birth, 85.7% were native of the Northeast Region. The average monthly income was R$ 1,801.00 (SD= R$ 438.00), and more than two thirds (71.2%) of the sugarcane cutters said they had religion (Table 1).
By means of rapid tests, a prevalence in the set of these markers was estimated at 4.1% (95% CI: 3.0-5.5), that is, out of every 100 sugarcane cutters, four were positive to at least one of the STI.  The bivariate analysis showed a statistically significant association between positivity for some investigated STI   (26)(27) , and in the context of sexually transmitted infections, this is the first research that presents data on the prevalence of STIs and associated factors.
In line with other studies developed with manual sugarcane cutters, our population was marked by men, young and with few schooling years (27)(28) . Young men predominance in this scenario is related to the type of work in sugarcane fields, which requires great effort and physical stamina (27) . On the other hand, the low schooling evidences the socioeconomic conditions of these

Discussion
The rural population in Brazil lives, generally, in conditions of extreme poverty, isolation and in regions marked by socioeconomic inequalities and health vulnerabilities (25) . Especially, manual sugarcane cutters bear unhealthy working conditions, long working hours, high migratory flow and wages conditioned to productivity (26) . In this context, these workers have characteristics that expose them to various health hazards, including sexual infections. Few studies have Rev. Latino-Am. Enfermagem 2020;28:e3306.
workers (11) , and it has been related to less knowledge, less concern about health care, and consequently greater vulnerability in these individuals (29) . Gender and education represent explanatory variables for different risky sexual behaviors (29)(30) .
In the present study, we observed that 4.1% (95% no case of HIV was identified among the individuals investigated (34) .
As in other STI studies, a positivity gradient for STIs was observed with advancing age, with individuals over 40 years of age presenting five times more chance of positivity for any of the infections investigated when compared to those under 30 years of age. This result probably reflects lifetime exposures (35)(36) .
One finding that drawn attention was the high frequency of alcohol and illicit drug consumption, and as observed in other studies (37)(38) , these variables are positively associated with STIs. Almost all cane cutters reported consumption of alcohol and 13.4% of illicit drugs in their lives. The consumption of these drugs seems to be a reality among sugarcane cutters, often stimulated to withstand the excessive workload in the field (39) . Furthermore, the consumption of alcohol often promotes the individual's disinhibition, in addition to reducing his or her memory, which contributes to reducing the perception of risk (40) . In fact, their daily consumption has been associated with inconsistent condom use and multiplicity of sexual partnerships (41) .
Similarly, illicit drug use can encourage sexual risk behavior among users, making them vulnerable to STIs (42) . Such behaviors contribute to the acquisition and maintenance of the STIs' transmission chain and constitute a serious public health problem.
Some studies have shown that practicing a religion reduces risk behaviors for STI by establishing behavioral norms for its followers (43)(44)(45) . In the present study, individuals who reported some religion presented lower positivity to STI, and this variable was negatively associated with these infections, reinforcing this hypothesis (46)(47) .
Sugarcane cutters in activity in the Midwest to disease prevention and treatment (48)(49) .
Some limitations of this study must be considered.
First, this is a cross-sectional study, i.e., it does not allow causal inference; however, it should be noted that the working conditions, and among the various strategies are initiatives aimed at promoting workers' health and safety. Rapid testing, together with a comprehensive approach to STIs, is an urgent and effective proposal to be implemented in this context of rural worker health prevention, as it provides a quick, easy and efficient way to prevent and diagnose STIs.