Treatment and education reduce the severity of schistosomiasis periportal fibrosis

INTRODUCTION
This study evaluates the factors associated with the development of severe periportal fibrosis in patients with Schistosoma mansoni.


METHODS
A cross-sectional study was conducted from April to December 2012 involving 178 patients infected with S. mansoni who were treated in the Hospital das Clínicas of Pernambuco, Brazil. Information regarding risk factors was obtained using a questionnaire. Based on the patients' epidemiological history, clinical examination, and upper abdomen ultrasound evaluation, patients were divided into 2 groups: 137 with evidence of severe periportal fibrosis and 41 patients without fibrosis or with mild or moderate periportal fibrosis. Univariate and multivariate analyses were conducted using EpiInfo software version 3.5.5.


RESULTS
Illiterate individuals (30.1%) and patients who had more frequent contact with contaminated water in towns in the Zona da Mata of Pernambuco (33.2%) were at greater risk for severe periportal fibrosis. Based on multivariate analysis, it was determined that an education level of up to 11 years of study and specific prior treatment for schistosomiasis were preventive factors for severe periportal fibrosis.


CONCLUSIONS
The prevailing sites of the severe forms of periportal fibrosis are still within the Zona da Mata of Pernambuco, although there has been an expansion to urban areas and the state coast. Specific treatment and an increased level of education were identified as protective factors, indicating the need for implementing social, sanitary, and health education interventions aimed at schistosomiasis to combat the risk factors for this major public health problem.

Schistosoma mansoni is a major public health problem worldwide that has great social and economic impact. The disease affects over 200 million people around the world. Approximately 6 million people are infected in Brazil, particularly in the Northeast region [1][2][3] .
One characteristic of this disease is the capacity to cause an infl ammatory response against the Schistosoma mansoni eggs deposited in the host's liver. This process can lead to periportal fi brosis (PPF) due to the deposition and accumulation of extracellular matrix, causing the host to develop portal hypertension that leads to splenomegaly and the emergence of varicose veins in the esophagus. Rupture of these esophageal varices with subsequent severe gastrointestinal bleeding occurs in 12 to 15% of patients, which leads to death in approximately 20% of cases [4][5][6] .
The disease presents in various clinical forms, with 5% to 10% of individuals developing severe liver and spleen lesions the hepatosplenic form described above of which schistosomal fi brosis is among the most important aspects 7 . The risk for developing the most severe hepatosplenic form of schistosomiasis increases according to the severity of the fi brosis 6,8 .
One factor related to PPF is the infection intensity. Several factors are related to the occurrence of schistosomal infection, including exposure time, frequency of contact with contaminated water, and age at infection. Different contacts with contaminated water bodies (natural waters, stream waters, water reservoirs) may determine different epidemiological patterns of infection and transmission 9 . Thus, understanding the evolution of the various clinical forms of schistosomiasis involves understanding a set of factors, such as poor housing and sanitation conditions, economic and sociocultural activities related to the use of contaminated water in rural areas, lack of health education, low adherence to control programs, and lack of an effective vaccine, all of which have contributed to morbidity 10 . Other factors, such as the exacerbation of the host's immune response, concomitant infections, virulence of the S. mansoni strain, and nutritional status of infected individuals, should be taken into account when determining an individual's susceptibility to developing the severe clinical form of the disease 5,11 .
Currently, the mechanism of liver fi brosis has been an object of extensive research, but much work still remains to better understand the complex mechanisms related to the inhibitory

RESULTS
and activating pathways involved in schistosomal fi brosis. Thus, understanding the causal factors that can affect the clinical outcome of this disease remains a challenge [11][12][13] . Therefore, this study aims to describe the epidemiological and clinical factors and to evaluate the factors associated with the development of moderate to severe PPF.
A cross-sectional study examining associations between several factors and the development of moderate to severe PPF was conducted from April to December 2012 and involved 178 patients infected with S. mansoni aged over 18 years and treated in the Gastroenterology Outpatient Clinic of Hospital das Clínicas/Universidade Federal de Pernambuco (HC/UFPE), a reference center for the treatment of schistosomiasis.

Selection of patients
All patients infected with S. mansoni examined during the study period were included. We excluded individuals with other previous liver-associated diseases, such as liver cirrhosis, steatosis, hepatitis B or C, and other clinical forms of diagnosed schistosomiasis. In total, 178 individuals were selected for the study and were divided into two groups.  The two groups were prospectively selected during the study period according to the following criteria: patients with HI schistosomiasis without splenomegaly and with mild or moderate periportal fi brosis (pattern C or D from Niamey's classifi cation 14 ) or those with no fi brosis and patients with HS schistosomiasis with advanced periportal fi brosis (pattern E or F from Niamey's classifi cation 14 ) with splenomegaly or previous history of splenectomy. All of these patients had a history of contact with contaminated water, a positive stool test for S. mansoni, or prior treatment for schistosomiasis.
The sample size was calculated using statistical software (EpiInfo version 3.5.5, Atlanta, U.S) to allow 80% power at a 5% signifi cance level. Considering an expected frequency of PPF severity of 8% and a 4% margin of error with a 95% confi dence level, the sample size was estimated to be 180 individuals 7,8 .
The variables related to risk factors for developing PPF were arranged in two groups: the socioeconomic and demographic variables, including gender, age, education level, family income, alcoholism, and site of contact with contaminated water; and the clinical variables, including history of severe gastrointestinal bleeding, hepatomegaly, splenomegaly, and specifi c treatment. The instrument used for investigating these factors was a pre-coded, structured questionnaire applied to individuals by a single operator.

Ultrasound evaluation
The diagnosis of the clinical form of disease was determined using the patient's clinical history and a clinical examination. An ultrasound evaluation of the upper abdomen was also performed by a single operator at the Gastrointestinal Endoscopy Unit of CH/ UFPE using a Siemens Acuson X 150 ® device with a 3.5-mHz convex transducer to confi rm the diagnosis and rule out other liver diseases (Figure 2). The parameters used to defi ne the PPF pattern were based on Niamey's classifi cation 14 : C -peripheral; D -central; E -advanced; and F -very advanced.

Statistical analysis
Data from the questionnaires were tabulated twice. Univariate and multivariate analyses were conducted using EpiInfo software version 3.5.5. For evaluating the association of selected factors and the fi brosis pattern, prevalence ratios (PRs) and 95% confi dence intervals (CIs) were calculated using the fi brosis pattern as a dependent variable and the selected factors as independent variables. The potentially confounding variables with the factors of interest were examined using a non-conditional logistic regression analysis. The association was regarded as signifi cant when p < 0.05.

Ethical considerations
All clinical and ultrasound examinations were performed according to a standardized protocol. The study was conducted within the standards required by the Declaration of

Clinical and ultrasound evaluation
Liver abnormalities were identifi ed in 170 patients who were attributed to S. mansoni according to Niamey's protocol 14   On multivariate analysis, there were inverse associations between education level (up to 11 years of study) and specifi c treatment with the advanced PPF pattern, indicating that these variables may be protective factors. Table 3 shows the odds ratios (ORs) associated with the variables that remained in the fi nal logistic regression model. For the fi nal analysis, we selected 9 variables (education, time of last contact with contaminated water, site of last contact with contaminated water, alcoholism, specifi c treatment for S. mansoni, family income, last specifi c treatment, age, and gender). This analysis was used to evaluate the association between the PPF pattern (dependent variable) and the selected variables (independent variables).
The variables with p < 0.20 in the univariate analysis were included in the logistic regression model. We had to exclude patients in both groups due to lack of information for this analysis. The exclusions occurred in the analysis of the variables 'last time of specifi c treatment' -16 cases/10 controls; 'specifi c treatment for S. mansoni' -5 cases/5 controls and 'time of last contact with contaminated water' -2 cases.

DISCUSSION
Protective associations were identifi ed between the education level up to 11 years of study and prior specifi c treatment and the advanced periportal fi brosis pattern.
It has been shown that specifi c treatment for S. mansoni can contribute to decreasing infection levels and improving clinical conditions such as hepatosplenomegaly and PPF [15][16][17] . As a result, the regression of PPF may prevent the emergence of portal hypertension, highlighting the importance of PPF diagnosis by obtaining accurate methods for monitoring this disease 18 . However, a higher education level might lead the patient to seek early treatment and could prevent reinfections.
Ultrasound examination and Niamey's classifi cation 14 were used to diagnose the clinical forms and the PPF stages, which are currently the most widely used techniques for this purpose in both fi eld and hospital studies 4 .
This study was hospital-based; individuals generally present with more severe clinical forms in hospital studies when compared to fi eld studies. There were many HS schistosomiasis patients with advanced fibrosis and even HI individuals presenting the more advanced fi brosis pattern D when compared to pattern C. Only 8 individuals did not exhibit fi brosis. In an area with a low prevalence of this disease, most of the population did not show fi brosis, and only 4.6% had fi brosis pattern C 18 .
We observed an improvement in the education level in the patients from rural areas compared with previous studies, possibly due to Brazilian socioeconomic growth in recent years 19,20 . It is well known that control measures such as sanitation and education are gradually improving in Brazil; these measures contribute to a decrease in schistosomiasis transmission. In addition, better economic conditions for all individuals in northeastern Brazil may help to solve this public health problem, which still affects many states in the region, particularly Pernambuco 19,21,22 . In addition, studies have described recent transmissions of schistosomiasis throughout this region and even in the City of Recife 19 .
This study demonstrated that the prevailing sites with severe forms of schistosomiasis are still within the Zona da Mata of Pernambuco by evaluating the towns with higher frequencies of contact with contaminated water, although there has been an expansion of the disease to urban areas, especially within the Metropolitan Region of Recife and near the coast. The development of the severe form requires a high parasitic load, which means that the individual has undergone repeated contact with the infection focus over a long time. This is more frequently observed in the Zona da Mata than in the current foci in the metropolitan region of Recife and the coast of Pernambuco. Contact with these more recent foci is less intense. Moreover, it has been shown that HS schistosomiasis needs 5 to 15 years for the infection to establish itself 23 .
The high (55.4%) frequencies of gastrointestinal bleeding and prior splenectomy (43.1%) for the treatment of portal hypertension in these patients and the signifi cant percentage of patients with no prior treatment (30.7%) reinforce the need for a systematic approach to the specifi c treatment of all cases with a positive diagnosis, particularly those with a diagnosis of the hepatosplenic form with advanced PPF. Evaluation and monitoring of esophageal varices and improvements in hospitals located in endemic areas to provide emergency care for HS schistosomiasis patients are needed to decrease the morbidity and mortality of this parasitic disease.
In conclusion, the risk factors evaluated in this study reinforce the impact of this disease in endemic areas of the State of Pernambuco, once again drawing attention to the fact that treatment and education constitute preventive factors for this disease. These data also indicate the need to implement social, sanitary, and health education interventions aimed at schistosomiasis to decrease or prevent disease occurrence, which is still a major public health problem.