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Revista de Saúde Pública

Print version ISSN 0034-8910

Rev. Saúde Pública vol.47 no.2 São Paulo Apr. 2013

http://dx.doi.org/10.1590/S0034-910.2013047004247 

Review

Association between Schistosomiasis mansoni and hepatitis C: systematic review

Associação entre esquistossomose mansônica e hepatite C: revisão sistemática

Asociación entre esquistosomiasis mansoni y hepatitis C: revisión sistemática

Daniele Silva de Moraes Van-LumeI 

Maria de Fátima Pessoa Militão de AlbuquerqueII 

Alexandre Ignácio de SouzaIII 

Ana Lúcia Coutinho DominguesIV 

Edmundo Pessoa de Almeida LopesIV 

Clarice Neuenschwander Lins de MoraisV 

Silvia Maria Lucena MontenegroV 

IPrograma de Pós-Graduação em Saúde Coletiva. Centro de Pesquisas Aggeu Magalhães. Fundação Oswaldo Cruz. Recife, PE, Brasil

IIDepartamento de Saúde Coletiva. Centro de Pesquisas Aggeu Magalhães. Fundação Oswaldo Cruz. Recife, PE, Brasil

IIICentro de Pesquisas Aggeu Magalhães. Fundação Oswaldo Cruz. Recife, PE, Brasil

IVDepartamento de Gatroenterologia. Hospital das Clínicas. Universidade Federal de Pernambuco. Recife, PE Brasil

VDepartamento de Imunologia. Centro de Pesquisas Aggeu Magalhães. Fundação Oswado Cruz. Recife, PE, Brasil


ABSTRACT

OBJECTIVE:

To perform a systematic review of the prevalence of the HCV/ S. mansonico-infection and associated factors in Schistosoma mansoni-infected populations.

METHODS:

The bibliographic search was carried out using the Medline, Lilacs, SciELO, Cochrane Library and Ibecs databases. The criteria for the studies' selection and the extraction data were based on systematic review methods. Forty five studies were found, with nine being excluded in a first screening. Thirteen articles were used for data extraction.

RESULTS:

The HCV infection rates in schistosomiasis populations range from 1% in Ethiopia to 50% in Egypt. Several studies had poorly defined methodologies, even in areas characterized by an association between hepatitis C and schistosomiasis, such as Brazil and Egypt, which meant conclusions were inconsistent. HCV infection rates in schistosomotic populations were heterogeneous and risk factors for acquiring the virus varied widely.

CONCLUSIONS:

Despite the limitations, this review may help to identify regions with higher rates of hepatitis C and schistosomiasis association. However, more studies are necessary for the development of public health policies on prevention and control of both diseases.

Key words: Comorbidity; Hepatitis C, epidemiology; Schistosomiasis, epidemiology; Review

RESUMO

OBJETIVO:

Realizar revisão sistemática sobre a prevalência da confecção do vírus da hepatite C e Schistosoma mansonie os fatores de risco associados a indivíduos com esquistossomose.

MÉTODOS:

Revisão realizada nas bases de dados Medline, Lilacs, SciELO, Biblioteca Cochrane e Ibecs. Os critérios de seleção e a obtenção dos dados foram baseados em métodos de revisão sistemática. Foram encontradas 45 referências relevantes, das quais nove foram excluídas na primeira triagem, 14 na leitura dos resumos e nove na leitura completa. Treze artigos foram selecionados para análise.

RESULTADOS:

A prevalência da associação entre vírus da hepatite C e Schistosoma mansonivariou de 1% na Etiópia a 50% no Egito. Alguns estudos apresentam metodologias pouco definidas, mesmo em áreas caracterizadas pela associação entre vírus da hepatite C e S. mansoni, como Brasil e Egito, o que não permitiu conclusões consistentes. As taxas de infecção pelo VHC em populações esquistossomáticas foram heterogêneas e os fatores de risco para adquirir o vírus foram variáveis.

CONCLUSÕES:

Apesar das limitações, esta análise pode ajudar a identificar regiões com maiores taxas dessa associação. Outros estudos serão necessários para o desenvolvimento de políticas públicas de prevenção e controle dessas doenças.

Palavras-Chave: Comorbidade; Hepatite C, epidemiologia; Esquistossomose, epidemiologia; Revisão

RESUMEN

OBJETIVO:

Realizar revisión sistemática sobre la prevalencia de la co-infección del virus de la hepatitis C y Schistosoma mansoni y los factores de riesgo asociados a individuos con esquistosomosis.

MÉTODOS:

Revisión realizada en las bases de datos MEDLINE, LILACS, SciELO, Biblioteca Cochrane e IBECS. Los criterios de selección y la obtención de los datos fueron basados en métodos de revisión sistemática.

RESULTADOS:

Fueron encontradas 45 referencias relevantes, de las cuales, nueve fueron excluidas en la primera selección, 14 en la lectura de los resúmenes y nueve en la lectura completa. Trece artículos fueron seleccionados para análisis. La prevalencia de la asociación entre virus de la hepatitis C y Schistosoma mansoni varió de 1% en Etiopia, a 50% en Egipto. Algunos estudios presentan metodologías poco definidas, inclusive en áreas caracterizadas por la asociación entre el virus de la hepatitis C y S. mansoni, como Brasil y Egipto, lo que no permitió conclusiones consistentes. Los cocientes de infección por el VHC en poblaciones esquistosómicas fueron heterogéneos y los factores de riesgo para adquirir el virus fueron variables.

CONCLUSIONES:

A pesar de las limitaciones, este análisis pudo ayudar a identificar regiones con mayores cocientes de esa asociación. Otros estudios serán necesarios para el desarrollo de políticas públicas de prevención y control de estas enfermedades.

Palabras-clave: Comorbilidad; Hepatitis C, epidemiologia; Esquistosomiasis, epidemiologia; Revisión

INTRODUCTION

Schistosomiasis is the second most important parasitic infection after malaria and affects more than 200 million people in 74 countries. 56 It is endemic, with high prevalence and morbidity rates in many countries, especially those in Africa, such as Egypt, 18 Kenya 9 and Sudan, 27, 44 and in South America, mainly Brazil.38, a

The prevalence of schistosomiasis ranged from 15 to 45% in Egypt and Brazil.18,38, aIn this country, six to eight million people are infected with Schistosoma mansoniand about 30 million people live under risk of infection. aThe prevalence of Schistosomiasis mansoni (SM) can reach up to 27% of the population in some areas of Northeastern Brazil, 38 turning this country into a major schistosomiasis endemic area in the world.

The diverse clinical patterns observed for this disease depend on many factors, including parasite strain, host genetic background, host nutritional and immunological state, and co-infections. 9, 10, 16, 31, 35 Schistosomiasis may progress to the most advanced stage of disease, the hepatosplenic form (HS). This clinical form is observed in endemic areas and is characterized by portal hypertension that may cause digestive hemorrhage. 28, 42, 48 When SM comes combined with other hepatic disease, especially the Hepatitis C Virus (HCV) infection, the progression of hepatic fibrosis into cirrhosis and hepatocellular carcinoma (HCC) can occur within a few years. 29, 40 Concomitant SM and HCV infection is observed with high frequency in Egypt 2, 7, 47 and Brazil. 39

Hepatitis C is also considered an important public health issue throughout the world, with approximately 3% of people (about 170 million) being infected with the HCV. 1, 2 It is also the most important cause of liver disease and HCC in developed countries, including the United Kingdom and USA, 5, 41, 53, 54 and in developing countries, such as Egypt 2, 25, 26 and Brazil. 6, 39, 45

In Egypt, eight to ten million are infected and 68 million people have been exposed to HCV 52 (a prevalence of 10 to 60%), mainly in rural areas. 15, 17, 21 The prevalence of HCV infection is lower in Brazil than in Egypt and varies from 2.5% to 4.9%, corresponding to approximately 3.9 to 7.6 million people. 11

HCV may be implicated as a factor influencing the severity of schistosomiasis in developing countries. Likewise, an influence of SM on HCV severity has been suggested by some authors. 29, 33, 39

There are many contradictory data about the prevalence of HCV/S. mansoni co-infection in SM endemic areas and the risk factors associated with increased susceptibility for HCV infection in a S. mansoni-infected person, especially in the HS form. 2, 4, 7, 49

The worldwide relevance of the hepatitis C and schistosomiasis association as a public health issue is mainly due to the severe clinical patterns and high morbidity associated with it, especially in developing countries. This study aimed to perform a systematic review of the prevalence of the HCV/S. mansoni co-infection in SM-infected population living in endemic areas and associated factors.

METHODS

The bibliographic search was performed through a systematic search covering the 1990s and up to May 2011. The terms “Schistosomiasis mansoni” and “Hepatitis C” were utilized to search the Medline, Lilacs, SciELO, Cochrane Library and IBECS databases. These databases fulfill the minimum criteria search to conduct a systematic review, in accordance with the literature. 22

Forty-five publications were obtained through the website search described and a first screening was performed. The criteria adopted for inclusion were:

• Studies in scientific article formats published on or after 1989, the year in which HCV was discovered;

• Titles published in English, Spanish or Portuguese with available abstracts;

• Studies performed with human populations.

Nine studies were excluded because they utilized experimental models, were presented as thesis or monograph or were redundant in different databases (Figure).

Figure.  Flowchart of the systematic review results of selected publications. 

A second screening was done by analyzing the 36 selected abstracts. Fourteen studies were excluded because they did not contain information about the prevalence of HCV/ S. mansoniassociation or the risk factors associated with HCV infection in a schistosomiasis population (Figure).

A total of 22 articles were selected for complete reading. This step was carried out by a pair of reviewers where each one, independently, filled a table with the criteria relevant to the articles selected for data extraction. 14, 22 There was no discordance between the two reviewers in regard to the articles selected, with kappaindex = 1 (p < 0.05). The inclusion criteria adopted in this step were:

• Population: subjects of both sexes infected by S. mansoniand living in endemic areas;

• Age group: > 18 years old;

• Measurement of HCV/ S. mansoniassociation: studies that described the methods utilized to measure the prevalence of HCV and S. mansoniinfections;

• Risk factors: studies that reported the risk factors associated with HCV infection and if there is a correlation with schistosomiasis.

Studies that used only serologic methods to evaluate the prevalence of S. mansoniinfection were excluded because the distinction between past and present infection is not possible, raising doubts about the confirmed SM diagnosis. 20

Of the 22 articles selected for the last step, 13 filled all inclusion criteria and offered data required to analyze the prevalence of hepatitis C and schistosomiasis association in SM endemic areas. The exclusion of the nine articles in the last screening are described in Figure. 1, 3, 20, 24, 25, 34, 4951

RESULTS

Table 1, 2and 3list the 13 articles that were analyzed.

Table 1. Authors, type of studies and their objectives. 

Author Country Type of study Objective
Silva JLA et al45 (2008) Brazil Cross-sectional To obtain the serological prevalence for HCV in SM patients
Mudawi HM et al36,a (2007) Sudan Cross-sectional To determine the prevalence of HCV and identify the most common genotype in patients with HSS
Mudawi HM et al37,a (2007) Sudan Population based cross-sectional To determine the HCV prevalence and the risk factors associated, in a population living in SM endemic area
Berthe N et al8 (2007) Ethiopia Population based cross-sectional To elucidate determinants of morbidity in SM
Blanton RE et al9 (2002) Egypt and Kenya Population based cross-sectional To compare the severity of hepatic lesions and morbidity in co-infection in two populations with different epidemiological patterns for SM and hepatitis C
Pereira LMMB et al40,a (2001) Brazil Cross-sectional with an external control group To analyze the frequency of HBV and HCV markers and to correlate this with severity of hepatic lesions in co-infected patients
Kamal S et al29,a (2000) Egypt Cross-sectional To investigate the influence of SM on chronic hepatitis C with respect to the natural course of the disease and others parameters
Aquino RTR et al6 (2000) Brazil Retrospective cases series To evaluate the frequency and the consequences of the co-infection of hepatitis B and C in patients with HSS
El-Sayed HF et al19,a (1997) Egypt Cross-sectional To determine the prevalence of HBV and HCV in a endemic area for SM and the risk factors associated with co-infection
Pereira LM et al39 (1995) Brazil Cross-sectional with an external control group To investigate the HCV participation in severity of hepatic lesions in SM patients
Abdel-Wahab MF et al2 (1994) Egypt Prospective cases series To estimate the prevalence and magnitude of HCV infection in Egypt
Kamel MA et al30 (1994) Egypt Population based cross-sectional To determine the epidemiological relationship between SM and HBV and HCV serologic markers
Lacerda CM et al32,a (1993) Brazil Cases series with an external control group To study the HBV and HCV serologic markers in 50 patients with HSS and compare the results with 50 controls

aAuthors used the logistic regression multivariate method to analyze the risk factors associated with HCV acquisition in an SM population. HSS: Heaptocellular carcinoma; HCV: Hepatitis C Virus; SM: Shistosomiasis mansoni; HBV: Hepatitis B Virus

Table 2. Systematic review of results of Hepatitis C Virus and Schistosoma mansonidiagnosis and prevalence of Hepatitis C Virus/ mansoniassociation. 

Population size Population characteristics HCV diagnosis SM diagnosis Prevalence of Association
184 subjects45 41.3% male Anti-HCV ELISA 3rd generation Not mentioned 11.9%
176 subjects36 81.3% male Mean age = 41.4 Anti-HCV ELISA 3rd generation HCV RNA PCR and genotype Clinical and history examinations Ultrasonography (US) with periportal fibrosis (PPF) 4.5% for anti-HCV 2.3% for HCV RNA PCR
410 subjects37 45% male Mean age = 35 91% have SM infection Questionnaire Anti-HCV ELISA 3rd generation HCV RNA PCR Presence of ova in stool samples Epidemiological history 2.2%
2.451 subjects8 1.615 SM infected 52.1% male Mean age = 18.8 Anti-HCV 3rd generation Kato-Katz Questionnaire US 21-30 years old = 1.6% 31-40 = 0.8% > 40 = 1%
237 Kenyans9 112 Egyptians Mean age Kenyans: 33.1 Mean age Egyptians: 34 Anti-HCV ELISA 3rd generation RT-PCR Parasitological exams US Egyptians: 39.7% Kenyans: 11.3%
234 subjects40 50 controls Mean age: 39 55.1% male; 44.9% female Anti-HCV HCV RNA PCR Clinical examination Presence of eggs in stools or rectal biopsy 20% for anti-HCV 12.4% for HCV RNA PCR
126 subjects29 84 men (66.6%) Mean age = 43 Group A (n = 33): HCV infection; mean age = 44.2 Group B (n = 30): Schistosomiasis; mean age = 38.2 Group C (n = 63): co-infection; mean age = 41.5 Anti-HCV ELISA 2nd generation HCV RNA PCR Presence of eggs in stool or rectal biopsy Epidemiological history 50%
101 HSS patients6 Mean age: 40.31 42.6% male 75.8% Caucasian; 8.1% black; 16.2% mixed ethnicity Anti-HCV HCV RNA PCR History and clinical examinations Medical records 12.9%
506 subjects19 Mean age: 20 52% male; 48% female Anti-HCV ELISA 2nd generation Kato-Katz technique US 10.3% 28% in people more than 40 years old
215 patients39 50 controls SM: 43 with HIS 173 with HSS 115 male (53.4%) Mean age = 38 Controls: 21 male (42%) Mean age = 45 Anti-HCV ELISA anti-core and NS3/NS4 Nested PCR History examination Presence of Schistosomaeggs in stools or rectal biopsy Liver biopsy 22% in patients 2% in controls
354 adults2 Patients admitted to Kasr El Aini Hospital, in Cairo, for chronic hepatic diseases evaluation Liver function tests, liver biopsies Anti-HCV ELISA 2nd generation History examination Liver function tests US Liver biopsies 32.9% 77% were male
1,550 subjects30 Mean age = 20.2 Anti-HCV ELISA 2nd generation in duplicate samples Kato-Katz US compatible with PPF 15.3%
50 HSS patients (G1)32 50 controls (G2) G 1: SM patients, 46% male; mean age = 41 G 2: 42% male; mean age = 44.4 Anti-HCV ELISA 1st generation Medical records 20%

RT-PCR: real time – polymerase chain reaction; HCV: Hepatitis C Virus; SM: Schistosomiasis mansoni; HSS: Hepatosplenic schistosomiasis; HBV: Hepatitis B Virus; HCC: hepatocellular carcinoma; HIS: hepato intestinal schistosomiasis

Table 3. Risk factors, results and conclusion of studies selected. 

Risk factors for HCV Results Conclusion
Blood transfusion45 Digestive endoscopy 90.5% of co-infected had HSS form 54.5% received blood transfusion Blood transfusion and endoscopy history are associated with the increase of HCV prevalence in HSS form.
No risk factor36,a Genotype 4 was the most prevalent in HS patients. The parenteral therapy was not associated with co-infection The HCV prevalence in HS patients is considered low (4.5%) and the genotype 4 is the most common in Sudan.
No risk factor37,a 91% had SM 11.2% had anti-HCV+, only 2.2% were HCV RNA PCR+ Between 21 and 40 years old, the anti-HCV reactivity was 7.8% HCV infection has low prevalence in Sudan and the anti-SM parenteral therapy cannot be associated with co-infection.
No risk factor8 65.9% were positive for SM 1.3% subjects with SM were positive for HCV The highest prevalence was found among children It is necessary to integrate helminth control targeting school-aged children to reduce the risk of PPF in future.
Age older9 Genetic background OPG mean was higher among the Kenyans than Egyptians The PPF pattern was higher among Egyptians Hepatitis C is 3 times more prevalent among Egyptians Geographical differences are observed in relation to PPF patterns among the two populations. HCV is associated with active infection only among Egyptians, who present more severity and morbidity for co-infection.
Blood transfusion40,a 57% were positive for HBV or HCV or both HCV infection may contribute to severity of liver damage when the subject has the HSS form.
Anti-SM therapy (76%)29,a Blood transfusion (22.2%) Nosocomial exposure The mortality in group C was 48% after 6 years in comparison with group A (12%) and B (3%). HCC is most frequent in co-infected (33%) patients than mono-infected. Mortality was not affected by age, HCV RNA titer or genotype virus Patients co-infected are characterized by more advanced liver disease, higher HCV RNA titers, predominance of HCV genotype 4, higher inflammatory activity, incidence of cirrhosis and HCC with much higher mortality rate.
Blood transfusion6 84.6% of anti-HCV+ had HCV RNA PCR+ with high aminotransferases, more cell decompensation and high rate of chronic hepatitis The rate of hepatitis B and C markers in HSS patients is higher than control group and it is responsible for a high frequency of liver damage.
History of surgeries19,a Anti-SM parenteral treatment Anti-HCV was positive in 10.3% of subjects and 5% was positive for anti-HBV and anti-HCV Hepatitis B and C are the major public health problems in Egypt. Studies about epidemiology, natural history, risk factors and modes of transmission are necessary.
No significance between groups was found for blood transfusion39 The HCV prevalence in co-infected group was higher (22%) than in control group (2%). 61.7% of co-infected had HCV-RNA circulating with high levels of liver enzymes, especially in HSS decompensated form Co-infection is a major factor contributing to the severity of liver disease in chronic SM and active replication of the virus in the liver or at extra-hepatic sites is strongly associated with severe liver disease.
Blood transfusions2 Hemodialysis Anti-SM parenteral treatment The prevalence of anti-HCV was 46% in renal chronic patients, 22.1% in soldiers and 47.2% in chronic hepatic diseases HCV infection prevalence is high in Egypt, especially among patients with liver disorders. More studies are necessary to confirm this transmission route.
No risk factors30 About 1550 samples examined by Kato-Katz technique, 49.1% were positive for SM. The anti-HCV was + in 15,9%, and increases with age No relationship among HBV or HCV and S. mansoniinfection is found in those living in endemic area for SM, with statistical significance.
Blood transfusion32,a Sporadic contamination Prevalence of HCV serologic marker was 20% in group 1 and 4% in group 2. Among 10 HSS patients, 7 had received blood transfusion A high prevalence for anti-HCV markers is found in SM patients in comparison with healthy people.

aAuthors who used the logistic regression multivariate method to analyze the risk factors associated with Hepatitis C Virus acquisition in a Schistosomiasis mansoni population. PCR: polymerase chain reaction; HCV: Hepatitis C Virus; SM: Schistosomiasis mansoni; HSS: Hepatosplenic schistosomiasis; HBV: Hepatitis B Vírus; HCC: hepatocellular carcinoma; HS: hepato schistosomiasis; PPF: periportal fibrosis; HSS: Hepatosplenic schistosomiasis

The prevalence of HCV/ S. mansoniassociation ranged from 0.8 37 to 50.0% among the studies, with the highest ranges in Egypt (10 to 50%). 2, 9, 19, 29, 30

Among the 13 articles included in the final step of the review, ten were cross-sectional studies, 8, 9, 19, 29, 30, 36, 37, 39, 40, 45 one was a retrospective cases series, 6 one was a prospective cases series 2 and the other was a cases series with an external control group. 32 Five studies 6, 32, 39, 40, 45 were conducted in Brazil, five in Egypt, 2, 9, 19, 29, 30 two in Sudan, 36, 37 one in Ethiopia 8 and one in Kenya. 9 A higher prevalence of HCV infection was found in the SM population of Egypt, compared to the other countries ( Table 1).

Eight studies 2, 6, 19, 32, 36, 37, 40, 45 sought to determine the serologic prevalence of HCV infection in an SM population and one study proposed to verify any epidemiologic relationship of schistosomiasis and HBV and HCV serologic markers. 30 Six studies 6, 9, 29, 37, 39, 40 aimed to evaluate the severity of hepatic lesions and morbidity of hepatitis C when associated with SM and to correlate this with serologic markers. The mean age of humans enrolled in these studies was 33.7 years and in four articles subjects were > 40 years 6, 29, 32, 36 ( Table 2).

The inclusion criteria used by the authors to choose subjects with schistosomiasis were mainly: people living in endemic areas with positive parasitological exams confirmed by the presence of S. mansonieggs in stool samples or rectal biopsies (eight studies) and/or ultrasonography (US) compatible with periportal fibrosis (PPF) (six studies). The epidemiological history was considered in seven studies to compose diagnosis when in conjunction with one or both criteria mentioned above.

The main exclusion criteria adopted for the selected studies was if the person did not live at the study site. People with no history of contaminated water contact and/or with liver disease caused by alcohol consumption, autoimmune disorders or by Hepatitis viruses A, B, D or with others etiologies were also excluded from these studies. Six studies did not mention the exclusion criteria adopted. 2, 9, 19, 30, 32, 36

The most commonly chosen technique of HCV diagnosis was 3rd generation anti-HCV ELISA, utilized in five studies. 8, 9, 36, 37, 45 Four other studies utilized 2nd generation anti-HCV ELISA. 2, 19, 29, 30 The quantification of the viral titers was performed by HCV RNA PCR in seven studies. 6, 9, 29, 36, 37, 39, 40

Six studies made appropriate epidemiologic and statistical analyses to confirm the correlation between risk factors associated and HCV infection in SM patients. 19, 29, 32, 36, 37, 40 The other articles suggested possible risk factors without any statistical correlation found ( Table 3).

Blood transfusion was cited by seven of them as a risk factor for HCV contamination. 2, 6, 29, 32, 39, 40, 45 The second most observed risk factor described in three studies was the antischistosomal mass treatment, due to the use of syringes and nosocomial equipments without proper sterilization. 2, 19, 29 Surgical procedures, 19, 29 digestive endoscopy, 45 old age, 9, 19 genetic background 9 and hemodialysis 2 were also cited as risk factors for HCV acquisition. Four studies did not find any association between SM infection and an increased risk of acquiring HCV. 8, 30, 36, 37

DISCUSSION

Schistosomiasis is an important public health issue associated with poverty and poor sanitary conditions. 13 All studies described were conducted in developing countries since the 1970s, especially in Egypt, Sudan, Ethiopia, Kenya and Brazil, confirming the impact of this disease in these countries. 13 The association between schistosomiasis and hepatitis C has been studied by many authors, showing the importance of research into this condition worldwide ( Tables 1, 2and 3).

The majority of articles were cross-sectional studies ( Table 1) and aimed to determine the prevalence of HCV infection in a confirmed SM population. Cross-sectional studies are important in identifying regions in developing countries that need more attention from the government authorities for the implementation of public health policies in regards to treatment and control for both hepatitis C and SM. On this point, this review may help to identify regions where the association of these diseases and the risk factors associated with HCV infection are relevant, and to aid the implementation of prevention and control actions.

A few studies pointed to a correlation between diseases with morbidity patterns, progression of liver damage 29, 39 and risk factors 2, 6, 9, 19, 29, 30, 36, 37, 39, 40, 45 in acquiring HCV. It could be useful to understand the clinical course of this particular condition and for treatment choices ( Tables 2and 3). When schistosomiasis and hepatitis C association is established, the clinical course develops into severe hepatocellular damage. Viral persistence and hepatic cirrhosis can develop faster than in mono-infected people. 6, 29

The high percentage of HCV infection in schistosomiasis populations of different countries caught the attention of the scientific community for the variable prevalence of disease association rates. 8, 19, 36, 37, 40, 45 The rates ranged from 10 to 50% in Egypt, 2, 9, 19, 29, 30 mainly due the mass treatment of the schistosomiasis infected population in the 1970s. This public policy was not adopted in other countries and similar prevalence rates cannot be observed. 8, 36, 37 There is a lack of a relationship between the high prevalence of HCV infection in schistosomiasis endemic areas and risk factors, although many of them were.

Disease association rates in Brazil, although not as high as in Egypt, can be considered relevant due to the high morbidity when HCV is present. When the study was conducted with hospital patients in Brazil, disease association rates were up to 20%. 32, 39, 40 Conflicting results among studies on HCV /S. mansoniassociation in Brazil,6,40,45,46, breinforce the need for further studies of this condition, especially with appropriate methodologies for prevalence and risk factor evaluations. Methodological issues are the main problem of the majority of studies worldwide, suggesting the inadequacy of study designs.

The serologic method was the most commonly used method of evaluating HCV infections, including recently developed techniques adapted from the older versions. The 3rd generation ELISA is performed by many research groups, since it is a fast and relatively cheap technique. 8, 9, 36, 37, 45 Some authors reject this method because, in S. mansoni,infection could produce auto-antibodies against HCV epitopes, mimicking HCV infection. 3 However, this immunoglobulin (Ig) production is not well defined in the literature and the auto-Ig’s ratios are low, which can be differentiated from HCV infection by increasing the cut-off point. As for schistosomiasis diagnosis, the method of choice continues being Kato-Katz test, based on the presence of S. mansonieggs in stool samples or in rectal biopsies, and US patterns to evaluate the periportal fibrosis. 43, 55 This review confirms that no significant diagnosis methods have been developed for either disease over the last decades.

The current systematic review also considered risk factors associated with an increased chance of acquiring HCV infection when the subject has SM. 19, 29, 32, 36, 37, 40 These data may be useful to direct monitoring and treatment campaigns for both diseases and may contribute to lower prevalence and morbidity rates in the future.

Blood transfusion was the risk factor most cited 6, 32, 39, 40, 45 in Brazil and the anti-schistosomiasis parenteral mass therapy, 2, 19, 29 in Egypt. Poorly sterilized syringes and equipment used during these campaigns 21, 26 may be the key to increased chances of acquiring HCV.

In the HS schistosomiasis form, common in endemic areas, the subject presents esophageal varices in most cases as a consequence of periportal hypertension and disease severity in SM. 43 Disruption of these veins can cause digestive bleeding and blood transfusion may be required for patient survival. b

The serological screening in Brazilian blood banks did not include anti-HCV markers before 1993, in spite of the recent discovery of HCV. Blood transfusion before this year can be considered as a risk factor for HCV acquisition. 12 The lack of proper sterilization of equipment and reused syringes during anti-schistosomiasis parenteral mass therapy 21, 23 increases the chance of HCV infection in SM patients in Egypt. The causes of HCV infection are different among the countries and in most cases the public policies are adopted as a reflex.

In most articles, the risk factors were based on patient reports and epidemiological history, without significant statistical analyses. More studies are needed to clarify HCV transmission routes and risk factors for HCV/ S. mansoniassociation. The last study on this issue was published in 2008, pointing to the lack of research in this area.

In conclusion, this revision shows the lack of well-designed studies with appropriate methodology for evaluating the prevalence of this condition in areas of endemic schistosomiasis. Despite the limitations of this study, the results may help to identify regions with higher HCV/ S. mansoniassociation rates. New public health policies attempting to reduce the current high prevalence and morbidity rates observed in hepatitis C and schistosomiasis could be proposed, especially in SM endemic regions.

ACKNOWLEDGMENTS

To the researchers Sinval Pinto Brandão Filho and Zulma Maria de Medeiros of the Centro de Pesquisas Aggeu Magalhães/FIOCRUZ-PE, for their important guidance.

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aMaciel RCR. Enzimas caniculares na forma hepatoesplênica da esquistossomose mansoni [dissertação de mestrado]. Recife: Universidade Federal de Pernambuco; 2006.

bMorais CNL. Avaliação da relação entre marcadores biológicos com os graus de fibrose no complexo hepatite C e esquistossomose [tese de doutorado]. Recife: Centro de Pesquisas Aggeu Magalhães da Fiocruz; 2007.

Research parcially supported by fellowship of Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – CAPES. Post Graduation Program in Public Health of the Centro de Pesquisas Aggeu Magalhães/FIOCRUZ-PE to the PhD thesis of Daniele Silva de Moraes Van-Lume.

Received: March 7, 2012; Accepted: July 15, 2012

The authors declare that there are no conflicts of interests.

Correspondence:, Silvia Maria Lucena Montenegro, Departamento de Imunologia, Centro de Pesquisas Aggeu Magalhães, Av. Moraes Rego, s/n Cidade Universitária, 50670-420 Recife, PE, Brasil, E-mail: silvia@cpqam.fiocruz.br

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