Epidemiology of Schistosomiasis Mansoni in Brazil

Maria José Conceição and José Rodrigues Coura 1Faculdade de Medicina da Universidade Federal do Rio de Janeiro-UFRJ,. DoctorServiço de Doenças Infecciosas e Parasitárias-Hospital Universitário Clementino Fraga Filho, Departamento de Medicina Preventiva da Faculdade de MedicinaUFRJ, Professor from Curso de Pós-Graduação em Doenças Infecciosas e Parasitárias-UFRJ 2Fundação Oswaldo CruzFiocruzMinistério da Saúde-Brasil. Laboratório de Doenças Parasitárias Brasil


Introduction
The present chapter emphasized the historical aspects of Schistosoma mansoni infection in Brazil.It was introduced in the state of Bahia, possibly during the traffic of slaves infected by the parasite, and the disordered migratory movements from Northeast region towards the Southeast and South regions contributed significantly for infection expansion; another contributing factor was the sugar cane culture.The sectional and longitudinal surveys pointed out high levels of prevalence and morbidity due to aspects related to race, age, sex, occupation, parasite load, specific treatment and reinfection.Treatment with oxamniquine has been shown non-responsive in groups of patients, and the use of praziquantel for more than three decades has begun to reveal therapeutic failure.Support for the researches about new drugs is critical.The decrease in the prevalence rates as well as in the severe forms, though without reaching the transmission control goals, should be considered an alert sign for schistosomiasis not being neglected in the country.The Brazilien authors have concluded in different endemic areas of Brazil that the indices of prevalence and morbidity are reducing, however the transmission control keeps the same high levels.On recommend the implementation of multiple measures as people should continue to receive treatment, improve sanitation conditions, potable water supply, and education in health, besides to avoid the frequent reinfections.characterizing schistosomiasis haematobium.Lutz confirmed its initial discovery as he found out, during the autopsies of patients who passed away due to severe infection by S. mansoni, female mated worms, in the portal vein, with egg-endowed lateral spicule.In 1919, Lutz described the evolving forms of the parasite.Uncontrolled migration may be related to outbreaks of S. mansoni focus in the northeast of the State of Santa Catarina (Schlemper Junior et al. 1996), and in the Southern most Brazilian State, Rio Grande do Sul (Graeff-Teixeira et al. 1999).The transmission of S. mansoni infection in some touristic rural places in endemic areas of Minas Gerais was detected in 17 people with toxemic form of the disease, after a bath in a swimming pool, where there was infected B. glabrata (Enk et al. 2004).Also in Minas Gerais, Massara et al. (2008) confirmed the diagnosis of schistosomiasis infection in visitors who frequented ecotourism area.In a touristic beach of Pernambuco, Brazil, Barbosa et al. (2001) described an outbreak of acute schistosomiasis.A follow-up study of fifteen-years was carried out in a locality of State of Rio de Janeiro, aiming to evaluate S. mansoni prevalence between 1360 inhabitants.The results showed 1.0%, of positivity.The authors concluded that over the years, it remained as a low prevalence area (Igreja et al. 2010).Other areas in the Rio de Janeiro State, also presented low infection levels reached and maintained by Nectomys squamipes rodents (Soares et al. 1995).

The contribution of studies developed by Brazilian authors in different endemic areas and their impact on the current situation of disease
Since 1908 there was two main stages regarding the disease study in Brazil.One aimed to detect the prevalence of infection and its clinical manifestations, and the other intended to understand the evolution of infection in the different areas over the years, as well as the main determining factors for the severity of clinical forms.Penna, cited by Lutz (1916), reported the infection in the School for Sailors, in Rio de Janeiro, which received students coming from Bahia, Sergipe, Alagoas and Rio Grande do Norte, but mostly from Sergipe and Pernambuco (Lutz and Penna, 1918).After that Maciel (1925), studying a group of sailors, found higher rates in those originated from Alagoas (34.6%), in comparison to those from Sergipe (32.7%),Bahia (23%), and finally Minas Gerais (2.9%).Cançado (1929) defined the main foci of infection in Minas Gerais.In 1937, Gilberto Freyre analyzed the main foci of infection in Pernambuco and Bahia, and the interference of sugar cane culture zones on the infection expansion, highlighting the intense migratory movements and the impact of disease spreading.He emphasized ¨the dissemination route¨ toward Southeast and South regions, through infected individuals coming from the Northeast, Bahia and Minas Gerais.Different epidemiological investigations unfolded, as Martins & Versiani (1938) in Minas Gerais; Meira (1947) in migrants settled in São Paulo; Pellon & Teixeira (1950) in students of 11 states (they were the first to delimit the endemic areas in the country); and Pessoa & Barros (1953) who conducted a survey with 1500 inhabitants of Sergipe.Longitudinal studies were initiated by Jansen (1946), who assessed the prevalence of S. mansoni in a population of Pernambuco, between 1937 and 1941, and started to treat children and adults with antimonial drugs.Sette (1953), in a review of the same group, from 1942 to 1951, revealed that 1.7% of treated individuals developed hepatosplenic form, while this rate reached 9.9% in the untreated group.Brener and Mourão (1953) worked in five different areas of Minas Gerais, which were reviewed ten years later, by Katz & Brener (1966).These authors found that less than 10% of hepatointestinal forms evolved to hepatosplenic forms, and among these, 25% had decompensation.Klöetzel & Klöetzel (1958), and Klöetzel (1966), in a municipality of Pernambuco, followed inhabitants evolutionarily, correlating severe clinical forms to higher parasite load.He concluded, in an original way, that chemoprophylaxis, in children and adolescents under severe risk of infection, constituted an effective measure for preventing progression to severe clinical forms.In 1958, Barbosa (1966) began to study four localities in Pernambuco, and only in one of them he introduced sanitation measures and use of molluscicides.In comparison with the others, it was observed a significant reduction of infection.Prata & Bina (1968) in Bahia, found no decrease in prevalence after five successive reviews.Since 1974, Coura et al. (1984) conducted evolutionary surveys, involving 3782 inhabitants from four counties of Rio Doce and Jequitinhonha Valleys, Minas Gerais, of which 47.3% were infected and 78.4% were treated, with infection recurrence and reduction of parasite load in all municipalities.Also in Minas Gerais, Conceição & Borges-Pereira (2002), Conceição et al. (2007), following up, in evolutionary terms, individuals for a period up to 30 years, in the longer term study conducted in Brazil, found out that there were decrease in prevalence and hepatosplenic forms, although without success in the transmission control, attributed to reinfections.These results corroborate the conclusions presented by Andrade (1998) pointing out a remarkable improvement in the scenario of disease prevalence and severe forms in Brazil.Klöetzel (1992) in a district of Alagoas concluded that the transmission was primarily peridomestic through the pollution of open ditches and some collections of water that required modest investments for the control.The measures have brought about the decline in the prevalence of schistosomiasis in the Northeast Brazil.In Minas Gerais, from 2008 to 2010, in two areas located in Rio Doce and Jequitinhonha Valleys, Carlôto (2011) showed in a total of 288 and 257 inhabitants, 22,9% and 20,2 %, respectively, of infection.It was emphasized the high prevalence rates, mainly in males and young people, besides a low intensity of infection, and the lack of sanitary conditions that indicated towards immediate control actions in both areas, including education in health.In a recent study carried out in one area of Maranhão, Brazil, Santos & Melo (2011) observed a schistosomiasis prevalence of 3.2% and 8.3 % of positivity in B. glabrata, raising control measures in the area.Drumond et al. (2010) have emphasized the program of surveillance for schistosomiasis control in Minas Gerais, Brazil, and the improvement related to the morbidity.Clinical and histopathological contributions came from the studies of Lenzi et al. (1998), Cheever et al. (2002), andLambertucci et al. (2005), respectively.An important advance in the understanding of the intermediate hosts of the infection has been achieved by Carvalho et al. (2008), andParaense (2008).In the Fig. 1 are represented the nineteen States of Brazil with transmission of S. mansoni infection.The states of Northeast present the highest levels of prevalence alongside the states of Bahia and Minas Gerais.Some states have foci of infection, and are not endemic areas, like Rio Grande do Sul, Santa Catarina, Paraná, São Paulo, Distrito Federal, Rio de Janeiro, Piauí, Maranhão and Pará. Figure 2 shows the prevalence of S. mansoni in a municipality of Minas Gerais, Brazil, studied by our working group up for more than thirty years, is observed on an ongoing basis the highest prevalence rates in males compared to females.

Specific treatment with oxamniquine or praziquantel, and the cases of patients that present treatment failure
Since 1978 until today, patients with the disease have been treated and followed up at University Hospital-UFRJ.They were diagnosed in the period from 1985 to 2001 and constitute a group of 102 patients with hepatosplenomegaly, of which 63% were male, from the municipality of Capitão Andrade,Minas Gerais (n=26), where we worked since 1973, and from different Brazilian regions (n=76).It must be emphasized that young patients between 11 and 14 years old, with splenomegaly, showed regression of the spleen, only with specific treatment.In the other cases, surgical indications were due to gastrointestinal hemorrhage resultant from esophageal varices rupture, hypersplenism, abdominal pain and discomfort, and hypogonadism (Conceição et al. 2002).Treatment with oxamniquine showed no response in 10.3% of patients, and treatment failure was experimentally confirmed (Katz et al. 1973, Conceição et al. 2000).Regarding praziquantel, it was presented a patient that underwent to three successive treatments and was still eliminating eggs of S. mansoni (Conceição et al. 2010).The publications on patients with lack of response to oxamniquine and, more recently, to praziquantel must encourage further support for researches on the synthesis of new drugs.In a municipality of Minas Gerais, Sarvel et al. (2011) evaluated the variation of prevalence after successive treatments with oxamniquine and praziquantel, and verified a reduction of 70.4% (1981) to 1.7% (2005).The variation of hepatosplenic form in the same period was 7% to 1.3%.The authors concluded that to reach best results it was necessary to improve the sanitary conditions as well as give specific treatment.Similar discussions on schistosomiasis mansoni control were emphasized by WHO (2002), Coura & Amaral (2005), Rey (2007), Katz & Coelho (2008), and by Coura & Conceição (2010), showing the Brazilian contribution on the clinical therapy.Co-morbidities like infections by hepatitis B and C virus, Salmonella spp.and other enterobacteria may add worse prognostic in the clinical evolution of schistosomiasis.The follow-up study of ten patients, including one who was eleven years old, infected by S. mansoni and Salmonela infantum, revealed prolonged fever, abdominal pain, diarrhoea, hepato and splenomegaly.There was regression of symptoms after treatment of both infections (Conceição et al. 2009).

Conclusion
The Brazilien authors have concluded in different endemic areas of Brazil that the indices of prevalence and morbidity are reducing, however the transmission control keeps the same high levels.On recommend the implementation of multiple measures as people should continue to receive treatment, improve sanitation conditions, potable water supply, and education in health, besides to avoid the frequent reinfections.The transmission control of Schistosomiasis mansoni infection in Brazil did not improve and that has been showed in nineteen different endemic areas of the country and in areas with focal transmission.Although the levels of prevalence and morbidity have presented reduction, on emphasize the necessity of the widest prevention measures acting on all elements of the natural history of disease: the agent, host and environment.Preventing schistosomiasis has been overlooked and created health problems, mainly with the population of the rural areas.

Fig. 1 .
Fig. 1.States of Brazil with transmission of S. mansoni infection