Abstract

INTRODUCTION

For decades schistosomiasis mansoni in Pernambuco, Northeastern Brazil, was identified as a rural endemic poverty-related disease. Recently, this disease has spread to remote coastal villages of this State were acute human cases and outbreaks of vector snails have been identified. This confirms the introduction and establishment of the disease in previously untouched areas. The disease, in the form of outbreaks or stabilized as endemic, has different epidemiological, clinical, economic and socio-cultural characteristics from those found in rural zones in the state. ³3 . Barbosa CS, Silva CB, Barbosa FS. Esquistossomose: reprodução e expansão da endemia no estado de Pernambuco no Brasil. Rev Saude Publica . 1996;30(6):609-16. DOI:10.1590/S0034-89101996000600016 ^{, 4}4 . Barbosa CS, Gonçalves JF, Albuquerque Y, Barbosa FS. Urban Schistosomiasis in Itamaracá Island, Pernambuco, Brazil: epidemiological factors involved in the recent endemic process. Mem Inst Oswaldo Cruz . 1998;93(Suppl 1):265-6. DOI:10.1590/S0074-02761998000700049 ^{, 6}6 . Barbosa CS, Domingues ALC, Abath F, Montenegro SML, Guida U, Carneiro J, et al. Epidemia de esquistossomose aguda na praia de Porto de Galinhas, Pernambuco, Brasil. Cad Saude Publica . 2001;17(3):725-8. DOI:10.1590/S0102-311X2001000300028 ^{, 9}9 . Barbosa CS, Araújo KC, Sevilha MAA, Melo F, Gomes ECS, Souza-Santos R. Current epidemiological status of schistosomiasis in the state of Pernambuco, Brazil. Mem Inst Oswaldo Cruz . 2010;105(4):549-54. DOI:10.1590/S0074-02762010000400034 ^{, 12}12 . Gonçalves F, Coutinho A, Santana W, Barbosa CS. Esquistossomose aguda, de caráter episódico, na ilha de Itamaracá, estado de Pernambuco. Cad Saude Publica . 1991;7(3):424-5. DOI:10.1590/S0102-311X1991000300011 ^{, 14}14 . Leal Neto OB, Albuquerque J, Gomes ECS, Barbosa CS. Estratégias do futuro para enfrentar problemas do passado. Scient Am Brasil . 2011;(106):48-51.

Unemployed rural workers migrate to the coastal areas of Pernambuco where they find temporary work in resorts, hotels and summer houses. Some of these coastal areas are important tourist centers where there is intense population growth combined with chaotic land occupation in which natural resources are destroyed by invasive and unscrupulous civil construction. On the periphery of these privileged tourist areas, the migrant population agglomerates, awaiting employment opportunities and living in settlements without basic sanitation or infrastructure, without access to health care or services. These living conditions favor contamination of the freshwater aquatic environment. Human waste thrown into the streams and ponds of the coastal areas contaminates the natural breeding sites of the host snails favoring the establishment of disease transmission. Extensive publication of scientific articles has recorded the occurrence of new outbreaks of host snails and acute human cases of schistosomiasis on the coast of Pernambuco and the Metropolitan Region of Recife (MRR) with data on the epidemiology, ecology and spatial distribution of the schistosomiasis. These records support and guide the actions of the health care services in controlling and preventing the disease on the coast of Pernambuco. ²2 . Araújo KCGM, Resendes APC, Souza-Santos R, Silveira Júnior JC, Barbosa CS, Análise espacial dos focos de Biomphalaria glabrata e de casos humanos de esquistossomose em Porto de Galinhas, Pernambuco, Brasil, no ano de 2000. Cad Saude Publica . 2007;23(2):409-17. DOI:10.1590/S0102-311X2007000200017 ^{, 5}5 . Barbosa CS, Pieri OS, Silva CB, Barbosa FS. Ecoepidemiologia da esquistossomose urbana na ilha de Itamaracá, Estado de Pernambuco. Rev Saude Publica . 2000;34(4):337-41. DOI:10.1590/S0034-89102000000400004 ^{, 7}7 . Barbosa CS, Montenegro SML, Abath FGC, Domingues ALC. Specific situations related to acute schistosomiais in Pernambuco, Brazil. Mem Inst Oswaldo Cruz . 2001;96(Suppl):169-72. DOI:10.1590/S0074-02762001000900026 ^{, 8}8 . Barbosa CS, Araújo KC, Antunes L, Favre T, Pieri OS. Spatial distribution of schistosomiasis foci on Itamaracá Island, Pernambuco, Brazil. Mem Inst Oswaldo Cruz . 2004;99(Suppl 1):79-83. DOI:10.1590/S0074-02762004000900014 ^{, 10}10 . Barbosa CS, Leal Neto OB, Gomes ECS, Araújo KCGM, Domingues ALC. The endemisation of schistosomiasis in Porto de Galinhas, Pernambuco, Brazil, 10 years after the first epidemic outbreak. Mem Inst Oswaldo Cruz . 2011;106(7):878-83. DOI:10.1590/S0074-02762011000700014. ^{, 11}11 . Gomes ECS, Leal Neto OB, Albuquerque J, Silva HP, Barbosa CS. Schistosomiasi s transmission and environmental change: a spatio-temporal analysis in Porto de Galinhas, Pernambuco – Brazil. Int J Health Geogr . 2012;11:51. DOI:10.1186/1476-072X-11-51 ^{, 16}16 . Paredes H, Souza-Santos R, Resendes APC, Souza MAA, Albuquerque J, Bocanegra S, et al. Spatial pattern, water use and risk levels associated with the transmission of schistosomiais on the north coast of Pernambuco, Brazil. Cad Saude Publica . 2010;26(5):1013-23. DOI:10.1590/S0102-311X2010000500023 ^{, 18}18 . Silva PCV, Domingues ALC. Aspectos epidemiológicos da esquistossomose hepatoesplênica no estado de Pernambuco, Brasil. Epidemiol Serv Saude . 2011;20(3):327-36. DOI:10.5123/S1679-49742011000300007 ^{, 20}20 . Richter J, Domingues ALC, Barata CH, Prata AR, Lambertucci JR. Report of the Second Satellite Symposium on Ultrasound in Schistosomiasis. Mem Inst Oswaldo Cruz. 2001;96(Suppl):151-6. DOI:10.1590/S0074-02762001000900023

The first indication of schistosomiasis transmission in Recife, PE, Northeastern Brazil, was in 2008 when a scientific expedition detected the presence of Biomphalaria straminea infected with Schistosoma mansoni in a pond located in Apipucos Park, in a neighborhood of the city. ^aaEpi Schisto Risk Modeling. [cited 2012 Sept 14]. Available from: http://www.epichisto.org/ The site is a beautiful, traditional leisure area, including children’s playgrounds and areas for playing sport, where some people fish and swim, and in which sewage dumping was found in several locations.

Based on these findings, epidemiological investigations were initiated to find evidence of schistosomiasis transmission in the city of Recife.

The aim of this study was to investigate breeding sites of host snails and autochthonous human cases of schistosomiasis in Recife.

METHODS

A malacological survey was carried out between July 2010 and September 2012, actively searching for host snails in fresh water at selected points in Recife. The snails were collected using scoops and tweezers in an active search of fresh water in epidemiologically important points (close to habitation). They were examined using the molecular Nested PCR technique, specific and efficient for identifying DNA of S. mansoni in Biomphalaria. ¹1 . Abath FG, Melo FL, Werkhauser RP, Montenegro L, Montenegro R, Schindler HC. Single-tube nested PCR using immobilized internal primers. Biotechniques . 2002;33(6):1210-4. ^{, 15}15 . Melo FL, Gomes AL, Barbosa CS, Werkhauser RP, Abath FG. Development of molecular approaches for the identification of transmission sites of Schistosomiasis. Trans R Soc Trop Med Hyg . 2006;100(11):1049-55. DOI:10.1016/j.trstmh.2005.12.008 This technique allows the rapid identification of aquatic environments contaminated with the parasite. Humans cases were identified between August and September 2011 using the Inquérito Nacional de Prevalência da Esquistossomose e Geohelmintoses (INPEG – National Survey on Prevalence of Schistosomiasis and Geohelmintoses), ^bbMinistério da Saúde/Fundação Oswaldo Cruz. Inquérito Nacional de Prevalência da Esquistossomose e Geohelmintoses. Brasília, DF; 2012. which sampled 2,718 schoolchildren between seven and 14 years old in 35 schools in Recife. Besides the 35 schools selected for the survey, a purposeful search for schistosomiasis cases was conducted in two schools that were very close to breeding sites with a high concentration of snails. The parasitological diagnosis for parasites in stool samples was performed by the Kato-Katz method using two slides for each sample. ¹³13 . Katz N, Chaves A, Pellegrino J. A simple device for quantitative stool thick-smear technique in Schistosomiasis mansoni. Rev Inst Med Trop Sao Paulo . 1972;14(6):397-400. Clinical tests were performed on those children with positive diagnosis for S. mansoni to investigate episodes of diarrhea with blood in the stool in the preceding two weeks, episodes of upper gastrointestinal bleeding (UGIB), splenomegaly or UGIB in the family. Ultrasound test was performed to establish the presence of splenomegaly, hepatomegaly and patterns of periportal fibrosis. The World Health Organization (WHO) Niamey classification was used to define periportal fibrosis as pattern A (no fibrosis), B (debatable fibrosis), C (peripheral fibrosis), or D (central fibrosis). ²⁰20 . Richter J, Domingues ALC, Barata CH, Prata AR, Lambertucci JR. Report of the Second Satellite Symposium on Ultrasound in Schistosomiasis. Mem Inst Oswaldo Cruz. 2001;96(Suppl):151-6. DOI:10.1590/S0074-02762001000900023

The autochthony of the cases was carefully investigated with the children’s relatives. Those children who reported any kind of exposure outside of Recife were ruled out as autochthonous case.

The locations of schools and households with positive cases of schistosomiasis mansoni were geocoded using Google Earth software version 6.1, with the completeness of the data reaching 95%. The breeding sites of snails were georeferenced using a Garmin eTrex GPS device, in the UTM projection system and the SAD69 datum. These data were included and processed in a Geographic Information System in ArcGIS 10.0 (Esri) software, creating a thematic map with spatialized attributes.

This project was approved by the Research Ethics Committee of the Centro de Pesquisas René Rachou (Process nº CAAE 0007.1.245.000.10). The research followed the ethical principles contained in Resolution nº 196/96, of the Conselho Nacional de Saúde , Ministry of Health. All participants signed an informed consent form. Anonymity was maintained at all stages of the study.

RESULTS

There were 30 breeding sites identified in Recife, from which 2,423 B. straminea snails were collected. As this species is not very susceptible to S. mansoni , the snails were subjected to the molecular Nested PCR diagnosis technique to search for DNA from the parasite. Four breeding sites with molluscs bearing S. mansoni DNA were found in Recife neighborhoods one in Caxangá, two in Apipucos and one in San Martin (Figure).

From the 2,718 schoolchildren investigated by parasitological survey INPEG, 9.05% were infected with Ascaris lumbricoides , 8.64% with Trichuris trichiura , 1.1% with hookworms and 0.44% with Schistosoma mansoni . The search for new cases among 179 children examined in the schools in the Varzea and Apipucos neighborhoods, which were not included in the INPEG sample, allowed two more schistosomiasis cases to be found. A total of 179 children were examined and 14 cases of schoolchildren parasitized by S. mansoni were diagnosed with loads between 46 and 816 eggs per gram of feces (EGP). These14 children were sent to Centro de Pesquisas Aggeu Magalhaes/Fiocruz – CPqAM/Fiocruz to be clinically examined and undergo ultrasound diagnosis (US). The mothers and children were counseled about the disease and how to prevent becoming infected again. The patients received specific medication for S. mansoni and other diagnosed parasitic diseases.

Nine children were excluded from the autochthony investigation as they reported exposure to locations outside of Recife city, even if the exposure had been for a few hours. Only five children could be considered autochthonous cases because their families assured the researchers that they had never left the city of Recife. Of the 14 cases which were positive for S. mansoni , it was not possible to carry out a clinical examination on one of them (AS, 11 years old) because the relatives did not give permission, but the autochthony of the case was investigated and confirmed in a home visit. Figure shows the geographic location of the households of the schistosomiasis cases diagnosed and the locations of snail breeding sites, some carrying S. mansoni parasite DNA.

DISCUSSION

This is the first report of children born and residing in the city of Recife parasitized by S. mansoni , with proper research to ensure autochthonous cases. There are reports of adult patients with schistosomiasis in peripheral areas of the Metropolitan Region of Recife; ¹⁸18 . Silva PCV, Domingues ALC. Aspectos epidemiológicos da esquistossomose hepatoesplênica no estado de Pernambuco, Brasil. Epidemiol Serv Saude . 2011;20(3):327-36. DOI:10.5123/S1679-49742011000300007 however, none of these cases were investigated for autochthony.

The parasitological survey (INPEG), conducted through random sampling, detected 0.44% of schistosomiasis cases while epidemiological search, conducted in schools close to the breeding of vector snails, was able to detect 1.1% of children parasitized by this helminth. Among the nine cases which were not counted as autochthonous, three of them reported one single exposure outside of Recife. The other five children diagnosed as autochthonous cases of schistosomiasis had not left Recife and reported exposure near to their homes in the rainy season, when streams and drainage ditches in the neighborhood overflow and host snails are passively carried into the streets and yards. This seasonal infection, featuring episodic transmission in urban areas, could be avoided by establishing sanitation strategies, such as adequate drainage for rainwater. With respect to the three children who reported one single exposure outside Recife city and were ruled out as autochthonous cases of the disease, the interviews recorded the hypothesis that the contamination may have been in this city since their parents mentioned systematic contact with streams and flooded streets around their residences.

Among the three children who had high parasite loads (one of which was autochthonous), between 458-816 EPG, two of them had specific symptoms and alterations seen in the ultrasound, suggesting numerous and/or intense exposure ( Table ). One child, (GLSS, eight years old) living in the Boa Viagem neighborhood, had a high parasite load (816 EPG) and reported one single exposure in an endemic area, when swimming in the river for two hours, with no recollection of symptoms (cercarial dermatitis or fever) after this contact. No breeding sites for host snails were found in the Boa Viagem neighborhood, but the child reported systematic and accidental contact when the water of the canal adjacent to his residence overflows.

Among the three children suffering from hepatomegaly, two were autochthonous cases. One of them (LRMSF, eight years old) developed the hepatosplenic clinical form, although the parasitological stool examination detected 48 eggs/gram of feces, suggesting an old infection which had not been specifically treated ( Table ). The liver damage in the three autochthonous cases, with stage B and C fibrosis, is a sign of the severity of the disease in its chronic course, similar to that observed in patients in endemic areas with recurrent exposure to the etiological agent.

Only one of the autochthonous case of the disease and three breeding sites of B. straminea with S. mansoni DNA were identified in the Apipucos neighborhood. This was the first child diagnosed with schistosomiasis in Recife. During the autochthony investigations of this case (AS, 11 years old), the parents confirmed that the child used to swim every day in Apipucos lake. The Ibura neighborhood had four breeding sites of host snails and two children with schistosomiasis, these are biological indicators of risk which merit special attention by environmental and epidemiological monitoring. The Vasco da Gama neighborhood had three cases of schistosomiasis and two of them were autochthonous; investigation with the family, asking about possible contact and exposure, leads to the assumption that these children may have been contaminated in the nearby swamps of Brejo do Beberibe and Apipucos, areas frequented by those children that were breeding sites of host snails.

Figure shows the exact location of the areas where there may be favorable conditions for disease transmission. Further investigations are necessary to identify and map the entire city in search of new areas of transmission, avoiding the spread of schistosomiasis in Recife. In spite of their limitations, the data shown in Figure are essential for guiding monitoring activities searching for new cases and investigating unhealthy environments.

The findings of the present investigation, represented by Biomphalaria straminea breeding sites containing snails carrying S. mansoni DNA, and by the autochthonous cases of schistosomiasis in children, indicate that the disease is being transmitted in Recife. These data, linked to the fact that, according to the Brazilian Institute of Geography and Statistics (IBGE) census of (2010), ^ccInstituto Brasileiro de Geografia e Estatística (IBGE). Censo 2010 [cited 2012 Sept 22]. Available from: http://www.censo2010.ibge.gov.br/primeiros_dados_divulgados/index.php?uf-26 around 50% of the municipality of Recife has no sanitation network, takes on significant epidemiological and public health relevance, calling for emergency actions in order to avoid schistosomiasis becoming endemic in the city. In coastal areas of Pernambuco where the disease is already established, the dynamic of transmission has specific epidemiological and clinical characteristics, represented by episodic outbreaks and acute clinical forms.

The results of this research point to the need to identify new cases of the disease and breeding sites in all neighborhoods of the city, perhaps using the technique of mice exposure in the breeding of Biomphalaria straminea to detect the presence of the parasite cercariae.

The results of this study are limited to the specific situation of Recife and may are useful for the Schistosomiasis Control Program (PCE) to take emergency actions in order to prevent the disease from spreading in Recife city.

References

Publication Dates

History