Snail host control in the eastern coastal areas of North-East (NE) Brazil

Pieri, Otávio Sarmento; Thomas, J. D.

doi:10.1590/s0074-02761987000800034

Cited by 6 publications

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“…The emphasis has been on the ecology and control of the mollusks that are the intermediate hosts (Barbosa 1992a,b, 1996, Barbosa & Barbosa 1994, 1996, Barbosa et al 1992, 1993, Bogéa et al 1996, Dannemann & Pieri 1989, 1991, 1993a, b, Favre et al 1995, 1997, Gazin et al 2000, Pieri 1995, Pieri & Dannemann 1996, Pieri & Thomas 1986, 1987, Randall et al 2001, Sarquis et al 1997, the ecological and epidemiological determinants of the disease (Barbosa 1992b, 1997, 1998a, b, Barbosa & Coimbra 2000, Barbosa & Gouveia 2000, Coutinho et al 1997, Gazin et al 2002, Gonçalves et al 1992, Simões-Barbosa et al 2001, and also the impact of chemotherapy treatment for infected individuals, in relation to the transmission dynamics of the disease , Favre et al 2002, Zani et al 2004). The knowledge resulting from these studies has made it possible to adapt the schistosomiasis evaluation and control strategies recommended by central health bodies -WHO at the worldwide level and the Health Surveillance Department of the Ministry of Health at the national level -to the regional characteristics and demands.…”

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confidence: 99%

Assessment of schistosomiasis, through school surveys, in the Forest Zone of Pernambuco, Brazil

Barbosa

Favre

Wanderley

et al. 2006

Mem. Inst. Oswaldo Cruz

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This work had the objective of assessing the present epidemiological situation regarding schistosomiasis through performing Kato-Katz coproscopic tests on representative samples of schoolchildren from each of the 43 municipality of endemic area of the state of Pernambuco, Brazil. The methodology is recommended by the World Health Organization to conduct sampled surveys among children at elementary school levels, ideal target group for baseline surveys: (i) schools are accessible; (ii) the greatest prevalence of schistosomiasis is found within this group; (iii) the data gathered from this age group can be used for intervention within the community as a whole. The following infection indicators were utilized: positivity (percentage of individuals examined with eggs of Schistosoma mansoni in the feces) and severity (geometric mean number of eggs per gram of feces, epg). These indicators allowed the area in general and the municipalities in particular toSince the last decade, the coastal and forest zones of the state of Pernambuco have been the target of various field investigations on schistosomiasis. The emphasis has been on the ecology and control of the mollusks that are the intermediate hosts (Barbosa 1992a,b, 1996, Barbosa & Barbosa 1994, 1996, Barbosa et al. 1992, 1993, Bogéa et al. 1996, Dannemann & Pieri 1989, 1991, 1993a, b, Favre et al. 1995, 1997, Gazin et al. 2000, Pieri 1995, Pieri & Dannemann 1996, Pieri & Thomas 1986, 1987, Randall et al. 2001, Sarquis et al. 1997, the ecological and epidemiological determinants of the disease (Barbosa 1992b, 1997, 1998a, b, Barbosa & Coimbra 2000, Barbosa & Gouveia 2000, Coutinho et al. 1997, Gazin et al. 2002, Gonçalves et al. 1992, Simões-Barbosa et al. 2001, and also the impact of chemotherapy treatment for infected individuals, in relation to the transmission dynamics of the disease , Favre et al. 2002, Zani et al. 2004). The knowledge resulting from these studies has made it possible to adapt the schistosomiasis evaluation and control strategies recommended by central health bodies -WHO at the worldwide level and the Health Surveillance Department of the Ministry of Health at the national level -to the regional characteristics and demands.A critical assessment of the schistosomiasis control actions implemented in Pernambuco by the national bodies prior to the introduction of the Unified Health System (Sistema Único de Saúde -SUS) showed that the situation in the endemic area continued to be of concern, despite the occurrence of an apparent reduction in preva- In view of the fact that the estimated population at risk of contracting schistosomiasis in the 43 municipalities in the Forest Zone of Pernambuco is 1.2 million (http:/ /www.ibge.gov.br/cidadesat/), it is unlikely that the covenanted targets will allow the real situation regarding schistosomiasis to be known over the short to medium term. One alternative recommended by WHO (2002) is to conduct sampled surveys among children at elementary school levels (i.e. between 7 and 14 years of age). These childre...

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confidence: 99%

Assessment of schistosomiasis, through school surveys, in the Forest Zone of Pernambuco, Brazil

Barbosa

Favre

Wanderley

et al. 2006

Mem. Inst. Oswaldo Cruz

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“…Since the number of intermediate hosts, their concentration, and rate of infection may be functions of rainfall, vegetation, topography, soil type, and characteristics of water bodies, geographic information system (GIS) methods may be suitable for analysis of the spatial relationships of the environment, mollusk intermediate hosts, and schistosomiasis in specific regions and communities. 6 The application of a GIS to define the epidemiology of vector-borne diseases and parasitism has been documented for a number of diseases such as malaria, 7 Lyme disease, 8 fascioliasis, 9 trypanosomiasis, 10 and dracunculiasis. 11 In early studies on schistosomiasis, climate and vegetation indices calculated from satellite data were used to define risk of S. japonicum in the Philippines.…”

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Geographic information systems and the environmental risk of schistosomiasis in Bahia, Brazil.

Bavia

Hale²,

Malone³

et al. 1999

The American Journal of Tropical Medicine and Hygiene

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Abstract. A geographic information system was constructed using maps of regional environmental features, Schistosoma mansoni prevalence in 30 representative municipalities, and snail distribution in Bahia, Brazil to study the spatial and temporal dynamics of infection and to identify environmental factors that influence the distribution of schistosomiasis. Results indicate that population density and the duration of annual dry period are the most important determinants of prevalence of schistosomiasis in the areas selected for study. Maximum rainfall, total precipitation during three consecutive months, annual maximum or minimum temperatures, and diurnal temperature difference were not shown to be significant factors influencing S. mansoni prevalence in local populations or distribution of snail hosts. Prevalence of the disease was highest in the coastal areas of the state. Higher prevalence tended to occur in areas with latossolo soil type and transitional vegetation.Schistosomiasis, which is caused by Schistosoma mansoni, was introduced into Brazil in the mid 1550s 1 and became established as a significant health problem in the endemic states of the northeast region of the country. Ecologic factors favorable to the intermediate snail hosts and the concentration of susceptible humans hosts living under substandard conditions have contributed to maintenance of the disease and expansion of the endemic area. 2 While spatial distribution and prevalence have remained constant in some regions since surveys done in the 1950s, outbreaks have been reported in regions previously considered free of schistosomiasis. Spread of the disease to newly settled areas is a major concern of the National Schistosomiasis Control Program.Studies done on rural communities in Bahia 3-5 have shown that the number, distribution, and rate of infection of the intermediate host Biomphalaria glabrata and contact with domestic water were key determinants of human infection prevalence and that snail populations responded to seasonal rainfall patterns, with an increase in reproduction during the period October through January and proportional decreases during months of drought. A study contrasting communities with high and low prevalence rates of S. mansoni in Sao Paulo State revealed that high altitude, low population density, high standards of sanitation, and limited numbers of breeding sites for B. tenagophila, the principal intermediate host in the Sao Paulo area, contributed to low rates of infection. 5 A knowledge of the factors contributing to the size and location of snail populations is pivotal to planning and implementing effective programs of suppression using molluscicides. Since the number of intermediate hosts, their concentration, and rate of infection may be functions of rainfall, vegetation, topography, soil type, and characteristics of water bodies, geographic information system (GIS) methods may be suitable for analysis of the spatial relationships of the environment, mollusk intermediate hosts, and schistosomiasis in specific...

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“…The main watercourses are the rivers Capibaribe and two of its perennial tributaries, Tapacurá and Goitá (FIDEM 2003). The area is also plentifully endowed with small water collections such as streams, marshes and pools, particularly in the rainy season (Pieri & Thomas 1987).…”

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confidence: 99%

Spatial distribution of Schistosoma mansoni infection before and after chemotherapy with two praziquantel doses in a community of Pernambuco, Brazil

Galvao

Favre

Guimarães

et al. 2010

Mem. Inst. Oswaldo Cruz

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Praziquantel chemotherapy has been the focus of the Schistosomiasis Control Program in Brazil for the past two decades. Nevertheless, information on the impact of selective chemotherapy against Schistosoma mansoni infection under the conditions confronted by the health teams in endemic municipalities remains scarce. This paper compares the spatial pattern of infection before and after treatment with either a 40 mg/kg or 60 mg/kg dose of praziquantel by determining the intensity of spatial cluster among patients at 180 and 360 days after treatment. The spatial-temporal distribution of egg-positive patients was analysed in a Geographic Information System using the kernel smoothing technique. While all patients became egg-negative after 21 days, 17.9% and 30.9% reverted to an egg-positive condition after 180 and 360 days, respectively. Both the prevalence and intensity of infection after treatment were significantly lower in the 60 mg/kg than in the 40 mg/kg treatment group. The higher intensity of the kernel in the 40 mg/kg group compared to the 60 mg/kg group, at both 180 and 360 days, reflects the higher number of reverted cases in the lower dose group. Auxiliary, preventive measures to control transmission should be integrated with chemotherapy to achieve a more enduring impact

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Snail host control in the eastern coastal areas of North-East (NE) Brazil

Cited by 6 publications

References 0 publications

Assessment of schistosomiasis, through school surveys, in the Forest Zone of Pernambuco, Brazil

Assessment of schistosomiasis, through school surveys, in the Forest Zone of Pernambuco, Brazil

Geographic information systems and the environmental risk of schistosomiasis in Bahia, Brazil.

Spatial distribution of Schistosoma mansoni infection before and after chemotherapy with two praziquantel doses in a community of Pernambuco, Brazil

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