Spatial distribution of schistosomiasis foci on Itamaracá Island, Pernambuco, Brazil

Acute cases of schistosomiasis have been found on the coastal area of Pernambuco, Brazil, due to environmental disturbances and disorderly occupation of the urban areas. This study identifies and spatially marks the main foci of the snail host species, Biomphalaria glabrata on Itamaracá Island. The chaotic occupation of the beach resorts has favoured the emergence of transmission foci, thus exposing residents and tourists to the risk of infection. A database covering five years of epidemiological investigation on snails infected by Schistosoma mansoni in the island was produced with information from the geographic positioning of the foci, number of snails collected, number of snails tested positive, and their infection rate. The spatial position of the foci were recorded through the Global Positioning System (GPS), and the geographical coordinates were imported by AutoCad. The software packages ArcView and Spring were used for data processing and spatial analysis. AutoCad 2000 was used to plot the pairs of coordinates obtained from GPS. Between 1998 and 2002 5009 snails, of which 12.2 percent were positive for S. mansoni, were collected in Forte Beach. A total of 27 foci and areas of environmental risk were identified and spatially analyzed allowing the identification of the areas exposed to varying degrees of risk.

Fecundity of Biomphalaria straminea and B. glabrata in the laboratory: a twelve-month comparative study

In the present comparative study a Biomphalaria straminea sample from Picos (Piauí) showed expressive advantages related to fecundity over a B. glabrata sample from Belo Horizonte (Minas Gerais) such as: higher egg-mass production in 10 out of 12 months of study; higher egg production in all months of study; higher egg per egg-mass ratio in 11 out of 12 months of study; 66% of the egg-masses containing more than 20 eggs while in B. glabrata 70% of the egg-masses showed less than 20 eggs; three times less empty egg capsules than B. glabrata; attainning maximum fecundity in half the time required by B. glabrata. Mortality however was higher and sooner in B. straminea, suggesting higher semelparity in this species than in B. glabrata, a possibility that requires confirmation through long-term studies with other samples of both species. This first finding of a B. straminea sample more fecund than B. glabrata is discussed in relation to other data from the literature, and some recommendations are made on the quantification of fecundity of planorbid snails

Aspectos etologicos na sobrevivencia dos caramujos vetores da xistosomose ao tratamento com moluscicidas. / Ethologic aspects of survival of schistosomiasis vector snails to treatment with molluscicides

Um levantamento dos fatores comportamentais considerados de importancia para a sobrevivencia dos caramujos vetores da xistosomose aos moluscicidas permitiu caracterizar como tendo funcao presumivelmente protetora: retracao na concha, afastamento de locais dessecados, saida da agua, enterramento e afastamento de agentes toxicos. A partir da constatacao de que as evidencias disponiveis ate agora pouco esclarecimento dao sobre a natureza dos mecanismos deflagadores de tais comportamentos e seu valor adaptativo em si, enfatizou-se a necessidade de um enfoque etologico para a descricao e analise dos aspectos pertinentes