Análise espacial e determinantes socioeconômicos e socioambientais associados à transmissão da esquistossomose mansoni no estado de Alagoas, Brasil

Abstract

The mansoni’s schistosomiasis (MS) is a serious and chronic parasitic disease, caused by trematode worms of the species Schistosoma mansoni (S. mansoni). Several factors (social and environmental) are associated with the high prevalence rates of MS in endemic areas. Data presented by the Schistosomiasis Control Program (SCP), in 2014, revealed 27,525 positive tests for MS in northeastern Brazil. Of these, 9,775 (35.51%) were reported in the state of Alagoas, that is the second state in the country with the highest prevalence rate of this parasitosis. In addition, it has a deficiency in water supply and in the population's sewage system. Most municipalities in Alagoas have Human Development Index (HDI) below the national average and the illiteracy rate in the state is still high. Therefore, this study aimed to analyze the spatial distribution and socioeconomic factors associated with MS cases in the municipalities of the Alagoas state, between 2007 and 2016. It is an epidemiological study, of the ecological type and time series, based on cases reported by the Information System of the Schistosomiasis Control Program (SISPCE). Socioeconomic factors were collected on the IBGE website and we used: HDI by Municipality (MHDI), Adequate Sanitation, Urbanization of public roads, Schooling Rate (SR) and Gross Domestic Product. The time trend was analyzed using the Joinpoint regression software. To assess the correlation between SCP data and socioeconomic variables, Spearman's correlation test (R) was applied and the association between variables was made through simple logistic regression. The spatial analysis maps were built using the QGIS and TerraView software. Alagoas state has 102 municipalities, of which 29 (28.43%) were classified as a moderate prevalence of MS and five (4.9%) as a high prevalence, most of them located mainly in the northwest region and coastal strip of the state. It was observed that positivity decreased in this period, from 8.11% in 2007 to 4.96% in 2016 (Annual Percentage Change, APC = -5.71%; p <0.05). However, there was also a reduction in the number of the population worked (APC = -2.84%; p <0.05) and of examinations performed (APC = -5.05%; p <0.05). There was a negative and significant correlation between infection by S. mansoni and MHDI (R = -0.34*) and TE (R = -0.24*). The main species of snail identified was Biomphalaria glabrata (94.79%). However, B. straminea showed a higher percentage of positivity for S. mansoni (10.11%). There was report of identification of B. tenagophila in Alagoas (n = 28; 0.5%). The lack of data in the municipalities from backwoods of the state is due to the non coverage of these areas by the PCE and may, therefore, indicate underreporting of cases. Despite the reduction in the number of cases over this period, the epidemiological scenario of MS in Alagoas is still worrying and insidious, requiring emergency planning, investments and improvements in the programs of diagnosis, control and prevention of the disease.