New epidemiological profile of schistosomiasis from an area of low prevalence in Brazil

Abstract

Introduction: Schistosomiasis, caused by infection from Schistosoma mansoni, is a disease that represents an important public health problem for Brazil, especially for states in the Northeast region. Thus, the aim of this study is to present a new epidemiological profile for the disease in a municipality with low prevalence in the state of Alagoas, Brazil. Methods: A cross-sectional study was conducted through a coproparasitological and malacological survey. A structured questionnaire was applied to the study participants to survey possible risk factors and a spatial analysis (kernel density) was used to measure the risk of infection. Results: Of the 347 participants, 106 (30.5%) were infected by Schistosoma mansoni, most of them from the urban area of the municipality (68.9%; 73/106). A 3-fold risk of infection was found for individuals living in the urban area and a risk of 2.15 times for self-declared farmers. Biomphalaria glabrata and B. straminea were the species found in the municipality, but no animals were diagnosed as infected by the parasite. Spatial analysis showed a random distribution of vectors and human cases of the disease, and the formation of two clusters of human cases in the urban area was seen. Conclusions: A new epidemiological profile for schistosomiasis from S. mansoni infection was presented in a municipality of low endemicity: a high proportion of positive individuals in the urban area; presence of snails without positive diagnosis for S. mansoni infection; random distribution of vectors and human cases; and absence of association between classical risk factors and human infection.

Noninvasive diagnosis of periportal fibrosis in schistosomiasis mansoni: A comprehensive review

“…Santos et al [ 14 ] demonstrated moderate to substantial reproducibility in the PPF classification according to the WHO protocol, mainly using image patterns. In field studies, using these patterns is reported to be simpler and more reproducible than applying other measurements, such as the thickness of the wall of the portal branch and the diameter of the portal, which are also recommended in the WHO protocol[ 40 , 41 ].…”

“…Recently, studies in low prevalence areas for schistosomiasis in Brazil have shown that the primary diagnostic approach performed by the Schistosomiasis Control Country Program may underestimate the real prevalence of this infection. In addition, there have been reports of a high proportion of infected individuals in the urban area, the presence of infected snails, a random distribution of vectors, and the absence of an association between classical risk factors and the human infection[ 14 ]. In low endemic countries, the determination of infected patients should combine different methods and algorithms for accurately estimating the prevalence and the indicators that could be used in the control of schistosomiasis[ 2 ].…”

GPS-based fine-scale mapping surveys for schistosomiasis assessment: a practical introduction and documentation of field implementation

“…The sustained implementation of control interventions, including mass drug administration (MDA) as the cornerstone, often supplemented with snail control, educational measures, or improvements in the socio-economic standard and access to clean water and sanitation, has resulted in decreasing schistosomiasis prevalences in many countries [ 8 – 11 ]. In areas where prevalences decline, the focality and heterogeneity of schistosomiasis becomes more pronounced [ 8 , 12 – 14 ]. Typically, within a few years of annual or biannual MDA across districts and countries, many communities reach low schistosomiasis prevalence and infection intensity [ 10 , 15 , 16 ].…”

“…Typically, within a few years of annual or biannual MDA across districts and countries, many communities reach low schistosomiasis prevalence and infection intensity [ 10 , 15 , 16 ]. Some areas, however, remain as pockets of high transmission with persistent or reoccurring high prevalence levels despite intense interventions [ 8 , 12 – 14 , 17 – 20 ].…”

Applicability of Euphorbia milii var splendens latex in the control of Biomphalaria tenagophila

“…Schistosomiasis is a disease whose etiological agents are trematode species of the genus Schistosoma Weiland, 1858 (Santos et al, 2020;Martins et al, 2021). About 200 million people are infected with at least one of the top five species that parasitize humans: Schistosoma haematobium (Bilharz, 1852), Schistosoma mansoni (Sambon, 1907), Schistosoma japonicum (Katsurada, 1904), Schistosoma intercalatum (Fisher, 1934) and Schistosoma mekongi (Voge, Brikener & Bruce, 1978).…”