**1. Introduction**

*Schistosoma* infection is a poverty-related parasitic infection, being the second most important neglected tropical disease in the world after malaria. Schistosomiasis is a blood-fluke-induced infection, which may present with acute and chronic disease forms. Schistosomiasis is caused by five distinct *Schistosoma* species distributed in tropical and subtropical areas. However,

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imported cases can also been seen in nonendemic areas. Human populations acquire infection after exposure to contaminated fresh water sources like dams, rivers, canals, lakes, and streams. *Schistosoma* infection falls on a large spectrum of clinical manifestations that ranges from absence of signs and symptoms to severe forms of disease. Although morbidity and mortality have been reduced along the years after use of mass drug administration (MDA) in endemic areas, large populations are still at risk of disability-related outcomes on a daily basis. A broad spectrum of clinical manifestations and also asymptomatic infections are observed [1, 2]. Three major species, *Schistosoma haematobium*, *Schistosoma japonicum*, and *Schistosoma mansoni*, and another two minor species, *Schistosoma mekongi* and *Schistosoma intercalatum*, are recognized as the mainly pathogenic *Schistosoma* species that infect human populations [3, 4]. Parasite transmission occurs after contamination of water collections with *Schistosoma* eggs eliminated by infected individuals, which further develop in the infective form called cercariae in freshwater snails. The release of *Schistosoma* cercariae from snails is followed by skin penetration of the definitive hosts (human and nonhuman species like buffalos in the case of *S. japonicum* or rodents in the case of *S. mansoni* infection). In the latter, *Schistosoma* immature forms evolve to adults that lay eggs, which are spread in the definitive hosts and/or eliminated in the environment through excreta, like urine in the case of *S. haematobium* and stool for the other species. In some areas, nonhuman definitive hosts are also essential to maintain *Schistosoma* life cycle, such as buffalos for *S. japonicum* and rodents for *S. mansoni* [5, 6]. Schistosomiasis world distribution is essentially in tropical and subtropical areas, with more than 90% of infected individuals living in sub-Saharan Africa [7, 8]. However, imported cases of schistosomiasis are also becoming increasingly frequent in nonendemic areas such as Europe. Spotlights were thrown on schistosomiasis in the recent years since elimination is believed to be a reachable goal for some endemic regions on the globe. Education, sanitation policies, and hygiene awareness proved to promote a high impact on infection transmission [9]. Also, field work in different transmission areas shows that chemotherapy plays an evident role in decreasing prevalence, parasite burden, and late morbidity [10].

Recently, a great deal of debate has been done over two main issues in schistosomiasis management in endemic and nonendemic areas: how to accurately diagnosis *Schistosoma* infections before and after therapy in addition to assess morbidity level. The adoption of promising new diagnostic tools and the development of new markers of disease progression might change the current scenario by improving schistosomiasis clinical management in both community and institutional settings.

The diagnosis of active *Schistosoma* infection is based on the demonstration of egg excretion by parasitological methods such as Kato-Katz (K-K), which has a low cost and can be per‐ formed in field studies. Direct egg detection achieves 100% specificity and high sensitivities parallel with high parasite burden. However, in individuals with less than 100 eggs per gram (epg), parasitological method loses sensitivity. Non-egg excretors are usually underdiagnosed. Furthermore, the assessment of cure rate is unreliable postchemotherapy use [11, 12]. More‐ over, the evaluation of the effectiveness of schistosomiasis control or eradication programs after (mass) chemotherapy is distorted. New approaches have been developed and proposed as complementary or in substitution to K-K. New approaches such as DNA detection assays and rapid tests have evolved in the last years [13]. The accurate assessment of schistosomiasis diagnosis, morbidity determination, and therapy response through new technologies became suitable for use in both institutional as well as community settings. The upgrade of diagnostic technology that encompasses the detection of active infection before chemotherapy and monitoring of treatment response will permit advances in public health policies as well as in individual clinical management [14, 15]. Moreover, the assessment of clinical presentation, the disease stage, and the prognosis have been the object of progresses that go side by side with the development of new image diagnostic apparatus. Also, biochemical, immunological, and molecular markers have been tested for the evaluation of fibrosis, vascular damage, and even cancer [16]. The present review aims to discuss the new surveillance strategies and their impact on schistosomiasis clinical management.

imported cases can also been seen in nonendemic areas. Human populations acquire infection after exposure to contaminated fresh water sources like dams, rivers, canals, lakes, and streams. *Schistosoma* infection falls on a large spectrum of clinical manifestations that ranges from absence of signs and symptoms to severe forms of disease. Although morbidity and mortality have been reduced along the years after use of mass drug administration (MDA) in endemic areas, large populations are still at risk of disability-related outcomes on a daily basis. A broad spectrum of clinical manifestations and also asymptomatic infections are observed [1, 2]. Three major species, *Schistosoma haematobium*, *Schistosoma japonicum*, and *Schistosoma mansoni*, and another two minor species, *Schistosoma mekongi* and *Schistosoma intercalatum*, are recognized as the mainly pathogenic *Schistosoma* species that infect human populations [3, 4]. Parasite transmission occurs after contamination of water collections with *Schistosoma* eggs eliminated by infected individuals, which further develop in the infective form called cercariae in freshwater snails. The release of *Schistosoma* cercariae from snails is followed by skin penetration of the definitive hosts (human and nonhuman species like buffalos in the case of *S. japonicum* or rodents in the case of *S. mansoni* infection). In the latter, *Schistosoma* immature forms evolve to adults that lay eggs, which are spread in the definitive hosts and/or eliminated in the environment through excreta, like urine in the case of *S. haematobium* and stool for the other species. In some areas, nonhuman definitive hosts are also essential to maintain *Schistosoma* life cycle, such as buffalos for *S. japonicum* and rodents for *S. mansoni* [5, 6]. Schistosomiasis world distribution is essentially in tropical and subtropical areas, with more than 90% of infected individuals living in sub-Saharan Africa [7, 8]. However, imported cases of schistosomiasis are also becoming increasingly frequent in nonendemic areas such as Europe. Spotlights were thrown on schistosomiasis in the recent years since elimination is believed to be a reachable goal for some endemic regions on the globe. Education, sanitation policies, and hygiene awareness proved to promote a high impact on infection transmission [9]. Also, field work in different transmission areas shows that chemotherapy plays an evident

role in decreasing prevalence, parasite burden, and late morbidity [10].

community and institutional settings.

128 An Overview of Tropical Diseases

Recently, a great deal of debate has been done over two main issues in schistosomiasis management in endemic and nonendemic areas: how to accurately diagnosis *Schistosoma* infections before and after therapy in addition to assess morbidity level. The adoption of promising new diagnostic tools and the development of new markers of disease progression might change the current scenario by improving schistosomiasis clinical management in both

The diagnosis of active *Schistosoma* infection is based on the demonstration of egg excretion by parasitological methods such as Kato-Katz (K-K), which has a low cost and can be per‐ formed in field studies. Direct egg detection achieves 100% specificity and high sensitivities parallel with high parasite burden. However, in individuals with less than 100 eggs per gram (epg), parasitological method loses sensitivity. Non-egg excretors are usually underdiagnosed. Furthermore, the assessment of cure rate is unreliable postchemotherapy use [11, 12]. More‐ over, the evaluation of the effectiveness of schistosomiasis control or eradication programs after (mass) chemotherapy is distorted. New approaches have been developed and proposed as complementary or in substitution to K-K. New approaches such as DNA detection assays
