Introductory Chapter: Changing Our Perspectives on Schistosomiasis

1. Introduction

Humanity in the 21st-century has made many scientific and cultural advancements. This development in technology improves people’s living conditions [1]. However, the growth of technology also causes physical deterioration of nature via many chemical, nuclear, and solid wastes during the use of food and energy sources or pollution of water [2, 3]. The ecological balance of nature is being destroyed albeit unintentionally. This causes logarithmic growth and mutation of all kinds of microorganisms in the environment, resulting in the emergence of different species [4, 5].

Schistosomiasis is a term that denotes a disease caused by parasites belonging to genus Schistosoma. It is a major disease affecting approximately 250 million people in 78 countries and many regions in the world, mainly Asia, Africa, and America [6, 7]. There are more than 20 species of Schistosoma (Schistosoma haematobium (S. haematobium) (1852), S. japonicum (1904), S. mansoni (1907), S. intercalatum (1934), S. mekongi (1978), S. guineensis and S. intercalatum et al.) in the tropical and subtropical regions of the world.

Schistosoma spp. involve humans and certain animals (monkeys, rodents, cattle, etc.) as definitive hosts, and snails (Biomphalaria, Bulinus, Oncomelania, etc.) as intermediate hosts. Since cercaria forms of Schistosoma are disseminated via contaminated water, they spread far and wide. In fact, the history of schistosomiasis in humans goes back to ancient times [8]. S. haematobium eggs have been found in the kidneys of Egyptian mummies. However, the first description of schistosomiasis was made by the German pathologist Theodore Maximilian Bilharz (1825 to 1862) by autopsy examinations on infected patients in Egypt. He named the worm that recovered from the portal vein as “Schistosoma hematobium”. Doctor Yoshinao Fujii (1818 to 1895) of Japan was described the symptoms of schistosomiasis. He noticed rush in the legs, fever, diarrhea and bloody stool among the villagers who worked in the trice fields of Katayama. In 1904, Fujiro Katsurada found the causative agent of Katayama fever and named the worm “Schistosoma japonicum”. Three years later, in 1907, S. mansoni was discovered as the third type of Schistosoma by Luigi Westenra Sambon (1865 to 1931).

Although they have been known for years, the diagnosis, treatment, and prevention of schistosomiasis did not reach their full maturity. That is why it is still a major health problem in many countries. Even more, schistosomiasis has increased drastically and resulted in financial problems by causing chronic diseases [9]. In response to this, the World Health Organization (WHO) initiated a long-term program to fight against schistosomiasis with various methods, such as education and praziquantel therapy, by launching an extensive project [10].

2. Conclusions

It is important to note once again that Schistosoma spp. are often seen in socio-economically underdeveloped regions. When dealing with Schistosoma spp., the intermediate hosts (the snails), the definitive hosts (humans and certain animal species), and the source of infection (infective waters) should be considered [11, 12].

When we look deeper into Schistosomiasis we find that the disease can be in two phases: acute and chronic. Schistosoma may involve many organs in the body by dissemination via bloodstream. Symptoms may vary according to involved organs. In the acute phase; high fever, Katayama fever (specific for Schistosoma japonicum and S. mansoni), myalgia, fatigue, abdominal pain, diarrhea, haematuria may be present. However, in chronic phase of schistosomiasis, different symptoms, due to more specific organ infoldments, can be found such as hepatosplenomegaly, gastrointestinal bleeding, and abdominal pain due to ascites and periportal fibrosis, bladder carcinoma (specific for Schistosoma hematobium), etc. Long-term consequences can also lead to socio-economic burden, such as dependent life and long-term treatment costs [13].

The diagnosis of schistosomiasis is not always easy in humans. History taking is very important to “think about” the disease in differential diagnosis. Laboratory tests such as antigen (circulating cathodic antigen (CCA)) or antibody tests are the most commonly used tests in diagnosis. However, these are not “gold standard test” [14, 15]. The Kato-Katz technique (antigen) is a stool screening method (38% sensitivity) because it is the fastest and cheapest method [14, 16]. Serological techniques antigen tests (ELISA, IHA, and IFAT) are widely used for the diagnosis of schistosomiasis [17]. The diagnosis of S. japonicum is made by PCR (52% of the PCR positive samples were positive) [14] and PCR ELISA for S. mansoni (sensitivity was high (97.4%), and the specificity was more satisfactory (85.1%)) [18]. The commonly recommended treatment of schistosomiasis is praziquantel [19]. There have been many medications tested against schistosomiasis but still, there is not any good alternative in use to praziquantel.

Putting the treatment of schistosomiasis aside, we should focus on the prevention of the disease all over the world, and especially in endemic regions. We should consider that the disturbance of ecologic balance might cause new species of Schistosoma, newly infected water basins, and snail types [20]. It may be more difficult to cope with these new forms.

In this book, we all aimed to draw attention to “schistosomiasis” and how we can change our perspectives to “combat” and -hopefully- eradicate this important parasite disease. To overcome schistosomiasis globally, we should make endeavor to respect nature to avoid disturbing the ecological balance, to perform new scientific multidisciplinary studies, and to work as one, as in the “One Health” concept.