Controle e tratamento da esquistossomose no Brasil: estudo de caso: praziquantel

Abstract

Schistosomiasis is a disease caused by worms of the genus Schistosoma. People become infected when larval forms of the parasite penetrate the skin during contact with infested water. The disease can result in abdominal pain, diarrhea, and blood in the stool. Liver enlargement and accumulation of fluid in abdominal area are common in advanced cases. The World Health Organization estimates that at least 206.4 million people required preventive treatment in 2016. The praziquantel is currently the only recommended drug for schistosomiasis. The Oswaldo Cruz Foundation classified schistosomiasis as one of the neglected diseases in Brazil. The objective of this work was to analyze the control of schistosomiasis in Brazil and make a case study of praziquantel. In the 80s, the German company Merck, developed praziquantel, a highly efficient drug against schistosomiasis produced at a low cost. This drug is the subject of new researches that are seeking new synthetic routes, whereas Merck has developed a method for the production of an enantiopure or enantioenriched (R)-Praziquantel, seeing that the eutomer (S)-Praziquantel is considered to have a bitter taste when compared to the (R)-Praziquantel distomer. The Chinese company, Zhejiang, currently possesses a patent to product praziquantel by using β-phenethylamine as an initial raw material. Concerning the combat of schistosomiasis in Brazil, between 1950 and 2000 the average number of infected people varied between 7% and 11%. In 2000, however, the government started several programs to combat schistosomiasis, which resulted on a reduction bringing the current number of positive cases to 1,79%. Nonetheless, Brazil still has a relatively big number of rural communities with an important number of schistosomiasis cases among its population. Mathematical models aid in understanding the most significant parameters that influence the transmission of diseases helping in planning the combat of such illnesses. Lastly, this work did a mathematical model to describe how this disease progressed in a population based on data from Brazil and the state of Minas Gerais between 1996 and 1997. Since 2000, Brazil has reduced the number of cases of schistosomiasis, even though there are still regions, mainly in the Northeast, which show high disease rates, and consequently the development of new procedures for praziquantel production may be beneficial for such regions. The model successfully simulated the schistosomiasis behavior in Minas Gerais and in Brazil and it has also predicted the behavior of the disease on a rural community in the state of Minas Gerais.