History of schistosomiasis epidemiology, current status, and challenges in China: on the road to schistosomiasis elimination

Abstract

Schistosomiasis is a snail-borne disease caused by worms of the genus Schistosoma. Worldwide, human schistosomiasis remains a serious public health problem, threatening ∼800 million people in 78 countries with a loss of 70 million disability-adjusted life years. Schistosoma japonicum is the only human blood fluke that occurs in China. As one of the countries suffering greatly from schistosomiasis, over the past 65 years, China has made great strides in controlling schistosomiasis, blocking the transmission of S. japonicum in five provinces, remarkably reducing transmission intensities in the other seven endemic provinces, and China is currently preparing to move toward the elimination of this disease before 2025. However, while on the road to schistosomiasis elimination, emerging challenges merit attention, including severe advanced cases, increased movements of population and livestock, large-area distribution of intermediate host snails, limitations of new drug developments and no vaccine available, as well as imported schistosomiasis and its potential risk.

Galectins, Eosinophiles, and Macrophages May Contribute to Schistosoma japonicum Egg-Induced Immunopathology in a Mouse Model

“…S. japonicum, mainly distributed in China, the Philippines, and Indonesia, can cause severe chronic schistosomiasis japonica (2). The eggs of S. japonicum immigrate and deposit in liver and intestine tissues, which recruit macrophages, neutrophils, and eosinophils into the tissues during granulomatous reactions (3), and fibrotic deposits distributed around granulomas results in pipestem fibrosis (4). However, so far, the mechanism of tissue fibrosis caused by S. japonicum remains not fully understood.…”

NLRP3 inflammasome activation results in liver inflammation and fibrosis in mice infected with Schistosoma japonicum in a Syk-dependent manner

“…According to WHO statistics, there were almost 240 million people worldwide infected with the various types of schistosomiasis in 2016, and more than 700 million people were living in endemic areas are at risk of infection 3 . Schistosoma japonicum ( S. japonicum ), is one of the three main species of schistosome responsible for human infections, and is the only human blood fluke that occurs in China 4 , 5 . Once a person is infected with S. japonicum , the cercariae penetrate the human skin, transform into schistosomula and migrate through the circulatory system to reach the portal system 6 .…”

Gut microbiota signatures in Schistosoma japonicum infection-induced liver cirrhosis patients

“…In conclusion, overall, we showed that gut microbial taxonomic pro les and diversity in S. japonicum infection-induced liver cirrhosis patients appear to be similar to the ones from age-matched healthy people. Therefore, in our context, patients with S. japonicum infection-induced liver cirrhosis present a "healthy" gut structure, which may partially explain the better prognosis of cirrhosis secondary to this infection, compared to cirrhosis of different etiology in China [26,27]. Future studies with much larger sample sizes across wider age ranges are, however, needed to further explore the relationship between S. japonicum infection-induced liver cirrhosis and gut microbiota and potentially disclose the possible mechanisms by which gut microbiota alterations in uence cirrhosis and/or vice versa.…”

“…Since 1995, due to the application of effective Schistosomiasis control measures, there are almost no newly reported cases in Zhejiang [1]. Therefore, patients with S. japonicum infectioninduced liver cirrhosis are not many and tend to be of advanced ages [27]. Therefore, we cannot exclude a possible age selection bias that, however, re ects the reality of the population studied: among the cirrhosis patients, 17 and 7 individuals were 80 or 90 years of age or older, respectively, and none of the others was less than 60 years old.…”

“…Schistosomiasis diagnosis was performed using the Kato-Katz method to detect S. japonicum eggs in stool samples. Liver cirrhosis was diagnosed according to clinical and biochemical data and imaging exams (CT or B ultrasonic scans) [26,27]. Liver function was evaluated with the Child-Pugh classi cation system [28].…”