Insight on Infectious Diseases from the Perspective of One Health

Schistosomiasis  japonica  is  caused  by  infection  of Schistosoma japonicum (S. japonicum),  which  infected 12 million residents  in  the  1950s  in  China and was  a heavy  burden  to  public  health  and  socioeconomic development  (1).  After  more  than  seven  decades  of effort  to  control  schistosomiasis,  the  prevalence  of schistosomiasis  has  been  reduced  dramatically  in China.  Among  the  450  endemic  counties  (including city  and  district-level  jurisdictions),  74.89% (337/450),  21.87%  (98/450),  and  3.33%  (15/450) have  achieved the  criteria  of  elimination,  transmission interruption,  and  transmission  control  of schistosomiasis,  respectively.  As  the  overall  endemic status  of  schistosomiasis  remains  at  a  low  level,  the strategies  shifted  from  snail  control  to  morbidity control  and  then  to  an  integrated  strategy  that emphasized infection source control. However, being a vector-borne  and  zoonotic  disease,  schistosomiasis japonica  is  intricately  linked  to  multiple  factors including  biological,  natural,  and  socioeconomic  risk factors. In order to eliminate schistosomiasis earlier and more thoroughly, the One Health approach should be adopted,  which  focuses  on  solving  complex  health problems from a macro-level perspective of interactions among human, animal, and environment, emphasizing multi-institution,  interdisciplinary,  and  cross-regional collaboration and communication. Human  schistosomiasis  is  a  water-borne  infectious disease  caused  by  infection  with  blood  flukes  of  the genus Schistosoma. The disease occurs worldwide in 78 countries  and  regions  in  Asia,  South  America,  the Middle  East,  and  Africa.  Globally,  over  780  million people  are  at  risk  of  infection and 250 million people are  infected,  of  which  90%  are  concentrated  in  subSaharan  Africa  (2–4).  The  estimated  global  burden of schistosomiasis  is  3.31  million  disability-adjusted  life years (DALYs) (5). In China, human schistosomiasis is only  caused  by  S. japonicum.  Like  other  humanhosting Schistosoma spp.,  the life cycle of S. japonicum includes  adult  worm,  egg,  miracidium,  sporocyst, cercariae, and schistosomula, requiring an intermediate host  and  a  definitive  host  to  complete  its  asexual  and sexual  production  separately  (Figure 1).  Oncomelania hupensis, an amphibious snail, is the only intermediate host  of  S. japonicum.  Humans  and  over  forty  other mammals serve as definitive hosts of S. japonicum and play  a  role  in  spreading  infections  when  they  excrete feces containing schistosome eggs to the environment. The control of schistosomiasis was a high priority in China soon after the founding of the People’s Republic of  China  in  1949,  and  schistosomiasis  japonica  was largely  brought  under  control  through  7  decades  of effort.  However,  great  challenges  still  exist  to completely  eliminate  schistosomiasis  from the country by  2030  due  to  climate  change,  natural  disasters, socioeconomic  development,  environmental protection,  etc.  The  progress  of  the  national schistosomiasis  control  program  and  the  experience accumulated  over  past  several  decades  in  China  is reviewed  in  this  article,  and  solutions  to  achieve  the elimination  of  schistosomiasis  through  a  One  Health approach are explored, which addresses complex health issues  from  a  holistic  perspective  of  human-animalenvironment interaction. Progress of the National Schistosomiasis Control Program in China From  Figure 2,  we  can  see  that  the  systematic  and large-scale  control  activities  against  schistosomiasis have  been  initiated  since  the  mid-1950s  in  China. During  the  whole  process,  the  selection  and implementation  of  control  strategies  were  in accordance with socioeconomic level,  the health needs of  the  people  in  the  epidemic  area,  and  the  law  of epidemic  change.  The  great  achievements  in  the prevention and control of schistosomiasis in China are China CDC Weekly 130 CCDC Weekly / Vol. 4 / No. 7 Chinese Center for Disease Control and Prevention closely related to the timely adjustment of  the control strategy,  which  has  gone  through  the  following  three stages. Strategy Focused on Snail Elimination (mid-1950s to the early 1980s) From  the  1950s  to  the  early  1980s,  because  of  the slow economic growth, scarce health resources, lack of low  toxicity  medicine,  and  insufficient  understanding of  epidemiology  towards  schistosomiasis,  large  scale chemotherapy  could  not  be  implemented  and transmission was difficult to be interrupted. Therefore, snail  control  was  the  most  suitable  way  to  reduce  the damage  caused  by  schistosomiasis.  The  main countermeasures  against  schistosomiasis  were  to eliminate snails through environmental modification in combination  with  massive  agricultural  activities  and molluscicide  using  pentachlorophenol  sodium  and other chemical drugs. In addition, human patients and infected  animals  were  treated,  and  interventions  such as  personal  protection,  feces  management,  safe  water usage, and government publicity were conducted. This strategy  had  great  achievements.  The  snail  breeding areas  decreased  significantly  nationwide,  especially  in waterway  network  regions,  and  4  provincial-level Eggs hatch in water releasing miracidia Miracidia penetrate developing into snails Cercariae penetrate skin developing into adult worms Adult worms lay eggs in body Eggs excrete with feces contaminating environment Cercariae release into water FIGURE 1. The life cycle of S. japonicum. The stage of mass chemotherapy The stage of infection source control The stage of consolidation and promotion The stage of mass prevention and treatment The stage of preparation 1977 The leading group of the Central Schistosomiasis Control was reorganized 2004 The leading group of the State Council for schistosomiasis was established The leadership stage of the Central Committee of the Communist Party of China 1955 The leadership stage of the central government

According to the International Committee on Taxonomy of Viruses Master Species List 2020, more than 9,000 virus species have been identified on earth (1), of which the World Health Organization (WHO) announced that more than 200 species were known as zoonotic viruses (2). Previous studies have also shown that zoonoses (hantavirus, Ebola virus, highly pathogenic avian influenza, West Nile virus, Rift Valley fever virus, norovirus, severe acute respiratory syndrome coronavirus 1, Marburg virus, influenza A virus) infected more than 2.5 billion people every year, among which 2.7 million died (3). Zoonotic viruses have aroused broad concerns in recent years so that people have been encouraged to avoid eating wild animals, and a series of animal protection laws and regulations were enacted, such as the Convention on International Trade in Endangered Species of Wild Fauna and Flora (4). Researchers from different fields and countries have tried to collaborate to explore virus associations between animals and humans worldwide (5). However, many studies only focused on investigating a specific virus when it received enough attention as in a localized or global epidemic, such as Ebola virus, H1N1, Zika virus, and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (6). Even so, it's difficult for people to know exactly when, where and how the virus jumped from animal or environment to humans because it is impossible to design an observational study on the whole landscape around a virus. To understand the overall evolution law of viruses, this study aimed to find the spatial and temporal distribution of viruses and related hosts through the public database.
The National Center for Biotechnology Information (NCBI) virus database is a database of gene sequences maintained by the National Institutes of Health that aggregates and annotates all publicly available nucleotide and protein sequences, and it has been used for studies exploring quantitative snapshots of viral genomic trends and overviewing virus real-time quantitative polymerase chain reaction (RT-qPCR) method performance (7)(8). In this study, we performed a spatiotemporal analysis on the viruses in the NCBI database and tried to disclose the potential time, place, and hosts that the virus appeared or stayed in their long evolutionary history. Our study indicated the top five widely distributed viruses and found that no virus had been reported in all countries/regions. In addition, the reported areas of viruses did not completely overlap with areas where their suspected hosts live. We also found that the 249 viruses isolated from humans were also isolated from 705 other mammals and 938 non-mammals. We attempted to map the distribution and evolution of viruses and identify suspected hosts globally based on the NCBI database, which was helpful for understanding the risk of virus infection in humans and was also a costeffective method for monitoring and predicting public health and safety events globally.
The data were downloaded from the NCBI Virus database and covered available data up to September 2021 (www.ncbi.nlm.nih.gov/labs/virus). The data included virus genomic sequence submission information (accession number, submitter, and release date), virus types (species, genus, and family), and biological sample description (location, organisms of sample, isolation, and collection date). Data that were duplicated, missing, or had unidentified collected dates, locations, or organisms of the biological samples were excluded. Because the NCBI only reported that the virus was isolated from an organism, not whether the organism was the host of the virus, we referred to the organisms as suspected hosts. Based on the standard of NCBI taxonomy, suspected hosts were classified into animals, plants, and microbes.
The numbers were calculated by virus species, suspected hosts, suspected host locations, and collection time. The spatiotemporal distribution was mapped in country/region units and the path was analyzed by linking the reported location of the viruses or suspected hosts. Potential zoonotic diseases were explored by observing the suspected hosts from which the viruses were isolated.
All statistical analyses were performed in R statistical software (version 4.1.0, The R Foundation for Statistical Computing, Vienna, Austria). Animal silhouettes representing hosts were downloaded from PhyloPic (http://www.phylopic.org). All maps were made by using ArcGIS (version 10.7,Esri Inc,Redlands,CA,USA).
A total of 605,504 records covering 24,234 viruses from 240 countries/regions with sample collection date from 1865 to September 22, 2021 were involved in the final analysis. We observed that 12,243 viruses were isolated from 4,187 animals, 2,856 from 2,074 plants, and 9,176 from 965 microbes ( Figure 1). However, more than 90% viruses (21,845 of 24,234) were reported in a single country/region, and the remaining 10% (2,389 of 24,234) Table S1). Homo sapiens were reported in 225 countries/regions in the past 154 years (from the United States in 1866 to the Faroe Islands in 2020), and approximately 1,075 viruses were isolated from this host. Bos taurus were reported in 143 countries/regions during the past 138 years (from France in 1882 to Luxembourg in 2020) and from which 273 viruses were isolated; Canis lupus familiaris were reported in 123 countries/regions during the past 89 years (from China in 1931 to Ghana in 2020) and from which 106 viruses were isolated; Gallus gallus were reported in 122 countries/regions during the past 118 years (from Italy in 1902 to Timor-Leste in 2020) and from which 287 viruses were isolated; Sus scrofa were reported in 110 countries/regions during the past 99 years (from China in 1921 to Paraguay in 2020) and from which 276 viruses were isolated (Supplementary Figure S1B, available in http://weekly. chinacdc.cn/). There were 27 viruses in the database reported to be isolated from animals as well as plants (animals-plants). Similarly, 9 and 5 viruses were isolated from animalsmicrobes and plants-microbes, respectively ( Figure 3A). Specifically, 249 viruses from humans were also isolated from the other 1,643 animals, among which 705 were mammals. Most of the 249 multi-suspected host viruses were reported in the United States (125 of 249), China (141 of 249), and Brazil (107 of 249), with 402, 344, and 187 suspected hosts, respectively ( Figure 3B). The first reported human-animal multi-suspected host virus was the Vaccinia virus, isolated from Homo sapiens in the United States in 1866 (Supplementary Table S2, available in http://weekly.chinacdc.cn/).
In the study period, 181 countries/regions reported at least 1 new virus. The top 5 countries reporting the highest number of new virus species were the United States, China,Brazil,Australia,and Italy,with 6,628,4,518,1,032,994,and 730 Table S1, available in http://weekly.chinacdc.cn/). These outcomes pose several concerning issues.
First, the top five most widely distributed viruses have been investigated and reported in most countries/regions (Supplementary Table S1, available in http://weekly.chinacdc.cn/), but no virus has been reported in all countries/regions. The surprising finding is the distribution of influenza A virus -a respiratory virus closely related to humans. We presumed it should be distributed everywhere and reported by all 240 countries/regions. Our study indicates that influenza A virus is the most reported location but 85 countries/regions have not yet reported it. It is possible that the NCBI database has not collected these viruses in these countries/regions or that these areas have not covered these viruses. In either case, these countries/regions deserve attention from the perspective of virus monitoring.
Second, the reported areas of viruses do not completely overlap with areas where their suspected hosts live. For example, influenza A virus has been reported in 155 countries/regions, but its 422 hosts live in 231 countries/regions. The results have two explanations: first, the 76 countries/regions may have influenza A virus but do not investigate and report it; second, the 76 countries/regions could have no influenza A virus, which implies that these areas are susceptible to influenza A virus. However, both viruses and suspected hosts all take approximately one hundred years to survive in a region (Supplementary Figure S1, available in http://weekly.chinacdc.cn/). This long period of history leaves many opportunities for people to find and be involved in their evolution.
Third, we found that 249 viruses from humans were also isolated from other 705 mammals and 938 nonmammals. It is not surprising that most mammals' zoonoses are from Sus scrofa, Gallus gallus, Anas platyrhynchos, Canis lupus familiaris, and Bos taurus, because these domestic mammals have a close relationship with humans. Bats (152 kinds of species in the database) and Paguma larvata covered 44 zoonoses and 3 zoonoses with humans in the reported data. We also found 27 viruses from animals and plants that are involved in insects, whether it is related with humans has not been reported ( Figure 2).
This study was subject to some limitations. First, NCBI is a public database, and the data quality may be uneven. However, NCBI has a form for submitted data, which guarantees that the basic information of submitted data is consistent at some level, and these data can meet the requirements of our spatiotemporal analysis. Second, we classified viruses and suspected hosts according to their submitted names. It will be regarded as two different viruses or suspected hosts if their names are spelled differently. For example, Enterovirus A, Enterovirus B, Enterovirus C, and Enterovirus sp. are regarded as different viruses in this study. This might be a slight overestimation of the virus species and suspected hosts submitted in the NCBI database but cannot change their whole spatiotemporal distribution, especially in the long history of their evolution. Further, we identified 249 zoonotic viruses in NCBI, which was consistent with the figure published by the WHO (2). Third, data reported by countries may not be complete, which could lead to bias in the analysis. Also, the advent of next generation sequencing (NGS) would cause bias on the temporal discovery of viruses because it was hard to perform large-scale genome sequencing of viruses before NGS became relatively affordable. Fourth, we did not analyze the path of each virus and their suspected hosts. Analysis of the overlap of viruses and their hosts is important for predicting the risk of a new virus outbreak in local areas, but beyond the scope of this study.
In conclusion, we attempted to map the distribution and evolution of viruses and suspected hosts globally based on the NCBI database, which is helpful for understanding the risk of virus infection in humans and is also a cost-effective method for monitoring and predicting public health and safety events globally. Conflicts

4.
World Health Organization. Regional Office for the Western Pacific. Zoonotic diseases: a guide to establishing collaboration between animal and human health sectors at the country level. Geneva: WHO Regional Office for the Western Pacific. 2008. https://iris.wpro.who.int/handle/ 10665.1/10415.

5.
Wilder-Smith A, Osman S. Public health emergencies of international concern: a historic overview. J Travel Med 2020;27 (8)

Summary What is already known about this topic?
Coastal areas of China have a higher reported incidence of other infectious diarrheal diseases (OIDD; excluding cholera, dysentery, typhoid, and paratyphoid) than inland areas of China.

What is added by this report?
The incidence of OIDD in high latitude coastal provincial-level administrative divisions (PLADs) near Bohai Sea was positively correlated with sea surface temperatures (SSTs), while in coastal PLADs near the South China Sea was negatively correlated.

What are the implications for public health practice?
The marine environmental risk factors acquired by remote sensing provide a new way for diseases surveillance and early warning. SSTs can be employed as predictor of OIDD in some coastal areas in China. Infectious diarrhea is an important public health problem worldwide (1). As a type of common and important infectious disease, it poses a serious threat to human health and was ranked as the leading cause of death among people of all ages, especially young children in developing countries (2). Other infectious diarrheal diseases (OIDD) refer to a group of intestinal infectious diseases with diarrhea that exclude cholera, bacterial and amoebic dysentery, typhoid, and paratyphoid. Spatial analysis and Pearson's correlation was employed to explore the association between the monthly OIDD incidence of the each coastal provincial-level administrative divisions (PLADs) and the average monthly sea surface temperature (SST) of its nearby offshore based on ten years data of China from 2009 to 2018. The results showed that the incidence of OIDD in coastal PLADs was higher than that of inland PLADs in China; coastal PLADs of high latitude areas near Bohai Sea had significant positive correlations with the SSTs, but those of low latitude areas near South China Sea were negatively correlated with the SSTs. SSTs can be a potential predictor of OIDD in some coastal areas in China. Meteorological conditions have been confirmed to impact pathogen exposures, in particular those associated with waterborne transmission. Several epidemiological studies used time series analysis to show that temperature or precipitation factors had a strong triggering effect on diarrhea (3). Extreme rainfall caused floods may contaminate drinking water by flushing diarrhea-causing pathogens from pastures and dwellings into drinking water supplies (4). High ambient temperatures can further promote diarrhea transmission by enhancing pathogen replication rates or by changing water usage behaviors and hygiene and sanitation practices (5). The ocean is the largest reservoir of viruses and bacteria globally. The marine environmental parameters including sea surface temperature, sea surface height anomaly and sea chlorophyll concentration are potential predictors of many infectious diseases such as cholera to coastal regions (6). SSTs in the central equatorial Pacific Ocean have been proved to be linked to diarrhea outbreaks to the many Asian and South American countries including Bangladesh, Peru, and Japan (5). While the association between meteorological factors and diarrhea incidence has been well documented in China, limited attention has been directed at whether the marine environmental factors especially the SST have an influence on the incidence of OIDD in coastal areas of China.
Ten years monthly-recorded OIDD data of China from 2009 to 2018 were extracted from the Datacenter of China Public Health Science. This database included all data since the initiation of network reporting system, which were the number of cases, incidence by PLAD. Only the diarrhea cases confirmed clinically or by laboratory tests, including microscopic examination and biochemical identification, were included in the database. SSTs data of the same period were acquired from NASA'S Jet Propulsion Laboratory (http://podaac.jpl.nasa.gov). The data were produced using the satellite images from the National Oceanographic and Atmospheric Administration Advanced Very High Resolution Radiometer (AVHRR). The SSTs data used in the study were monthly AVHRR Oceans Pathfinder SST data with a spatial resolution of 4 km.
Descriptive statistics methods were used to describe the study variables in coastal PLADs of China. ArcGIS software (version 10.2, ESRI, Redlands, USA) was employed for the spatialization of the OIDD incidence data. Meanwhile, Pearson's correlation analysis was conducted to assess the associations between SSTs and OIDD incidence and a two-tailed test of significance was used. The total cases and monthly OIDD incidence of each PLAD in the mainland of China was shown in Table 1. The average incidence of OIDD in coastal PLADs was significantly higher than that in inland PLADs. A total of 9,527,747 OIDD cases were reported in China from 2009China from to 2018,303 cases in the 11 coastal PLADs that accounted for 54% of the total cases. The average monthly incidence in China was 5.817/100,000. While the monthly incidence in coastal PLADs was higher than the average, which reached 7.230/100,000. Tianjin Municipality had the highest incidence of monthly OIDD, which was 19.846/100,000. Because the consultation rate of OIDD in China was estimated to be between 50% to 80%, some cases were missed, and the true incidence was higher than the reported incidence.
The dynamic curve of monthly OIDD incidence in coastal PLADs and China from 2009 to 2018 was shown in Figure 1. The data exhibit a clear seasonality with the outbreaks concentrated in summer and winter. The monthly OIDD incidences between 2009 and 2018 in coastal PLADs were always higher than that in inland PLADs all the year around. The time series monthly SSTs extracted from the four offshore areas vary greatly from each other. The average monthly SST in Bohai Sea was 13.2 ℃ and varied from 1℃ to 27 ℃; the characteristics of SST in Yellow Sea were similar to that of the Bohai Sea; the average value of SSTs in Yellow Sea was 15.3 ℃ and it varied from 5 ℃ to 28 ℃, both of which had seasonality. While average monthly SST in the South China Sea was 27.9℃ and varied only from 25 ℃ to 30 ℃. In the East China Sea, the average monthly SST was 22.2 ℃ and varied only from 16 ℃ to 30 ℃.
Pearson's correlation coefficient was employed to analyze the association between the monthly OIDD incidence of each coastal PLAD and the average monthly SST of its adjacent offshore sea. Marine environmental factors may have a delayed effect on the OIDD outbreaks, so one-month lag effects for SST were created in the study. The correlation analysis was used for both the current and one-month lag OIDD with the SST. As shown in Table 2, the PLADs of Liaoning, Hebei, Tianjin, Shandong, and Shanghai had significant correlations with the SSTs. The monthly OIDD incidences in Fujian and Guangdong were significantly negative correlated with the SSTs. However, Jiangsu, Zhejiang, Hainan, and Guangxi had little or no significant correlation with SSTs.

DISCUSSION
Our findings confirm the average OIDD incidence in coastal PLADs was higher than in inland areas of China and demonstrated an association between coastal SSTs and local OIDD incidence. Specifically, we found that coastal PLADs of high latitude areas near Bohai Sea had significant positive correlations with the SSTs, but those of low latitude areas near South China Sea were negatively correlated with the SSTs. No matter in coastal PLADs or inland areas, reported cases mostly occurred in summer and winter, and the incidence dynamic curve showed bimodal fluctuation.

2009-01
Coastal PLADs Inland PLADs 17.5 Incidence (1/ The incidence of OIDD in coastal PLADs from 2009 to 2018 was higher than that of inland PLADs. A possible reason should be related to the impact of marine environmental factors. Although the underlying mechanisms by which marine environmental factors influence infectious diarrheal diseases have not been fully clarified, these marine environments, such as SST, can impact the production or transmission of some pathogens in coastal areas. Pathogens may spread quickly through the contaminated water after flooding. In addition, the consumption and improper preservation of seafood in coastal PLADs may also be important factors affecting the OIDD incidence. There is a spatial heterogeneity of OIDD distribution in China that the incidence of OIDD in different latitude coastal PLADs varies from each other. This further reinforced results of a former study that suggested the difference of the health effects of temperature in different regions is related to latitude. The effect of temperature on OIDD could be modified by latitude (7). The risk of OIDD was higher in high latitude areas at low temperatures, suggesting that high latitude areas were vulnerable areas in cold seasons (8).
For these areas, we should improve the public's awareness of OIDD prevention and medical treatment and enhance the supply of medical resources. Many former studies have shown that high temperatures may increase the risk of infectious diarrhea by affecting pathogen activity, accelerating food decomposition, and increasing drinking water demand (9). However, some areas have shown that infectious diarrhea is negatively correlated with temperature.
This study was subject to some limitations. First, the SSTs were extracted from satellite retrieved products, which itself is subject to a certain level of error. Second, the mechanism of the impact of the marine environment on the incidence of diarrhea is not clear yet, and the optimal impact of the marine environment on it is unknown. Therefore, we only calculate the average value of the sea surface temperature in each offshore sea area for analysis of the association with OIDD. Finally, sea surface temperature plays an important role in the survival and reproduction of infectious diarrhea in host environments a side from humans and will affect the transmission speed of diarrhea, so there are still some other marine variables that maybe impact on the incidence of OIDD in coastal PLADs. Sea surface height can reflect the characteristics of climate change such as drought stress, water surface rise, and flooding caused by El Niño events. Seawater salinity and seawater chlorophyll

ABSTRACT
Schistosomiasis japonica is caused by infection of Schistosoma japonicum (S. japonicum), which infected 12 million residents in the 1950s in China and was a heavy burden to public health and socioeconomic development (1). After more than seven decades of effort to control schistosomiasis, the prevalence of schistosomiasis has been reduced dramatically in China. Among the 450 endemic counties (including city and district-level jurisdictions), 74.89% (337/450), 21.87% (98/450), and 3.33% (15/450) have achieved the criteria of elimination, transmission interruption, and transmission control of schistosomiasis, respectively. As the overall endemic status of schistosomiasis remains at a low level, the strategies shifted from snail control to morbidity control and then to an integrated strategy that emphasized infection source control. However, being a vector-borne and zoonotic disease, schistosomiasis japonica is intricately linked to multiple factors including biological, natural, and socioeconomic risk factors. In order to eliminate schistosomiasis earlier and more thoroughly, the One Health approach should be adopted, which focuses on solving complex health problems from a macro-level perspective of interactions among human, animal, and environment, emphasizing multi-institution, interdisciplinary, and cross-regional collaboration and communication.
Human schistosomiasis is a water-borne infectious disease caused by infection with blood flukes of the genus Schistosoma. The disease occurs worldwide in 78 countries and regions in Asia, South America, the Middle East, and Africa. Globally, over 780 million people are at risk of infection and 250 million people are infected, of which 90% are concentrated in sub-Saharan Africa (2)(3)(4). The estimated global burden of schistosomiasis is 3.31 million disability-adjusted life years (DALYs) (5). In China, human schistosomiasis is only caused by S. japonicum. Like other humanhosting Schistosoma spp., the life cycle of S. japonicum includes adult worm, egg, miracidium, sporocyst, cercariae, and schistosomula, requiring an intermediate host and a definitive host to complete its asexual and sexual production separately (Figure 1). Oncomelania hupensis, an amphibious snail, is the only intermediate host of S. japonicum. Humans and over forty other mammals serve as definitive hosts of S. japonicum and play a role in spreading infections when they excrete feces containing schistosome eggs to the environment.
The control of schistosomiasis was a high priority in China soon after the founding of the People's Republic of China in 1949, and schistosomiasis japonica was largely brought under control through 7 decades of effort. However, great challenges still exist to completely eliminate schistosomiasis from the country by 2030 due to climate change, natural disasters, socioeconomic development, environmental protection, etc. The progress of the national schistosomiasis control program and the experience accumulated over past several decades in China is reviewed in this article, and solutions to achieve the elimination of schistosomiasis through a One Health approach are explored, which addresses complex health issues from a holistic perspective of human-animalenvironment interaction.

Progress of the National Schistosomiasis Control Program in China
From Figure 2, we can see that the systematic and large-scale control activities against schistosomiasis have been initiated since the mid-1950s in China. During the whole process, the selection and implementation of control strategies were in accordance with socioeconomic level, the health needs of the people in the epidemic area, and the law of epidemic change. The great achievements in the prevention and control of schistosomiasis in China are closely related to the timely adjustment of the control strategy, which has gone through the following three stages.

Strategy Focused on Snail Elimination (mid-1950s to the early 1980s)
From the 1950s to the early 1980s, because of the slow economic growth, scarce health resources, lack of low toxicity medicine, and insufficient understanding of epidemiology towards schistosomiasis, large scale chemotherapy could not be implemented and transmission was difficult to be interrupted. Therefore, snail control was the most suitable way to reduce the damage caused by schistosomiasis. The main countermeasures against schistosomiasis were to eliminate snails through environmental modification in combination with massive agricultural activities and molluscicide using pentachlorophenol sodium and other chemical drugs. In addition, human patients and infected animals were treated, and interventions such as personal protection, feces management, safe water usage, and government publicity were conducted. This strategy had great achievements. The snail breeding areas decreased significantly nationwide, especially in waterway network regions, and 4 provincial-level administrative divisions including Shanghai, Guangdong, Guangxi, and Fujian had interrupted the transmission of schistosomiasis by 1985. However, this strategy required a large quantity of manpower that was not possible after the economic system reforms in the late 1970s. In addition, this strategy was not practical in marshland and lake regions where water levels fluctuated and mountainous areas where economic development was slowed.

Strategy Focused on Morbidity Control (mid-1980s to 2003)
With the recognition of the impossibility of reaching schistosomiasis elimination under the circumstances at that time and the availability of praziquantel, the drug effective against schistosomiasis that had low toxicity, China adjusted its strategy from snail control to morbidity control following guidelines from the World Health Organization (WHO) and supported by the World Bank Loan Project (WBLP) in the mid-1980s. Mass drug administration (MDA) was conducted simultaneously to human beings and domestic animals, supplemented by snail control and government publicity. The morbidity control strategy was boosted nationwide by the WBLP for schistosomiasis control in China, which spanned from 1992 to 2001 and covered 8 endemic PLADs. The number of cases with schistosome infection decreased from 1.64 million in 1989 to 0.82 million by 2001, with a reduction rate of 49.94%. However, the morbidity control strategy that focused on chemotherapy could not prevent reinfection of schistosomes in human beings and livestock. Moreover, schistosomiasis rebounded significantly after the termination of WBLP, especially after the occurrence of serious flooding in 1998 along the Yangtze River Valley (6). The lag effect of flood disasters and the implementation of the strategy of "returning farmland to lakes and removing embankments for flood discharge" further increased the distribution area of snails in China, expanded the scope of epidemic areas, and increased the population threatened by infection.

Strategy Focused on Infection Source Control (Since 2004)
Because of the low-level incidence, a comprehensive strategy was formulated to interrupt transmission via controlling schistosome egg contamination or infectious sources' exposure to the environment, particularly in snail habitats (7). In addition to implementing conventional countermeasures such as chemotherapy on human beings and livestock, molluscicide, and health education, interventions focusing on the control of the source of infection were strengthened, such as raising livestock in pens, herding bovine in snail-free areas (avoiding eggs polluting the snail environment), replacing bovine with machines (reducing the number and kind of susceptible animals), reconstructing the sanitary toilets (conducting harmless treatment of excrement), and collecting the excrement of fishermen (avoiding eggs polluting water). In addition, engineering projects conducted by local ministries of agriculture, forestry, water conservancy, land resources, and others were integrated with the snail control projects to remove the snail breeding areas and prevent environmental pollution from the feces of human beings and animals (8). China reached transmission control criteria issued by the Chinese government as well as criteria of schistosomiasis elimination as a public health problem defined by the WHO by 2015.

Perspectives to Eliminate Schistosomiasis Through the One Health Approach
Being a vector-borne and zoonotic disease, schistosomiasis japonica is intricately linked to multiple factors including biological, natural, and socioeconomic risk factors, such as widespread snail habitats, a variety of animal hosts, frequent occurrences of floods, increased population mobilization, and transportation of goods, which are all threatening the obtained achievements and hindering the process of schistosomiasis elimination. The One Health approach, focusing on solving complex health problems from the overall perspective of humananimal-environmental interaction, advocates for multisectoral, cross-regional, and trans-disciplinary collaborations in all aspects (9)(10). Thus, to realize the goal set by the strategic plan of healthy China 2030 to eliminate schistosomiasis in China, the One Health approach should be applied in national control program.

Integrated Surveillance and Response System
It was reported that about 75% of emerging infectious diseases of humans have emerged from animals during the past few decades (11). Thus, the importance of surveillance of schistosome-susceptible animals should not be neglected. Therefore, there must be a merger of monitoring clinical practice, veterinary practice, vector surveillance, and environmental surveillance to more effectively evaluate and plan an appropriate response to the transmission of schistosomiasis. In order to promote integrated surveillance and response systems, general reference laboratories, surveillance centers based on epidemiological and big data related to schistosomiasis would be useful for pooling resources and providing rapid access information (5). Some surveillance indicators, such as observed risk factors, newly identified infected cases in humans and animals, and infection status of wild animals following examination, would allow for rapid responses before an outbreak occurs (12).

Multisectoral Collaboration
The transmission and distribution of schistosomiasis are influenced by many types of factors including the environments, pathogens, vectors, local economic conditions, and level of societal development. Interventions such as blocking the transmission of schistosomiasis from infection source to surroundings, treating or culling infected livestock, raising schistosome-unsusceptible poultries, replacing cattle with machines, and herding livestock in snail-free areas are imperative in order to control animal reservoir hosts. All of these need veterinarians, livestock producers, health workers, and political decisionmakers to work together. For snail control, there are two major approaches, which are chemical control by molluscicide and environmental modification. The former faces great challenges due to increasing environmental protection laws that prohibit controlling snail habitats along the Yangtze River and wetland eco-zones. The latter mainly relies on the projects being chaired by the ministries of water conservancy, agriculture, forestry, land resources, etc. (13).

Interdisciplinary Research
Interdisciplinary research, with the collaboration of scientists in the field of biology, ecology, computer science, and more, is a key component in understanding the complex transmission patterns and exploring interventions against schistosomiasis. Understanding the transmission dynamics of schistosomiasis in human-environment-animal interface will benefit schistosomiasis elimination (14). Furthermore, interdisciplinary research will help connect schistosomiasis control with information technology and big data organically, establishing an efficient and sensitive early warning system worldwide (15). Moreover, increased emphasis on comparative diseases etiology, pathology, genomics, proteomics, and metabolomics is important to potentially discover novel treatments for humans and animals.

CONCLUSION
Schistosomiasis japonica is a vector-borne zoonotic disease, requiring integrated approaches for prevention and elimination to deal with the relationship among animals, the environment, and humans. Although great achievements have been reached in China through more than 70 years of effort, the elimination of schistosomiasis is a constant challenge complicated by many different biological and environmental factors involved in the circulation of the diseases, including widespread snail habitats, various animal hosts, frequent occurrence of flooding, and increased population mobilization and goods transportation. As human influence on the environment increases and the transmission of disease becomes more complex, adopting the One Health approach is an essential key to elimination of this disease. Therefore, strengthening multi-institution, interdisciplinary, and cross-regional cooperation and conducting further research to this disease are important to accelerate the process of schistosomiasis elimination.