**4. Ecological determinants**

#### **4.1 Intensive pig farming practice**

In general, the pig industry in China has three breeding modes: backyard farm, specialized household farm, and large-scale commercial farm [23]. For thousands of years, small-scale farmers raised all sorts of pork in China. Prior to 1978, these so-called backyard farms, which raised fewer than five pigs per year along with crops and other livestock, produced at least 95 percent of the country's pork [46].

In 2007, backyard farmers accounted for approximately 27% of the national pork production though the smallholder share was much higher in some regions of China. For example, in Sichuan, the historic and current national leader in pork production was backyard farms, which contributed 70% of the entire pork in the province, compared to roughly 20% in Guangdong Province [23]. Feeding troughs, the human toilet, and the pigsty used to be always next to each other in those backyard farms, and pigs could easily consume human stool or contaminated food and water. Following China's Reform and Opening (which began in 1978), the structure of pig farming in China has changed extensively kicking off the trend toward large-scale commercial pig Taenia solium *Taeniasis and Cysticercosis Prevalence and Control Practice in China DOI: http://dx.doi.org/10.5772/intechopen.110628*

raising, which still continues today [46]. Production on these farms ranges from 500 to 50,000 pigs per year and is rapidly expanding. It is not unusual for a single company to produce 100,000 hogs in a single year [23]. In 1985, these farms accounted for only 2.5% of total pork production in the country, but by 2007, their share had increased to 22% [23]. In that situation, the human toilet and the pigsty were completely separated, and the pigs were not allowed to have direct access to consume human excreta or contaminated feeds and water. The specialized household farm (5–500 pigs per year) falls somewhere between the backyard farm and the large-scale commercial farm. In Sichuan, specialized households accounted for 25% of the total, while large-scale commercial farms contributed only 5% [23]. As farming practices have changed, it has become increasingly difficult for pigs to come into contact with human stool or contaminated feeds and water, and the transmission of *T. solium* would be cut off (**Figure 1**). As a result, if environmental reconstruction can create unfavorable conditions for these intermediate hosts, the *T. solium* transmission route could be disrupted, and the disease transmission could be minimized to a greater extent [21].

#### **4.2 Human toilet revolution**

Many pathogens can be found in human feces, including *T. solium* eggs, which can cause serious intestinal infections. The discharge of large amount of untreated feces sludge into the open environment endangers public health [47]. The human toilet revolution in extensively rural areas in China is a step-by-step campaign aimed at ensuring hygienic separation of human excreta from human contact, providing sanitary and comfortable space for users, preventing human excreta from polluting the environment, and realizing resource recycling [47].

The toilet revolution aims to increase the use of sanitary toilets, which definitely aids in disease prevention. During the ongoing toilet retrofitting campaign in rural areas, China has made significant progress. In China, the number of sanitary and innocuous-sanitary toilets has increased in the last decade, while significant regional diversification requires to be completed [48]. Sanitary toilet coverage in the rural areas has increased from 7.5% in 1993 to 78.5% in 2015, while harmless sanitary toilet coverage reached 57.5% by the end of 2015 [47]. The numbers have been increasing in most regions. Overall, the toilet revolution has made significant progress in improving sanitation infrastructure in rural China.

Currently, the concept of a toilet revolution is being enlarged and extended. Furthermore, it is not confined to the toilet, but to the entire sanitary system [47]. Consequently, pigs are getting very little opportunity to feed on human stool, and the transmission of *T. solium* between humans and pigs is being controlled.
