The specific characteristic of the epidemic of echinococcosis in China is that dogs are the common infectious source for both CE and AE. CE and AE display common risk factors with 115 counties endemic for both diseases. The natural and geographical environment, climate, and customs of the Qinghai-Tibet Plateau is different from that of the non-Qinghai-Tibet Plateau and the transmission cycles of E. granulosus and E. multilocularis are also different. Population characteristics and risk factors in the Qinghai-Tibet Plateau and in the non-Qinghai-Tibet Plateau regions are thus also different. Some risk factors are similar in both regions such as middle-aged populations, low-education, occupations as herdsman or farmers . Within the Qinghai-Tibet Plateau some groups at risk of CE and AE are similar: middle-aged, low-educated women who spend most of their time at home . They frequently feed dogs and livestock, collect cow dung for fuel, shear wool, and perform other household duties. Therefore, they are extremely susceptible to E. granulosus and E. multilocularis . Age and low education level are risk factors for echinococcosis based on community studies conducted in Argentina . According to an epidemiological survey conducted in Chile, poor socioeconomic status and lack of education have also been linked to CE in humans .
In both the Qinghai-Tibet Plateau and the non-Qinghai Plateau, the susceptibility factors of echinococcosis are centered on children. However, in the former, the most affected group is made of children at school (15%), whereas in the latter the majority of affected children are not at school, only a minority being pupils (6.94%). Because of pastoral lifestyle and conditions, children are expected to help with household duties from a young age. The process involves contact with cattle and the possibility of coming into direct or indirect contact with dogs, which is exacerbated by inadequate local sanitation and a lack of hygiene awareness among children. There is thus a considerable chance of contracting echinococcosis. Unlike schistosomiasis, malaria, and other parasitic infections, echinococcosis has a slow onset and a hidden course. Most patients have been infected as children and youngsters and are very vulnerable since the symptoms are unclear and difficult to detect and treat .
As a result, improving surveillance, prevention, and control of echinococcosis infection in children is critical. It is crucial to expand health education and raise public awareness of echinococcosis prevention and control in the long run. Religious practices, in particular when associated with poor education, might be an aggravating factor in the Qinghai-Tibet Plateau. People in this region are Buddhists and thus they praise and highly respect all life forms. Lamas in temples will often take in or feed abandoned stray dogs leading to a higher concentration of such dogs, who represent a major risk of infection near temples [20–21].
The source of drinking water is also a major risk factor . E. granulosus eggs can only be inactivated after being stored at -80°C for at least seven days and they can survive for more than 200 days at 7°C and 50 days at 21°C . E. multilocularis eggs can also survive in water at 4°C for 16 months . Parasitic eggs are very resistant in the environment and can even withstand common disinfectants. Boiling is the most effective method of inactivating Echinococcus eggs . Therefore, drinking water is the most common way to become infected with echinococcosis . Springs, rivers, ponds and ditches, but also wells and even tap water can be polluted by Echinococcus eggs from dog feces. The traditional Tibetan lifestyle of many people in the Qinghai-Tibet Plateau is to be settled in the winter in permanent residences and to follow a nomadic life during summer. During this nomadic period, people and dogs share the same water supply, which is not boiled, tap or well water but surface water such as springs and rivers often of poor quality. Echinococcus eggs in dog feces are likely to pollute surface water. Indeed, nomadic herders often prefer pastures with natural water sources to set up tents, and livestock and dog excrements are randomly discharged in the surrounding environment, polluting the surrounding water sources . Drinking or using contaminated surface water increases the risk of infection. Furthermore, herdsmen, traditionally collect cow dungs as fuel, which will be brought into tents for usage . These customs also increase the risk of infection with echinococcosis. Of course, drinking clean water minimizes the risk of infection, and thus tap water is an echinococcosis protective factor [21, 31–32]. However, it is not compatible with the traditional semi-nomadic way of life.
Although most patients in the non-Qinghai-Tibet Plateau tend to drink water with a higher level of cleanliness, economic development in some places is lagging. Therefore, water storage is still a traditional lifestyle and thus water purity cannot be ensured. However, building water pipelines in CE and AE endemic areas is challenging because of geographical and climatic factors, particularly the Qinghai-Tibet Plateau. Depending on local economic and environmental conditions, appropriate actions should be taken to disinfect and treat local household water, strengthen water source management, install disinfection or filtration units in order to enable local populations to access safe domestic water, and limit the danger of Echinococcus egg exposure.
In the case of the Qinghai-Tibet Plateau, the vast number of both domestic and feral dogs around strongly increases the risk of contamination, in particular for children. Their health awareness is low, and they lack prevention expertise. As aggravating factors, geographical characteristics in endemic areas, adverse climatic conditions and economic factors make access to clean drinking water more problematic and thus, increase again the likelihood of infection in children. Most studies revealed the presence of both feral dogs and domestic dogs, particularly on the Qinghai-Tibet Plateau. However, feral dogs are less common in non-Tibetan societies, probably because of a different cultural background . Canines are the ultimate hosts of Echinococcocus, and their feces contain eggs and contaminate the environment, water sources and animal hair . A survey on domestic dogs in an epidemic area showed the presence of positive Echinococcus antigens 4.25% of dog feces . Feral dogs are also prevalent in CE and AE endemic areas [35–36]. Dog management and control are critical measures in preventing and controlling echinococcosis as the zoonotic risk of CE and AE increases with the number of dogs and time dogs are maintained . The Tibetan semi-nomadic way of life is unique and should be maintained. However, it should come along with efficient control measures on animal husbandry and dogs, otherwise echinococcosis will remain a severe human concern . However, these control measures are difficult to implement.
The main source of income in the agricultural and pastoral areas is livestock raising, which uses dogs to look after and protect herds. Cattle and sheep are also intermediate hosts of E. granulosus. During domestic and sporadic slaughter, the internal organs of livestock will generally be fed to dogs along with the parasites they may contain . In-house slaughter represents a risk of echinococcosis 4.67 times higher . Centralized slaughter can successfully cut off this transmission pathway, reducing the risk of dog illness and thus safeguarding the health of residents. The first strategy for preventing and controlling echinococcosis is to decrease or destroy Echinococcus eggs, and the second is to reduce the probability of interaction with Echinococcus eggs . Human proximity to definitive hosts (dogs) and animal intermediate hosts (livestock or small mammals) will increases the potential risk of echinococcosis (CE and AE) .
Non-Qinghai-Tibet Plateau is mainly dominated by CE prevalence. The lifestyle of local residents is different from that of residents on the Qinghai Tibet Plateau, being mainly settled. So they can get clean, tap drinking water. In this case, the main risk factor for CE is the presence of domestic and feral dogs feral. Because the geographical and natural environment is different from the Qinghai Tibet Plateau, the main risk factors of AE are dogs in the surrounding environment and drinking water with low cleanliness.
Canine deworming and health education, particularly for vulnerable communities, are essential to enhance their understanding of mechanisms of infection and change inadequate hygiene practices. However, this study does have some drawbacks. The collection of influencing factors is limited, such as for CE, the infection rate of livestock, and for AE, the infection rate of small rodents.