Hospital and community surveys reveal the severe public health problem and socio-economic impact of human echinococcosis in Ningxia Hui Autonomous Region, China

Hepatic alveolar echinococcosis: Comparative computed tomography study between two Chinese and two European centres

The main endemic areas for alveolar echinococcosis (AE) are in Central Europe and Western China, and in >98% of cases, AE manifests in the liver. The aim of this work was to compare European and Chinese patient groups for number, size, and computed tomography (CT) appearance of hepatic AE lesions. A total of 200 CT scans of patients with hepatic AE were evaluated by four blinded, experienced radiologists from two European (Besancon, Ulm) and two Chinese centres (Xining, Urumqi). In addition to noting the number, size, and localisation of the lesions, the radiologists evaluated morphological appearance using the Echinococcus multilocularis Ulm Classification - CT scheme. Chinese patients were younger than European patients (36.8 ± 13.2 vs. 63.5 ± 17.7; p < 0.0001) and had significantly larger lesions (120.4 ± 50.8 vs. 70.9 ± 39.8; p < 0.0001). The morphological appearance of the lesions on CT differed significantly between the two groups (p < 0.05), as did the number of lesions (2.6 ± 3.9 in European centres versus 3.8 ± 5.0 in Chinese centres; p = 0.0062). Patient age and AE-related morphological manifestations differ between Europe and China, but the reasons for the differences are unknown.

Echinococcosis transmission on the Tibetan Plateau

Since the mid-1990s detailed studies and field investigations on the Tibetan Plateau have revealed human echinococcosis to be an under-reported major public health problem, particularly in the dominant pastoral communities in the eastern and central regions. Human prevalence surveys showed that cystic echinococcosis (CE, caused by Echinococcus granulosus) and alveolar echinococcosis (AE, caused by Echinococcus multilocularis) are co-endemic with higher burdens of each disease than other endemic world regions. Epidemiological investigations identified some major risk factors for human CE and AE including dog ownership, husbandry practices and landscape features. Dogs appear to be the major zoonotic reservoir for both E. granulosus and E. multilocularis, but the latter is also transmitted in complex wildlife cycles. Small mammal assemblages especially of vole and pika species thrive on the Plateau and contribute to patterns of E. multilocularis transmission which are influenced by landscape characteristics and anthropogenic factors. Tibetan foxes are a principal definitive host for both E. multilocularis and E. shiquicus. In 2006 a national echinococcosis control programme was initiated in Tibetan communities in northwest Sichuan Province and rolled out to all of western China by 2010, and included improved surveillance (and treatment access) of human disease and regular deworming of dogs with annual copro-testing. Control of echinococcosis in Tibetan pastoral communities poses a difficult challenge for delivery and sustainability.

Estimating the prevalence of Echinococcus in domestic dogs in highly endemic for echinococcosis

BACKGROUND

Cystic echinococcosis (CE) and alveolar echinococcosis (AE) are highly endemic in Xiji County of Ningxia Hui Autonomous Region (NHAR) in China where the control campaign based on dog de-worming with praziquantel has been undertaken over preceding decades. This study is to determine the current prevalence of Echinococcus granulosus and E. multilocularis in domestic dogs and monitor the echinococcosis transmission dynamics.

METHODS

Study villages were selected using landscape patterns (Geographic Information System, GIS) for Echinococcus transmission "hot spots", combined with hospital records identifying risk areas for AE and CE. A survey of 750 domestic dogs, including copro-sampling and owner questionnaires, from 25 selected villages, was undertaken in 2012. A copro-multiplex PCR assay was used for the specific diagnosis of E. granulosus and E. multilocularis in the dogs. Data analysis, using IBM SPSS Statistics, was undertaken, to compare the prevalence of the two Echinococcus spp. in dogs between four geographical areas of Xiji by the χ2 test. Univariate analysis of the combinations of outcomes from the questionnaire and copro-PCR assay data was carried out to determine the significant risk factors for dog infection.

RESULTS

The highest de-worming rate of 84.0% was found in the northwest area of Xiji County, and significant differences (P <  0.05) in the de-worming rates among dogs from the four geographical areas of Xiji were detected. The highest prevalence (19.7%, 59/300) of E. multilocularis occurred in northwest Xiji, though the highest prevalence (18.1%, 38/210) of E. granulosus occurred in southwest Xiji. There was no significant difference (P >  0.05) in the prevalence of E. granulosus in dogs from the northwest, southwest, northeast, and southeast of Xiji, but there were significant differences (P <  0.05) between dogs infected with E. multilocularis from the four areas. None of the other independent variables was statistically significant.

CONCLUSIONS

The results from this study indicate a high prevalence of both E. granulosus and E. muiltilocularis in dogs in Xiji County, NHAR. Transmission of E. multilocularis was more impacted by geographical risk-factors in Xiji County than that of E. granulosus. Dogs have the potential to maintain the transmission of both species of Echinococcus within local Xiji communities, and the current praziquantel dosing of dogs appears to be ineffective or poorly implemented in this area.

Childhood suffering: hyper endemic echinococcosis in Qinghai-Tibetan primary school students, China

Background

As part of an ongoing program that aims to use early detection and timely treatment to improve the control of echinococcosis, especially in younger age groups, we undertook a series of active surveys among Qinghai-Tibetan children in the Qinghai Province of Northwestern China in 2011 and 2012. The significant outcomes that resulted from this study emphasize the need to draw attention to echinococcosis, both alveolar echinococcosis (AE) and cystic echinococcosis (CE), so that policy development is promoted and suitable avenues for control are identified in the highly endemic areas on the Tibetan Plateau.

Methods

A total of 19 629 primary school students, aged 6–18 years, with a dominant Tibetan background underwent abdominal ultrasound examination, and 86.4% of the compliant students donated 2–5 ml of venous blood for serological tests. All the abnormal ultrasound results were recorded. If identified as echinococcosis, the disease lesion was assessed according to the WHO-Informal Working Group on Echinococcosis (WHO-IWGE) classification for AE and CE. Among the surveyed students, the prevalence by school was compared among geo-locations, sex and age groups. The clinical image presentations were analyzed according to lesion number, size, the location in the liver and the classification stage. Statistical significance was set at P-value < 0.05 for comparisons among groups.

Results

A total of 341 students (1.7%) were identified by ultrasound as having either CE (119, 0.6%) or AE (222, 1.1%). The highest prevalence rates of childhood AE cases occurred in the Tehetu (12.1%) and Moba (11.8%) townships in Dari County. There was a high seropositive rate (37.0%) and a heterogeneous distribution of cases, with a prevalence ranged from 0 to 12.1% for AE and 0–2.9% for CE. Moreover, the seropositive rate ranged from 0.7–45.1% across different schools.

Conclusions

The high prevalence of echinococcosis in Qinghai-Tibetan primary school students reflects a lack of knowledge about Echinococcus spp. transmission. The combination of systematic education for children and regularly performed anthelmintic treatment for dogs could achieve the goal of sustainable hydatidosis control.

Electronic supplementary material

The online version of this article (10.1186/s40249-018-0455-y) contains supplementary material, which is available to authorized users.

Echinococcosis: Control and Prevention

Human cystic echinococcosis (CE) has been eliminated or significantly reduced as a public health problem in several previously highly endemic regions. This has been achieved by the long-term application of prevention and control measures primarily targeted to deworming dogs, health education, meat inspection, and effective surveillance in livestock and human populations. Human CE, however, remains a serious neglected zoonotic disease in many resource-poor pastoral regions. The incidence of human alveolar echinococcosis (AE) has increased in continental Europe and is a major public health problem in parts of Eurasia. Better understanding of wildlife ecology for fox and small mammal hosts has enabled targeted anthelmintic baiting of fox populations and development of spatially explicit models to predict population dynamics for key intermediate host species and human AE risk in endemic landscapes. Challenges that remain for echinococcosis control include effective intervention in resource-poor communities, better availability of surveillance tools, optimal application of livestock vaccination, and management and ecology of dog and wildlife host populations.

The landscape epidemiology of echinococcoses

Echinococcoses are parasitic diseases of major public health importance globally. Human infection results in chronic disease with poor prognosis and serious medical, social and economic consequences for vulnerable populations. According to recent estimates, the geographical distribution of Echinococcus spp. infections is expanding and becoming an emerging and re-emerging problem in several regions of the world. Echinococcosis endemicity is geographically heterogeneous and over time it may be affected by global environmental change. Therefore, landscape epidemiology offers a unique opportunity to quantify and predict the ecological risk of infection at multiple spatial and temporal scales. Here, we review the most relevant environmental sources of spatial variation in human echinococcosis risk, and describe the potential applications of landscape epidemiological studies to characterise the current patterns of parasite transmission across natural and human-altered landscapes. We advocate future work promoting the use of this approach as a support tool for decision-making that facilitates the design, implementation and monitoring of spatially targeted interventions to reduce the burden of human echinococcoses in disease-endemic areas.

Economic and financial evaluation of neglected tropical diseases

Economic and financing studies are particularly important for decision-making when resources are scarce or considerably limited. This is the case for neglected tropical diseases (NTDs). In fact, the definition of NTDs is an economic one. The shortage of resources for NTD control may be due in large part to the fact that the burden of NTDs and economic value of control measures have not been fully characterized. A number of economic study methodologies are available: cost of illness can quantify the extent, magnitude, and change of a problem; cost of intervention studies can outline the feasibility and guide the design of a policy or intervention; and cost-benefit, cost-effectiveness, and return-on-investment studies can determine the potential value of different interventions and policies. NTDs have unique characteristics that require special consideration in such analyses. Hence, approaches used for other diseases may need modifications to capture the full impact of NTDs. While the existing literature has made important findings, there is a need for substantially more work, as many NTDs and their associated interventions and policies require more evaluation. With increasing work in this area, NTDs may not be as 'neglected' in the future as they are now.

Cystic echinococcosis in a single tertiary care center in Rome, Italy

Background. Cystic echinococcosis (CE) is a chronic, clinically complex, and neglected disease. Its prevalence in Italy, a country of medium to high endemicity, remains poorly defined, as notification has long ceased to be mandatory. Methods. We set up a retrospective cohort study involving all CE patients followed at our institute between January 2005 and December 2012. Demographical and clinical features were recorded and analyzed. Results. CE was found in 28 patients (64.3%), mostly Italians from the central regions (50%), followed by subjects from the islands (33.3%) and Southern Italy (16.7%). Their median age was 45 years (IQR: 38.5–66.5), with Eastern Europeans being significantly younger (28 years, IQR: 19–39) than other patients (P ≤ 0.0001). A total of 149 cysts, mostly with hepatic localization (96%), were described. Based on the WHO classification, the cysts were mainly small (80.5%) and active (CE1 (73.8%); CE2 (7.4%)). Active cysts were more common in Eastern Europeans (85.7%) than Italians (66.7%). Conclusion. Our data confirm CE occurrence in Italy. We emphasize the importance to have a national CE registry, opportunely recently introduced. This is essential to assess CE prevalence in this country, implement appropriate control measures, and improve patient management.

Reinfection studies of canine echinococcosis and role of dogs in transmission of Echinococcus multilocularis in Tibetan communities, Sichuan, China

In the eastern Tibetan plateau both human cystic and alveolar echinococcosis (AE) caused by infection with Echincoccus granulosus or Echinococcus multilocularis, respectively are highly endemic. The domestic dog plays a key role in zoonotic transmission in this region. Our primary objective was to investigate the role of domestic dogs in maintaining transmission of E. multilocularis in Shiqu county, Sichuan. A cohort of 281 dogs was followed up over one year after a single treatment with praziquantel followed by re-infection surveillance at 2, 5 and 12 months post-treatment. Faecal samples were tested by an Echinococcus genus-specific coproantigen ELISA and two species-specific copro-PCR tests. Total Echinococcus coproantigen prevalence in Shiqu at baseline was 21% and 9·6% after 2 months. E. multilocularis copro-PCR was positive in 11·2% of dogs before treatment (vs 3·6% with E. granulosus copro-DNA), 2·9% at 2 months post-treatment, and 0% at 5 month and 12 months. The results suggest that dogs may have the potential to maintain E. multilocularis transmission within local pastoral communities, and thus dog dosing could be an effective strategy to reduce transmission of E. multilocularis as well as E. granulosus in these co-endemic Tibetan communities.

Environmental changes impacting Echinococcus transmission: research to support predictive surveillance and control

Echinococcosis, resulting from infection with tapeworms Echinococcus granulosus and E. multilocularis, has a global distribution with 2-3 million people affected and 200,000 new cases diagnosed annually. Costs of treatment for humans and economic losses to the livestock industry have been estimated to exceed $2 billion. These figures are likely to be an underestimation given the challenges with its early detection and the lack of mandatory official reporting policies in most countries. Despite this global burden, echinococcosis remains a neglected zoonosis. The importance of environmental factors in influencing the transmission intensity and distribution of Echinococcus spp. is increasingly being recognized. With the advent of climate change and the influence of global population expansion, food insecurity and land-use changes, questions about the potential impact of changing temperature, rainfall patterns, increasing urbanization, deforestation, grassland degradation and overgrazing on zoonotic disease transmission are being raised. This study is the first to comprehensively review how climate change and anthropogenic environmental factors contribute to the transmission of echinococcosis mediated by changes in animal population dynamics, spatial overlap of competent hosts and the creation of improved conditions for egg survival. We advocate rigorous scientific research to establish the causal link between specific environmental variables and echinococcosis in humans and the incorporation of environmental, animal and human data collection within a sentinel site surveillance network that will complement satellite remote-sensing information. Identifying the environmental determinants of transmission risk to humans will be vital for the design of more accurate predictive models to guide cost-effective pre-emptive public health action against echinococcosis.

A retrospective study on burden of human echinococcosis based on Hospital Discharge Records from 2001 to 2009 in Sardinia, Italy

Cystic Echinococcosis (CE) is an infective zoonosis that represents a worldwide important public health problem. In humans, its manifestations may range from asymptomatic infection to severe disease and possible death, and lead to economic losses from treatment costs and lost wages. Recent studies suggest that this disease has a large social impact in endemic areas, and estimates of burden in terms of monetary and no-monetary impact on human health are essential to allocate financial and technical resources. In Sardinia, the most affected Italian region per number of inhabitants, CE is still endemic, although three eradication campaigns have been carried out in 1962, 1978, and 1987, respectively. To date, the burden of human CE in Sardinia remains poorly defined. In this work, a retrospective study was carried out using public Hospital Discharge Records spanning from 2001 to 2009. During these years, a total of 1409 discharges were recorded: 1196 (84.88%) records corresponding to patients hospitalized for symptoms directly correlated to CE (primary diagnosis), and 213 (15.11%) records corresponding to patients hospitalized for symptoms not directly correlated to CE and with an afterwards or concurrent diagnosis of echinococcosis made during the hospitalization (secondary diagnosis). The annual regional average record (discharge rate) was 9.3/100,000 inhabitants. Direct cost associated with diagnosis, surgery or chemotherapy, medical care, and hospitalization in humans were evaluated in this work. Furthermore, burden of disease was also evaluated by using the disability-adjusted life years (DALYs), the preferred disease-burden measure of the World Health Organization. Knowing the burden of human CE in Sardinia is extremely important to enable the prioritization of control measures for this preventable neglected disease. This is the first study describing the measure of the overall disease burden in an Italian region endemic for this disease, performed by calculating the number of CE patients from Hospital Discharge Records.

Immunogenetics of human echinococcosis

Susceptibility and resistance to human Echinococcus infection and disease, although poorly understood, appear to reflect a complex interaction of parasite and host immunological and genetic factors. Disease stage, progression, and prognosis following treatment appear to be strongly influenced by cytokine and antibody profiles, and more recent evidence has suggested an important role of dendritic cells (DCs) and T regulatory cells (Tregs) in immunomodulation. Microarrays have supported these findings, highlighting both known and novel pathways involved in chronic murine disease. Genetic studies to date have been few and with limited success. Advanced genomic approaches, such as genome-wide association studies (GWAS), may provide further insight to identify the relevant pathways involved, thereby facilitating a new approach for the development of new clinical therapies.

Impact of anthropogenic and natural environmental changes on Echinococcus transmission in Ningxia Hui Autonomous Region, the People's Republic of China

Echinococcus transmission is known to be affected by various environmental factors, which may be modified by human influence or natural events including global warming. Considerable population growth in the last fifty years in Ningxia Hui Autonomous Region (NHAR), the People’s Republic of China (PRC), has led to dramatic increases in deforestation and modified agricultural practices. In turn, this has resulted in many changes in the habitats for the definitive and intermediate hosts of both Echinococcus granulosus and E. multilocularis, which have increased the risks for transmission of both parasites, affecting echinococcosis prevalence and human disease. Ecological environmental changes due to anthropogenic activities and natural events drive Echinococcus transmission and NHAR provides a notable example illustrating how human activity can impact on a parasitic infection of major public health significance. It is very important to continually monitor these environmental (including climatic) factors that drive the distribution of Echinococcus spp. and their impact on transmission to humans because such information is necessary to formulate reliable future public health policy for echinococcosis control programs and to prevent disease spread.

Immunology and immunodiagnosis of cystic echinococcosis: an update

Cystic echinococcosis (CE) is a cosmopolitan zoonosis caused by the larval cystic stage of the dog tapeworm Echinococcus granulosus. This complex multicellular pathogen produces various antigens which modulate the host immune response and promote parasite survival and development. The recent application of modern molecular and immunological approaches has revealed novel insights on the nature of the immune responses generated during the course of a hydatid infection, although many aspects of the Echinococcus-host interplay remain unexplored. This paper summarizes recent developments in our understanding of the immunology and diagnosis of echinococcosis, indicates areas where information is lacking, and suggests possible new strategies to improve serodiagnosis for practical application.

Case studies emphasising the difficulties in the diagnosis and management of alveolar echinococcosis in rural China

Background

Human alveolar echinococcosis (AE) is caused by the accidental ingestion of the eggs of the fox tapeworm Echinococcus multilocularis. AE occurs frequently in rural western China due to the poor levels of hygiene, the close contact of people with dogs, and the lack of appropriate facilities for the correct and rapid diagnosis of the disease.

Findings

We describe a case of a patient with hepatic AE, and AE metastases of the brain. She was mistakenly diagnosed with suspected undifferentiated metastatic cancer of the liver and brain, and with a pulmonary bacterial infection, but was subsequently correctly diagnosed during a follow-up field survey for echinococcosis. The diagnosis of brain AE was confirmed by pathological examination of tissue biopsies removed during neurosurgery. We also briefly describe other symptomatic and asymptomatic AE cases, identified by chance, likely due to the inadequate facilities available in rural communities in China for AE diagnosis and management, since the rapid and accurate diagnosis of metastatic AE requires a high level of expertise in the appropriate diagnostic procedures.

Conclusions

This report highlights the necessity for an upgrade in the diagnosis, treatment, prevention and control of AE in rural China.

Impact of increased economic burden due to human echinococcosis in an underdeveloped rural community of the People's Republic of China

Background

Ningxia is located in western People's Republic of China, which is hyperendemic for human cystic echinococcosis (CE) throughout the entire area with alveolar echinococcosis (AE) hyperendemic in the south. This is in part due to its underdeveloped economy. Despite the recent rapid growth in P.R. China's economy, medical expenditure for hospitalization of echinococcosis cases has become one of the major poverty generators in rural Ningxia, resulting in a significant social problem.

Methodology/Principal Findings

We reviewed the 2000 inpatient records with liver CE in surgical departments of hospitals from north, central and south Ningxia for the period 1996–2002. We carried out an analysis of health care expenditure of inpatient treatment in public hospitals, and examined the financial inequalities relating to human echinococcosis and the variation in per capita income between various socioeconomic groups with different levels of gross domestic product for different years. Hospital charges for Yinchuan, NHAR's capital city in the north, increased approximately 35-fold more than the annual income of rural farmers with the result that they preferred to seek health care in local county hospitals, despite higher quality and more efficient treatment and diagnosis available in the city. Household income levels thus strongly influenced the choice of health care provider and the additional expense impeded access of poor people to better quality treatment.

Conclusions/Significance

Information on socioeconomic problems arising from echinococcosis, which adds considerably to the burden on patient families and communities, needs to be collected as a prerequisite for developing policies to tackle the disease in rural Ningxia.

This paper compares medical expenditure for hospital treatment of echinococcosis in NHAR, western People's Republic of China, for different years, different regions and different socioeconomic groups. The results show that the level of household income strongly influences health care decisions. This study represents an effort to determine the effect of hospital charges for inpatient treatment of echinococcosis on the choice of provider in NHAR, and quantitatively examines this topic for the rural poor. The findings show that low income individuals from rural areas opted to visit a local county hospital rather than an urban hospital for hydatid surgery despite the inferior infrastructure, personnel and general health care facilities available. There are a number of policy implications. For example, enhancing the quality and service of county hospitals in rural areas will benefit those with lower incomes, thus improving access of rural residents to health facilities for higher quality diagnosis and efficient treatment. Thus, we advocate that government policy should be to increase investment in health care in poor rural areas, and to launch relevant medical aid projects to help those in poverty.

The global burden of alveolar echinococcosis

BACKGROUND

Human alveolar echinococcosis (AE) is known to be common in certain rural communities in China whilst it is generally rare and sporadic elsewhere. The objective of this study was to provide a first estimate of the global incidence of this disease by country. The second objective was to estimate the global disease burden using age and gender stratified incidences and estimated life expectancy with the disease from previous results of survival analysis. Disability weights were suggested from previous burden studies on echinococcosis.

METHODOLOGY/PRINCIPAL FINDINGS

We undertook a detailed review of published literature and data from other sources. We were unable to make a standardised systematic review as the quality of the data was highly variable from different countries and hence if we had used uniform inclusion criteria many endemic areas lacking data would not have been included. Therefore we used evidence based stochastic techniques to model uncertainty and other modelling and estimating techniques, particularly in regions where data quality was poor. We were able to make an estimate of the annual global incidence of disease and annual disease burden using standard techniques for calculation of DALYs. Our studies suggest that there are approximately 18,235 (CIs 11,900-28,200) new cases of AE per annum globally with 16,629 (91%) occurring in China and 1,606 outside China. Most of these cases are in regions where there is little treatment available and therefore will be fatal cases. Based on using disability weights for hepatic carcinoma and estimated age and gender specific incidence we were able to calculate that AE results in a median of 666,434 DALYs per annum (CIs 331,000-1.3 million).

CONCLUSIONS/SIGNIFICANCE

The global burden of AE is comparable to several diseases in the neglected tropical disease cluster and is likely to be one of the most important diseases in certain communities in rural China on the Tibetan plateau.

Species identification of human echinococcosis using histopathology and genotyping in northwestern China

Human cystic echinococcosis, caused by infection with the larval stage of Echinococcus granulosus, and alveolar echinococcosis, caused by the larval form of E. multilocularis, are known to be important public health problems in western China. Echinococcus shiquicus is a new species of Echinococcus recently described in wildlife hosts from the eastern Tibetan plateau and its infectivity and/or pathogenicity in humans remain unknown. In the current study, parasite tissues from various organs were collected post-operatively from 68 echinococcosis patients from Sichuan and Qinghai provinces in eastern China. The tissues were examined by histopathology and genotyped using DNA sequencing and PCR-RFLP. Histopathologically, 38 human isolates were confirmed as E. granulosus and 30 as E. multilocularis. Mitochondrial cob gene sequencing and PCR-RFLP with rrnL as the target gene confirmed 33 of 53 of the isolates to have the G1 genotype of sheep/dog strain of E. granulosus as the only source of infection, while the remaining 20 isolates were identified as E. multilocularis. No infections were found to be caused by E. shiquicus. Additionally, 5 of 20 alveolar echinococcosis patients were confirmed to have intracranial metastases from primary hepatic alveolar echinococcosis lesions. All these cases originated from four provinces or autonomous regions but most were distributed in Sichuan and Qinghai provinces, where high prevalence rates of human alveolar echinococcosis and cystic echinococcosis were previously documented.

A correlative study of ultrasound with serology in an area in China co-endemic for human alveolar and cystic echinococcosis

We correlated ultrasound (US) imaging classifications for human alveolar echinococcosis (AE) and cystic echinococcosis (CE) with serology (ELISA and immunoblotting (IB) incorporating native and recombinant/purified echinococcal antigens) in community surveys (2001-2003) and follow-up (2002 and 2003) of US-confirmed cases in Ningxia, China. One hundred and seventy-one cases (96 with AE, 75 with CE) were identified; of these, US classification and serological data were obtained for 142 and 112 cases, respectively. Seropositive-rates increased in CE patients with highly viable unilocular cyst lesions (Types CL, CE 1 or CE 2) to degenerating primary lesions (CE 3), but then decreased in subjects with inactive (CE 4) or dead (CE 5) cysts. In contrast, there was a constant increase in seropositivity from the early (P1, P2) to the advanced stages (P3, P4) with AE cases. For US-confirmed cases, follow-up by US combined with serology is invaluable for studying the clinical progression of echinococcosis and for detecting recurrent cysts or reinfection post-treatment.