Public health importance of cystic echinococcosis in China

Clinical Implications for the Comprehensive Interpretation of Radiologic and Immunodiagnostic Tests in Patients Suspected of Parasitic Hepatic Cyst, a Rare Case in Korea

Cystic echinococcosis (CE) is a representative neglected tropical disease (NTD) with increased morbidity and mortality but is ignored and overlooked in developed countries. Serological and radiographic findings are helpful in distinguishing these parasites; however, conflicting results of these can make it difficult to diagnose if medical knowledge of hepatic parasitic disease, including the etiology, features of imaging, and immunodiagnostic test, is not acquired. We report the case of a male patient with dyspepsia and right epigastric pain who had positive results for cysticercosis antibodies on immunodiagnostic examination. Abdominal ultrasonography revealed two huge communicating cystic lesions measuring 8–11 cm. Further evaluations for cysticercosis of the brain (neurocysticercosis) and eyes (intraocular cysticercosis) were unremarkable throughout the brain imaging test and fundus examination. A laparoscopic right hemi-hepatectomy was performed for diagnosis and treatment. On histopathological examination, diverse stages of Echinococcus granulosus were identified. Albendazole was administered postoperatively, and the patient was also followed up. We should be aware of the etiologies that have been prevalent in parasite infection thought to be the cause of hepatic cysts. Moreover, we make an effort to ascertain the patient’s nationality, past travel experiences, and immediate environment, including any animals and pets. We present the case of a patient who was worried about the possibility of liver invasion of cysticercus due to the positivity of the cysticercosis antibody and was ultimately diagnosed with CE.

The polymorphic analysis of cox1 and cob genes of Echinococcus granulosus in the Ngari region of Tibet in China

Cystic echinococcosis (CE) is an important zoonotic parasitic disease caused by Echinococcus granulosus (E. granulosus). CE seriously threatens human health and the development of animal husbandry. The Ngari region is one of the world's highest endemic regions for CE, while genetic polymorphisms of E. granulosus were unclear. Paraffin slices of liver Cyst were collected from seventy-nine surgical patients with echinococcosis in the Ngari region. DNA was extracted from samples. The cox1 and cob genes of mitochondrial DNA of E. granulosus were simultaneously amplified and sequenced. The sequencing results were compared with the standard sequence (KU925397.1and HF947574.1). Phylogenetic trees and the haplotype network of cob and cox1 genes were constructed and analyzed genotypes of E. granulosus isolated from humans in the Ngari Region of Tibet. Out of 79 hydatid cyst samples collected from surgery patients, 60 isolates were identified as G1/ G3, and two isolates were identified as G6/ G7. Analysis of the cob/ cox1 genes revealed 9/7 mutations resulting in 8/6 haplotypes, respectively. The cob and cox1 neutrality indices computed by Tajima's D and Fu's Fs tests showed high negative values in Echinococcus granulosus sensu stricto (E. granulosus s. s.). The result suggested that E. granulosus in the Ngari region experienced population expansion or a negative selection. We found that G1/ G3 was still the main genotype, and G6/ G7 was found occasionally in humans of the Ngari region. Therefore, we recommend future surveys and control efforts to investigate G1/ G3 and G6/ G7 transmission in the Ngari region.

Pulmonary Mucormycosis and hydatid cyst: A case report

Mucormycosis is a group of life-threatening diseases caused by a fungus of the Mucoraceae family and has a higher mortality rate compared with other known fungal infections. Hydatid cyst, caused by Echinococcus, is a crucial health concern in endemic areas and the disease is characterized by slow-growing cysts in the liver, lungs, or other organs. In this report, a woman with coexistence of hydatid cyst and Mucormycosis is introduced. The patient was a 52-year-old woman with approximately 6 years' history of uncontrolled diabetes mellitus and hypothyroidism, who presented with cough, sputum, and dyspnea 2 months ago. On the initial auscultation of the lungs, there was a decreased sound at the base of the left lung, and she had a fever. In blood tests, she had a high titer of erythrocyte sedimentation rate and 3+ C-Reactive Protein. The symptoms in favor of hydatid cyst were observed in lung computed tomography and in pleural needle biopsy, hydatid cyst was confirmed. With this indication, she underwent wedge resection, and resection of the left lower lung cyst. Two samples are taken from the cyst side and the pathology report was consistent with Mucormycosis (wide filaments with a 90-degree angle). The patient was immediately treated with liposomal amphotericin for 4 weeks. The Lung CT scan was performed before and after treatment. Albendazole was treated to treat hydatid cyst. After discharge, the treatment of the patient continued with oral Posaconazole, and after the treatment finalization, the general condition of the patient was good, and she did not have any complaints. In pulmonary diseases that do not respond significantly to surgical treatment (such as hydatid cyst), fungal disease (mucor) must be considered simultaneously. Mucormycosis is more prevalent in patients with uncontrolled diabetes, and it is necessary to be considered if these patients were infected with pneumonia and their symptoms did not improve with usual treatments.

A systematic review and meta-analysis on prevalence and distribution of Taenia and Echinococcus infections in Ethiopia

Background

Tapeworm infections are among the tropical neglected parasitic diseases endemically occurring in Ethiopia. This systematic review and meta-analysis aims at estimating the pooled prevalence and distribution of Taenia and Echinococcus infections in humans and animals from reports from Ethiopia.

Methods

The systematic search was conducted in four bibliographic databases (PubMed, Google Scholar, Africa Journal Online and Science Direct). Additional data were retrieved from grey literature. Studies that met the inclusion criteria were considered for the systematic review and meta-analysis. The meta-analysis was conducted using MetaXL add-in for Microsoft Excel. Heterogeneity and inconsistency were evaluated using Cochran’s Q and I² statistics, respectively.

Results

The study provides a country-based database of Taenia and Echinococcus infections consisting of 311 datasets from 201 publications which were mostly abattoir surveys; of these, 251 datasets were subjected to meta-analysis. Most of the studies were from Oromia (32.8%) followed by Amhara (22.9%) regional states. The pooled prevalence of cystic echinococcosis in intermediate and accidental hosts was calculated as 22% (95% CI 18–26%) and high study variability (Q = 24,420.65, I² = 100%, P = 0.000). Moreover, a pooled prevalence of Echinococcus infections in final hosts was calculated as 33% (95% CI 20–48%) and low study variability (Q = 17.24, I² = 65%, P = 0.001). Similarly, study subjects (human, cattle, sheep, goat and wolf) were infected by Taenia spp. with pooled prevalence of 3% (95% CI 2–4%) and moderate study variability (Q = 279.07, I² = 89, P = 0.000). Meanwhile, the pooled prevalence of Taenia hydatigena, T. ovis and T. multiceps infections in intermediate hosts were calculated as 38%, 14% and 5%, respectively. The random effect meta-analysis of bovine cysticercosis showed a pooled prevalence of 7% (95% CI 5–9%) and high study variability was of (Q = 4458.76; I² = 99%, P = 0.000). Significant differences in prevalence of Taenia and Echinococcus infections between study sites or different livestock origins have been reported.

Conclusion

The study evidenced a comprehensive dataset on the prevalence and distribution of Taenia and Echinococcus infections at different interfaces by regions and hosts and hence can aid in the design of more effective control strategies.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-021-04925-w.

Review on Epidemiology and Public Health Significance of Hydatidosis

Hydatidosis is a zoonotic parasitic disease caused by larval stages (hydatid cysts) of cestodes belonging to the genus Echinococcus and the family Taeniidae. Hydatid cyst, which is the larval stage of Echinococcus, is a bladder-like cyst formed in various organs and tissues following the growth of the oncospheres of an Echninoccus tape worm in that specific organ or tissue. The epidemiology and control of hydatidosis is often considered to be a veterinary matter since the disease can be regulated by controlling parasites in animals. However, collaboration between veterinarians and public health workers is essential for the successful control of hydotidosis. Therefore, the objective of this paper was to review The epidemiology, economic and public health importance of hydatidosis. The developmental stage of Echinococcus is that eggs develop to oncospheres, this oncospheres develop to hydatid cyst in the intermediate host and the hydatid cyst if consumed by final host develops to the adult Echinococcus. Human echinococcosis is a zoonotic infection caused by the tape worm of the genus Echinococcus. Echinococcus granucosus granulosis cause cystic echinococcosis (CE), Echinococcus multilocularis cause alveolar echinoloccosis (AE), and Echinococcus vogeli and Echinococcus oligarthus cause polycystic echinococcosis (PE). From these Echinococcus mulitilocularis is rare but is the most virulent, Echinococcus vegeli and Echinococcus oligarthus are the rarest. Hydatidosis is a zoonotic cosmopolitan parasitic disease found in almost all countries of the world. This disease causes a significant economic loss directly by causing organ or carcass condemnation and indirectly by affecting human and animal health which increase the cost for diagnosis, treatment and control of the disease. Public awareness creation about the transmission and control of the disease and its public health significance and collaboration between veterinarians and public health workers in the prevention and control of the disease is mandatory.

The echinococcoses in Asia: The present situation

Human alveolar and cystic echinococcosis, caused by the accidental ingestion of eggs of the tapeworms Echinococcus multilocularis and Echinococcus granulosus sensu lato, respectively, are endemic in Asia. Various Echinococcus species are maintained in domesticated and/or wild mammals through predator-prey interactions. Molecular analysis is used to help differentiate infecting parasite species and genotypes, with the goal of better understanding parasite life cycles in order to aid in the planning and implementation of control programs. This paper discusses the various echinococcoses in Asia, with limited reference to neighboring areas, including parts of Central Asia, Russia, Europe and North America.

Cystic pulmonary hydatidosis

Cystic echinococcosis (CE) is a zoonotic parasitic disease caused by the larval stages of the cestode Echinococcus granulosus. Worldwide, pulmonary hydatid cyst is a significant problem medically, socially, and economically. Surgery is the definitive therapy of pulmonary hydatidosis. Benzimidazoles may be considered in patients with a surgical contraindication. This review will focus on pathogenesis, lifecycle, clinical features, and management of pulmonary hydatid disease.

Parasitic Diseases of the Lung

Parasitic infection is a major healthcare problem that affects millions of the world’s population. Immigration and global warming have changed the natural distribution of parasitic diseases far removed from endemic areas. The respiratory system can be affected by a broad spectrum of helminthic and protozoal parasitic diseases. The diagnosis of parasitic infection of the respiratory system may be delayed due to myriad clinical and radiographic presentations of parasitic diseases which make the diagnosis of these entities challenging. Pulmonologists need to be familiar with the epidemiology, clinical presentation, pathophysiology, and bronchoscopic findings of parasitic lung diseases, in order to provide proper management in a timely fashion. This review provides a comprehensive view of both helminthic and protozoal parasitic diseases that affect the respiratory system, especially the central airways.

Knowledge, attitude, and practices (KAP) and risk factors analysis related to cystic echinococcosis among residents in Tibetan communities, Xiahe County, Gansu Province, China

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A community based cross-sectional study of CE was conducted in Tibetan communities.

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This is the first knowledge, attitude, and practice (KAP) study of CE in the areas.

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Most of residents had positive attitude toward treatments of the disease.

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Their practice about prevention and control of the disease was not so good.

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Feeding dogs with offal is still one of risk factors of CE transmission.

Cystic echinococcosis (CE) is a global parasitic zoonosis caused by Echinococcus granulosus. The disease is highly endemic in western China, especially in Tibetan areas, because of poor economic development and hygiene conditions, limited community knowledge of CE, a large scale of dogs, and home slaughtering of livestock. Although many researchers have analyzed risk factors of CE transmission in Tibetan Plateau, there are rare reports of knowledge, attitude, and practice (KAP) of residents about CE in Tibetan communities. In our current study, community based cross-sectional study was conducted in three townships in Xiahe County, Gannan Tibetan Autonomous Prefectures of Gansu Province from May to September 2013. A total of 972 participants originating from Tibetan communities of 31 villages in the 3 townships were registered and data were collected using structured questionnaires. From the total of 972 study participants (457 males and 515 females), 65.9% heard of the disease CE. Most of them (96.1%) would like to accept CE inspection. About half of the peoples feed their dogs often and major of them do not play with the dogs. Risk factors included resident, knowing dog could be infected, knowing eating could be route of infection, oldest dog's age, usually feed your dog by self, feed dogs with internal organs. In general our findings showed that most of residents had positive attitude toward treatments of the disease, but their practice about disease prevention and control was low. Therefore, our study called for continued and strengthened education of changing the life style, especially the behaviors related to dogs.

Epidemiological Investigations on Cystic Echinococcosis in North-West (Sidi Kacem Province) Morocco: Infection in Ruminants

Despite alarming statistics on cystic echinococcosis (CE) in humans and the importance of dog and ruminant populations, no epidemiological investigations have been performed on CE in Sidi Kacem Province (North-West of Morocco). A part of large research project was devoted to determine the status of CE in ruminants. This paper reports the results of the investigations carried out in the 10 abattoirs of this region, over four successive years (April 2009–March 2013). A total of 1,302 sheep, 652 head of cattle, and 136 goats were postmortem examined and hydatid cysts were collected and examined. The overall CE prevalence of infection was 42.9% in cattle, 11.0% in sheep, and 1.5% in goats. The prevalence shows significant association with age in sheep and cattle; sheep above 3 years and cattle above 5 years are highly infected (64.0% and 72.2%, resp.). Only liver and lungs are found to be infected. Molecular analyses identified G1, G2, and G3 of E. granulosus sensu stricto in liver and lung samples. Cyst fertility was significantly higher in sheep (54.9%) than in cattle (50.3%). These findings suggest that control measures should target not only sheep but also cattle.

Epidemiology and control of echinococcosis in central Asia, with particular reference to the People's Republic of China

At least 270 million people (58% of the total population) are at risk of cystic echinococcosis (CE) in Central Asia including areas of Mongolia, Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, Uzbekistan, Afghanistan, Iran, Pakistan and western China. The annual surgical incidence rate in Uzbekistan and Tadjikistan has been estimated to be as high as 25-27 cases/100,000 with the highest prevalence reaching 10% (range from 0.8 to 11.9%) in some Tibetan communities in western China. Echinococcus transmission in the region is largely associated with social factors including limited community knowledge of echinococcosis, small-scale household animal production, home killing of livestock, and the feeding of dogs with uncooked offal. Alveolar echinococcosis (AE) is also endemic in Central Asia and is recognized as a major problem in some Tibetan communities with up to 6% of villagers infected in some villages. In western China, 5-30% of the population are seropositive against E. granulosus antigens, indicating that a large number of individuals have been exposed to the parasite. Although echinococcosis control programs have been initiated in some countries in Central Asia, control efforts are generally fragmented and uncoordinated. Monthly deworming of dogs with praziquantel (PZQ), as a key measure to control the Echinococcus parasites, has been used in western China. However, the approach has proven difficult in local semi-nomadic communities. Additional control measures including health education, domestic livestock animal treatment/vaccination and dog vaccination are needed in CE-endemic areas to accelerate progress.

Survey of hydatidosis infection in slaughtered camel (Camelus dromedarius) in Tabriz area, Northwest Iran

Hydatid Disease is the name given to the condition caused by the zoonotic tapeworm Echinococcus granulosus. The tapeworm spends most of its adult life in the intestine of its definitive host, namely canids and in particular the dog. The tapeworm eggs become voided in the canids' faeces and as a result of ingesting the eggs, infection passes to the intermediate host, commonly herbivores while grazing. However, humans can become accidentally infected and hydatid cysts may develop throughout the body. During April 2010-February 2014, a total 198 camels, which had been sent to the abattoir, the daily number of hydatid infected livers and lungs of camels slaughtered at Tabriz abattoir were recorded. To be sure about the validity of recorded data, observed data were collected daily. Approximately 29 (14.64 %) of camels were infected according to this survey. Age wise, the prevalence of infection in young animals (under the age of 5 years) was 4 (2.02 %), whereas in animals between 5 and 10 years and over, the prevalence of infection was 11 (5.55 %) and 14 (7.07 %) respectively. Sex wise, female animals had a higher prevalence with 17 (19.76 %) cases in camels, whereas in the males, there were 12 (10.71 %) cases in camels. There was a notable difference found in our study between male and female animals (P < 0.05). Infections were recorded in two visceral organs with the Lungs having the highest prevalence in camels, and the liver had low infected in camels. The results of this study suggest that infection of camels with hydatid cyst is common in Tabriz, Iran and that this may constitute economic and health problems in the meat industry.

The effect of preoperative albendazole treatment on the cuticular membranes of pulmonary hydatid cysts: should it be administered preoperatively?

The aim of this study

The aim of this study was to investigate the effects of preoperative albendazole treatment on the tensile strength of the cuticular membranes of pulmonary hydatid cysts.

Material and methods

A study including 44 patients operated on for pulmonary hydatid cysts was carried out between January 2009 and November 2010. The patients were divided into two groups according to their preoperative albendazole administration. Seventeen patients (with 20 cysts) in group A were operated on after three cycles of peroral 10 mg/kg/day albendazole treatment, whereas 27 patients (with 29 cysts) in group B underwent the operation without any preoperative administration of albendazole. Fresh tissue tensile stress tests were carried out on the cuticular membranes excised from both groups.

Results

The results of this study demonstrated that the tensile strength values of the cuticular membrane of the cysts excised from group A were lower than those obtained from group B, with a statistically significant difference.

Conclusions

Albendazole treatment decreases the tensile strength of the cuticular membranes of pulmonary hydatid cysts, which may lead to their perforation. The patients should be operated on as soon as possible and without any preoperative medical treatment in order to prevent complications before the definitive surgical operation.

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.

A review on diagnostic and preventive aspects of cystic echinococcosis and human cysticercosis

Cystic echinococcosis and human cysticercosis have recently been included in the list of "neglected tropical diseases" by the World Health Organization (WHO). Both are zoonoses which are prevalent throughout the world and lead to considerable mortality, morbidity, and economic losses as well. This review deals with the disease burden of these two neglected cestode infections. Diagnostic modalities with their specific advantages and disadvantages have also been discussed. Recent developments in immunodiagnostic assays for the two diseases have been dealt with. Various control strategies including the use of veterinary vaccines have been highlighted.

Worldwide epidemiology of liver hydatidosis including the Mediterranean area

The worldwide incidence and prevalence of cystic echinococcosis have fallen dramatically over the past several decades. Nonetheless, infection with Echinococcus granulosus (E. granulosus) remains a major public health issue in several countries and regions, even in places where it was previously at low levels, as a result of a reduction of control programmes due to economic problems and lack of resources. Geographic distribution differs by country and region depending on the presence in that country of large numbers of nomadic or semi-nomadic sheep and goat flocks that represent the intermediate host of the parasite, and their close contact with the final host, the dog, which mostly provides the transmission of infection to humans. The greatest prevalence of cystic echinococcosis in human and animal hosts is found in countries of the temperate zones, including several parts of Eurasia (the Mediterranean regions, southern and central parts of Russia, central Asia, China), Australia, some parts of America (especially South America) and north and east Africa. Echinococcosis is currently considered an endemic zoonotic disease in the Mediterranean region. The most frequent strain associated with human cystic echinococcosis appears to be the common sheep strain (G1). This strain appears to be widely distributed in all continents. The purpose of this review is to examine the distribution of E. granulosus and the epidemiology of a re-emerging disease such as cystic echinococcosis.

Differential expressions of MHC-DQB1 mRNA in Chinese merino sheep infected with Echinococosus granuclosus

The purpose of the present study was to investigate the dynamic changes of MHC-DQB1 mRNA expression in sheep infected with Echinococosus granuclosus. A total of 14 healthy Chinese merino sheep were experimentally infected with E. granuclosus. The blood samples were collected on days 0 (initiation of the infection), 7, 21, 30, and 60 post-infection, respectively. On day 60 post-infection, when the experiment was terminated, all sheep were euthanized to make a diagnosis of cystic echinococcosis (CE) using routine meat inspection and microscopical examination, respectively. The sheep were then divided into two groups according to the diagnostic results: group A (n = 8) consisted of sheep which were diagnosed as CE infection, while group B (n = 6) comprised sheep diagnosed as self-cured or healthy controls. Blood samples obtained during the period of the study were correspondingly divided into groups A and B. The mRNA expression levels of DQB1 revealed significant alterations detected at different stages of E. granuclosus infection in the two groups. Results showed that in group A, DQB1 mRNA expression underwent a progressive increase from day 0 to day 21 post-infection (P = 0.073), and suddenly, suffered from a dramatic drop until day 30 post-infection, and then jumped rapidly and peaked on day 60 post-infection (P = 0.004). Meanwhile, in group B, DQB1 mRNA expression displayed a sharp increase from day 0 to day 7 post-infection (P = 0.000), which thereafter showed a marked decrease until day 30 post-infection, and experienced a plateau from day 30 to day 60 post-infection, remaining at or above that on day 0. It is concluded that DQB1 mRNA expression levels varied in different stages of E. granuclosus infection in sheep. In addition, it appears that the ability to eliminate the parasites possibly depends, at least in part, on the DQB1 expression in the early stage of infection, especially in the first week post-infection.

Seroepidemiological survey of helminthic parasites of stray dogs in Sari City, northern Iran

The objective of this study was to determine the prevalence rate of helminthic parasites in stray dogs' population especially zoonotic infections and to identify potential risk factors in the different areas of Sari city in Caspian area, north of Iran. During the period from April to September 2007, 50 stray dogs were collected from urban areas of Sari city. Recovered parasites were fixed in alcohol and stained by carmine then observed by microscope. The taxonomic study was carried out by measuring different parts of the body of helminthes and statistical tests were performed using the Chi-square test. A total of 27 adult and 23 juvenile stray dogs were collected and the overall prevalence rate of infection was 90%. The three most common helminthes were Toxocara canis (60%), Ancylostoma caninum (46%) and Dipylidium caninum (36%). Other parasites were Uncinaria stenocephala (12%), Taenia hydatigena (6%), Spirocerca lupi (6%), Dirofilaria immitis (6%), Toxascaris leonina (2%), Rictularia sp. (2%), Taenia ovis (2%) and Taenia taeniformis (2%). Five species of zoonotic helminthes recovered were T. canis, A. caninum, U. stenocephala, D. caninum and D. immitis. Hookworm infections (58%) were more common significantly in the young stray dogs (p < 0.01). In regard to prevalence ofA. caninum, T. canis and U. stenocephala, there was significant difference between juvenile and adult dogs (p < 0.05). The results highlight the potential role of stray dogs for transmission of helminthic parasites particularly zoonotic parasites that are a significant risk to human health.

Widespread co-endemicity of human cystic and alveolar echinococcosis on the eastern Tibetan Plateau, northwest Sichuan/southeast Qinghai, China

Cystic echinococcosis (CE) or hydatid disease is known to be cosmopolitan in its global distribution, while alveolar echinococcosis (AE) is a much rarer though more pathogenic hepatic parasitic disease restricted to the northern hemisphere. Both forms of human echinococcosis are known to occur on the Tibetan Plateau, but the epidemiological characteristics remain poorly understood. In our current study, abdominal ultrasound screening programs for echinococcosis were conducted in 31 Tibetan townships in Ganze and Aba Tibetan Autonomous Prefectures of northwest Sichuan Province during 2001-2008. Hospital records (1992-2006) in a major regional treatment centre for echinococcosis in Sichuan Province were also reviewed. Of 10,186 local residents examined by portable ultrasound scan, 645 (6.3%) were diagnosed with echinococcosis: a prevalence of 3.2% for CE, 3.1% for AE and 0.04% for dual infection (both CE and AE). Human cystic and alveolar echinococcosis in pastoral areas was highly co-endemic, in comparison to much lower prevalences in semi-pastoral or farming regions. The high ultrasound prevalence in these co-endemic areas in northwest Sichuan Province was also reflected in the hospital study, and hospital records furthermore indicated another possible highly co-endemic focus in Guoluo Prefecture of Qinghai Province, located at the border of northwest Sichuan. These chronic cestode zoonoses constitute an unparalleled major public health problem for pastoral Tibetan communities, and pose great difficulties for adequate treatment access and effective transmission control in such remote regions.

Dot immunogold filtration assay (DIGFA) with multiple native antigens for rapid serodiagnosis of human cystic and alveolar echinococcosis

A new 3-min rapid dot immunogold filtration assay (DIGFA) for serodiagnosis of human cystic and alveolar echinococcosis was developed using four native antigen preparations: crude and partially purified hydatid cyst fluid extracts from Echinococcus granulosus (EgCF and AgB), E. granulosus protoscolex extract (EgP) and Echinococcus multilocularis metacestode antigen (Em2). The overall sensitivity of DIGFA in a hospital diagnostic setting was 80.7% for human cystic echinococcosis (CE) (n=857) and 92.9% for human alveolar echinococcosis (AE) (n=42). Highest specificity was 93.4% with AgB extract for CE, and 90.3% with Em2 antigen for AE when CE versus AE cross-reactivity was excluded. Anti-AgB antibodies were present in 35.5% of AE cases and anti-Em2 in 7.4% of CE cases. In endemic communities in northwest China screened for echinococcosis, the sensitivity of DIGFA ranged from 71.8% to 90.7% in comparison to abdominal ultrasound; specificity for CE using AgB was 94.6% and for AE using Em2 was 97.1%. This simple eye-read rapid test can be used for both clinical diagnostic support, as well as in conjunction with ultrasound for mass screening in endemic CE and AE areas.

Echinococcosis in China, a review of the epidemiology of Echinococcus spp

Cystic echinococcosis (CE) and alveolar echinococcosis (AE) are highly significant infectious diseases occurring worldwide and caused by metacestodes of tapeworms Echinococcus granulosus and E. multilocularis, respectively. Both human CE and AE have highest prevalence rates in western and northwestern China. Livestock is the main intermediate host of E. granulosus, and wild small mammal are the main intermediate hosts of E. multilocularis. Since they range freely in pastoral areas, prey on wild small mammals and offal of livestock after slaughter, and have close relationships with humans, domestic dogs are the most important definitive host of both Echinococcus spp. with the highest risk of transmitting CE and AE to humans. Pastoralism is the occupation with the highest risk of being infected with the both kinds of echinococcosis due to the proximity of livestock, dogs, and wildlife host species. In this review, we summarize the epidemiology of human echinococcosis, the situation of parasite transmission in animal hosts, and possible transmission patterns in China. In addition, human activities and their potential influence on the transmission of echinococcosis are also discussed.

MANAGEMENT OF COMPLICATED HYDATID CYST OF THE THORAX

BACKGROUND

Complicated hydatid cyst of the thorax is important to the clinical approaches and treatment methods in hydatid disease. The aim of this study was to evaluate the problems of complicated pulmonary hydatid cyst, including choice of surgical methods, diagnostic clues and to discuss the inherent risks of medical therapy and the delay of surgical treatment in pulmonary hydatid disease.

METHODS

Between 2002 and 2006, 40 operations were carried out in 37 patients whose diagnoses were complicated hydatid cyst. The surgical approach was a posterolateral thoracotomy in all patients; a phrenotomy in two patients and a thoracoabdominal approach in one patient and two-stage bilateral thoracotomy in four patients. The preferred surgical treatment procedure was cystotomy and modified capitonnage, which was carried out in 26 patients (70%). Other procedures included a cystotomy in five (14%) and decortication in six (16%) patients. Segmentectomy was carried out in 1 (3%), and wedge resection in four patients (11%).

RESULTS

In 25 patients (67.5%), there were single hydatid cysts; whereas 12 patients (32.5%) had multiple cysts. Eleven patients had preoperative hydatid cyst history. Iatrogenic rupture of an intact hydatid cyst occurred in three patients. Extrathoracic involvement was apparent in 10 patients (27%). Intrathoracic but extrapulmonary involvement was apparent in six patients (16%). The morbidity ratio was 5%; there was prolonged air leak and atelectasis in one patient each. The mortality ratio was 3% (one patient). The average hospitalization duration for all patients was 5.7 days (range, 3-17 days). The mean follow up was 18.4 months with no recurrence.

CONCLUSION

Complicated hydatid cyst may have different clinical manifestations and may present radiologically as a primary lung tumour. In patients with suspicious lung masses owing to endemic area, history of a hydatid cyst or contralateral or extrathoracic hydatid cyst involvement at the same time should indicate a complicated pulmonary hydatid cyst. Preoperative anthelmintic therapy must be avoided owing to the risk of perforation. Treatment of a complicated hydatid cyst differs from that of an intact hydatid cyst. Anatomic resection may be necessary owing to destroyed lung tissue secondary to suppuration from a hydatid cyst; however, parenchymal preserving surgery is preferable in an uncomplicated hydatid cyst. A modified capitonnage method is recommended for complicated hydatid cyst treatment as it has a low morbidity rate.

A study on intestinal helminthes of dogs, foxes and jackals in the western part of Iran

Human infection especially with helminth parasites is an emerging health issue, as the human environment is increasingly shared with infected animals, either pets or wild life. In this survey, the intestinal content of 83 stray dogs, 22 red foxes and 10 golden Jackals collected from the West Azarbaijan, Kordestan and Kermanshah provinces in the west of Iran, were studied for the presence of helminth parasites. The percentage of different species recovered from these animals is listed as follows: From stray dogs: Toxocara canis (6.02%), Toxascaris leonina (32.53%), Ancylostoma caninum (3.61%), Oxynema sp. (1.35%), Rictularia affinis (12.05%), Taenia hydatigena (53.01%), Taenia ovis (7.23%), Taenia multiceps (4.82%), Echinococcus granulosus (13.25%), Dipylidium caninum (38.55%), Mesocestoides lineatus (26.50%) and Macracanthorhynchus hirudinaceus (4.82%). From red foxes: T. canis (4.54%), T. leonina (31.82%), A. caninum (4.54%), Uncinaria stenocephala (13.64%), Oxynema sp. (9.09%), R. affinis (54.54%), Strongyloides sp. (4.54%), Physaloptera sp. (4.54%), T. hydatigena (9.09%), E. granulosus (4.54%), D. caninum (9.09%), M. lineatus (81.82%), Joyeuxiella pasqalei (27.27%), Diplopylidium nolleri (4.54%), M. hirudinaceus (22.72%) and Macracanthorhynchus sp. (9.09%). From golden jackals: T. canis (10%), T. leonina (30%), R. affinis (50%), T. hydatigena (10%), D. caninum (20%), M. lineatus (70%), J. pasqalei (30%.), Alaria canis (10%), M. hirudinaceus (30%) and Macracanthomynchus sp. (10%).

Genotyping of human cystic echinococcosis in Xinjiang, PR China

The Xinjiang Uygur Autonomous Region, multi-ethnic province in northwestern China, is one of the most important foci of human cystic echinococcosis (CE) in the world. Two Echinococcus granulosus genotypes (G1 and G6) are known to infect the intermediate hosts in this area but, to date, the source of the human infection remains unclear. The current study aimed to genetically analyse 67 hydatid cysts removed from 47 CE patients for which epidemiological, clinical and serological data were also recorded. Mitochondrial cox 1 gene sequencing suggested that the E. granulosus G1 genotype is the major source of infection (45/47 CE patients). Nevertheless, for the first time in China, 2 patients were found with hydatid cysts of the G6 genotype. In addition, 45 E. granulosus gravid tapeworms, isolated from 13 dogs, were genotyped. The majority of adult worms (42/45) exhibited the G1 genotype, whereas 3 adult tapeworms with the G6 genotype were found in one dog, that also harboured E. granulosus tapeworms of the G1 genotype. This sympatric occurrence of G1 and G6 genotypes of E. granulosus, not only in the same area but also in the same definitive host, raises the interesting question of putative genetic recombination between these E. granulosus genotypes.

Parasitic diseases of the respiratory tract

PURPOSE OF REVIEW

The human pulmonary system can be affected by a variety of parasites. This review focuses on the most common parasitic infestations involving the lung, except for protozoon disease.

RECENT FINDINGS

In many parasitic lung conditions, the clinical manifestations and the imaging findings are non-specific and can make diagnosis challenging. Hydatid disease and paragonimiasis involve the lung directly. Chronic schistosomiasis can lead to pulmonary hypertension. Strongyloides stercoralis infestation is capable of transforming into a fulminant fatal disease. In many types of nematode infestations, the pulmonary phase can cause acute eosinophilic pneumonia. Chest radiographs of patients with paragonimiasis and dirofilariasis can cause diagnostic confusion. Cases of tropical pulmonary eosinophilia typically present with refractory bronchial asthma. Most of these diseases are initially diagnosed by detecting eggs or larvae in stool, sputum, pleural fluid or tissue, and are confirmed by serologic testing. Cystic hydatid disease generally requires surgical treatment, whereas almost all other parasitic lung conditions can be treated medically.

SUMMARY

Although most parasites that affect the lung are endemic to tropical and subtropical regions, immigration and travel practices have resulted in transfer of these diseases to other areas. It is important for physicians to know the epidemiologic characteristics, clinical presentations, and treatments of choice for these conditions.

Human cystic echinococcosis in two Mongolian communities in Hobukesar (China) and Bulgan (Mongolia)

In order to investigate the prevalence of human cystic echinococcosis (CE) in traditional Mongolian communities in western Mongolia and Xinjiang (northwest China), studies were carried out between 1995 and 2000, on two ethnically identical populations in Hobukesar (China) and Bulgan (Mongolia). The prevalence of human hepatic CE in the two communities was significantly different. In Hobukesar, human CE prevalence by ultrasound was 2.7% (49/1844), while in Bulgan it was 0.2% (4/1609) (P<0.001). Dog surveys showed that coproantigen-positive rates or dog necropsy positives were similar in both communities (35.0% in Hobukesar and 35.7% in Bulgan). Comparing possible risk factors, there appeared to be some significant differences between the two communities, which might contribute to the observed difference in CE prevalence. These included: the proportion of herdsman or farmers recorded; the proportions of dog ownership and livestock ownership; and the proportion of families practising home slaughter. The presence of a Russian dog-dosing programme up to the mid-1980s may explain the lower prevalence of human CE in the Bulgan population; no similar programme operated in the China-administered Hobukesar community.

Pulmonary parasitosis: applied clinical and therapeutic issues

BACKGROUND

The aim of this study is to review the problems encountered in treating pulmonary hydatid and bilharsiasis and to highlight the risks associated with chemotherapy and the delay of their surgical treatment.

METHODS

The medical records of 60 patients with pulmonary hydatid and bilharsiasis were retrospectively investigated. The patients were divided into two groups based on whether the parasite was hydatid (group 1, n=56) or schistosomiasis (group 2, n=4). The group 1 was divided into group 1a (complicated cyst n=32) and group 1b (n=24 noncomplicated hydatids).

RESULTS

In all cases of pulmonary bilharsiasis and intact pulmonary hydatid cysts, the lesions were either incidental findings or the patient had presented with haemoptysis, cough, dyspnea and chest pain. The differences between the groups with respect to the rates of preoperative complications and postoperative morbidity, frequency of decortication and hospital stay were statistically insignificant (p>0.05).

CONCLUSIONS

Complicated cases have higher rates of preoperative and postoperative complications but the differences are insignificant. Complicated cases are easier to diagnose. This underlines the need for paying more attention to the possibility of pulmonary parasitosis especially in lower lobe lesions in endemic areas.

Complicated hydatid cysts of the lung: clinical and therapeutic issues

BACKGROUND

The clinical presentation and the preoperative and postoperative complications associated with pulmonary hydatid cysts depend on whether the cyst is intact or ruptured. The aim of this study was to review the problems encountered in treating ruptured pulmonary hydatid cysts and to highlight the risks associated with chemotherapy and the delay of surgical treatment in pulmonary hydatid disease.

METHODS

The medical records for 67 patients of pulmonary hydatidosis were retrospectively investigated. The patients were divided into two groups based on whether the pulmonary cyst was intact (group 1, n = 34) or complicated (group 2, n = 33). A complicated cyst was defined as one that had ruptured into a bronchus or into the pleural cavity. All patients were treated surgically. Data related to symptoms, preoperative complications, surgical procedures performed, postoperative morbidity, hospitalization time, and cyst recurrence were collected from each individual's records, and the group findings were compared.

RESULTS

In most cases of intact pulmonary hydatid cysts, the lesions were either incidental findings or the patient had presented with cough, dyspnea and chest pain. In addition to these symptoms, the patients with complicated cyst had presented with problems such as expectoration of cystic contents, repetitive hemoptysis, productive sputum, and fever. The differences between the groups with respect to the rates of preoperative complications and postoperative morbidity, frequency of decortication, and hospital stay were statistically significant (p < 0.05).

CONCLUSIONS

Surgery is the primary mode of treatment for patients with pulmonary hydatid disease. Complicated cases have higher rates of preoperative and postoperative complications and require longer hospitalization time and more extensive surgical procedures than uncomplicated cases. This underlines the need for immediate surgery in any patient who is diagnosed with pulmonary hydatidosis.

Echinococcosis on the Tibetan Plateau: prevalence and risk factors for cystic and alveolar echinococcosis in Tibetan populations in Qinghai Province, China

Infections by larval stages of tapeworms of the genus Echinococcus (echinococcosis or hydatid disease) are zoonotic infections of major public health importance throughout much of the world. Humans become infected through accidental ingestion of eggs passed in faeces of canid definitive hosts. Tibetan populations of China have some of the highest documented levels of infections by both Echinococcus granulosus and E. multilocularis, the causes of cystic and alveolar echinococcosis, respectively. In this study we measured the prevalence of cystic (CE) and alveolar (AE) echinococcosis disease in Tibetan communities in Qinghai, Province, China, and identified putative risk factors for both infections in these communities. 3703 volunteers in three predominately Tibetan counties of Qinghai were surveyed between June 1997 and June 1998. Parasitic lesions were diagnosed by imaging of characteristic space-occupying lesions in abdominal organs (ultrasound) or the lungs (radiographs). Specific serodiagnostic assays (Dot-ELISA and Em2-ELISA) were performed on sera of positively imaged subjects to further distinguish the disease agent. All participants completed a questionnaire documenting age, sex, education level, occupation, lifestyle (nomadic or settled), slaughter practices, drinking water source, hygienic practice and association with dogs. Data were analyzed using SAS version 8. 6·6% of the volunteers had image-confirmed infection with E. granulosus (CE) and 0·8% had E. multilocularis (AE) infection. The significant univariate factors for echinococcal infection (both CE and AE) included livestock ownership, Tibetan ethnicity, female gender, low income, herding occupation, limited education, water source, age greater than 25 years old, poor hygienic practices, offal disposal practices and dog care. Multivariate analysis revealed that livestock ownership was a significant risk factor for both forms of the disease, as well as age greater than 25 years, female gender, herding occupation, and being nomadic (vs semi-nomadic or settled). No additional significant risk factors were identified among the 344 nomadic participants. Being female and being older than 25 years of age were significant factors among the 1906 semi-nomadic participants. Among the 1445 settled participants, allowing dogs to sleep indoors was statistically significant. Issues such as inadequate assessment of animal ownership, selection bias, disease misclassification, and loss of information may have led to reduction in strength of some risk factor associations and need to be addressed in future epidemiologic analysis of echinococcosis in this population.

Biological, epidemiological, and clinical aspects of echinococcosis, a zoonosis of increasing concern

Echinococcosis in humans is a zoonotic infection caused by larval stages (metacestodes) of cestode species of the genus Echinococcus. Cystic echinococcosis (CE) is caused by Echinococcus granulosus, alveolar echinococcosis (AE) is caused by E. multilocularis, and polycystic forms are caused by either E. vogeli or E. oligarthrus. In untreated cases, AE has a high mortality rate. Although control is essentially feasible, CE remains a considerable health problem in many regions of the northern and southern hemispheres. AE is restricted to the northern hemisphere regions of North America and Eurasia. Recent studies have shown that E. multilocularis, the causative agent of AE, is more widely distributed than previously thought. There are also some hints of an increasing significance of polycystic forms of the disease, which are restricted to Central and South America. Various aspects of human echinococcosis are discussed in this review, including data on the infectivity of genetic variants of E. granulosus to humans, the increasing invasion of cities in Europe and Japan by red foxes, the main definitive hosts of E. multilocularis, and the first demonstration of urban cycles of the parasite. Examples of emergence or reemergence of CE are presented, and the question of potential spreading of E. multilocularis is critically assessed. Furthermore, information is presented on new and improved tools for diagnosing the infection in final hosts (dogs, foxes, and cats) by coproantigen or DNA detection and the application of molecular techniques to epidemiological studies. In the clinical field, the available methods for diagnosing human CE and AE are described and the treatment options are summarized. The development of new chemotherapeutic options for all forms of human echinococcosis remains an urgent requirement. A new option for the control of E. granulosus in the intermediate host population (mainly sheep and cattle) is vaccination. Attempts are made to reduce the prevalence of E. multilocualaris in fox populations by regular baiting with an anthelmintic (praziquantel). Recent data have shown that this control option may be used in restricted areas, for example in cities, with the aim of reducing the infection risk for humans.

Control of echinococcosis and cysticercosis: a public health challenge to international cooperation in China

Echinococcosis, both cystic and alveolar, and Taenia solium cysticercosis are the most serious zoonotic cestodoses worldwide. Because of the emerging importance of these diseases in China, several international workshops and meetings were held in this country from 1998 to 2001. Based on round table discussions in Chengdu 2000, the proposal of a strategy to control echinococcosis and cysticercosis has been prepared in China. It includes a comprehensive approach based on a careful analysis of the local situations (particularly concerning the particularities of the cycle, ecology, and ethology of the animal hosts, and behavioral characteristics of the population at risk), the use of newly developed tools both in animals and human (immunology, molecular biology, and imaging), and the association of the traditional control measures (control of slaughtering, antiparasitic treatment and control of the definitive hosts, and health education) with more recent developments such as vaccination of the intermediate hosts. Plans on for the control of echinococcosis and cysticercosis in China are summarized.

Cystic echinococcosis in semi-nomadic pastoral communities in north-west China

In order to determine the prevalence of human cystic echinococcosis (CE) in semi-nomadic traditional pastoralist groups in north-west China, 2 large community studies were undertaken in Altai and Tacheng Prefectures in 1990/91 and 1995/96, respectively. The Kekergash community (Altai) comprised mainly ethnic Kazakhs, whereas the Narenhebuke community (Tacheng) comprised mainly Mongolians. Populations were screened for CE by abdominal ultrasound scan (US) and serological tests. The total prevalence of confirmed human CE was higher in Narenhebuke (2.7%, 49/1844) than in Kekergash (0.9%, 17/1861; P < 0.01). Within each community there was no significant difference of CE prevalence between the Kazakh and Mongolian groups, although Han Chinese exhibited twice the rate of CE (4.9%) in Narenhebuke compared to the dominant Mongolian population. For each community, human CE prevalence increased with age and there was a greater risk associated with the practice of home slaughter of livestock. Dogs were screened for Echinococcus granulosus infection and re-infection levels using a highly specific coproantigen test. The proportion of dogs with positive coproantigen tests was significantly higher in Narenhebuke (36.0%, 50/139) compared to Kekergash (17.8%, 16/90). In Narenhebuke the re-infection levels of dogs, as determined by coproantigen positivity, were higher in the winter quarters (49.4%, 39/79) compared to the summer quarters (18.3%, 11/60; P < 0.01). Furthermore, coproantigen re-test positivity was 25% at 3 months and 29.2% at 7 months. Highest dog coproantigen positivity was obtained over the winter period.

Echinococcosis: an emerging or re-emerging zoonosis?

The aim of this review is a critical discussion of factors actually or potentially contributing to persistence or emergence of echinococcosis in humans. Alveolar echinococcosis (AE), a life-threatening infection of humans, is caused by a larval stage of Echinococcus multilocularis. The adult parasite inhabits the intestine of foxes and other carnivores and has a wide distribution in the northern hemisphere (North America and northern and central Eurasia). Recent surveys in central Europe have extended the known geographical occurrence of E. multilocularis in foxes from four countries at the end of the 1980s to at least 11 countries in 1999. Cases of human AE previously regularly reported from only four countries are now recorded from seven countries, but the annual incidences are low. Since adequate information from earlier surveys is not available, it is not possible to conclude if the new findings reflect a recent extension of the parasite's range or just the first identification of hitherto unnoticed endemic areas. Evidence of parasite spreading has been reported from North America and Japan. Factors with the potential of enhancing the infection risk for humans in the future include increasing fox populations and parasite prevalences, progressing invasion of cities by foxes, the establishment of urban cycles of the parasite, and the spill-over of the E. multilocularis infection from wild carnivores to domestic dogs and cats. In view of the potential severity and fatality of AE in humans health authorities should initiate internationally coordinated countermeasures. Although control programmes against human cystic echinococcosis (CE), caused by E. granulosus, have been established in some countries and effective control strategies are available, the parasite has still a wide geographical distribution affecting many countries of all continents. Thus, human CE is persisting in many parts of the world with high incidences, and in some areas it is a re-emerging problem. For example, alarming increases of the number of human cases have been reported from Bulgaria and Kazakhstan, and the People's Republic of China. Progress in control can only be expected if health authorities attribute a higher priority to this disease and if all modern diagnostic and control options (for example vaccination of intermediate host animals) can be used.