Biomedical subjects

Philip S Craig

Publications and source records attributed to Philip S Craig.

At least 19 recordsLinked to original sources

PubMed2006

Taeniasis/cysticercosis in a Tibetan population in Sichuan Province, China.

The results of a preliminary survey of taeniasis/cysticercosis in Yajiang County, Ganze Tibetan Prefecture in southwest Sichuan Province, China, indicated a very high prevalence of taeniasis (22.5%), with Taenia saginata as the dominant species. There was also a significant occurrence of late-onset epilepsy (8.5% prevalence and 16.4% seropositive for Taenia solium antibodies) attributable in large part to probable neurocysticercosis caused by T. solium. The poor sanitation and hygiene in this Tibetan community likely contributed to a high risk of human cysticercosis despite a low level of T. solium taeniasis (actually no T. solium carriers were detected amongst the 21 proven Taenia carriers). In addition, three taeniasis cases were confirmed by DNA genotyping as Taenia asiatica, which is the first report of this tapeworm in Tibetans, the first report for Sichuan Province and only the third report for mainland China.

Adolescent↗

PubMed2006

Hydatid cysts: does every picture tell a story?

Ultrasound imaging is an effective aid to the detection of abdominal cystic echinococcosis. Recently, the images produced have provided more information than just a diagnosis. Different cyst morphologies have been classified into types, and such classifications can be considered to represent a natural history of cyst development. Understanding how cyst structures alter with time is crucial to evaluating the effectiveness of different treatment regimes and to understanding natural degeneration of cysts that can occur. However, the developmental events seen in ultrasound need to be matched more closely to immunological and cellular events if we are to have a fuller appreciation of disease progression and regression. At a community level, the relative proportions of cyst types could also provide epidemiological information on disease transmission.

Animals↗

PubMed2006

Echinococcus multilocularis: developmental stage-specific expression of Antigen B 8-kDa-subunits.

Antigen B (AgB) initially found in hydatid cyst fluid of Echinococcus granulosus is a polymeric lipoprotein of 160 kDa, and is an aggregate of several different but homologous small proteins with approximately 8 kDa. Four genes encoding these 8-kDa-subunits have been identified from E. granulosus. In this study we isolated five genes encoding 8-kDa-subunits of AgB from Echinococcus multilocularis. Sequence comparison of isolated cDNA clones demonstrated that one of these five clones was completely identical to EmAgB8/1 which had been isolated previously by our group, and three of them were 94.5, 90.8, and 91.9% homologous to E. granulosus antigen B 8-kDa subunit genes, EgAgB8/2, EgAgB8/3, and EgAgB8/4, respectively. The remaining clone shared 51-58% homology with the nucleotide sequences of AgB genes. Gene-specific RT-PCR and Western blot analyses revealed that these genes were expressed in a developmentally regulated manner in E. multilocularis vesicles, protoscoleces, and immature adult worms. Possible functions of different expression manners are also discussed.

Amino Acid Sequence↗

PubMed2006

A hospital-based retrospective survey of human cystic and alveolar echinococcosis in Ningxia Hui Autonomous Region, PR China.

A retrospective study of in-patient records for the period 1985-2001 collected from 11 hospitals in Ningxia Hui Autonomous Region (NHAR), China revealed a total of 2216 cases of echinococcosis. The survey showed that cystic echinococcosis (CE) occurs throughout NHAR but that human alveolar echinococcosis (AE) cases were only located in a confluence area of three counties, Xiji, Haiyuan and Guyuan. Incidence rates between counties within southern NHAR showed a highly heterogeneous distribution of cases, suggestive of different echinococcal transmission patterns. There was a significant difference in incidence between males and females, and farm labourers accounted for the majority of cases. Radical surgery with or without albendazole/mebendazole drug treatment was the major method of treatment for CE and repeat surgery was common; drug treatment alone was used mainly for AE. Epigastric pain was the main reason for patients seeking medical advice, the liver was the primary location of echinococcosis lesions and the majority of echinococcosis cases were diagnosed by ultrasound. Over a 12 year period, the average bed utilization rate in the Second Provincial Hospital of NHAR for patients with echinococcosis was 78% and echinococcosis cases accounted, on average, for 0.7% among the total hospital in-patients. Taking inflation into account, charges for echinococcosis hospitalization and treatment increased three-fold over the period 1994-2002. This study indicates that echinococcosisis is a significant public health problem in NHAR, especially in the south. The data from the hospital retrospective study are clearly underestimates and community surveys are required to determine the true echinococcosis prevalence levels, especially in the more remote areas of NHAR.

China↗

PubMed2006

Post-survey follow-up for human cystic echinococcosis in northwest China.

In Hobukesar, Xinjiang Uygur Autonomous Region, (China), a mass-screening programme for human cystic echinococcosis (CE)was performed during 1995 and 1996. After the survey 51 cases were followed-up using ultrasound scan and serology for 1-8 years(1996-2003). These included 20 CE cases treated by surgery (endocystectomy), four CE cases treated by percutaneous drainage(PAIR), six untreated CE cases, five ultrasound 'query' cases, eight cases of isolated hepatic calcifications, four previous CE surgery cases whose ultrasound was now normal, and four seropositive cases who exhibited a normal hepatic ultrasound. Follow-up results indicated that in the untreated CE patients, one case exhibited a spontaneous cure within 4 years, another case changed from a hepatic hydatid cyst that contained a floating laminated membrane (type CE3) to a cyst that contained daughter cysts (type CE2)within 1 year of follow-up. In the 20 surgically treated cases, two recurrent CE cases occurred within 4 years, and five cases had had residual cavities for more than 4 or 8 years. Of the 4 PAIR treated cases, two recurrent cases of CE occurred within 4 or 8 years of follow-up. Serological follow-up data showed that specific IgG antibody levels were persistently positive in most CE cases, but exhibited a decreasing tendency in cases that were effectively treated by surgery; In contrast, serum IgG levels in the PAIR group or in the recurrent CE cases after surgery exhibited an increasing tendency. At least one persistent seropositive case with an isolated hepatic calcification was considered to be abortive CE.

Albendazole↗

PubMed2006

Community surveys and risk factor analysis of human alveolar and cystic echinococcosis in Ningxia Hui Autonomous Region, China.

OBJECTIVE: To determine the true community prevalence of human cystic (CE) and alveolar (AE) echinococcosis (hydatid disease) in a highly endemic region in Ningxia Hui, China, by detecting asymptomatic cases. METHODS: Using hospital records and "AE-risk" landscape patterns we selected study communities predicted to be at risk of human echinococcosis in Guyuan, Longde and Xiji counties. We conducted community surveys of 4773 individuals from 26 villages in 2002 and 2003 using questionnaire analysis, ultrasound examination and serology. FINDINGS: Ultrasound and serology showed a range of prevalences for AE (0-8.1%; mean 2%) and CE (0-7.4%; mean 1.6%), with the highest prevalence in Xiji (2% for CE, 2.5% for AE). There were significant differences in the prevalence of CE, AE and total echinococcosis between the three counties and villages (with multiple degrees of freedom). While hospital records showed 96% of echinococcosis cases attributable to CE, our survey showed a higher prevalence of human AE (56%) compared to CE (44%). Questionnaire analysis revealed that key risk factors for infection were age and dog ownership for both CE and AE, and Hui ethnicity and being female for AE. Drinking well-water decreased the risk for both AE and CE. CONCLUSION: Echinococcosis continues to be a severe public health problem in this part of China because of unhygienic practices/habits and poor knowledge among the communities regarding this disease.

Adolescent↗

PubMed2006

Pasture types and Echinococcus multilocularis, Tibetan communities.

Our study showed that open pastures had more small mammal burrows than fenced pastures in Tibetan pastoralist communities in 2003. This characteristic was linked to a higher prevalence of Echinococcus multilocularis in dogs and indicates that pasture type may affect E. multilocularis transmission.

Animals↗

PubMed2006

Unique family clustering of human echinococcosis cases in a chinese community.

We have identified a significant focus and unusual clustering of human cases of cystic echinococcosis (CE) and alveolar echinococcosis (AE) in the village of Nanwan, Xiji County, Ningxia Hui Autonomous Region, in one of the most highly endemic areas for both diseases in China. The village, a Chinese Hui Islamic community, is composed of 167 members of four extended families. A total of 28 people died (12 of echinococcosis) since the village was first settled in the 1950s. Despite similar life patterns, the number of AE and CE cases occurring in each family was different. Overall, the prevalences of AE and CE were 9% (20 cases) and 5.9% (13 cases), with a combined prevalence of 14.9%. In contrast to CE, a comparison of the prevalence of AE indicated significant differences between the four family clusters. Although suggestive that host genotype might play a role in susceptibility to AE, this hypothesis requires further investigation.

Adolescent↗

PubMed2006

Socioeconomic and behavior risk factors of human alveolar echinococcosis in Tibetan communities in Sichuan, People's Republic of China.

Data from two cross-sectional investigations on 7,138 subjects were used to explore risk factors of human alveolar echinococcosis (AE) in Tibetan communities. The overall human AE prevalence was 3.1% (223 of 7,138), females had a higher prevalence (3.6%, 132 of 3,713) than males (2.7%, 91 of 3,425; P = 0.011), and herdsmen had a higher prevalence (5.2%, 154 of 2,955) than farmers (1.8%, 12 of 661; P < 0.001) and urban populations (2.1%, 49 of 2,360; P < 0.001). Age in all populations, number of dogs kept, fox skin ownership in farmers, not preventing flies from landing on food in herdsmen, using open streams as drinking water sources, and playing with dogs in urban populations were statistically significant risk factors. The results suggest that AE is highly endemic in the eastern Tibetan plateau, in Sichuan Province, the role of the dog is important for human infection, and other factors associated with environmental contamination may vary according to structure and practices of communities.

Adolescent↗

PubMed2006

Dual infection of animal hosts with different Echinococcus species in the eastern Qinghai-Tibet plateau region of China.

The eastern Qinghai-Tibet plateau of China is a highly endemic region of echinococcosis where Echinococcus granulosus sensu stricto (sheep strain), Echinococcus multilocularis, and Echinococcus shiquicus are distributed sympatrically. We developed a polymerase chain reaction-based restriction fragment length polymorphism (PCR-RFLP) method for the identification of the three species in this region. The PCR-RFLP showed the dual infection of animals with different Echinococcus spp. The first case was a domestic dog concurrently infected with adults of E. granulosus and E. multilocularis. The second case was a plateau pika (Ochotona curzoniae) harboring metacestodes of E. multilocularis and E. shiquicus in the liver. The high susceptibility of some mammalian hosts to the parasites and the high prevalence of the three co-endemic species probably increase the chance of mixed infections in the eastern Tibetan plateau.

Animals↗

PubMed2005

Taeniasis/cysticercosis in Papua (Irian Jaya), Indonesia.

Reports showed that an important parasitic zoonotic disease caused by Taenia solium, Taenia saginata and Taenia asiatica is found endemic in several areas of Indonesia including Papua, Bali and North Sumatra. At present it is known that the highest prevalence of taeniasis/cysticercosis in Indonesia, caused by T. solium is among the indigenous communities in Papua (formerly Irian Jaya). In the early 1970s, 8-9% of stool samples from the Enarotali hospital, Paniai District (Irian Jaya) were found positive with Taenia eggs. The samples were from members of the Ekari (Kapauku) ethnic group. Stool samples from the Moni ethnic group, living east of surrounding lakes, were egg negative. Cysticerci of T. solium were discovered in pigs. During the years 1973-1976 cases of burns increased and were ultimately found to be primarily associated with epileptic seizures induced by neurocysticercosis cases. Among 257 cases of burns, 88 cases (62.8%) were suffering from epileptic seizures before or during hospitalization. In the year 1981 T. solium seropositive persons were mostly (16%) found in the endemic Obano village. In 1997 the parasite was discovered in Jayawijaya District, which is located approximately 250 km east of Paniai District. During 1991-1995, a local health center in Assologaima, Jayawijaya District reported 1120 new cases with burns and a further 293 new cases of epileptic seizures among 15,939 inhabitants. The histopathologic appearance and mitochondrial DNA analysis found the cysts to be similar to those of T. solium from other regions of the world. Sensitive and specific serological diagnostic methods were used and improved. Cysticerci were detected in dogs, as well as in pigs. A coproantigen test for detection of adult tapeworms in patients was carried out. Medical treatment with praziquantel for taeniasis and albendazole for cysticercosis (with prednisone and sodium phenytoin treatment in cases with neurocysticercosis) was undertaken. Lifestyle, religion, and socioeconomic aspects are important issues in the perpetuation and enhancing the endemicity of T. solium taeniasis and cysticercosis in Papua, Indonesia.

Animals↗

PubMed2005

Taeniasis and cysticercosis in Bali and North Sumatra, Indonesia.

It has been reported that three human Taenia species are distributed in Indonesia: Taenia solium, Taenia asiatica and Taenia saginata. T. asiatica is well known in North Sumatra, especially on Samosir island in Lake Toba. T. solium and T. saginata are known from Bali. T. solium is most serious public health issue in Papua (former Irian Jaya). In this report, we briefly review the present situation of these three human Taenia species mainly in Bali and North Sumatra. For community based epidemiological survey, we have adopted and applied questionnaire, microscopic observation of eggs, coproantigen tests, coproDNA tests, mitochondrial DNA analysis and morphology for isolated specimens, serology for cysticercosis and taeniasis. For detection of taeniasis cases of both T. saginata and T. asiatica, questionnaire by expert doctors is perfect to detect worm carriers. Corpoantigen test developed for detection of taeniasis of T. solium is also highly reliable to detect taeniasis carriers in the community. Epidemiological data from these two islands 2002-2005 are reviewed with backgrounds of historical culture, religions and customs.

Animals↗

PubMed2005

Spatial modelling and ecology of Echinococcus multilocularis transmission in China.

Recent research in central China has suggested that the most likely transmission mechanism for Echinococcus multilocularis to humans is via domestic dogs which are allowed to roam freely and hunt (infected) small mammals within areas close to villages or in areas of tented pasture. This assertion has led to the hypothesis that there is a landscape control on transmission risk since the proximity of suitable habitat for susceptible small mammals appears to be the key. We have tested this hypothesis in a number of endemic areas in China, notably south Gansu Province and the Tibetan region of western Sichuan Province. The fundamental landscape control is its effect at a regional scale on small mammal species assemblages (susceptible species are not ubiquitous) and, at a local scale, the spatial distributions of small mammal populations. To date the research has examined relationships between landscape composition and patterns of human infection, landscape and small mammal distributions and recently the relationships between landscape and dog infection rates. The key tool to characterize landscape is satellite remote sensing and these data are used as inputs to drive spatial models of transmission risk. This paper reviews the progress that has been made so far in spatial modeling of the ecology of E. multilocularis with particular reference to China, outlines current research issues, and describes a framework for building a spatial-temporal model of transmission ecology.

Animals↗

PubMed2005

Transmission ecology of Echinococcus multilocularis: what are the ranges of parasite stability among various host communities in China?

A striking feature of the transmission ecology of Echinococcus multilocularis in China is the diversity of hosts that contribute to the parasite cycle. Considering the population dynamics of key reservoir intermediate hosts and the ratio of their preferred habitat in a landscape (ROMPA) is essential to understanding transmission, but the numerous communities in which the parasite cycles and the extent of those communities is currently far from being fully documented. On the Tibetan plateau grassland management influences intermediate host species populations and the sheer size of the area could be a major contributing factor to sustaining transmission in the region. In Southern Gansu and Southern Ningxia the processes of deforestation have temporarily provided optimal habitat for key reservoir intermediate hosts of E. multilocularis, resulting in high transmission and human disease, however currently the parasite may be extinct locally. Faced with this pattern of potentially transient transmission in a diversity of communities the question of the dispersal potential of the parasite arises. The reforestation program currently active across much of Western China has the potential to give rise to a massive increase in habitat favourable to suitable intermediate hosts and emergence or re-emergence of the zoonosis alveolar echinococcosis in many areas. This potential epidemic could be mitigated by both natural and human induced parasite dispersal mechanisms including fox migration and the sale of infected dogs originating from stable endemic foci on the Tibetan plateau. However, currently the degree of genetic exchange between discrete transmission foci is unknown and it is expected that genetic techniques could provide crucial information regarding this important question.

Animals↗

PubMed2005

Genetic variation in Taenia solium.

Neurocysticercosis is a major zoonotic larval cestode infection that has a worldwide distribution and is of significant public health importance. Knowledge of the genetic structure of Taenia solium can be applied to the epidemiology and transmission of this disease, since genetic variants may differ in infectivity and pathogenicity. Molecular epidemiological approaches can also enable detailed studies of transmission. On a global scale, mitochondrial markers have differentiated between T. solium isolates from Asia and isolates from Africa/Latin America. Intraspecific variation in T. solium has been detected to some extent, using RAPD markers to differentiate between T. solium populations from different regions within Mexico. Markers currently available for T. solium have not been used to analyse genetic variation at the community or local level. The development of highly polymorphic markers such as microsatellites in T. solium can provide the means to examine genetic heterogeneity of tapeworm infection at the household, community and regional level. Preliminary studies suggest it is possible to analyse population genetic variation in communities using a range of polymorphic markers.

Animals↗

PubMed2005

Usefulness of severe combined immunodeficiency (scid) and inbred mice for studies of cysticercosis and echinococcosis.

The topics in this review are the usefulness of immunodeficient and inbred mice for studies of developmental biology, drug efficacy and host specificity in cysticercosis and echinococcosis. In non-obese diabetic severe combined immunodeficiency (NOD/Shi-scid) mice of both sexes, in vitro hatched oncospheres of all three human taeniid species (Taenia solium, Taenia saginata and Taenia asiatica) developed into cysticerci comparable to or bigger than those developed in their known intermediate host animals, whereas only females were susceptible to these infections in other scid mice of BALB/c, C57BL or C.B-17 inbred strains. Detailed morphological observation from post-oncospheral to cysticercus developmental stages is expected to be easy when we use NOD/Shi-scid mice experimentally inoculated with in vitro hatched oncospheres. Metacestocidal effect of oxfendazole was evaluated in NOD/Shi-scid mice experimentally inoculated with oncospheres of T. solium. In Echinococcus multilocularis infection, larval tissue proliferated without induction of inflammatory host responses in scid mice, thus facilitating isolation of the larval vesicles and protoscoleces for biochemical and molecular biological studies. Trans portal inoculation of metacestode tissues resulted in proliferation of secondary echinococcal foci localized exclusively in the liver without metastasis to other tissues or organs. The advantages of a mouse model for Echinococcus granulosus are also described.

Animals↗

PubMed2005

Epidemiology of human alveolar echinococcosis in China.

Globally human alveolar echinococcosis (AE) is a rare zoonotic helminthic disease confined to the Northern Hemisphere as sporadic infections in rural populations, principally in some areas of North America, west-central Europe, the Near East, Siberia, Central Asia, Japan and China. In China the first human cases were reported from western regions in the 1960s, but most hospital records remain fragmented and inadequate. From the mid-1990s mass screening surveys using portable ultrasound scanners recorded higher prevalences (up to 6% by county) than in any other areas of the world with some village rates as high as 15%. Risk factors identified for AE cases included ethnicity, sex, age and occupation. The role of the dog in transmission of Echinococcus multilocularis to humans now appears to be significant and may be one of the most important risk factor, in combination with landscape/land-use features conducive to maintaining wildlife host populations.

Animals↗

PubMed2005

Coproantigens in taeniasis and echinococcosis.

The application of modern immunodiagnostic or molecular diagnostic techniques has improved the diagnosis of the taeniid cestode infections, echinococcosis and taeniasis. One particularly promising approach is the detection of parasite-specific antigens in faeces (coproantigens). This approach has been applied to both Echinoccocus and Taenia species and it has gained increasingly widespread use. Taeniid coproantigen tests are based on either monoclonal or polyclonal antibodies raised against adult tapeworm antigens. These tests have the following common characteristics; they are largely genus-specific, specificity is high (>95%), parasite antigen can be detected in faeces weeks prior to patency, levels of coproantigen are independent of egg output, coproantigen is stable for days at a range of temperatures (-80 degrees C to 35 degrees C), for several months in formalin-fixed faecal samples, and coproantigen levels drop rapidly (1-5 days) following successful treatment. In the genus Taenia, most work has been done on Taenia solium and coproantigen tests have reliably detected many more tapeworm carriers than microscopy. For Echinococcus species, there is a broad positive correlation between test sensitivity and worm burden with a reliable threshold level for the test of >50 worms. Characterisation of taeniid coproantigens in order to further improve the tests is ongoing. Studies indicate taeniid coproantigens to include high molecular weight (>150 kDa), heavily glycosylated molecules with carbohydrate moieties contributing substantially to the levels of antigen detected in faeces. Application of the existing coproantigen tests in epidemiological and control programmes for Echinococcus and Taenia species infection has begun to contribute to an improved understanding of transmission and of surveillance of these important zoonotic cestodes.

Animals↗