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Philip S Craig

Publications and source records attributed to Philip S Craig.

At least 37 records · Page 2Linked to original sources
PubMed2005

Echinococcus shiquicus, a new species from the Qinghai-Tibet plateau region of China: discovery and epidemiological implications.

In Shiqu County of the Qinghai-Tibet plateau, many wild and domestic mammals are involved in the transmission cycles of Echinococcus spp. Echinococcus multilocularis and Echinococcus granulosus genotype G1 (sheep strain) are sympatrically distributed in the plateau. In 1995, we identified a unique strobilate stage of Echinococcus from the Tibetan fox, Vulpes ferrilata, but considered it to be a variant of E. multilocularis. Subsequent molecular genetic studies revealed that a hydatid cyst from the plateau pika, Ochotona curzoniae, had unique mitochondrial DNA sequences which are dissimilar to any published sequences of Echinococcus. The same sequences were subsequently found in adult worms from Tibetan foxes. Morphological, genetic and ecological features of the cestode led us to designate a new species Echinococcus shiquicus. E. shiquicus has been found at other areas surveyed on the plateau; however, no infections in humans caused by E. shiquicus have been yet identified.

Animals↗
PubMed2005

Simultaneous alveolar and cystic echinococcosis of the liver.

Alveolar echinococcosis (AE) and cystic echinococcosis (CE), caused by infection with the larval stages of Echinococcus multilocularis and E. granulosus, respectively, are of major clinical importance. Reports of infection with AE or CE are very common, but instances of simultaneous or dual infection are rare. We report on four cases with mixed AE/CE infections in the liver, diagnosed using retrospective surgical records and active community surveys in southern Ningxia Hui Autonomous Region (NHAR), PR China, a recognized hyperendemic area for echinococcosis.

Adolescent↗
PubMed2005

Canine echinococcosis in northwest Libya: assessment of coproantigen ELISA, and a survey of infection with analysis of risk-factors.

In order to determine the prevalence and risk factors for canine echinococcosis in different endemic localities in the Tripoli area of northwest Libya, stray dogs were examined post-mortem, and owned dogs screened for Echinococcus granulosus infection using a standardised genus specific coproantigen ELISA. The prevalence of E. granulosus infection at necropsy in stray-dogs was 25.8% (15/58, 95% CI 15.3-39.0%), and 21.6% (72/334, 95% CI 17.3-26.4%) of owned dogs tested were positive by coproantigen ELISA. Sheepdogs appeared to have a significantly higher copro-positive prevalence (19/19 positive, p=0.003), compared to 23.6% of other dog classes (e.g. 52/220 guard dogs and household pets). Worm burdens in necropsied dogs ranged from 29 to 2900 (mean 1064) and were positively correlated to coproantigen ELISA OD values (r(s)=0.87, p<0.001), but negatively correlated with dog age (r(s)=-0.69, p=0.001). Dog age was a significant factor in copro-prevalence as there was an increasing coproantigen-positive tendency in younger dogs (< or =5 years, p=0.04). A total of 45/132 (34%, 95% CI 25.9-42.1%) of farms/homestead had at least one dog that was coproantigen positive. Overall copro-prevalence in dogs by locality varied, with Alkhums (Leptis-Magna) district having the highest copro-prevalence at 38.7% (24/62, 95% CI 26.6-50.8%) (p=0.001). Coproantigen testing of a cohort of owned dogs before and approximately 15 months after praziquantel treatment showed a significant decrease in the coproantigen positive rate from 21.6% (72/334) to 9% (21/233) post-treatment. The overall E. granulosus coproantigen positive rate ('re-infection rate') within the same cohort of dogs was 22 % (10/45) by 15 months post-treatment. Significant risk factors for a copro-positive owned dog were associated with non-restraint of dogs, and owners that did not de-worm their dogs. Home slaughtering of livestock and lack of knowledge about E. granulosus transmission were also significant risk factors for a canine coproantigen positive result.

Age Factors↗
PubMed2005

Echinococcus shiquicus n. sp., a taeniid cestode from Tibetan fox and plateau pika in China.

The taeniid cestode Echinococcus shiquicus n. sp. was found from the Tibetan fox Vulpes ferrilata and the plateau pika Ochotona curzoniae in the Qinghai-Tibet plateau region of China. In the adult stage, E. shiquicus from the foxes is morphologically similar to Echinococcus multilocularis. However, the new species is differentiated by its smaller rostellar hooks, fewer segments, distinct position of genital pore in the mature segment and fewer eggs in the gravid segment. Hydatid cysts of E. shiquicus found in the livers from the pikas were essentially unilocular but an oligovesicular cyst was also found. The data of mitochondrial and nuclear DNA sequences proved E. shiquicus to be a valid taxon.

Amino Acid Sequence↗
PubMed2005

Modeling the transmission of Echinococcus granulosus and Echinococcus multilocularis in dogs for a high endemic region of the Tibetan plateau.

Echinococcus granulosus and Echinococcus multilocularis abundance and prevalence data, for domestic dogs of Shiqu County, Sichuan Province, People's Republic of China, were fitted to mathematical models to evaluate transmission parameters. Abundance models, assuming the presence and absence of immunity, were fit for both E. granulosus and E. multilocularis using Bayesian priors, maximum likelihood, and Monte Carlo sampling techniques. When the models were compared, using the likelihood ratio test for nested models, the model assuming the presence of immunity was the best fit for E. granulosus infection, with a purgation based prevalence of 8% (true prevalence interval of 8-19% based on the sensitivity of purgation) and a mean abundance of 80 parasites per dog, with an average infection pressure of 560 parasites per year. In contrast, the model assuming the absence of immunity was the best fit for E. multilocularis infection, with a purgation based prevalence of 12% (true prevalence interval of 13-33% based on the sensitivity of purgation) and a mean abundance of 131 parasites per dog, with an average infection pressure of 334 or 533 parasites per year assuming a 5 or 3 month parasite life expectancy, respectively. The prevalence data for both parasites was then fit to a set of differential equations modeling the transition between infection states in order to determine number of infectious insults per year. Infection pressure was 0.21, with a 95% credibility interval of 0.12 to 0.41, infections per year for E. granulosus and 0.52, with a 95% credibility interval of 0.29-0.77, infections per year for E. multilocularis assuming a 5 month parasite lifespan or 0.85, with a 95% credibility interval of 0.47-1.25 infections per year, assuming a 3 month E. multilocularis lifespan in dogs.

Animals↗
PubMed2005

Echinococcosis in Tibetan populations, western Sichuan Province, China.

We screened 3,199 people from Shiqu County, Sichuan Province, China, for abdominal echinococcosis (hydatid disease) by portable ultrasound combined with specific serodiagnostic tests. Both cystic echinococcosis (CE) (Echinococcus granulosus infection) and alveolar echinococcosis (AE) (E. multilocularis) were co-endemic in this area at the highest village prevalence values recorded anywhere in the world: 12.9% were infected with one or the other form (6.8% CE and 6.2% AE). Prevalences of both CE and AE were significantly higher in female than male patients and increased with the age of the person screened. Pastoral herdsmen were at highest risk for infection (prevalence 19.0%). Prevalence of CE varied in 5 townships from 0% to 12.1%, whereas AE prevalence ranged from 0% to 14.3%. Risk factors associated with both infections included the number of owned dogs, frequency of contact with dogs, and sources of drinking water.

Adolescent↗
PubMed2004

The Tibetan hare Lepus oiostolus: a novel intermediate host for Echinococcus multilocularis.

Multicystic hydatids have been found in the livers of hares ( Lepus oiostolus) examined from the Qinghai-Tibet plateau of China. In this study, the causative species was definitively identified as Echinococcus multilocularis by mitochondrial DNA sequencing. This is the first confirmation of larval E. multilocularis from hares. The hydatids contained protoscolices, suggesting that the hare may contribute to the transmission of E. multilocularis on the Tibetan plateau.

Animals↗
PubMed2004

Fenced pasture: a possible risk factor for human alveolar echinococcosis in Tibetan pastoralist communities of Sichuan, China.

Alveolar echinococcosis, infection caused by the parasitic helminth Echinococcus multilocularis, is a zoonosis strongly linked to climatic and ecological factors. Cross-sectional survey data were used to test a hypothesis that partial fencing of pastures could promote alveolar echinococcosis transmission in semi-nomadic pastoral communities of the Tibetan plateau, PR China. Using multiple stepwise logistic regression with consideration of factors of age and gender, it was shown that partial fencing around the settlements in winter pasture was significantly and independently associated with the risk of human alveolar echinococcosis in the surveyed villages (P = 0.021). The underlying reason may lie in overgrazing, an assumed cause of population outbreaks of small mammal intermediate hosts of the parasite on the Tibetan plateau. Overgrazing may have been exacerbated by the reduction of communal pastures nearby the settlements due to introduction of partial fencing around group tenure pastures acquired by Tibetan pastoralist families.

Adolescent↗
PubMed2004

DNA differential diagnosis of taeniasis and cysticercosis by multiplex PCR.

Multiplex PCR was established for differential diagnosis of taeniasis and cysticercosis, including their causative agents. For identification of the parasites, multiplex PCR with cytochrome c oxidase subunit 1 gene yielded evident differential products unique for Taenia saginata and Taenia asiatica and for American/African and Asian genotypes of Taenia solium with molecular sizes of 827, 269, 720, and 984 bp, respectively. In the PCR-based detection of tapeworm carriers using fecal samples, the diagnostic markers were detected from 7 of 14 and 4 of 9 T. solium carriers from Guatemala and Indonesia, respectively. Test sensitivity may have been reduced by the length of time (up to 12 years) that samples were stored and/or small sample volumes (ca. 30 to 50 mg). However, the diagnostic markers were detected by nested PCR in five worm carriers from Guatemalan cases that were found to be negative by multiplex PCR. It was noteworthy that a 720 bp-diagnostic marker was detected from a T. solium carrier who was egg-free, implying that it is possible to detect worm carriers and treat before mature gravid proglottids are discharged. In contrast to T. solium carriers, 827-bp markers were detected by multiplex PCR in all T. saginata carriers. The application of the multiplex PCR would be useful not only for surveillance of taeniasis and cysticercosis control but also for the molecular epidemiological survey of these cestode infections.

Animals↗
PubMed2004

Molecular cloning, expression, and serological evaluation of an 8-kilodalton subunit of antigen B from Echinococcus multilocularis.

Full-length cDNA and genomic DNA encoding an 8-kDa subunit of antigen B from Echinococcus multilocularis (designated EmAgB8/1) were isolated from an E. multilocularis metacestode cDNA library and a protoscolex genomic DNA library, respectively. The open reading frame of the cDNA clone encodes a polypeptide comprising 85 amino acids with a 20-amino-acid NH(2)-terminal signal sequence, which was confirmed following N-terminal sequencing of the native antigen. Reverse transcription-PCR analysis revealed that the clone encoding EmAgB8/1 is predominantly transcribed in larval E. multilocularis. The gene consists of two exons (encoding the signal sequence and mature protein) separated by a 91-bp intron. The mature form was expressed in Escherichia coli, and its antigenic reactivity was compared with that of a counterpart, an 8-kDa subunit of antigen B from Echinococcus granulosus (EgAgB8/1) by Western blotting and enzyme-linked immunosorbent assay (ELISA) with serum samples from patients confirmed to have cystic echinococcosis (CE) and alveolar echinococcosis (AE). Recombinant EmAgB8/1 showed positive reactions in Western blots with 81.3% (65 of 80) of serum samples from CE patients and 40.6% (26 of 64) of serum samples from AE patients, while recombinant EgAgB8/1 showed positive reactions with 86% (43 of 50) and 42% (19 of 45) of the serum samples from these CE and AE patients, respectively. By the ELISA, both EmAgB8/1 and EgAgB8/1 exhibited similar positive reactions with 88% (44 of 50) of serum samples from CE patients and 37.8% (17 of 45) serum samples from AE patients. Statistical analysis revealed that the sensitivity of EmAgB8/1 was comparable to that of EgAgB8/1 for the serodiagnosis of echinococcal diseases. There was no cross-reaction with sera from patients with cysticercosis, which often cross-react when native antigens are used for serodiagnosis.

Amino Acid Sequence↗
PubMed2004

Human cystic echinococcosis: evaluation of post-treatment serologic follow-up by IgG subclass antibody detection.

Assessment of post-treatment disease activity among patients with cystic echinococcosis (CE) is insensitive using detection of CE-specific total IgG antibody. This study investigated whether serum concentrations of CE-specific IgG subclasses 1-4 correlate better with disease activity than total IgG. We studied a cohort of patients (n = 28) with symptomatic CE treated with anthelminthic drugs and surgery and who were followed up clinically and radiologically for a mean of 5.6 years (range = 3-12 years). Serial archived sera collected during follow-up were retrospectively analyzed by enzyme-linked immunosorbent assays using crude horse hydatid cyst fluid as antigen. Changes in concentrations of antibodies were correlated with clinical and radiologic outcome. At diagnosis, concentrations of CE-specific total IgG, IgG1, and IgG2 antibodies were significantly elevated in a greater proportion of patients compared with IgG3 and IgG4 antibodies. During post-treatment follow up, the IgG2 antibody response provided the best correlate of disease activity.

Adult↗
PubMed2003

Canine echinococcosis in northern Jordan: increased prevalence and dominance of sheep/dog strain.

A total of 112 stray and semi-stray dogs (Canis familiaris) from four different geographical areas in northern and middle Jordan were necropsied to evaluate the prevalence and intensity of intestinal helminthiasis. Of these, 33 dogs (29.5%) were infected with Echinococcus granulosus and 61 (54.5%) with other Taenia species. Other cestodes found included Dipylidium caninum in 36 dogs (32.1%), Diplopylidium in 6 dogs (5.4%), Mesocestoides sp. in 3 dogs (2.7%) and Joyuexiella in 1 dog (0.9%). Toxocara nematodes were found in 10 dogs (9.2%) and only 1 dog was positive for acanthocephalans. Among the dogs infected with E. granulosus, 8 dogs (24.2%) had a worm load higher than 1,000 worms. The ratio of infected male to female dogs was 1.9:1.0. Strain analysis of E. granulosus using random primers revealed the dominance of the G1 strain (sheep/dog strain) in the region. Only one dog harbored another E. granulosus strain, which resembled the G4 strain pattern.

Animals↗
PubMed2003

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.

Animals↗
PubMed2003

Retrospective surgical incidence and case distribution of cystic echinococcosis in Jordan between 1994 and 2000.

A retrospective follow-up study on the surgical incidence of cystic echinococcosis (CE) was carried out in major governmental, military and private hospitals throughout Jordan between 1994 and 2000. A total of 472 cases were recorded over the 7-year period and an overall mean annual surgical incidence (MASI) of 2.3 per 100,000 inhabitants was estimated. The highest number of surgical cases was recorded in hospitals of the middle region of the country. The highest MASI (3.6 per 100,000) was found in the southern region while the lowest (1.4 per 100,000) was in the northern region of the country. Taking into consideration the population size and the origin of surgically confirmed cases of each region, a relative surgical index (RSI) was calculated at which the highest (RSI=3.4) was among cases originated from the southern region and the lowest (RSI=0.7) was among those originated from the middle region of Jordan. The northern region and desert areas (badia) showed comparable RSI at 1.0 and 1.1, respectively. Males younger than 15 years of age showed significantly higher surgical incidence than females of comparable age at a ratio of 1.6:1, whereas the number of female cases of different age groups over 15 years of age was consistently higher than that of males at a ratio of 1.25-2.5:1.0. The liver was the primary site of cyst development in 69.4% of the cases and the lung involvement accounted for 13.3% of the cases. Diagnosis of CE in Jordan relies mostly on imaging methods with serological techniques being rarely used for diagnosis. The frequency of CE recurrence was 27.5% of the cases, which may be attributed to the low use of chemotherapeutic antihelminthics among surgically treated cases.

Adolescent↗
PubMed2003

Multiple genotypes of Taenia solium--ramifications for diagnosis, treatment and control.

Mitochondrial DNA sequences of Taenia solium have fully been analyzed. Analysis of the full length of cytochrome c oxidase subunit 1 (1620 bp) and cytochrome b (1068 bp) genes of T. solium, isolated from Asia (China, Thailand, Indonesia and India), from Latin America (Mexico, Ecuador, Bolivia, Peru and Brazil) and from Africa (Tanzania, Mozambique and Cameroon), has revealed that the two phylogenies obtained were similar to each other regardless of the genes examined. The isolates from Asia formed a single cluster, whereas those from Latin America combined with those from Africa to form an additional cluster. It was estimated that these two genotypes emerged approximately 4-8 x 10(5) years ago. These results together with recent study of the ancient of human taeniid cestodes emerged several MYA in Africa, historical data on swine domestication, distribution of pigs and colonization patterns suggest that T. solium was introduced recently into Latin America and Africa from different regions of Europe during the colonial age, which started 500 years ago, and that T. solium of another origin independently spread in Asian countries, perhaps from China. Why did not T. solium of European origin invade or spread into Asia during the colonial age? Analysis of T. solium distribution must include other Taenia species, especially T. saginata and T. asiatica, which can not be differentiated from each other morphologically. BESS T-base analysis for differentiation of all human Taenia species including the two genotypes of T. solium, and T. saginata and T. asiatica has also been characterized. BESS T-base analysis differentiates African isolates from Latin American isolates as well but more samples should be analyzed for obtaining conclusive evidence for the latter. Serological analysis of cyst fluid of T. solium cysticerci obtained in China and Indonesia and from Mozambique and Ecuador indicates geographical differences in their banding patterns. These differences are discussed in the light of possible differences in pathology of T. solium worldwide. As it has been speculated that the ancient T. solium emerged several million years ago in Africa, it is necessary to analyze more isolates from Africa. Such working hypothesis may be evaluated combined with symptomatology and serology when we get additional DNA data from such areas, since there are some varieties of manifestation of neurocysticercosis with or without subcutaneous cysticercosis and of antigens of cyst fluid of T. solium from Asia and from Africa and/or America. Transfer of techniques of molecular identification and sero- and immuno-diagnoses between researchers and technicians from endemic countries using their own materials should be promoted with the aim of better international cooperation for the control of cysticercosis.

Animals↗
PubMed2003

Immunodiagnostic tools for taeniasis.

Most diagnostic work conducted on the Taenia species zoonoses has been carried out on the larval stage of Taenia solium in man, reflecting the relative severity of the pathology caused by this stage of that organism. This review will, however, concentrate on the immunodiagnosis of the adult intestinal stages of these parasites in humans. Diagnosis of T. solium will be examined in most detail because of the relative importance of this parasite but relevant work from other cestodes of man and animals will also be discussed. In addition both classical and molecular approaches to diagnosis will be briefly covered. There have been a number of advances in immunodiagnosis of taeniasis over recent years that have improved both diagnostic sensitivity and specificity. Techniques for the detection of Taenia specific coproantigens in human taeniasis infections have been shown to more than double the numbers of T. solium cases accurately diagnosed in epidemiological studies. More recently, work on the serological diagnosis of T. solium have led to the development of a sensitive and specific enzyme linked immuno-transfer blot for the detection of species and stage specific circulating antibodies to adult worm excretory-secretory antigens. Work is ongoing to further improve these assays.

Animals↗