Biomedical subjects

James C Allan

Publications and source records attributed to James C Allan.

4 recordsLinked to original sources

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↗

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↗

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↗

PubMed2002

Current consensus guidelines for treatment of neurocysticercosis.

Taenia solium neurocysticercosis is a common cause of epileptic seizures and other neurological morbidity in most developing countries. It is also an increasingly common diagnosis in industrialized countries because of immigration from areas where it is endemic. Its clinical manifestations are highly variable and depend on the number, stage, and size of the lesions and the host's immune response. In part due to this variability, major discrepancies exist in the treatment of neurocysticercosis. A panel of experts in taeniasis/cysticercosis discussed the evidence on treatment of neurocysticercosis for each clinical presentation, and we present the panel's consensus and areas of disagreement. Overall, four general recommendations were made: (i) individualize therapeutic decisions, including whether to use antiparasitic drugs, based on the number, location, and viability of the parasites within the nervous system; (ii) actively manage growing cysticerci either with antiparasitic drugs or surgical excision; (iii) prioritize the management of intracranial hypertension secondary to neurocysticercosis before considering any other form of therapy; and (iv) manage seizures as done for seizures due to other causes of secondary seizures (remote symptomatic seizures) because they are due to an organic focus that has been present for a long time.

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