[Identification of Taenia solium with abnormal number of scolex hooklets]

To identify 3 suspected adults Taenia solium with abnormal number of hooklets on scolex collected from 3 patients of Dali in Yunnan Province.

Tapeworms were observed with unaided eyes. Morphology of the scolices and gravid proglottids was observed under microscope. DNA of gravid proglottids of the 3 adult tapeworms was extracted. T. solium mitochondrial cytochrome c oxidase subunit 1 gene (cox1) fragment and the full coxz1 gene were amplified by PCR. The cox1 gene of one isolate was sequenced. Eggs were hatched and oncospheres were inoculated into mice subcutaneously. Each mouse was subcutaneously injected with 1 mg dexamethasone once daily. Sixty days after infection, all mice were sacrificed and the morphology of cysticerci was observed. Two macaque monkeys were fed with eggs (2.5 x 10(5) per monkey). Euthanasia and autopsy were performed on day 47. Morphology of cysticerci were observed by light and scanning electron microscopy, and pathological changes of livers were observed.

The number of hooklets on scolices of the three tapeworms was 0, 4 and 10, respectively, and lateral uterine branches in gravid proglottids were 7-12. PCR results of co1l gene fragment with species-specific primer for T. solium were all positive. The complete sequence of cox1 gene had 99.8% identity to the reported T. solium sequences. Cysticerci were obtained from hypoderm of mouse, muscles and hearts of monkey. Four suckers and 26-28 hooklets ranged in two rows around rostellum on scolex were microscopically observed. Milia-like lesions were found in monkey liver. Histological examination showed that there was fibrous connective tissue hyperplasia and eosinophil infiltration around lesion, and parasites were found in some cysts.

The three tapeworms with abnormal number of hooklets have all been identified as T. solium. The larvae can infect macaque and lead to muscle and liver cysticercosis.