Epidemiology, treatment and follow-up of human echinococcosis on the eastern Tibetan Plateau, China

The current study aimed to determine the prevalence of human echinococcosis in Tibetancommunities of Sichuan Province, undertake genotyping of human echinococcosis isolatesfrom the Tibetan Plateau, and assess the clinical efficacy of albendazole in human cystic andalveolar echinococcosis. In addition, specific IgG serologic responses against recombinantantigens (AgB and Em 18) were also examined in Tibetan cystic and alveolar echinococcosispatients.Abdominal ultrasound screening programmes for echinococcosis were conducted in 31Tibetan townships in Ganze and Aba Tibetan Autonomous Prefectures of northwest SichuanProvince during 2001-2008. Hospital records (1992-2006) in a major regional treatmentcentre for echinococcosis in Aba Prefecture were also reviewed. Of 10.186 local residentsexamined by portable ultrasound scan, 645 (6.3%) were diagnosed with echinococcosis: aprevalence of 3.2% for cystic echinococcosis (CE), 3.1% for alveolar echinococcosis (AE)and 0.04% for dual infection (both CE and AE). Further analysis revealed that human cysticand alveolar echinococcosis in pastoral areas was highly co-endemic, in comparison to muchlower human prevalences found in semi-pastoral or farming regions. The high ultrasoundprevalence of hepatic echinococcosis in these co-endemic areas in northwest SichuanProvince was also reflected in the hospital study, and hospital records furthermore indicatedanother possibly highly co-endemic transmission focus in Guoluo Prefecture of QinghaiProvince, located at the border of northwest Sichuan.Parasite isolates from 68 human cases originating from Sichuan and Qinghai provincesin eastern China were postoperatively examined by histopathology and PCR-RFLP forspecific identification of Echinococcus spp. Histopathologically, 38 human isolates wereconfirmed as E. granulosus and 30 as E. multilocularis. PCR-RFLP with rrnL as the targetgene confirmed 33 of 53 of the isolates to have the Gl genotype of sheep/dog strain of E.granulosus as the only source of infection, while the remaining 20 were confirmed as E.multilocularis. No human infections were shown to be caused by E. shiquicus which is alsoendemic in wildlife hosts in the region.Specific IgG responses to recombinant antigen B and Eml8 in ELISA were examined in422 ultrasound-detected echinococcosis patients, including 246 with CE, 173 with AE, and 3·with dual infection. As a result, rAgB-specific antibody was detected in 77.6% of CE and86.1% of AE cases, while rEmlS-specific antibody was present in 28.9% of CE and 87.3% ofAE patients. All three patients with dual infection exhibited specific antibodies responding torAgB and rEml8. Further analysis revealed that rAgB-specific antibody was elevated in asignificantly greater proportion (87.3%) of CE patients with cysts at active or transitionalstages (CE1, CE2 or CE3), compared to 54.8% of other patients with cysts at an early or aninactive stage (CL or CE4 or CE5). Additionally, rAgB-specific antibody was detected in95.6% of CE2 cases, which was statistically greater than that (73.7%) in CE1 patients.Although rEmlS-specific antibody was elevated in 28.9% of CE patients, the positive reactionwas much weaker in CE than in AE cases. Serum levels and concentrations of rEmlS-specificantibody were further indicated to be strongly disease phase correlated in AE patients, withpositive rates of 97.4% in cases with alveolar lesions containing central necrosis and 66.7% inpatients with early alveolar lesions that measured