Prevalence of taeniasis and sero - prevalence of anti - cysticercus antibody among residents in Tibetan agricultural areas of Sichuan Province / 中国血吸虫病防治杂志

Objective To investigate the prevalence and epidemiological characteristics of taeniasis and cysticercosis among residents in Tibetan agricultural areas of Sichuan Province, so as to provide insights for the prevention and control of taeniasis and cysticercosis. Methods From 2016 to 2022, Kangding City, Daocheng County, Derong County, Ruoergai County and Muli Tibetan Autonomous County were sampled from Tibetan agricultural areas of Ganzi Tibetan Autonomous Prefecture, Aba Tibetan and Qiang Autonomous Prefecture and Liangshan Yi Autonomous Prefecture in Sichuan Province, and 1 to 6 townships were sampled from each county (district), followed by 4 to 7 villages sampled from each township. Primary school children were sampled using a cluster sampling method, and permanent residents at ages of over 16 years were randomly sampled from each village. Participants’ demographics, history of tapeworm excretion during the past year and clinical symptoms and signs of cysticercosis were collected through questionnaire surveys, and participants’ stool and venous blood samples were collected. Taenia eggs were detected in stool samples using the direct smear method, and deworming was performed among taeniasis patients with areca nut-squash seeds. The tapeworm species were identified using a multiplex PCR assay, and serum specific IgG antibody against cysticercus was detected using enzyme-linked immunosorbent assay (ELISA). Results A total of 5 249 respondents participated in the questionnaire survey, including 603 respondents (11.5%) with a self-reported history of proglottids secretion during the past year. A total of 3 976 residents were subjected to stool examinations, and the detection of Taenia eggs was 6.5%. Of 258 participants undergoing deworming, there were 403 cases (94.2%) with excretions of Taenia worms or proglottids. The mean prevalence of taeniasis was 10.9% (439/4 043), and there were gender-, age- and region-specific prevalence rates of taeniasis (χ2 = 36.73, 126.31 and 163.41, all P values < 0.05). Multiplex PCR assays detected 41 cases with T. solium infections (12.5%), 197 cases with T. saginata infections (59.9%) and 91 cases with T. asiatica infections (27.6%) among 329 patients undergoing deworming, and there were region-specific prevalence rates of T. solium, T. saginata and T. asiatica infections (χ2 = 45.39, P < 0.05). In addition, the sero-prevalence of anti-cysticercus IgG antibody was 7.0% (345/4 933), and there were age- and region-specific sero-prevalence rates of anti-cysticercus IgG antibody (χ2 = 13.49 and 51.76, both P values < 0.05). Conclusions Multiple Taenia species are prevalent in Tibetan agricultural areas of Sichuan Province and the sero-prevalence of anti-cysticercus antibody is high among residents. Monitoring and control of taeniasis and cysticercosis should be strengthened.

A case with severe neurocysticercosis / 中国血吸虫病防治杂志

This case report described the diagnosis and treatment of an ethnic Tibetan case with severe neurocysticercosis residing in agricultural areas of Sichuan province.

Impact of the neglected Cysticercus cellulose infection on mental health among school-aged children in Tibetan agricultural areas / 中南大学学报(医学版)

To determine the impact of Cysticercus cellulose (C. cellulose) infection on mental health among school-aged children in Tibetan agricultural areas of Sichuan Province.
 Methods: In October 2015, all primary schools located in Tibetan agricultural areas in Yajiang, Ruoergai, and Muli county of Sichuan Province were selected as the research sites. All school-aged children at five- and six-grade were enrolled for the study by a multistage stratified cluster sampling method. Antibodies against C. cellulose were detected. Mental Health Test and questionnaire survey were conducted for school-aged children to collect data. The impact of C. cellulose infection on mental health among school-aged children was analyzed with the multilevel linear regression.
 Results: A total of 2 453 school-aged children were investigated. The C. cellulose seropositive rate was 6.03% (148/2 453). There were 0.16% (4/2 453) patients with seropositive accompanied by seizure, 2.28% (56/2 453) with seropositive accompanied by headache, 2.08% (51/2 453) with seropositive accompanied by frequent weak, and 0.41% (10/2 453) were seropositive accompanied by frequent nausea. The rate of C. cellulose infection was 4.53% (111/2 453). The mean score of the mental health test was 6.59±2.61. There were significant difference in score of mental health test in children whose demographic characteristics were different. The mental health scores of school-aged children were clustered at the school level. After controlling the factors of demographic characteristics, the result of multilevel model demonstrated that the factor of school-aged children with C. cellulose seropositive accompanied by headache was statistically significant (β=1.14, P=0.017).
 Conclusion: The status of C. cellulose infection among school-aged children in Tibetan agricultural areas is not optimistic. C. cellulose infection has impacted on mental health of local school-aged children. It is necessary to strengthen the prevention and control of C. cellulose infection in epidemic area.

Evaluation of ELISA kit for detection of serum specific IgG antibodies against Taenia solium in diagnosis of human cysticercosis / 中国血吸虫病防治杂志

Objective To evaluate the ELISA kit for detection of IgG antibodies against Taenia solium cysticercus in hu-mans,so as to provide a reference for its application in clinical practice. Methods The sera collected from the patients with neurocysticercosis,echinococcosis,taeniasis and healthy people,respectively,were checked by ELISA for specific IgG anti-bodies against T. solium cysticercus,as described in the instruction of the kit. Results Of the 30 patients with neurocysticerco-sis at active stage,28 showed seropositive reaction,indicating a sensitivity of 93.33%. There were no positive reactions in the 100 healthy people. Two of the 42 persons with taeniasis were seropositive with an infection rate of 4.76%. Forty-one of the 60 persons with echinococcosis showed positive reactions,suggesting that the cross reaction rate of the kit with echinococcosis was 68.33%. Conclusions The assessed ELISA kit has a reasonably high sensitivity but a poor specificity,and the cross reaction rate with echinococcosis is very high. It is urgent to improve the sensitivity and specificity of the diagnostic kit for detection of T. solium cysticercosis in China.

Modelling and spatial discrimination of small mammal assemblages: an example from western Sichuan (China).

We investigate the relationship between landscape heterogeneity and the spatial distribution of small mammals in two areas of Western Sichuan, China. Given a large diversity of species trapped within a large number of habitats, we first classified small mammal assemblages and then modelled the habitat of each in the space of quantitative environmental descriptors. Our original two step "classify then model" procedure is appropriate for the frequently encountered study scenario: trapping data collected in remote areas with sampling guided by expert field knowledge.In the classification step, we defined assemblages by grouping sites of similar species composition and relative densities using an expert-class-merging procedure which reduced redundancy in the habitat factor used within a multinomial logistic regression predicting species trapping probabilities. Assemblages were thus defined as mixtures of small mammal frequency distributions in discrete groups of sampled sites.In the modelling step, assemblages' habitats and environments of the two sampled areas were discriminated in the space of remotely sensed environmental descriptors. First, we compared the discrimination of assemblage/study areas by linear and non-linear forms of Discriminant Analysis (Linear Discriminant Analysis versus Mixture Discriminant Analysis) and of Multiple Regression (Generalized Linear Models versus Multiple Adaptive Regression Splines). The "best" predictive modelling technique was then used to quantify the contribution of each environmental variable in discriminations of assemblages and areas.Mixtures of Gaussians provided a more efficient model of assemblage coverage in environmental space than a single Gaussian cluster model. However, non-linearity in assemblage response to environmental gradients was consistently predicted with lower deviance and misclassification error by Multiple Adaptive Regression Splines. The two study areas were mainly discriminated along vegetation indices. However, although the Normalized Difference Vegetation Index (NDVI) could discriminate forested from non-forested habitats, its power to discriminate assemblages in Maerkang, where a greater diversity of forest habitat was observed, was seen to be limited, and in this case NDVI was outperformed by the Enhanced Vegetation Index (EVI). Our analyses highlight previously unobserved differences between the environments and small mammal communities of two fringe areas of the Tibetan plateau and suggests that a biogeograph-ical approach is required to elucidate ecological processes in small mammal communities and to reduce extrapolation uncertainty in distribution mapping.

Human Echinococcosis: A Neglected Disease?

Human echinococcosis is a zoonotic larval cestode disease usually caused by <I>Echinococcus granulosus</I> or <I>E. multilocularis</I>. Infection is chronic taking years for symptoms to develop. Because diagnosis and treatment are difficult and reservoirs of infection are maintained in domestic livestock, dogs or wildlife, the disease is difficult to assess in terms of public health and requires long-term control interventions. Estimates of numbers of cystic echinococcosis cases that may occur in 2 large endemic zones, North Africa⁄Middle East and China⁄Central Asia, indicates > 423,000 and > 484,000 cases respectively. Globally, 3.6 million DALYs could be lost due to echinoccocosis. Echinococcosis is therefore a neglected disease which is under-reported and requires urgent attention in common with a number of other zoonoses in order to reduce morbidity and to help alleviate poverty in poor pastoral areas of the sub-tropics and temperate zones

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.