RESUMEN
BACKGROUND: Echinococcosis is a global zoonotic parasitic disease caused by Echinococcus larvae. This disease is highly endemic in Sichuan Province, China. This study investigates the prevalence and spatial distribution characteristics of human echinococcosis at the township level in Sichuan Province, geared towards providing a future reference for the development of precise prevention and control strategies. METHODS: Human prevalence of echinococcosis was evaluated using the B-ultrasonography diagnostic method in Sichuan Province between 2016 and 2019. All data were collected, collated, and analyzed. A spatial distribution map was drawn to intuitively analyze the spatial distribution features. Eventually, the spatial autocorrelation was specified and local indicators of spatial association (LISA) clustering map was drawn to investigate the spatial aggregation of echinococcosis at the township level in Sichuan Province. RESULTS: The prevalence of echinococcosis in humans of Sichuan Province was 0.462%, among which the occurrence of cystic echinococcosis (CE) was 0.221%, while that of alveolar echinococcosis (AE) was 0.244%. Based on the results of the spatial distribution map, a predominance of echinococcosis in humans decreased gradually from west to east and from north to south. The Global Moran's I index was 0.77 (Z = 32.07, P < 0.05), indicating that the prevalence of echinococcosis in humans was spatially clustered, exhibiting a significant spatial positive correlation. Further, the findings of local spatial autocorrelation analysis revealed that the "high-high" concentration areas were primarily located in some townships in the northwest of Sichuan Province. However, the "low-low" concentration areas were predominantly located in some townships in the southeast of Sichuan Province. CONCLUSIONS: Our findings demonstrated that the prevalence of echinococcosis in humans of Sichuan Province follows a downward trend, suggesting that the current prevention and control work has achieved substantial outcomes. Nevertheless, the prevalence in humans at the township level is widely distributed and differs significantly, with a clear clustering in space. Therefore, precise prevention and control strategies should be formulated for clusters, specifically strengthening the "high-high" clusters at the township level.
Asunto(s)
Equinococosis , Echinococcus , Animales , China/epidemiología , Equinococosis/epidemiología , Humanos , Prevalencia , Análisis Espacial , ZoonosisRESUMEN
The prevalence of E. multilocularis is a major public health problem in China. To better understand the molecular epidemiology and evolutionary patterns of E. multilocularis, an adequate dataset regarding the genetic variance of this parasite is necessary. However, for now, available genetic data of E. multilocularis is still insufficient. In the study, the EmsB microsatellite and the partial mitochondrial cox1 gene were combined to investigate the genetic diversity of 64 E. multilocularis samples from human, dogs and voles. These samples were collected in the Western Sichuan Plateau, where the highest village-based human prevalence of alveolar echinococcosis was recorded worldwide. The aim of the study is to gather more informative genetic data of E. multilocularis in the areas, especially those obtained using the EmsB marker. The microsatellite analysis revealed 7 different EmsB profiles, 1 of which was found in 90.63% of the total samples collected from all 3 hosts. This major profile was identical to the one detected in the same area 16 years ago. The rest of the 6 profiles, each represented by only 1 isolate, did not correspond to any of the profiles previously reported. All the profiles detected in the study belonged to the Asian cluster. Meanwhile, according to sequence analysis of the 758 bp cox1 region, 4 haplotypes all assigned to the Asian clade were detected among the isolates. A star-like haplotype network was exhibited with a centrally positioned haplotype found in 93.75% of the samples. The overall haplotype and nucleotide diversities were both low. These findings provided evidence for a founder event or bottleneck and subsequent population expansion in E. multilocularis. The EmsB profiles were not fully consistent with the cox1 haplotypes. The same correspondence relationship was mainly observed in samples with the major profile P5 and the main haplotype EmHa1. A total of 54 isolates assigned to profile P5 were classified to the EmHa1 haplotype. In conclusion, both the microsatellite and mtDNA markers showed low variability within the Tibetan population of E. multilocularis. An EmsB profile and a cox1 haplotype were found to be predominant in the study area, which appears to remain steady for over a decade. The results reinforce the higher potential of the microsatellite DNA marker with high discriminative power to identify the very low genetic polymorphism of E. multilocularis than that of the partial cox1 sequencing. The data obtained in the study would be helpful to enlarge the data pool to further probe the possible origins and dispersal of E. multilocularis in China.
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Echinococcus multilocularis , Animales , China/epidemiología , ADN Mitocondrial/genética , Perros , Echinococcus multilocularis/genética , Marcadores Genéticos , Variación Genética , Humanos , Repeticiones de Microsatélite , Polimorfismo GenéticoRESUMEN
Human alveolar echinococcosis (AE) is considered a neglected zoonotic disease by the World Health Organization (WHO). The causative pathogen, Echinococcus multilocularis, lives as an adult tapeworm in the intestinal tract of canines. AE was identified as an emerging public health issue in Tibetan communities of Shiqu County 20 years ago. On St. Lawrence Island, Alaska (USA), in the 1980s peri-domestic transmission of E. multilocularis was controlled by regular deworming of owned dogs over a 10-year period. In Tibetan communities, on the Tibetan Plateau, control of E. multilocularis transmission is challenging due to the continental setting, complex epidemiology, disease ecology, geography, and socio-cultural factors. However, a control programme based on deworming owned dogs using praziquental (PZQ) has been carried out since 2006. Assessment was conducted in townships where baseline data were available 10 years prior. Purging of dogs by oral administration of arecoline was used to measure E. multilocularis prevalence, trapping small mammals around communities was employed to assess the change in infection of pikas and voles, and analysis of human AE abdominal ultrasound-based data was used to understand the change in prevalence in the past decade. In all three evaluated townships, the E. multilocularis prevalence in owned dogs was significantly (P < 0.01) reduced from 7.23% (25/346) during 2000-2003 to 0.55% (1/181) in 2016. Human AE ultrasound-based prevalence (adjusted for age and sex) in five evaluated townships decreased significantly (P < 0.01) from 6.25% (200/3,198) during 2000-2002 to 3.67% (706/19,247) during 2015-2017. The 2016 prevalence of E. multilocularis metacestodes in small mammal intermediate hosts was not significantly different from the prevalence in 2008. The control programme was effective in reducing E. multilocularis infection in owned dogs and human AE prevalence, but did not significantly impact infection in wildlife intermediate hosts.
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Enfermedades de los Perros , Equinococosis , Echinococcus multilocularis , Animales , China/epidemiología , Enfermedades de los Perros/tratamiento farmacológico , Enfermedades de los Perros/epidemiología , Enfermedades de los Perros/prevención & control , Perros , Equinococosis/tratamiento farmacológico , Equinococosis/epidemiología , Equinococosis/prevención & control , Prevalencia , TibetRESUMEN
Echinococcosis is considered by the World Health Organization (WHO) to be a neglected zoonotic disease in the world. Some Tibetan communities were found to be highly endemic for echinococcosis just 20 years ago. Until recently, we were able to understand the overall disease burden of echinococcosis in Tibetan communities after prevalence data being available from nationwide investigations from 2012 to 2016. Data were abstracted from 9 publications regarding to echinococcosis prevalence between 2016-2018; from 10 data bases on echinococcosis prevalence for 151 Tibetan counties; and statistics of population, Gross Domestic Product (GDP) and health staff from 44 local statistic bureaus and government websites at provincial, prefecture and county level, and 2 books of provincial yearly statistics. These data were used to estimate the Disability Adjusted Life Years (DALYs) due to cystic echinococcosis (CE) and alveolar echinococcosis (AE). The distribution of DALYs was presented geographically and economically. The echinococcosis DALYs in the Tibetan communities were estimated to be 126,159 (95%UI 122,415-137,675) annually using the method recommended by WHO. AE DALYs were estimated to be 105,829 (95%UI 101,969-117,090), which were more than CE DALYs of 20,330 (95%UI 19,690-21,581). Echinococcosis affects people more in underdeveloped areas. There was a tendency that a higher echinococcosis DALYs were usually correlated a higher altitude. Health services are also poorly provided in terms of number of health staff of 5.05 per 1000 population in comparison with the national average of 5.8 per 1000 population. The data suggest that the echinococcosis burden in the center region of Qinghai-Tibet plateau is higher than that of other regions, and consequently more control and health services should be provided to the region.
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Equinococosis/epidemiología , Salud Pública , Costo de Enfermedad , Equinococosis/prevención & control , Humanos , Años de Vida Ajustados por Calidad de Vida , Tibet/epidemiologíaRESUMEN
BACKGROUND: Echinococcosis caused by Echinococcus is one of the most major infectious diseases in north-west highland of China. E. granulosus sensu strict, E. multilocularis, and E. canadensis are known to be the only three species related to human health transmitting in the areas. To achieve targeted treatment and control of echinococcosis, the accurate identification and discrimination of the species are important. However, currently the available diagnostic approaches do not present ideal results either in accuracy or efficiency. METHODS: In the study, a set of primers were designed to aim at the three human-pathogenic Echinococcus species in China. The one-step multiplex PCR assay was developed and evaluated for the specificity and sensitivity. A total of 73 parasitic lesions and 41 fecal materials obtained from human and various animals collected in the clinic and the field were tested to assess the applicability of this method. RESULTS: The multiplex PCR effectively detected the individual DNA from the targeted species and their random mixtures generating with distinguishable expected size of products. The detection limit of the assay for each of the three species was 5 pg/µl when they were tested separately. When DNA mixtures of the targeted species containing the same concentration were used as templates, the lowest amount of DNA which can be detected was 50 pg/µl, 10 pg/µl and 5 pg/µl for E. granulosus s. s., E. multilocularis, and E. canadensis respectively. No cross-reactivity was observed when DNA from eight genetically close species was used as control templates. The multiplex PCR identifications of all samples were in line with the original sequencing results except for those infected with E. shiquicus, which showed negative signals in the developed assay. Of all the tested stool materials, 16 were previously found positive for Echinococcus by visual and microscopic examination. Among these 16 samples, 13 were confirmed by the multiplex PCR, and the other three tested negative. Additionally, the multiplex PCR identified another 14 positive feces from the remained 25 stool samples which absence of worms. CONCLUSIONS: The developed multiplex PCR shows advantages in fast diagnosis and large-scale epidemiological investigation, which proven to be a promising tool utilized in clinic and surveillance system.
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Equinococosis/diagnóstico , Echinococcus/aislamiento & purificación , Reacción en Cadena de la Polimerasa Multiplex/métodos , Animales , China , Diagnóstico Diferencial , Equinococosis/clasificación , Equinococosis/parasitología , Echinococcus granulosus/aislamiento & purificación , Echinococcus multilocularis/aislamiento & purificación , HumanosRESUMEN
Echinococcus granulosus sensu stricto (s.s.), Echinococcus multilocularis and Echinococcus canadensis are the common causes of human echinococcosis in China. An accurate species identification tool for human echinococcosis is needed as the treatments and prognosis are different among species. The present work demonstrates a method for the simultaneous detection of these three Echinococcus species based on multiplex polymerase chain reaction (mPCR). Specific primers of this mPCR were designed based on the mitochondrial genes and determined by extensive tests. The method can successfully detect either separated or mixed target species, and generate expected amplicons of distinct size for each species. Sensitivity of the method was tested by serially diluted DNA, showing a detection threshold as less as 0.32 pg for both E. granulosus s.s. and E. canadensis, and 1.6 pg for E. multilocularis. Specificity assessed against 18 other parasites was found to be 100% except weakly cross-react with E. shiquicus. The assay was additionally applied to 69 echinococcosis patients and 38 healthy persons, confirming the high reliability of the method. Thus, the mPCR described here has high application potential for clinical identification purposes, and can further provide a useful tool for evaluation of serology and imaging method.
Asunto(s)
Equinococosis/diagnóstico , Echinococcus/aislamiento & purificación , Reacción en Cadena de la Polimerasa Multiplex/métodos , Animales , Equinococosis/parasitología , Echinococcus granulosus/aislamiento & purificación , Echinococcus multilocularis/aislamiento & purificación , Humanos , Reacción en Cadena de la Polimerasa Multiplex/instrumentaciónRESUMEN
Cystic echinococcosis (CE) and alveolar echinococcosis (AE) are highly co-endemic in Sichuan, a part of Qinghai-Tibet Plateau where is a typical Tibetan nomadic community living area. In order to better understand the Echinococcus spp. of human being infected origins in this area, 140 lesions were collected from echinococcosis patients who were received operations during the period of 2014-2016 in different geographic districts in this region. Partial DNA sequences of the mitochondrial cox1 gene were analyzed. The genetic characterization of the isolates from 3 different places including Ganzi, Aba and Liangshan were assessed. Of all the 140 samples, the great majority was identified as Echinococcus granulosus sensu stricto (n = 108). Echinococcus multilocularis was confirmed to be another important pathogen of the human infections (n = 31). Additionally, one Echinococcus canadensis (G6/7) isolate from Ganzi was confirmed. Comparing the clinical diagnosis with the sequencing results, 6.4% (9/140) of the cases were misdiagnosed between AE and CE, and another 8.6% (12/140) were unclassified to sub-type in echinococcosis. Higher rates of misdiagnosis and unclassified diagnosis were found in AE cases (12.9%, 4/31 and 16.1%, 5/31 respectively) compared to CE (4.6%, 5/109 and 6.4%, 7/109 respectively). In E.granulosus s.s., a total of 34 haplotypes were detected, and 4 haplotypes were inferred from E.multilocularis. The haplotype networks of the 2 species exhibited a similar star-shaped feature with a dominant haplotype in the center. Geographically specific haplotypes were observed in Ganzi and Aba respectively. This study provides insight into the current species causing human echinococcosis in the Tibetan districts of Sichuan. E.granulosus s.s. and E.multilocularis are confirmed to be the main causative agents, and the existence of E.canadensis (G6/7) is also observed in the region. Molecular diagnosis was proven to be essential for the confirmation of human echinococcosis in the area.
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Echinococcus granulosus/genética , Echinococcus multilocularis/genética , Adulto , Anciano , Animales , Equinococosis/parasitología , Femenino , Haplotipos , Humanos , Masculino , Persona de Mediana EdadRESUMEN
BACKGROUND: Human cystic echinococcosis (CE) and alveolar echinococcosis (AE) are highly endemic in Tibetan communities of Sichuan Province. Previous research in the region indicated that domestic dog was the major source of human infection, and observations indicated that domestic dog could have more access to intermediate hosts of Echinococcus spp.: both domestic livestock (CE) viscera and small mammals (AE), in early winter and again in spring. We hypothesized that there would therefore be a significant increase in the risk of canine infection with Echinococcus spp. in these two seasons and conducted a reinfection study to investigate this further. METHODS: Faecal samples were collected from owned dogs in seven townships in Ganze Tibetan Autonomous Prefecture (Sichuan Province, China), and Echinococcus spp. infection status was determined using copro-antigen ELISA. Dogs were sampled in April (spring), July (early summer), September/October (autumn/early winter) and December (winter) in 2009; and in April (spring) 2010. Dogs were treated with praziquantel following each of the five sample collections to eliminate any tapeworms. Information on dog sex, age and body weight was also collected. The t-test, Fisher's exact test, Poisson regression and logistic regression were used to compare means and prevalences, and to identify factors associated with infection status. RESULTS: The proportion of female dogs was significantly lower than that of male dogs; female dogs had significantly higher (22.78 %) baseline copro-ELISA prevalence than males (11.88 %). Dog body weight, sex, age, county and previous infection status at any sampling point had no influence on the re-infection prevalence in general. Poisson regression did not found a significant influence on the re-infection prevalence due to different deworming/sampling time spans. Dogs exhibited significantly higher re-infection prevalences in spring and early summer of 2009 and in early winter between September/October and December of 2009, suggesting a higher infection pressure in these seasons comparing with other seasons. CONCLUSION: Following praziquantel treatment, dog body weight, sex, age, county, deworming time span and previous infection status at any sampling point had no influence on the re-infection prevalence in the region in general. The differences between re-infection prevalences were probably due to the seasonality in Echinoccocus spp. infection pressure in the region. Early winter, spring and early summer should be important seasons for optimal dog deworming intervention in these Tibetan communities.