Infection of sheep by Echinococcus multilocularis in Gansu, China: evidence from mitochondrial and nuclear DNA analysis.

BACKGROUND: In the normal life cycle of the parasite (Echinococcus multilocularis) that causes alveolar echinococcosis, domestic and wild carnivores act as definitive hosts, and rodents act as intermediate hosts. The presented study contributes to the research on the distribution and transmission pattern of E. multilocularis in China having identified sheep as an unusual intermediate host taking part in the domestic transmission of alveolar echinococcosis in Gansu Province, China. METHODS: From 2020 to 2021, nine whitish different cyst-like were collected from the liver of sheep in Gansu Province for examination. A near complete mitochondrial (mt) genome and selected nuclear genes were amplified from the cyst-like lesion for identification. To confirm the status of the specimen, comparative analysis with reference sequences, phylogenetic analysis, and network analysis were performed. RESULTS: The isolates displayed ≥ 98.87% similarity to E. multilocularis NADH dehydrogenase sub-unit 1 (nad1) (894 bp) reference sequences deposited in GenBank. Furthermore, amplification of the nad4 and nad2 genes also confirmed all nine samples as E. multilocularis with > 99.30% similarity. Additionally, three nuclear genes, pepck (1545 bp), elp-exons VII and VIII (566 bp), and elp-exon IX (256 bp), were successfully amplified and sequenced for one of the isolates with 98.42% similarity, confirming the isolates were correctly identified as E. multilocularis. Network analysis also correctly placed the isolates with other E. multilocularis. CONCLUSIONS: As a result of the discovery of E. multilocularis in an unusual intermediate host, which is considered to have the highest zoonotic potential, the result clearly demonstrated the necessity for expanded surveillance in the area.

Establishment of a secondary infection laboratory model of Echinococcus shiquicus metacestode using BALB/c mice and Mongolian jirds (Meriones unguiculatus).

Echinococcus shiquicus is peculiar to the Qinghai­Tibet plateau of China. Research on this parasite has mainly focused on epidemiological surveys and life cycle studies. So far, limited laboratory studies have been reported. Here, experimental infection of E. shiquicus metacestode in BALB/c mice and Mongolian jirds (Meriones unguiculatus) was carried out to establish alternative laboratory animal models. Intraperitoneal inoculation of metacestode material containing protoscoleces (PSCs) obtained from infected plateau pikas were conducted on BALB/c mice. Furthermore, metacestode material without PSCs deriving from infected BALB/c mice was intraperitoneally inoculated to Mongolian jirds. Experimental animals were dissected for macroscopic and histopathological examination. The growth of cysts in BALB/c mice was infiltrative, and they invaded the murine entire body. Most of the metacestode cysts were multicystic, but a few were unilocular. The cysts contained sterile vesicles, which had no PSCs. The metacestode materials were able to successfully infect new mice. In the jirds model, E. shiquicus cysts were typically formed freely in the peritoneal cavity; the majority of these cysts were free while a small portion adhered loosely to nearby organs. The proportion of fertile cysts was high, and contained many PSCs. The PSCs produced in Mongolian jirds also successfully infected new ones, which confirms that jirds can serve as an alternative experimental intermediate host. In conclusion, a laboratory animal infection was successfully established for E. shiquicus using BALB/c mice and Mongolian jirds. These results provide new models for the in-depth study of Echinococcus metacestode survival strategy, host interactions and immune escape mechanism.

Update on the genetic diversity and population structure of Echinococcus granulosus in Gansu Province, Tibet Autonomous Region, and Xinjiang Uygur Autonomous Region, Western China, inferred from mitochondrial cox1, nad1, and nad5 sequences.

The identification of additional Echinococcus granulosus sensu lato (s.l.) complex species/genotypes in recent years raises the possibility that there might be more variation among this species in China than is currently understood. The aim of this study was to explore intra- and inter-species variation and population structure of Echinococcus species isolated from sheep in three areas of Western China. Of the isolates, 317, 322, and 326 were successfully amplified and sequenced for cox1, nad1, and nad5 genes, respectively. BLAST analysis revealed that the majority of the isolates were E. granulosus s.s., and using the cox1, nad1, and nad5 genes, respectively, 17, 14, and 11 isolates corresponded to Elodea canadensis (genotype G6/G7). In the three study areas, G1 genotypes were the most prevalent. There were 233 mutation sites along with 129 parsimony informative sites. A transition/transversion ratio of 7.5, 8, and 3.25, respectively, for cox1, nad1, and nad5 genes was obtained. Every mitochondrial gene had intraspecific variations, which were represented in a star-like network with a major haplotype with observable mutations from other distant and minor haplotypes. The Tajima's D value was significantly negative in all populations, indicating a substantial divergence from neutrality and supporting the demographic expansion of E. granulosus s.s. in the study areas. The phylogeny inferred by the maximum likelihood (ML) method using nucleotide sequences of cox1-nad1-nad5 further confirmed their identity. The nodes assigned to the G1, G3, and G6 clades as well as the reference sequences utilized had maximal posterior probability values (1.00). In conclusion, our study confirms the existence of a significant major haplotype of E. granulosus s.s. where G1 is the predominant genotype causing of CE in both livestock and humans in China.

Current Knowledge on Chemosensory-Related Candidate Molecules Potentially Involved in Tick Olfaction via Haller's Organ.

Ticks are obligatory hematophagous ectoparasites and vectors of many animal and human pathogens. Chemosensation plays a significant role in tick communication with their environment, including seeking out blood meal hosts. Studies on the structure and function of Haller's organ and its components have improved our understanding regarding tick olfaction and its chemical ecology. Compared with the knowledge on insect olfaction, less is known about the molecular basis of olfaction in ticks. This review focused on the chemosensory-related candidate molecules likely involved in tick olfaction. Members of the ionotropic receptor family and a new class of odorant-binding proteins are now known to be involved in tick olfaction, which appear to differ from that of insects. These candidate molecules are more closely related to those of mites and spiders than to other arthropods. The amino acid sequences of candidate niemann-pick type C2 and microplusin-like proteins in ticks exhibit features indicating their potential role as binding proteins. In the future, more comprehensive pertinent research considering the existing shortcomings will be required to fully understand the molecular basis of tick olfactory chemoreception. This information may contribute to the development of new molecular-based control mechanisms to reduce tick populations and related disease transmission.

Comparison of mitochondrial genetic variation of Taenia hydatigena cysticerci from China and Mongolia.

Parasitic infection is one of the many challenges facing livestock production globally. Cysticercosis tenuicollis is a common parasitic disease in domestic and wild ruminants (intermediate host) caused by the larval stage of Taenia hydatigena that primarily infects dogs (definitive host). Although genetic studies on this parasite exist, only a few describe the genetic variation of this parasite in Mongolia. Our aim was thus, to identify the mitochondrial differences in ovine isolates of Cysticercus tenuicollis entering China from Mongolia and comparison with existing Chinese isolates from sheep and goats based on the recently described PCR-RFLP method and mitochondrial genes of NADH dehydrogenase subunit 4 (nad4) and the NADH dehydrogenase subunit 5 (nad5). Sixty-nine isolates were collected during routine veterinary meat inspections from sheep that originated from Mongolia, at the modern slaughterhouses in Erenhot City, Inner Mongolia. Additional 114 cysticerci were also retrieved from sheep and goats from northern (Inner Mongolia Autonomous Region, Ningxia Hui Autonomous Region, and Gansu Province), western (Tibet Autonomous Region), and southern (Jiangxi Province and Guangxi Province) China. The PCR-RFLP approach of the nad5 showed nine mitochondrial subclusters A1, A2, A3, A5, A8, A9, A10, A11, and B of T. hydatigena isolates from sheep and goats from Mongolia and China. Meanwhile, haplogroup A1 RFLP profile was more widespread than other variants. These data supplements existing information on the molecular epidemiology of T. hydatigena in China and Mongolia and demonstrate the occurrence of similar genetic population structures in both countries.

Echinococcus granulosus sensu lato in animal intermediate hosts: What is with the organ location?

Organ or tissue tropism/preference in many parasites is essential for their establishment, survival and pathogenesis. In protozoan parasites e.g. Trypanosoma and Plasmodium, tissue tropism is associated with many important aspects such as transmission, treatment, and pathogenesis. In these parasites, tissue tropism is achieved by mechanisms such as sequestration, extravasation, transcellular migration, and vascular permeability. In contrast, little is known about the mechanism behind organ tropism/preference and the potential implication in parasitic metazoans like Echinococcus. Since intraspecies/genetic variation was described for Echinococcus, the organ preference of currently known species and subspecies among animal intermediate hosts remains unclear or perhaps poorly investigated. Here, analysis of 89,359 Echinococcus cysts from different animal intermediate hosts across 47 countries suggests a potential organ distribution pattern in different animal intermediate hosts. For example, E. granulosus s.s. (G1, G3) and E. canadensis (G7) were found more in the liver of sheep and pigs, respectively than in other organs, whereas E. ortleppi and E. canadensis G6 were significantly higher in the lung of cattle and camels, respectively. While the mechanism of organ tropism in Echinococcus and whether it is species/genotype-dependent, host-dependent, or a combination of both is still a subject of future investigations, further and detailed investigation could provide significant information that may be applicable in the diagnosis and treatment of organ-specific cystic echinococcosis or designing host or genotype-specific interventions.

Expansion of Cyclophyllidea Biodiversity in Rodents of Qinghai-Tibet Plateau and the "Out of Qinghai-Tibet Plateau" Hypothesis of Cyclophyllideans.

The Cyclophyllidea comprises the most species-rich order of tapeworms (Platyhelminthes, Cestoda) and includes species with some of the most severe health impact on wildlife, livestock, and humans. We collected seven Cyclophyllidea specimens from rodents in Qinghai-Tibet Plateau (QTP) and its surrounding mountain systems, of which four specimens in QTP were unsequenced, representing "putative new species." Their complete mitochondrial (mt) genomes were sequenced and annotated. Phylogenetic reconstruction of partial 28S rDNA, cox1 and nad1 datasets provided high bootstrap frequency support for the categorization of three "putative new species," assigning each, respectively, to the genera Mesocestoides, Paranoplocephala, and Mosgovoyia, and revealing that some species and families in these three datasets, which contain 291 species from nine families, may require taxonomic revision. The partial 18S rDNA phylogeny of 29 species from Taeniidae provided high bootstrap frequency support for the categorization of the "putative new species" in the genus Hydatigera. Combined with the current investigation, the other three known Taeniidae species found in this study were Taenia caixuepengi, T. crassiceps, and Versteria mustelae and may be widely distributed in western China. Estimates of divergence time based on cox1 + nad1 fragment and mt protein-coding genes (PCGs) showed that the differentiation rate of Cyclophyllidea species was strongly associated with the rate of change in the biogeographic scenarios, likely caused by the uplift of the QTP; i.e., species differentiation of Cyclophyllidea might be driven by host-parasite co-evolution caused by the uplift of QTP. We propose an "out of QTP" hypothesis for the radiation of these cyclophyllidean tapeworms.

A systematic review and meta-analysis on prevalence and distribution of Taenia and Echinococcus infections in Ethiopia.

BACKGROUND: Tapeworm infections are among the tropical neglected parasitic diseases endemically occurring in Ethiopia. This systematic review and meta-analysis aims at estimating the pooled prevalence and distribution of Taenia and Echinococcus infections in humans and animals from reports from Ethiopia. METHODS: The systematic search was conducted in four bibliographic databases (PubMed, Google Scholar, Africa Journal Online and Science Direct). Additional data were retrieved from grey literature. Studies that met the inclusion criteria were considered for the systematic review and meta-analysis. The meta-analysis was conducted using MetaXL add-in for Microsoft Excel. Heterogeneity and inconsistency were evaluated using Cochran's Q and I2 statistics, respectively. RESULTS: The study provides a country-based database of Taenia and Echinococcus infections consisting of 311 datasets from 201 publications which were mostly abattoir surveys; of these, 251 datasets were subjected to meta-analysis. Most of the studies were from Oromia (32.8%) followed by Amhara (22.9%) regional states. The pooled prevalence of cystic echinococcosis in intermediate and accidental hosts was calculated as 22% (95% CI 18-26%) and high study variability (Q = 24,420.65, I2 = 100%, P = 0.000). Moreover, a pooled prevalence of Echinococcus infections in final hosts was calculated as 33% (95% CI 20-48%) and low study variability (Q = 17.24, I2 = 65%, P = 0.001). Similarly, study subjects (human, cattle, sheep, goat and wolf) were infected by Taenia spp. with pooled prevalence of 3% (95% CI 2-4%) and moderate study variability (Q = 279.07, I2 = 89, P = 0.000). Meanwhile, the pooled prevalence of Taenia hydatigena, T. ovis and T. multiceps infections in intermediate hosts were calculated as 38%, 14% and 5%, respectively. The random effect meta-analysis of bovine cysticercosis showed a pooled prevalence of 7% (95% CI 5-9%) and high study variability was of (Q = 4458.76; I2 = 99%, P = 0.000). Significant differences in prevalence of Taenia and Echinococcus infections between study sites or different livestock origins have been reported. CONCLUSION: The study evidenced a comprehensive dataset on the prevalence and distribution of Taenia and Echinococcus infections at different interfaces by regions and hosts and hence can aid in the design of more effective control strategies.

Neglected tropical zoonotic diseases in Tigray region, northern Ethiopia: Spatial distribution and trend analysis of rabies, tuberculosis, schistosomiasis, and visceral leishmaniasis in humans.

Neglected tropical zoonotic diseases (NTZDs) continue to affect the health and livelihoods of humans particularly the poor and marginalized populations in developing countries. Mapping the distribution and burden of these diseases will support making an informed decision. A retrospective study was conducted to map the spatial distribution and analyse trend of NTZDs in Tigray region, Northern Ethiopia. A health management information system (HMIS) data between 2012/13 and 2016/17 was obtained from Tigray National Regional State Health Bureau. The Quantum-GIS software was used to map the spatial distribution and burden of selected NTZDs at zonal level. Only four of the NTZDs namely rabies, tuberculosis (TB), schistosomiasis and visceral leishmaniasis (VL) from the records of HMIS data were considered. A high incidence rate (IR) at least for one of the NTZDs was reported in males above 15 years old. In the 5-year period, of the 60,099 reported NTZD cases, 30.3% (18,220), 26.6% (16,005), 23.3% (14,001), 14.4% (8,661), and 5.3% (3,212) were, respectively, schistosomiasis, extra-pulmonary TB, rabies, pulmonary TB, and visceral leishmaniasis. The year-wise analysis showed an irregular trend for the NTZDs where both the decreasing and increasing trends didn't show statistically significant variation. However, the overall regional number of TB cases showed a decreasing trend, where the decrease for extra-pulmonary TB (1.8 cases per 100,000 population) was higher than pulmonary TB (0.5 cases per 100,000 population). Similarly, the annual number of rabies and VL cases showed a decreasing trend. On the other hand, the number of schistosomiasis cases showed an increasing trend (8.2 cases per 100,000 population). The annual average number of TB (171 cases per 100,000 population), schistosomiasis (354 cases per 100,000 population), and VL (63 cases per 100,000 population) cases were much higher in Western zone compared to the rest of the zones. The incidence rate of rabies was higher in Mekelle and Southeastern (100 cases per 100,000 population) and Northwestern (97 cases per 100,000 population) zones. Intervention strategies applied in the region should take into account the zonal distribution and burden of NTZDs.

Prioritization of neglected tropical zoonotic diseases: A one health perspective from Tigray region, Northern Ethiopia.

Neglected tropical zoonotic diseases (NTZDs) continue to have a major effect on the health of humans and animals. In this study, a one health approach was used to prioritize and rank neglected tropical zoonotic diseases at the regional and zonal levels in Tigray National Regional State, Ethiopia. For prioritization of NTZDs a cross-sectional study through a structured questionnaire was administered to 313 health experts from human and animal health sectors. In addition, focus group discussions (FGD) were held with purposively selected key informants. Descriptive, and Multivariable analysis was applied to report the results and a ranked list of diseases was developed at the zonal and regional level. In the region, 8 of the 12 World Health Organization listed NTZDs were considered major diseases including anthrax, brucellosis, bovine tuberculosis, taeniasis, leishmaniasis, rabies, schistosomiasis, and soil-transmitted helminths. Considering the zoonotic and socioeconomic importance of the diseases at the regional level, rabies ranked 1stwhereas anthrax, bovine tuberculosis, leishmaniasis, and brucellosis were ranked from 2nd to 5th, respectively. The FGD result also supported the prioritization result. The Multivariable analysis showed a statistically significant difference in the zonal distribution of anthrax (р = 0.009, OR = 1.16), taeniasis (p<0.001, OR = 0.82), leishmaniasis (p<0.001, OR = 1.91), rabies (p = 0.020, OR = 0.79) and soil-transmitted helminths (p = 0.007, OR = 0.87) but not for brucellosis (p = 0.585), bovine tuberculosis (p = 0.505), and schistosomiasis (p = 0.421). Anthrax (p<0.001, OR = 26.68), brucellosis (p<0.001, OR = 13.18), and taeniasis (p<0.001, OR = 6.17) were considered as the major zoonotic diseases by veterinary practitioners than human health practitioners whereas, leishmaniasis was recognized as a major health challenge by human health professionals. Understanding the priority diseases in the region is supportive for informed decision-making and prioritizes the limited resources to use. Furthermore, strengthening the collaboration between human and animal health professions is important to control the diseases.

Outbreak investigation of an unknown gastrointestinal illness in District Victoria, Country Mala, 2016.

This case study is based on an outbreak investigation conducted by multisectoral team from animal and public health offices in Kaktong (a remote village in Zhemgang District Bhutan) during July-September 2010. This outbreak caused by ingestion of infected cow meat which had died after a brief illness (bleeding of unclotted blood from nostrils). The owner of the affected cow had opened the carcass and dressed the meat, which he shared or sold within the village for human consumption. It simulates an epidemiological investigation including active and passive case finding, descriptive and analytical epidemiology, laboratory confirmation, risk communication with implementation of control measures. This case study is designed for the training of front-line public health professional, basic, intermediate and advanced level field epidemiology trainees. The case study will build the capacity of the trainees regarding investigating illnesses caused by animal-human interface.