Recently, there have been epidemics of human cystic echinococcosis (CE) and alveolar echinococcosis (AE) in Kyrgyzstan. This study investigated 2 districts for the presence of Echinococcus granulosus s.l. and Echinococcus multilocularis eggs; species identity was confirmed by polymerase chain reaction in dog feces and the level of environmental contamination with parasite eggs in 2017–2018 was also investigated. In the Alay district 5 villages with a high reported annual incidence of AE of 162 cases per 100 000 and 5 villages in the Kochkor district which had a much lower incidence of 21 cases per 100 000 were investigated. However, the proportion of dog feces containing E. granulosus s.l. eggs was ~4.2 and ~3.5% in Alay and Kochkor respectively. For E. multilocularis, the corresponding proportions were 2.8 and 3.2%. Environmental contamination of Echinococcus spp. eggs was estimated using the McMaster technique for fecal egg counts, weight and density of canine feces. The level of environmental contamination with E. multilocularis eggs was similar at 4.4 and 5.0 eggs per m2 in Alay and Kochkor respectively. The corresponding values for E. granulosus s.l. were 8.3 and 7.5 eggs per m2. There was no association between village or district level incidence of human AE or CE and the proportion of dog feces containing eggs of Echinococcus spp. or the level of environmental contamination. Increased contamination of taeniid eggs occured in the autumn, after the return of farmers with dogs from summer mountain pastures.

Three recombinant Taenia ovis antigens (To45, To16, To18) each induce protective immunity in lambs or ewes against infection with T. ovis metacestodes. The degree and duration of immunity were assessed in lambs born from vaccinated ewes. Treatment group sizes varied, typically not fewer than 5 animals per group. Ewes were immunised with one T. ovis recombinant protein prior to lambing and the degree and duration of passive immunity in their lambs was assessed by challenge infection up to 18 weeks. Lambs were fully protected up to 6 weeks of age but immunity waned from 6 to 12 weeks and there was no protection when lambs were challenged at 15 weeks. Immunisation of lambs with the homologous recombinant antigen was not effective when vaccinations were given when maternal antibody was high. Lambs were effectively immunised in the presence of passively protective antibody when vaccinated with an antigen that was different to that given to ewes. Vaccination of lambs with a combination of two proteins, To16 and To18, was more effective than giving these single antigens and gave a significant reduction of cyst numbers when lambs were challenged 12 months after immunisation. These results indicate that the use of combinations of T. ovis recombinant antigens could enable complete protection of lambs against infection, if a delivery system becomes available that will maintain antibody at protective levels for 12 months. Alternatively, a third injection given at 6 months may promote the anamnestic response to give long lasting protection.

Taenia ovis larvae can result in economic losses in small ruminants due to condemnation of infected tissues or whole carcasses. From 2017 to 2018, the T. ovis prevalence in 16,180 sheep and 7560 goats at the Najafabad slaughterhouse in Isfahan was determined. More sheep (477; 2.9%) than goats (90; 1.2%) were found to be infected, and the prevalence was higher in animals <1 y (p < 0.0001), and higher in spring in sheep (8.2%) and goats (2.2%). Female sheep were more frequently infected than males (p < 0.0001); this did not hold true for goats. Of the tissues examined, T. ovis was found more often in the heart muscle of sheep compared with other tissues; however, infections in the heart muscle, masseter muscle, diaphragm, and triceps were similar in goats. Granulomas and caseous necrosis in the heart muscles were associated with the accumulation of mononuclear inflammatory cells and the formation of fibrous tissue around the parasite. Based solely on infected tissues found in this study, the economic loss caused by the presence of T. ovis larvae was estimated to be 4167 United States dollars (USD). Control methods, such as proper disposal of infected tissues and anthelmintic treatment of infected dogs, are necessary to decrease infection and prevent economic loss in small ruminants.

Little is known about the genetic and morphological characters of Taenia ovis. The purpose of the present study was to characterize sheep isolates of T. ovis using rostellar hook morphometry as well as mitochondrial genes sequence analysis. Ninety sheep specimens of Cysticercus ovis were collected from 18 slaughterhouses in Iran. The mean ± s.d. for total length of large and small hooks were 174.1 ± 6.4 and 116.7 ± 5.4 µm, respectively. CO1 and 12S rRNA sequence analysis showed 11 and nine haplotypes, respectively. The level of pairwise nucleotide variations between individual haplotypes of CO1 and 12S rRNA genes were 0.3-1.1 and 0.2-1.0%, respectively. Level of nucleotide variation in CO1 and 12S rRNA between T. ovis haplotypes from present study and eight other Taenia species was found to be 11.3-17.8 and 5.3-16.3%, respectively. Phylogenetic analysis clustered all T. ovis isolates into a single clade comprised of the all CO1 and 12S rRNA haplotypes. CO1 nucleotide difference between T. ovis ovis and T. asiatica was 13.6% that is lesser than the corresponding difference between T. ovis ovis and T. ovis krabbei, warranting the designation of two separate species as T. ovis and T. krabbei. Interclass correlation coefficients showed that there was no significant association between rostellar hook length variation and the variability of the mitochondrial genes.

Data on several infections of sheep and goats, including parasite infections, are routinely collected during inspection of harvested rangeland goats after slaughter. This is an important role of the Australian National Sheep Health Monitoring Program (NSHMP). Our study investigated the presence of metacestodes of Taenia hydatigena, T. ovis and Echinococcus granulosus in slaughtered goats from Queensland, New South Wales and Western Australia. During the period of the study (2007-2013) 374,580 goats were slaughtered and inspected by trained abattoir meat inspectors as part of the NSHMP. Taenia hydatigena was found most commonly, followed by T. ovis. Despite one probable false positive, the surveyed population of goats was demonstrated to be free of infection by E. granulosus at a design prevalence of 0.1%. In areas where goats, foxes and wild dogs (dingoes [Canis lupus dingo] and dingo/domestic dog [Canis lupus] hybrids) co-exist they could be perpetuating the transmission of T. hydatigena and T. ovis as a wildlife reservoir. Rangeland goats do not appear to be an intermediate host for E. granulosus. Despite having similar lifecycles, T. hydatigena and T. ovis appeared to occur with different geographical patterns. This is the first time rangeland goats have been investigated for infection with taeniid metacestodes in such large numbers and over a wide geographical area.

We report Taenia ovis infection in Danish sheep for the first time. In spring 2016, the metacestode stage of T. ovis was at slaughter observed in heart muscles, diaphragm and skeletal muscles from approx. a third of all sheep from one specific farm localised in South Jutland. The diagnosis was confirmed by molecular typing of the mitochondrial cytochrome c oxidase I (cox1) gene. Three newly imported dogs were suspected but the definitive host was unidentifiable. The finding is not regulated in the meat control procedures. However, infected meat is usually condemned due to aesthetic reasons causing economic losses. Thus, finding of T. ovis is of concern to sheep meat producers in the area, as the infection could have spread further on to other farms.

Taenia ovis is a tapeworm that is mainly transmitted between dogs and sheep or goats and has an adverse effect on sheep industry. miRNAs are short regulatory non-coding RNAs, involved in parasite development and growth as well as parasite infection. The miRNA profile of T. ovis remains to be established. Herein, 33 known miRNAs belonging to 23 different families were identified in T. ovis metacestodes using deep sequencing approach. Of them, expression of some miRNAs such as tov-miR-10 and -let-7 was absolutely predominant. Moreover, comparative analysis revealed the presence of a miR-71/2b/2c cluster in T. ovis, which was also completely conserved in other 6 cestodes. The study provides rich data for further understandings of T. ovis biology.

Taenia ovis metacestodes reside in the muscle of sheep and goats, and may cause great economic loss due to condemnation of carcasses if not effectively controlled. Although advances have been made in the control of T. ovis infection, our knowledge of T. ovis biology is limited. Herein the protein profiling of T. ovis metacestodes was determined by liquid chromatography-linked tandem mass spectrometry. A total of 966 proteins were identified and 25.1% (188/748) were annotated to be associated with metabolic pathways. Consistently, GO analysis returned a metabolic process (16.27%) as one of two main biological process terms. Moreover, it was found that 24 proteins, including very low-density lipoprotein receptor, enolase, paramyosin and endophilin B1, were abundant in T. ovis metacestodes. These proteins may be associated with motility, metabolism, signaling, stress, drug resistance and immune responses. Furthermore, comparative analysis of 5 cestodes revealed the presence of Taenia-specific enolases. These data provide clues for better understanding of T. ovis biology, which is informative for effective control of infection.

Taenia ovis is a tapeworm that is mainly transmitted between dogs and sheep. Although T. ovis infection is not a public health issue, it causes a great financial loss due to condemnation of carcasses.  The first outbreak of T. ovis infection in China occurred in 2015. Reassessment of adverse effects of T. ovis infection on Chinese sheep industry in future is necessary.
The first T. ovis outbreak in China suggests that the epidemic situation across the country is underestimated. For the transmission of T. ovis, many factors, including eggs, dogs and wild canids, human behaviours and sheep trade, should be seriously considered. In blocking the transmission chain, regular treatments of the infected dogs using anthelmintics play a crucial step, but at the moment it is difficult to be fully executed in China, largely due to the behaviours, customs and faith of local farmers. Moreover, combined with no clinical symptoms in the infected adult sheep and goats, the lack of pre-mortem diagnostic tools makes it harder to practice a national wide surveillance as well as inspection and quarantine in increasingly frequent free sheep trade activities in China, leading to an inability to restrict T. ovis infection into small areas. Furthermore, the ongoing campaigns against Echinococcus granulosus may have an adverse effect on control of T. ovis infection because of no consideration of a role of dogs in the transmission of the parasite.
Lack of national epidemic data, pre-mortem diagnostic reagents and vaccines severely hampers the implementation of disease control campaigns and the restriction of T. ovis infection into small areas. Consequently, sheep and goats are at an increasing risk of T. ovis exposure and the possibility of large-scale outbreaks across China in future is possible, causing great adversity towards sheep industry.

Infection of Taenia ovis metacestodes in sheep or goats causes great economic losses due to condemnation of carcasses. T. ovis infection is not formally recorded in China to date. In October, 2015, T. ovis infection occurred in Jingtai County, China, and 113 of 192 sheep from one farm were infected. Cysts resided in the cardiac and skeletal muscle, and evaginated metacestodes had four suckers and scolex armed with approximately 23 hooks. Using cox1 and nad1 as molecular markers, the sample was further identified and the results showed that the cox1 and nad1 nucleotide sequences of the sample shared 99% identity with that of T. ovis and 75%-91.3% with those of other Taenia species. Taken together, these results confirm the first occurrence of T. ovis in China.