Taenia multiceps coenurosis: a review

Taenia multiceps is a taeniid cestode that inhabits the small intestines of both wild and domestic carnivores. The larval stage, Coenurus cerebralis, is typically found in the central nervous system (CNS) of a wide range of livestock and, to a lesser extent, in the extra-cerebral tissues of sheep and goats. This review covers all aspects of the life cycle of T. multiceps and its epidemiology, molecular characterization, pathogenesis, diagnosis, therapy, control and zoonotic potential. Coenurosis caused by the larval stage of T. multiceps has a worldwide distribution and is often fatal in intermediate hosts, which can result in substantial economic losses in livestock farming. Molecular characterization using the mitochondrial genes cytochrome c oxidase subunit 1 and nicotinamide adenine dinucleotide dehydrogenase subunit 1 of different T. multiceps populations has revealed significant genetic variation and the presence of three major haplotypes. The disease mostly affects young sheep and is referred to as either acute or chronic coenurosis. Acute coenurosis occurs as a result of oncospheres migrating through the CNS, while chronic coenurosis occurs as a consequence of the coenurus maturing, which causes displacement and pressure atrophy of brain tissue. Non-cerebral coenurosis has been most commonly reported in goats. The best diagnostic method for cerebral coenurosis involves the interpretation of clinical signs with accurate localization of the cyst using diagnostic imaging techniques. A vaccine based on recombinant oncosphere antigens has proved to be an effective tool against T. multiceps infection in sheep. Additionally, use of anthelmintics during the parasite's migration stages reduces the development of cysts in the sheep brain. Surgery is considered the most effective method for the treatment of cerebral coenurosis in small ruminants, but is often not carried out because of the limited finances of many sheep and goat breeders. However, coenurosis can also be controlled effectively through preventative measures, such as anthelmintic treatment of dogs and the proper disposal of intermediate host carcasses. The parasite is also zoonotic, and cases of coenurosis have been reported in humans with coenuri located in the brain, spinal cord and eyes.

Clinical, pathological, and CT scan findings of multiple Coenurus cerebralis cysts in a non-native lamb in Iran

Coenurus cerebralis is the larval stage of Taenia multiceps which involves particularly the central nervous system of humans and ungulates. A six-month-old Charollais lamb was presented with cortical blindness, dullness, convulsion, head deviation, reluctancy to move, drooling of saliva and ataxia. Haematological findings revealed an inflammatory process. CSF analysis showed leukocytosis associated with increased total protein. By CT imaging, nine cysts were detected in the cerebrum and one in the cerebellum. Hounsfield units were below 10 in all these regions. CT images perfectly revealed multiple Coenurus cysts in various parts of the brain, which was confirmed by necropsy. At necropsy, cysts of variable size were noted at different anatomical sites of the brain. In the cerebrum, atrophy, liquefactive necrosis and mild demyelination were presenty adjacent to the cystic structures. Perivascular and perineuronal oedema, neuronal degeneration, hyperaemia and thrombosis were also seen in the cerebrum. The meninges revealed oedema, thrombosis, and mononuclear meningitis. Based on authors’ knowledge, this is the first study in Iran on Coenurus cysts in a lamb brain utilising CT scan

Comparative Transcriptome Analyses of the Developmental Stages of Taenia multiceps

Cerebral coenurosis, caused by the larvae of Taenia multiceps (Coenurus cerebralis), is a fatal central nervous system disease in sheep and other herbivores and occasionally humans. Comparative transcriptomic profiles of the developmental stages of the parasite remain unknown. In this study, RNA sequencing was used to determine the transcriptome profiles of different stages of the life cycle of T. multiceps, including Oncosphere, Coenurus cerebralis (Pro with Cyst), and Adult (Adu), as well as scolex-neck proglottids (Snp), immature–mature proglottids (Imp), and gravid proglottids (Grp) of the adult stage. A total of 42.6 Gb (average 6.1 Gb) Illumina pair-end reads with a 125-bp read length were generated for seven samples. The total number of differentially expressed genes (DEGs) in the various life stages ranged from 2,577 to 3,879; however, for the tissues of the adult worm, the range was from 1,229 to 1,939. Kyoto Encyclopedia of Genes and Genomes analysis showed that the DEGs mainly participated in cellular and metabolic processes, binding and catalytic activity, genetic information processing, and environmental information processing. In addition, a large number of genes related to development and parasite–host interaction were identified. Quantitative reverse transcription-polymerase chain reaction confirmed that the levels of 28 selected DEGs were consistent with those determined using RNA sequencing. The present study provides insights into the mechanisms of the development and parasitic life of T. multiceps.

First Report on Molecular Characterization of Taenia multiceps Isolates From Sheep and Goats in Faisalabad, Pakistan

Coenurus cerebralis is the larval stage of Taenia multiceps commonly found in the brain (cerebral form), intramuscular and subcutaneous tissues (non-cerebral form) of ungulates. Globally, few reports exist on the molecular characterization and genetic diversity of C. cerebralis with none available for Pakistan. The current study molecularly characterized 12 C. cerebralis isolates surgically recovered from sheep (n = 4) and goats (n = 8) from a total of 3,040 small ruminants using a portion of the cytochrome c oxidase subunit 1 (cox1) mitochondrial (mt) gene. NCBI BLAST search confirmed the identity of each isolate. A high haplotype and a low nucleotide diversity with three haplotypes from the 12 isolates were observed. The findings suggest the existence of unique haplotypes of C. cerebralis in Pakistan. The negative value of Tajima's D and the positive value of Fu's Fs were inconsistent with population expansion, however, the sample size was small. Bayesian phylogeny revealed that all Pakistani isolates alongside the Chinese sequences (obtained from GenBank) constituted a cluster while sequences from other regions constituted another cluster. This is the first molecular study to determine the genetic diversity of C. cerebralis in Pakistan and serves as a foundation for prospective studies on the prevalence and population structure of C. cerebralis in the country. Furthermore, in this study, we amplified only a partial segment of the cox1 gene from a limited sample size. This could have implications on the interpretation of the actual population structure in reality. Thus, we recommend future studies to consider a larger sample size in a massive epidemiological survey for further insights.

Histopathological, immunohistochemical, and parasitological studies on pathogenesis of Coenurus cerebralis in sheep

Introduction

This study consisted in histopathological and immunohistochemical examinations of the central nervous system of 15 sheep suspected of infection with Coenurus cerebralis. The sheep displayed compulsive circling and were submitted for necropsy in 2012–2016.

Material and Methods

Species identification was made on the basis of the PCR analysis and parasitological examination of the cysts.

Results

Coenurus cerebralis cysts were detected only in the cerebral tissue of 13 sheep and in the cerebral and cerebellar tissues of 2 animals. Out of the 33 parasite cysts, most (21.21%) were located in the right and left frontal lobes of the cerebrum. The largest cyst measured 6 × 5 cm and the smallest cyst was 2 × 2 cm in size. The highest and lowest numbers of scolices were 55 and 21, and the number of rostellar hooks ranged between 22 and 30. Histopathological examination revealed the presence of typical parasitic granulomatous inflammatory foci. Immunohistochemical staining showed that most common in the periphery of the parasite cysts were, in descending order by cell number, GFAP, CD163, CD3, and CD79α-positive cells.

Conclusion

The study confirms the role of cellular defence mechanisms in the pathogenesis of Coenurus cerebralis infection in sheep.

Prevalence and Identity of Taenia multiceps cysts "Coenurus cerebralis" in Sheep in Egypt

Coenurosis is a parasitic disease caused by the larval stage (Coenurus cerebralis) of the canids cestode Taenia multiceps. C. cerebralis particularly infects sheep and goats, and pose a public health concerns. The present study aimed to determine the occurrence and molecular identity of C. cerebralis infecting sheep in Egypt. Infection rate was determined by postmortem inspection of heads of the cases that showed neurological manifestations. Species identification and genetic diversity were analyzed based on PCR-sequence analysis of nuclear ITS1 and mitochondrial cytochrome oxidase (COI) and nicotinamide adenine dinucleotide dehydrogenase (ND1) gene markers. Out of 3668 animals distributed in 50 herds at localities of Ashmoun and El Sadat cities, El Menoufia Province, Egypt, 420 (11.45%) sheep showed neurological disorders. Postmortem examination of these animals after slaughter at local abattoirs indicated to occurrence of C. cerebralis cysts in the brain of 111 out of 420 (26.4%), with overall infection rate 3.03% of the involved sheep population. Molecular analysis of representative samples of coenuri at ITS1 gene marker showed extensive intra- and inter-sequence diversity due to deletions/insertions in the microsatellite regions. On contrast to the nuclear gene marker, considerably low genetic diversity was seen in the analyzed mitochondrial gene markers. Phylogenetic analysis based on COI and ND1 gene sequences indicated that the generated sequences in the present study and the reference sequences in the database clustered in 4 haplogroups, with more or less similar topologies. Clustering pattern of the phylogenetic tree showed no effect for the geographic location or the host species.

Clinical, pathological and molecular evaluations and CT scan screening of coenurosis (Coenurus cerebralis) in sheep and calves

Abstract The aims of this study were to diagnose coenurosis by means of computerized tomography (CT) scan imaging and molecular characterization of the CO1 gene using the polymerase chain reaction (PCR). Sheep and calves were necropsied, and CT scans on the cephalic region were performed on the animals. Sections of brain tissue infected with parasites were then stained with hematoxylin and eosin for microscopic examination. Material collected from brain cysts was fixed in 70% ethanol. PCR amplification was carried out using the CO1 mitochondrial gene. A total of 60 calves and 80 sheep were examined clinically and, of these, 15 calves and 38 sheep showed signs of depression, with counterclockwise circling movements and altered head carriage. Four sheep and one calf were necropsied, and C. cerebralis cysts were detected in all of them. A hypodense cyst was monitored in the right cerebellar hemisphere on a CT scan on one sheep. A cyst was found in the left frontal lobe on a CT scan on one calf. Microscopically, C. cerebralis cysts were surrounded by a fibrous or epithelial wall that presented necrosis on cerebral sections of both the sheep and the cattle. The CO1-PCR assay yielded a 446 bp band, which was sequenced and phylogenetically analyzed: the results confirmed the presence of T. multiceps. This study reports the first use of CT imaging on naturally infected calves and sheep for diagnosing coenurosis.

Efficacy of albendazole against Taenia multiceps larvae in experimentally infected goats

A controlled trial was conducted to evaluate the efficacy of three therapeutics regimes of albendazole (ABZ) against Taenia multiceps larvae in experimental infected goats. Forty-nine goats experimentally infected with 3000 T. multiceps eggs were selected and randomly divided into treatment or control groups. Treatment with 10mg/kg for 3 days for group 1 (G1), 10mg/kg for group 2 (G2) and 20mg/kg/day for group 3 (G3) was applied 2 months after infection; group 4 (G4) served as a control group. A treatment with doses of 10mg/kg/day for 3 days on group 5 (G5) and group 6 (G6) was used as control, 5 months after the infection. The efficacy of ABZ was assessed as percentage of non-viable cysts which were determined by morphologic characteristics, movement and methyl blue staining technique. The efficacy of ABZ against 2 months old cysts was significantly different from the control and were 90.3% (28/31), 72.7% (8/11) and 73.9% (14/19) for G1, G2 and G3, respectively. No differences were observed in cyst viability between treated and control groups for 5-month old cysts. The results in this study indicate that ABZ is effective in goats against 2-month-old cysts of T. multiceps larva located in tissues outside the brain.

Taenia multiceps brain cyst removal in two wild Nubian ibex (Capra nubianas)

Two wild adult Nubian ibex (Capra nubiana) were captured and admitted to the Hebrew University Veterinary Teaching Hospital with various neurologic signs, including alerted mentation, head tilt, and pathologic nystagmus. The lesion in the central nervous system was localized to the forebrain in one ibex and to the cerebellum of the other. Both ibex's were diagnosed with brain cyst using computed tomography (CT). Craniectomy was performed to remove the cysts, and both animals returned to their natural environment after a rehabilitation period. Parasitologic examination revealed cysts of Taenia multiceps coenurus. This is the first report to describe the neurologic signs, CT findings, surgical procedure, and follow-up postsurgery information in wild Capra nubiana.

Cloning and characterization of the fatty acid-binding protein gene from the protoscolex of Taenia multiceps

Taenia multiceps (Cestoda: Taeniidae), a worldwide cestode parasite, is emerging as an important helminthic zoonosis due to serious or fatal central nervous system disease commonly known as coenurosis in domestic and wild ruminants including humans. Herein, a fatty acid-binding protein (FABP) gene was identified from transcriptomic data in T. multiceps. This gene, which contains a complete coding sequence, was amplified by reverse-transcriptase polymerase chain reaction. The corresponding protein, which was named TmFABP, had a molecular weight of 14 kDa, and subsequently was recombinantly expressed in Escherichia coli. The fusion protein was purified on Ni-NTA beads (Bio-Rad). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot analyses showed that the purified recombinant protein caused immunogenicity. Immunohistochemical studies showed that TmFABP was expressed at the tegumental level in the protoscolices and in the cells between the body wall and parenchyma layer of the cestode. In sections from gravid proglottids, intense staining was detected in the uterus and eggs. Based on this, TmFABP could be switched on during differentiation of germinative layers to protoscoleces and from metacestodes to adult worms. Taken together, our results already reported for T. multiceps suggest the possibility of TmFABP developing a vaccine to control and prevent coenurosis.