Comparative molecular characterization and phylogenetic analysis of cerebral and non-cerebral coenurosis in Indian goats.

Coenurus cerebralis is the larval stage of Taenia multiceps, which infects the muscles and brain of goats and, to a lesser extent, sheep. The resulting cerebral and non-cerebral infections caused by the larval form (metacestode) of this cestode are commonly known as coenurosis. A weak emaciated carcass of five months old female goat, on necropsy, revealed numerous parasitic cysts (n = 56, grossly visible) in the visceral cavity including heart, diaphragm, thoracic cavity, abdominal cavity and pelvic inlet. A large number of variable sized parasitic cysts were also observed embedded in the pericardium and myocardium causing functional damage to the heart. The parasite caused extensive tissue damage at gross and microscopic levels in the heart including traumatic destruction of the myocardium with degenerative and necrotic changes and infiltration of mononuclear cells. On parasitological examination, the cysts were identified as Coenurus cerebralis, as the scolices had characteristic four suckers and a rostellum with a double crown of hooks. Further confirmation was done using polymerase chain reaction targeting specific ND1 and CO1 genes. Phylogenetic analysis of CO1 and ND1 genes showed a major branch comprising two clades of T. multiceps grouped as separate entities with the first clade showing T. multiceps/Coenurus cerebralis native CIRG strain (cerebral) being placed in proximity to T. multiceps/Coenurus cerebralis CIRG strain (non-cerebral/visceral) compared to the Chinese strains of T. multiceps. The phylogenetic analysis of ND1 and CO1 genes of C. cerebralis of cerebral and non-cerebral isolates revealed close proximity but expressed in two different disease forms (i.e., visceral coenurosis and neural coenurosis) which indicated that they were very close divergent from a common ancestor. On the basis of the observations it was concluded that goat died due to cardiac dysfunction resulting from severe systemic infection of metacestode of T. multiceps was closely related to isolate that caused neural coenurosis in another goat. Based on the sequencing analysis and phylogenetic information, the possible differences in the clinical manifestation (neural or visceral) could be attributed to the pathogenesis.

Cerebral and non-cerebral coenurosis: on the genotypic and phenotypic diversity of Taenia multiceps.

We characterised the causative agents of cerebral and non-cerebral coenurosis in livestock by determining the mitochondrial genotypes and morphological phenotypes of 52 Taenia multiceps isolates from a wide geographical range in Europe, Africa, and western Asia. Three studies were conducted: (1) a morphological comparison of the rostellar hooks of cerebral and non-cerebral cysts of sheep and goats, (2) a morphological comparison of adult worms experimentally produced in dogs, and (3) a molecular analysis of three partial mitochondrial genes (nad1, cox1, and 12S rRNA) of the same isolates. No significant morphological or genetic differences were associated with the species of the intermediate host. Adult parasites originating from cerebral and non-cerebral cysts differed morphologically, e.g. the shape of the small hooks and the distribution of the testes in the mature proglottids. The phylogenetic analysis of the mitochondrial haplotypes produced three distinct clusters: one cluster including both cerebral isolates from Greece and non-cerebral isolates from tropical and subtropical countries, and two clusters including cerebral isolates from Greece. The majority of the non-cerebral specimens clustered together but did not form a monophyletic group. No monophyletic groups were observed based on geography, although specimens from the same region tended to cluster. The clustering indicates high intraspecific diversity. The phylogenetic analysis suggests that all variants of T. multiceps can cause cerebral coenurosis in sheep (which may be the ancestral phenotype), and some variants, predominantly from one genetic cluster, acquired the additional capacity to produce non-cerebral forms in goats and more rarely in sheep.

Experimental cerebral and non-cerebral coenurosis in goats: A comparative study on the morphological and molecular characteristics of the parasite.

This experimental study was conducted to test whether cerebral and non-cerebral forms of Coenurus cerebralis belong to one origin or they are originated from two different tape worms. In the first step of the study, two groups of dogs were orally infected with the protoscoleces of cerebral and non-cerebral cysts and four months after infection, the adult worms were collected and morphologically characterized. Then the obtained eggs from two groups of adult worms were orally inoculated to two groups of goats to trace the predilection sites and also to compare the morphological and molecular characteristics of the larval stage of the parasites. The results showed that, both cerebral and non-cerebral coenuri, produced morphologically similar worms in the experimentally infected dogs. We observed only non-cerebral coenurus cysts in two groups of experimentally infected goats and the morphological characteristics of the cysts of two different groups were also similar. The molecular findings also showed that the cysts of two groups were 100% identical to each other based on the CO1 and nad1 sequences. In conclusion, our morphological and molecular findings reinforce the evidence that Taenia multiceps is the single origin of both cerebral and non-cerebral form of C. cerebralis but in goats, the cysts show more tendency to non-cerebral organs.

Characteristics of non-cerebral coenurosis in tropical goats.

The epidemiological, clinical, and biochemical profile of non-cerebral coenurosis in goats and the morphological characteristics of the responsible metacestodes (cysts) were examined in a cross-sectional survey of slaughtered goats in abattoirs of the United Arab Emirates (U.A.E.) originating from Abu Dhabi and various tropical countries. The age, country of origin, and location of each cyst in the body of goats were recorded. Blood samples collected from infected and matching healthy goats were subjected to biochemical analysis. Data on the morphological characteristics of the cysts as well as the clusters, scoleces, and rostellar hooks in one cyst from each affected carcass were collected. The data collected were subjected to statistical analysis. A total of 2,284 slaughtered goats were examined and 40 goats were diagnosed as infected with non-cerebral coenurus cysts. The prevalence of non-cerebral coenurosis was 1.75% and the degree of parasite aggregation (k) was 0.003, which is indicative of overdispersion (k<1). The only abnormalities observed in the infected goats were palpation of large single cysts in thigh muscles and higher serum aspartate aminotransferase (AST) value. A total of 76 non-cerebral coenurus cysts from 14 different body locations were collected. No cysts were found in the brain or spinal cord. Cysts located in psoas muscles had on average significantly bigger volumes and higher numbers of scoleces and clusters compared to cysts located in other body parts (P-value=0.000). Significant differences in the morphometric measurements of the rostellar hooks were observed between cysts found in goats from different countries of origin (P-value<0.05) perhaps due to initial steps of allopatric speciation by geographic isolation. A significant positive correlation was found between number of scoleces and volume of cysts (b=6.37>5; R-Sq=89.4%; P-value=0.000) and between number of clusters and number of scoleces (b=25.13>1; R-Sq=79.8%; P-value=0.000) indicative of following a positive allometric growth as well as between number of clusters and volume of cysts (b=0.25<0.5; R-Sq=69.4%; P-value=0.000) indicative of following a negative allometric growth. The biological significance of the observed allometries is not known, but perhaps for evolutionary reasons the parasite is investing its resources more on the growth of scoleces, less on the growth of cyst volume, and even less on the number of clusters.