Cystic echinococcosis in the sheep: causes of its persistence in Sardinia

Epidemiological and Molecular Characterization of Echinococcus granulosus Isolated from Small Ruminants in Kashmir Valley, India

BACKGROUND

Cystic Echinococcosis (CE) is an emergent or re-emergent zoonosis and remains a public health and economic problem all over the world.

METHODS

The present study was carried on the prevalence and genotypes of Echinococcus present in small ruminants in Kashmir valley. A total of 2100, sheep (2052) and goats (48), slaughtered or spontaneously dead, from various areas of Kashmir valley were screened for the presence of hydatidosis. In case of goat none of the cases were found positive for hydatidosis, whereas, all the positive cases (85) were recorded in sheep only. The overall prevalence of hydatidosis was 4.04%. The prevalence was higher in female sheep (5.46%) compared to males (2.83%). Season-wise highest prevalence was in summer (4.55%), followed by autumn (4.1%), spring (3.89%) and winter (2.5%).The liver was observed to be the most frequently infected organ with relative prevalence of 61.17% followed by lungs (38.82%).The rDNA-ITS1 fragment of positive samples was amplified with BD1 / 4S primers.

RESULTS

The length of amplified fragment for all isolated samples was 1000bps. The products obtained on PCR were digested with four restriction enzymes (Rsa 1, Alu 1, Msp 1 and Taq1). Rsa 1, Alu 1, Msp 1 yielded identical fragments, 300 and 700 bp in sheep. TaqI restriction enzyme had no effect on PCR product and after digestion; intact 1000bps fragment was seen.

CONCLUSION

Phylogenetic analysis of ITS1 gene revealed that the common sheep strain (G1) is the predominant genotype in sheep in Kashmir valley.

Cystic echinococcosis in the endemic island of Sardinia (Italy): has something changed?

Cystic echinococcosis (CE) is a disease of livestock and humans caused by the larval stage of the Echinococcus granulosus sensu lato (s.l.) species complex and occurs especially in areas where sheep breeding is widespread. This survey evaluates, after more than a decade since the last epidemiological survey, the current situation and trend of CE in sheep of the highly endemic island of Sardinia (Italy). From 2012 to 2018, out of a total of 1416 sheep, 65.3% were found positive for CE. Cyst fertility has increased slightly from 10.3% in 2006 (Scala et al. 2006) to 11.7% in the present survey (χ2 = 1.07; P = 0.30018) with a peak of 14.0% in the province of Sassari. Overall, 6815 hydatids were found and classified as sterile (26.2%), fertile (14.4%), caseous (5.3%), or calcified (54.1%) based on their morphology. All isolates were identified as E. granulosus sensu stricto (former G1/G3, strains). Results shown as the implementation of new European Council Regulations and in particular of 21/2004 that established a system for the individual identification and tracking of sheep could be a step forward towards a better control of animal movement, preventing illegal slaughtering on the island as well as in other countries experiencing similar problems. Even if at first sight the general situation of Sardinia regarding CE seems a little better compared with the past, our findings indicate that in some Provinces the epidemiological situation is not improved since 2006.

A study of morphological aspects of cystic echinococcosis in sheep in Sardinia

We have investigated the morphological and structural aspects of hydatid cysts recovered from sheep raised in southern Sardinia during two surveys conducted over the 20 years since the last control attempt at the end of the 1980s. In the first study carried out during 1995-1997, a few years after the last control attempt, a total of 10,334 cysts were examined, recovered from 1029 infected sheep out of a total of 1375 inspected (prevalence 74.84%). In the second survey, conducted ten years later during the period 2005-2010 in the absence of specific control measures, a total of 6249 cysts were recovered from 916 parasitized sheep out of the 1414 examined (prevalence 64.78%). Cysts were grouped into 5 different types: "Unilocular", "Multisepted", "Calcified", "Caseous", "Hyperlaminated". Unilocular: fertile, consist of a single fluid-filled cavity; multisepted: generally sterile, fluid filled, with cavity divided into spheroidal chambers (3-dozen); calcified: sterile, small, with internal chambers almost virtual due to the thickening of internal septa; caseous: sterile, the cavity filled with a thick yellowish matrix; hyperlaminated: sterile, with a virtual cavity filled with extensively folded and overlapping sheets of hyperproduced laminated tissue. A thorough knowledge and the precise characterization of each type of lesion, making it possible to establish detailed parameters for cyst classification, appears very useful for the harmonization of data collection. From a surveillance and control perspective it is proposed that, in addition to other relevant epidemiological information, data from meat inspection be further improved, including morpho-functional indications about cyst type.

A preliminary investigation into the genetic variation and population structure of Taenia hydatigena from Sardinia, Italy

Cysticercosis caused by the metacestode stage of Taenia hydatigena is endemic in Sardinia. Information on the genetic variation of this parasite is important for epidemiological studies and implementation of control programs. Using two mitochondrial genes, the cytochrome c oxidase subunit 1 (cox1) and the NADH dehydrogenase subunit 1 (ND1) we investigated the genetic variation and population structure of Cysticercus tenuicollis from Sardinian intermediate hosts and compared it to that from other hosts from various geographical regions. The parsimony cox1 network analysis indicated the existence of a common lineage for T. hydatigena and the overall diversity and neutrality indices indicated demographic expansion. Using the cox1 sequences, low pairwise fixation index (Fst) values were recorded for Sardinian, Iranian and Palestinian sheep C. tenuicollis which suggested the absence of genetic differentiation. Using the ND1 sequences, C. tenuicollis from Sardinian sheep appeared to be differentiated from those of goat and pig origin. In addition, goat C. tenuicollis were genetically different from adult T. hydatigena as indicated by the statistically significant Fst value. Our results are consistent with biochemical and morphological studies that suggest the existence of variants of T. hydatigena.

Epidemiological updates and economic losses due to Taenia hydatigena in sheep from Sardinia, Italy

The aim of this study was to investigate the epidemiology and transmission of Taenia hydatigena in sheep and dogs from Sardinia and the economic estimation of losses due to this metacestodosis in lambs. A total of 7781 Sarda breed lambs were examined at abattoirs for the detection of Cysticercus tenuicollis or necrotic-haemorrhagic tracks of their migration. Morphological and molecular identification of parasites was carried out. Individual faecal samples from 300 dogs were examined for copromicroscopic investigations and coproELISA assay. An overall prevalence of 14.6% for T. hydatigena cysticercosis was found in the examined lambs. In total, 10,807 parasitary tracks were found, with an abundance of 1.39 and an average intensity of 9.52. The molecular analysis of the isolates showed an overall pairwise nucleotide divergence for the CO1 and ND1 was of 0-3.1 and 0-3.3%, respectively. Low intra- and interspecific variation was recorded for C. tenuicollis isolates used in this study which suggested the absence of differentiation. Microscopic examination of dog faeces showed a total prevalence of 31.3% for endoparasites in the examined samples (94/300). Taeniid eggs were found in 8.3% of the dogs. The results of the monoclonal antibody ATH4 ELISA test showed a prevalence of 11% (33/300) for T. hydatigena coproantigens. The total economic costs related to cysticercosis amounted to almost € 330,000. The prevalence of C. tenuicollis in 14.6% of 30-40-day-old lambs highlights the high parasitic pressure by T. hydatigena in the territory of Sardinia, Italy.

Cystic echinococcosis in sheep in Sardinia. Changing pattern and present status

The epidemiological status of cystic echinococcosis (CE) in sheep in Sardinia over the 20 years since the last control attempt at the end of the 1980s has been assessed, comparing the results of two surveys carried out in abattoirs in southern Sardinia. In the first, conducted in 1995-1997 (5-7 years after the last control effort), CE prevalence of about 75% was observed in the 1375 sheep sampled, with intensity of 10.0 and mean abundance of 7.5. The most affected organ was the liver, whereas a large percentage of infected animals presented cysts in both the liver and lung. Overall, about 26% of parasitized sheep were found to be heavily infected and 12.15% of infected animals harboured fertile cysts. In the second survey, carried out ten years after the first, during the period 2005-2010 in absence of specific control measures, a total of 1414 sheep were examined. CE prevalence was 65%, 78% in the most rural Oristano province and 58% in the most "urbanised" province of Cagliari. Frequency of sheep infected in both the liver and lung had decreased slightly compared to the first survey, particularly in the Cagliari province, as had intensity and mean abundance, though to a lesser extent in the Oristano province. 14.6% of parasitized sheep were heavily infected, showing a general decline over the 10 years between the two surveys, particularly in the Cagliari area where the figure had more than halved. Conversely, about 14% of infected sheep hosted at least 1 fertile cyst, a slight increase compared to the 1st survey. Finally, the trend of CE transmission in Sardinian sheep according to surveys carried out from 1952 to 2010 has been analysed and the results are discussed in the light of the significant socio-economic and structural transformations that have actually modified the zoonosis scenario on the island.

A retrospective analysis of human cystic echinococcosis in Sardinia (Italy), an endemic Mediterranean region, from 2001 to 2005

To assess the current impact of human CE in Sardinia (Italy) and to monitor the changes over time, a survey has been carried out for the period 2001-2005 using hospital inpatient discharge reports (HDR) as information source, supplementing data wherever possible with additional information retrieved directly from medical records. The total of 726 admissions with "Echinococcosis" as primary diagnosis (annual rate of 8.9 per 100,000 inhabitants) concerned 540 CE cases with an annual mean incidence rate of 6.62 per 100,000 inhabitants. Male-to-female ratio was 1.36, suggesting a marked risk associated with traditional male occupations. Age-specific incidence showed increasing rates of clinical CE with age for both genders. The liver was found to be the most common localization, affecting 72% of patients, while pulmonary CE was more frequent in males than in females. CE risk was unevenly distributed in the island. The more pastoral areas had the highest probability of humans becoming infected, with an incidence rate of clinical cases of approximately 14.0 per 100,000 for areas with sheep/inhabitants index of >6. Compared to the past, incidence rates appear to be decreasing both for pulmonary and hepatic localizations, while there is a reversal of the CE "urbanization" trend resulting in "ruralization", accompanied by a greater degree of parasite ecological "isolation" and focus-points of infection risk. In spite of this decrease, the cost of hospital care alone (approximately 4 million euros) suggests that the monetary plus non-monetary costs of CE are still very high but not fully recognised.