Genotype and Phenotype of Echinococcus granulosus Derived from Wild Sheep (Ovis orientalis) in Iran

Echinococcus species in wildlife

Transmission of Echinococcus spp. in life cycles that involve mainly wildlife is well recognized for those species with small mammals as intermediate hosts (e. g. E. multilocularis), as well as for E. felidis and the 'northern' genotypes of E. canadensis (G8 and G10). In contrast, the remaining taxa of E. granulosus sensu lato are best known for their domestic life cycles, and the numerous wild mammal species (mainly ungulates) that have been recorded with cystic echinococcosis in the past were mainly considered a result of spill-over from the dog-livestock transmission system. This view was challenged with the advent of molecular characterization, allowing discrimination of the metacestodes, although the contribution of wild mammals to various Echinococcus life cycles has remained uncertain for scarcity of wildlife studies. Numerous records of cysts in wild ungulates date back to the 20th century, but cannot with certainty be allocated to the Echinococcus species and genotypes that are recognized today. This means that our current knowledge is largely restricted to studies of the past two decades that kept adding gradually to our concepts of transmission in various geographic regions. In particular, new insights were gathered in the past years on E. granulosus s.l. in wildlife of sub-Saharan Africa, but also on transmission patterns of E. multilocularis in previously neglected regions, e. g. North America. Here, an update is provided on the current state of knowledge on wild mammals as hosts for all Echinococcus species, listing >150 species of wild hosts with references, as well as estimates on their epidemiological impact and our current gaps of knowledge.

Echinococcus granulosus comparative genotyping in sheep in Saudi Arabia and Egypt

Background

Cystic echinococcosis (CE), which is triggered by the parasite Echinococcus granulosus, is a global zoonotic disease that is common in rural regions in which there are frequent encounters between dogs and other domestic animals. The disease can have devastating consequences, impacting the health of people and animals and leading to huge financial losses, especially in the agricultural industry. In the Kingdom of Saudi Arabia (KSA) and Egypt, despite the high incidence of disease, few investigations have been conducted into the genetic variation in species of the genus Echinococcus.

Aim

This study sought to compare the genetic features of the hydatid cysts carried in sheep in KSA with those found in Egypt.

Methods

DNA from the protoscolices was used in a PCR targeting the mitochondrial NADH dehydrogenase 1 (NAD1), cytochrome c oxidase subunit 1 (COX1), and nuclear actin II (ACT II) genes, and the resulting amplification products of 30 KSA and Egyptian isolates were sequenced and compared.

Results

Among the sheep in KSA, the overall prevalence of CE was 0.51%. Of the sheep cyst DNA samples, 95%, 100%, and 52% were positive for the Cox1, nad1, and act II genes, respectively. Targeting all three genes, all KSA samples belonged to the E. granulosus genotype (G1), whereas all Egyptian isolates belonged to E. granulosus (G1) and E. canadensis (G6).

Conclusion

We conclude that isolates of E. granulosus from the two countries shared a common origin in Arabic North Africa, with sheep and camels as common hosts.

Echinococcoses in Iran, Turkey, and Pakistan: Old Diseases in the New Millennium

Echinococcosis is considered a cosmopolitan zoonosis caused by different species of small taeniid tapeworms of the genus Echinococcus and is regarded as a neglected zoonosis. Cystic and alveolar echinococcoses are endemic diseases of Tibetan, Pamir, and Iranian plateaus. All of the countries within the Iranian plateau are affected by echinococcosis. Pakistan, Turkey, and Iran are the three most populous countries of the region, in which echinococcosis is highly endemic. The three neighboring countries share strong cultural and socioeconomic ties. The present study aimed to provide a broad review of the status of cystic and alveolar echinococcosis, summarizing the current knowledge about geographical distribution, molecular epidemiology, and transmission dynamics of Echinococcus granulosus sensu lato and Echinococcus multilocularis in this region. Additionally, we aimed to understand disease burden and risk factors as basic requirements for establishing a surveillance system and planning prevention and control programs. A considerable body of information is available on different aspects of echinococcosis in this region; however, several information and research gaps need to be filled before planning control programs. None of the countries in the region have an elaborate echinococcosis control program. Effective control programs require multi/intersectoral coordination within a One Health approach with a long-term political and administrative commitment and enhanced international collaboration among the three countries.

Molecular characterization of Echinococcus granulosus in livestock of Al-Madinah (Saudi Arabia)

Echinococcus granulosus is the causative agent of cystic echinococcosis, which has serious impacts on human and/or animal health, resulting in significant economic losses. Echinococcus granulosus comprises a number of intra-specific variants or strains at the genetic level. In Saudi Arabia, few studies were performed on genetic variations in Echinococcus species. Therefore, the present study aimed to investigate the phenotypic and genetic characterization of hydatid cysts harboured by sheep and camels in Al-Madinah Al-Munawarah. Samples of hydatid cysts were collected from local sheep (n = 25) and camels (n = 8). The morphological criteria of protoscoleces were investigated. To investigate the molecular characterization, random amplified polymorphic DNA polymerase chain reaction (RAPD-PCR), single-stranded conformation polymorphism (SSCP) were carried out. DNA was extracted from individual fertile cysts and subjected to RAPD-PCR analysis (using five arbitrary primers) and PCR amplification of cytochrome c oxidase I (cox1) and 12S ribosomal ribonucleic acid (12S rRNA) genes. The PCR products were subjected to SSCP analysis for genetic discrimination in E. granulosus isolates. In addition, partially sequencing of the mitochondrial DNA cox1 genes was achieved for assessing the phylogenetic positions of collected isolates using some global published sequence data of cox1 genes. The rostellar hooks of camel and local sheep isolates show remarkable variability in their dimensions. Five distinct SSCP patterns were identified in the 12S rRNA gene, showing intraspecific variations in E. granulosus of camels and local sheep. Sequencing of (cox1) genes of both local sheep and camels exhibit high similarity with those of the same gene (E. granulosus sensu stricto) published in NCBI BLAST.

Genetic survey of cystic echinococcosis in farm animals in Oman

Echinococcus granulosus sensu lato (s.l.) is the causative agent of cystic echinococcosis (CE) in animals and humans with a worldwide distribution affecting pastoral and agro-pastoral communities. Little is known about the genetic diversity and public health significance of E. granulosus s.l. among animals and human in Oman. This study was undertaken to investigate the circulating genotypes of E. granulosus s.l. in farm animals (camels, cattle, goats and sheep) by using multiplex PCR (mPCR) and sequence analysis of a fragment of the NADH dehydrogenase subunit 1 (NADH-1) gene. In this study, 39 hydatid cyst isolates from dromedary camels (n = 17), cattle (n = 12), goats (n = 9) and sheep (n = 1) from five governorates in Oman were collected. These isolates were analysed genetically to classify E. granulosus s.l. using a single-tube mPCR and further subjected to sequence analysis of mitochondrial NADH-1 gene. The results of mPCR revealed that most of the cyst isolates (71.8%) belonged to E. granulosus sensu stricto G1/G2/G3 genotypes, whereas 28.2% were linked to E. canadensis G6/G7 genotypes. However, sequencing of these isolates has confirmed the existence of the two genotypes E. canadensis G6 and E. granulosus sensu stricto G1 genotype. This study provides a molecular evidence of E. granulosus s.l. genotypes in Oman and confirms the predominance of the sheep and camel strains and their role in the transmission dynamics of CE in animals. The study will serve as a foundation for future planning and implementation for CE control program in Oman.

Prevalence and characterization of hydatidosis in Najdi sheep slaughtered in Riyadh city, Saudi Arabia

Hydatidosis is considered to be one of the important zoonotic diseases and has a significant public health importance due to the difficulties of the diagnosis. Domestic animals act as intermediate hosts and the main reservoir for the disease in humans. The main purpose of this work therefore was to determine the prevalence of hydatidosis in Najdi sheep slaughtered in Riyadh city, Saudi Arabia. Cyst location and cyst fertility and viability were also estimated, together with effect of seasons, age and sex on the prevalence of the infection. The prevalence of hydatidosis was evaluated by post-mortem examination, with intensive inspection of the visceral organs of 2785 Najdi sheep. The infection was found to prevail throughout the year in both sex, with an overall prevalence of 2.33%. The highest prevalence was recorded in winter (6.48%) while the lowest was encountered in summer (1.36%). Females were proved to be more prone to infection (70.7%) than males (29.3%). In the present study, younger sheep tended to have a higher prevalence of infection than older ones. The most commonly infected organ was the liver, with a prevalence of 81.5%. The recorded cysts showed a fertility rate of 75.4%, and a high viability rate of 61.2%. Hepatic cysts were the most fertile and viable ones (46%), while calcified cysts were not recorded during the study. Measurements of recorded cysts in all organs ranged from 2 to 6 cm in diameter. In conclusion, the high fertility and viability rate of the recorded cysts suggest that sheep are a potential source of hydatidosis transmission to dogs and the continuation of its life cycle in this region. Consequently, authorities are recommended to instigate stricter regulation of the slaughtering process, including the secure disposal of infected offal so as to minimise the transmission of cysts from slaughter houses, along with treatment of stray dogs.

Global Distribution of Alveolar and Cystic Echinococcosis

Alveolar echinococcosis (AE) and cystic echinococcosis (CE) are severe helminthic zoonoses. Echinococcus multilocularis (causative agent of AE) is widely distributed in the northern hemisphere where it is typically maintained in a wild animal cycle including canids as definitive hosts and rodents as intermediate hosts. The species Echinococcus granulosus, Echinococcus ortleppi, Echinococcus canadensis and Echinococcus intermedius are the causative agents of CE with a worldwide distribution and a highly variable human disease burden in the different endemic areas depending upon human behavioural risk factors, the diversity and ecology of animal host assemblages and the genetic diversity within Echinococcus species which differ in their zoonotic potential and pathogenicity. Both AE and CE are regarded as neglected zoonoses, with a higher overall burden of disease for CE due to its global distribution and high regional prevalence, but a higher pathogenicity and case fatality rate for AE, especially in Asia. Over the past two decades, numerous studies have addressed the epidemiology and distribution of these Echinococcus species worldwide, resulting in better-defined boundaries of the endemic areas. This chapter presents the global distribution of Echinococcus species and human AE and CE in maps and summarizes the global data on host assemblages, transmission, prevalence in animal definitive hosts, incidence in people and molecular epidemiology.

Ecology and Life Cycle Patterns of Echinococcus Species

The genus Echinococcus is composed of eight generally recognized species and one genotypic cluster (Echinococcus canadensis cluster) that may in future be resolved into one to three species. For each species, we review existing information on transmission routes and life cycles in different geographical contexts and - where available - include basic biological information of parasites and hosts (e.g., susceptibility of host species). While some Echinococcus spp. are transmitted in life cycles that involve predominantly domestic animals (e.g., dog - livestock cycles), others are wildlife parasites that do or do not interact with domestic transmission. In many cases, life cycle patterns of the same parasite species differ according to geography. Simple life cycles contrast with transmission patterns that are highly complex, involving multihost systems that may include both domestic and wild mammals. Wildlife transmission may be primary or secondary, i.e., resulting from spillovers from domestic animals. For most of the species and regions, existing information does not yet permit a conclusive description of transmission systems. Such data, however, would be highly relevant, e.g., for anticipation of geographical changes of the presence and frequency of these parasites in a warming world, or for initiating evidence-based control strategies.