Molecular and Epidemiology Data on Cystic Echinococcosis in Tunisia

Cystic echinococcosis (CE) or hydatidosis is a widespread zoonose in the world. In Tunisia, despite the deployed prevention program, CE remains a serious public health problem. With a human surgical annual incidence averaging 12.6/100000 inhabitants, Tunisia is one of the most endemic areas amongst the Mediterranean countries. Three Echinococcus species have been described: E. granulosus sensu stricto (G1 and G3 genotypes), E. canadensis, and E. equinus. CE, which commonly starts during childhood and described as a young adult disease, may be observed at any age. The liver and the lungs are the most commonly involved organs but the cyst can occur almost anywhere in the body. In production animals, the prevalence of CE is ranged from 16.42% to 40.42% in sheep, 8.56% in cattle, 6% in dromedaries, 2.9% in goats, and 8.48% in donkeys. The elevated number of stray and semi-stray dogs and their frequent contamination by E. granulosus infected viscera is the major cause of the CE spread. A high prevalence of E. granulosus infection has been reported in Tunisian dogs ranging from 3.75% to 27.1%, depending on the regions. Thus, the sanitary education concerning hydatidosis should be reinforced and efforts should be made to implement a targeted educational program

Gastrointestinal parasites of canids, a latent risk to human health in Tunisia

Abstract Background Although data on the parasite environmental contamination are crucial to implement strategies for control and treatment, information about zoonotic helminths is very limited in Tunisia. Contamination of areas with canid faeces harboring infective parasite elements represents a relevant health-risk impact for humans. The aim of this study was to assess the environmental contamination with eggs and oocysts of gastrointestinal parasites of dogs and wild canids in Tunisia with special attention to those that can be transmitted to humans. Results One thousand two hundred and seventy faecal samples from stray dogs and 104 from wild canids (red foxes and golden jackals) were collected from different geographical regions throughout Tunisia. The helminth eggs and protozoan oocysts were concentrated by sucrose flotation and identified by microscopic examination. The most frequently observed parasites in dog samples were Toxocara spp. (27.2%), E. granulosus (25.8%), and Coccidia (13.1%). For wild canid faeces, the most commonly encountered parasites were Toxocara spp. (16.3%) followed by Capillaria spp. (9.6%). The parasite contamination of dog faeces varied significantly from one region to another in function of the climate. Conclusion To our knowledge, the study highlights for the first time in Tunisia a serious environmental contamination by numerous parasitic stages infective to humans. Efforts should be made to increase the awareness of the contamination risk of such parasites in the environment and implement a targeted educational program

In vitro scolicidal activity of Thymus capitatus Hoff. et Link. essential oil on Echinococcus granulosus protoscoleces

Cystic echinococcosis remains a serious public health problem worldwide. Surgery is considered as the first option of treatment. Various investigations were carried out to find a convenient scolicidal agent for reducing the risk of post-surgical recurrence of the disease but most of them are associated with adverse side effects. The present study aimed to evaluate the in vitro scolicidal activity of Thymus capitatus Hoff. et Link. essential oil against Echinococcus granulosus protosco- leces. Three concentrations of essential oil (1, 2 and 3 mg/mL) were tested for 1 to 10 min on E. granulosus protosoleces and their viability was assessed by eosin staining test. The essential oil concentrated at 2 and 3 mg/mL killed 100% protoscoleces after 5 and 1 min, respectively. Furthermore, GC/MS and GC-FID analyzes indicated that carvacrol (82.4%) was the major compo- nent of the essential oil. The current investigation showed the potent scolicidal effect of T. capitatus essential oil in vitr

Microsatellite Investigations of Multiple Echinococcus granulosus Sensu Stricto Cysts in Single Hosts Reveal Different Patterns of Infection Events between Livestock and Humans

International audienceCystic echinococcosis (CE) caused by the cestode Echinococcus granulosus sensu lato (s.l.) is a worldwide zoonosis and E. granulosus sensu stricto (s.s.) is the most common species associated with animal and human diseases. The objective of this study was to obtain a better understanding of CE infection in livestock and humans from very low and high endemic areas—France and Tunisia—by studying the genetic diversity of E. granulosus s.s. at the intra-individual host level. This genetic diversity was studied using EgSca6 and EgSca11 microsatellite profiles in 93 sheep from France and Tunisia, and in 12 cattle and 31 children from Tunisia only, all presenting multiple CE cysts (2 to 10 cysts). Overall, 96% of sheep, 92% of cattle, and 48% of children had at least two cysts with different microsatellite profiles. Inversely, 35% of sheep, 17% of cattle, and 65% of children had at least two cysts with the same microsatellite profile. The genotyping results for the CE samples highlight high and similar genetic diversity in France and Tunisia, suggesting that the probability of being successively infected by CE of the same microsatellite profile was rare in both countries. Therefore, our results suggest that in rare cases, several eggs of the same microsatellite profile, from two to seven in our data, can be ingested simultaneously in a single infection event and develop into several cysts in livestock and children. They also indicate that multiple infection events are frequent in livestock, even in a low endemic country such as France, and are less frequent but not negligible in children in a high endemic country such as Tunisia. Moreover, this is the first time that genetic evidence of secondary CE has been found. Further studies are needed to better assess the pattern of infection events in livestock and humans, especially by studying the genetic diversity of adult worms in definitive hosts

Investigating the genetic diversity of Echinococcus granulosus sensu stricto with new microsatellites

International audienceCystic echinococcosis is a zoonotic disease with worldwide distribution caused by the larval stage of the Cestode parasite Echinococcus granulosus sensu lato. Due to the predominance or even the exclusive presence of E. granulosus sensu stricto (s.s.) among E. granulosus species in many areas, the genetic diversity needs to be further investigated at the species level to better understand the inter-and intra-focus epidemiological features. Short sequences of mitochondrial or nuclear genes generally lack or have limited discriminatory power, hindering the detection of polymorphisms to reflect geographically based peculiarities and/or any history of infection. A high discriminatory power can only be reached by sequencing complete or near complete mitogenomes or relatively long nuclear sequences, which is time-consuming and onerous. To overcome this issue, a systematic research for single-locus microsatellites was performed on the nuclear genome of E. granulosus s.s. in order to investigate its intra-species genetic diversity. Two microsatellites, EgSca6 and EgSca11, were selected and characterized. The test of a panel of 75 cystic echinococcosis samples revealed a very high discrimination index of 0.824 for EgSca6, 0.987 for EgSca11, and 0.994 when multiplexing both microsatellites. Testing cystic echinococcosis samples from both liver and lungs in five sheep revealed that these two microsatellites appear to be of particular interest for investigating genetic diversity at the intra-individual host level. As this method has many advantages compared to classical sequencing, the availability of other targets means that it is potentially possible to constitute a panel facilitating large-scale molecular epidemiology studies for E. granulosus s.l

Genetic differences between Tunisian camel and sheep strains of the cestode Echinococcus granulosus revealed by SSCP

Ovine and dromedary Echinococcus granulosus isolates from Tunisia were identified as G1 and G6 strains based on polymorphism of the mitochondrial cytochrome C oxydase CO1. Single strand conformation polymorphism (SSCP) was used in order to examine the genetic variation within and between Tunisian G1 and G6 strains and to estimate the extent of selfing. The dromedary isolates are genetically distinct from sheep isolates (high value of genetic variation between populations: Fst = 0.46). No significant deficiency in heterozygotes was found in sheep isolates, whereas heterozygote deficiency (suggesting selfing) was found in a limited number of camel isolates.Les Echinococcus granulosus de Tunisie ont été identifiés comme appartenant aux lignées G1 et G6 en se fondant sur le polymorphisme de la cytochrome oxydase CO1. Le polymorphisme de conformation simple brin (SSCP) a été utilisé afin d’évaluer la variabilité génétique intra et inter-isolats des lignées G1 et G6, et pour estimer le taux d’autofécondation. Les isolats issus de dromadaires sont génétiquement distincts des isolats ovins (valeur de Fst : 0,46). Il n’y a pas de déficit significatif en hétérozygotes chez les isolats ovins. Un déficit en hétérozygotes est présent dans les isolats du dromadaire, ce qui suggère l’autofécondation comme l’un des modes de reproduction