Incrimination of dogs in transmissions of hydatidosis
4.1 Dogs infestation
In canids, particularly in dogs, infestation occurs by ingestion of intermediate host organs harboring the parasite at the larval stage (hydatid cyst). The protoscolexes released from the hydatid cyst grow into adult worms and live in the small intestine, particularly in the duodenum.
The eggs are eliminated in the external environment by detaching the last proglottis from the mature worm and excreting it in the feces. In passage, some proglottis, which have been ruptured, release eggs at the marginal part of the anus. Anal pruritus provokes a licking reflex in the dog, which allows the dog to recover numerous eggs that will be found in the lingual papillae and the oral cavity and then, by licking, in the dogs pelage.4.2 Relationship between dogs, human and livestock animals infestation
In Morocco, current evidence indicates that the transmission cycle of E. granulosus is mainly based on a domestic cycle involving dogs and livestock species (sheep, cattle, camels, goats and horses) [21]. According to a preliminary study carried out in the Middle Atlas, the prevalence of infestation in animals (all ages) is 29.82% in cattle (N = 102), 13.29% in sheep (N = 107) and 2.36% in goats (N = 16) (unpublished study). These regions of the Middle Atlas represent a hotspot of hydatid infestation with a prevalence of infestation of 91.7% in adult sheep (age > 4 years), and a prevalence of 1.9% in humans [22]. A large population of canids is present in these areas, which include owned dogs, stray dogs, jackals and foxes [23]. In 2019, the prevalence of E. granulosus reached 23-39% in owned dogs and 51-68% in stray dogs, while the risk of monthly incidence was 2-8% and 19-41% in owned and stray dogs, respectively [7]. In addition, the study conducted by Azlaf & Dakkak in various regions of Morocco revealed prevalence rates of 10.58% in sheep, 1.88% in goats, 22.98% in cattle, 12.03% in camels and 17.8% in horses [21].
The study conducted by El Berbri et al. in the region of Sidi Kacem revealed a prevalence of 42.9% in cattle, 11% in sheep and 1.5% in goats [24].However, the abundance of dogs, especially stray dogs that eat infested offal in slaughterhouses and clandestine slaughter practices but also on farms that allow owned and sometimes stray dogs to feed on condemned offal, especially in rural areas, contribute to the persistence of hydatidosis. This represents a serious public health problem and has a significant socio-economic impact. The Echinococcus granulosus infestation is a major financial burden derived from human health costs and losses in livestock production.
Thus, one of the interesting models that reveals great relevance on the burden of Echinococcus granulosus on humans is the example of Morocco, of which the studies helped lot to extend the understanding of its various aspects. In the following section, we therefore put the focus on the most pertinent finding on the prevalence within the various categories of dog’s populations in Morocco.
5.