**Abstract**

Dogs are involved in the transmission of several parasitic zoonosis. Among these, hydatidosis is very endemic in many countries of the world. Dog populations are very variable from one region to another, which increases the infestation risks across human populations especially in the developing countries such as in Morocco. Moreover, the risk of exposure is higher in dogs with access to rural slaughterhouses than in owned dogs. As for preventive measures, this calls for effective implementation of the appropriate dogs' treatment against hydatidosis. Thus, the following chapter updates the most relevant information on the impact of hydatidosis upon human populations and livestock animals, as to stretch understanding on the vector contribution of dogs.

**Keywords:** Dogs, Morocco, hydatidosis, zoonotic diseases, echinococcus granulosus

#### **1. Introduction**

Dog-borne zoonotic diseases include all the infectious diseases targeting dogs that can be transmitted to humans. Though they present major zoonosis causing a heavy burden upon the human population worldwide, these diseases are mostly neglected as few insufficient scientific research efforts are realized to face it (WHO, 2007b). Several examples of zoonosis are present with high prevalence up to time, such as bovine tuberculosis, brucellosis, cystic echinococcosis, visceral leishmaniosis, rabies [1], especially in the developing and North African countries in the poorest and most marginalized regions, in rural areas. Some of these diseases share the same definitive host represented by the dog. Especially hydatid cyst disease, which is endemic to hyper-endemic in agricultural countries in Europe, North, East and South Africa, South and North America, the Middle East and Asia [2–6]. Morocco is one of these highly endemic countries [7, 8].

The hydatid cyst, or *Cystic echinococcosis*, is caused by a small tapeworm parasite of canids, *Echinococcus granulosus*, which is then transmitted to humans via dogs. It has been reported in numerous reports that the incidence of the disease has increased in various parts of the world [9]. In Morocco for example, the annual incidence is 5.2 cases/100,000 inhabitants [10]. For this reason, several studies have been carried out in the world and in Morocco to evaluate chemoprevention in dogs in order to truncate the parasite cycle and reduce the incidence of the disease.

Hence, the purpose of this chapter is to compile recent data regarding the identification of the main source of infestation in dogs and the determination of the prevalence of infestation. As the canine population varies considerably from one region to another, like everywhere else in the world, in Morocco there are approximately 18,000 owned dogs and 3,000 stray dogs in endemic areas. A high prevalence of *E. granulosus* infestation in dogs has been recorded in these regions, estimated at 3.6% in Oulmes, 19.6% in Sidi Kacem and 23.7% in the Middle Atlas. This makes it possible to put the spotlight on the dog as the main reservoir and vector of this disease. Therefore, the risk of exposure is higher in stray dogs with access to rural slaughterhouses than in owned dogs, which is complicated to control. Hence, it is urgent the need for a very appropriate and regular chemoprevention program in dogs [7, 11].

## **2. Dogs vector of the major zoonotic diseases: an overview on**  *Echinococcus granulosus*

The dog has a high importance in the social life of the human population. These multiple and diverse functions make it an indispensable domestic animal, particularly for households in rural areas where the relationship between dogs and humans is very close. Unfortunately, the risk of transmission of pathogenic agents from dogs to other animals, mainly mammals, is an issue of major concern. Dogs indeed can act as reservoirs of pathogens as they may transmit *Leishmania spp*. (leishmaniasis), *Leptospira interrogans* (leptospirosis), *Toxoplasma gondii* (toxoplasmosis), *Neospora caninum* (neosporosis), *Dirofilaria immitis* (dirofilaria/heartworm disease), *Brucella canis* (brucellosis), *Sarcoptes scabiei* (scabies), *Echinococcus spp.* (echinococcosis), *Rickettsia rickettsii* (Brazilian spotted fever). Various canine viruses (e.g. distemper virus, adenovirus, coronavirus, herpes virus, parvovirus), rabies virus, among other pathogens for both humans and wildlife [12, 13]. Especially, *Echinococcus granulosus,* is up to now one of the zoonosis with a considerable endemic situation upon human populations and livestock animals.

Echinococcosis, the *Echinococcus granulosus* induced disease, is asymptomatic in dogs. Even with a high parasite load (from 1500 to 6000 worms per dog), this parasitosis may progress unperceived with no clinical signs. Moreover, due to the small size of the eliminated segments, no external signs can be seen. Nevertheless, anal pruritus can be induced following the penetration of gravid segments into the anal glands [14]. As the eggs are not visible by the human eye, there are no external signs of the infestation, explaining the danger of this parasite, which can easily spread and contaminate the environment, especially when dogs move from one place to another.

### **3. Impact of hydatidosis disease upon human's population and livestock animals production**

Eggs of the *E. granulosus* parasite are disseminated in the environment by dogs. Thus, they are transmitted to a wide range of intermediate hosts, including sheep and humans, causing an infestation with the hydatid cyst (larval stage of the parasite) [7].

The abundance of stray dogs and slaughter practices that allow dogs' access to condemned offal, particularly in rural areas, contribute to the persistence of hydatidosis. Hydatidosis is 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. The economic burden of cystic echinococcosis on the global livestock industry has been

**81**

**Table 1.**

*Incrimination of Dog Vector of Cystic Echinococcosis and Impact of the Appropriate Dogs'…*

estimated at over \$2 billion per year. Despite the substantial socio-economic impact,

In humans, hydatid cyst is the cause of significant morbidity and mortality worldwide and is responsible for a significant economic loss in the public health sector [16, 17]. Hydatid cyst has several consequences, including the direct costs of diagnosis, hospitalization, surgical treatment, post-surgical care, for the patient and family members, without forgetting the indirect losses of mortality, pain and social consequences of lost working days and the cessation of agricultural activities by those affected or at risk [16–18]. People with hydatid cysts never restore a perfect

At the livestock animal level, it involves losses in production, and their importance varies according to the breed and type of production concerned [19]:

• Cost of destruction of infected viscera and dead animals;

• Brutal mortality following the rupture of a hydatid cyst.

Meat 2,5–10 Milk 2,5–5 Fertility 9,9 – 12,1

Meat 5–10 Wool 10–40 Fertility 9,9 – 12,1

Meat 5–20 Fertility 9,9 – 12,1

Meat 2,5–10

*Reduction rate of animal products caused by hydatidosis [18].*

• Possible restriction on the export of animals and their products;

a reason for reforming adult sheep whose productive life is reduced;

**Parameter Reduction rate (%) Reference Cattle** [4]

**Sheep** [4, 18]

**Goat** [18]

**Camelin** [20]

• Organs not usable and seized at the slaughterhouse, especially liver and lung;

• Parasitic hydatid cachexia associated with poly-parasitism in animals, which is

In sheep farming, it is estimated that 7–10% of milk losses, 5–20% of meat or whole carcass weight losses, and 10–40% of wool losses occurred (**Table 1**) [18]. In 1980, an assessment carried out in Italy [6] showed a 10% reduction in the commercial value of an infected sheep, a percentage which takes into account the cost of destroying viscera. It should be noted that the economic impact of infected viscera depends on the country's regulations and the number of animals slaughtered under veterinary control, as well as the cost of the equipment used [19]. According

*DOI: http://dx.doi.org/10.5772/intechopen.95776*

hydatidosis is still a neglected zoonosis [15].

health condition even after they have recovered [4].

*Incrimination of Dog Vector of Cystic Echinococcosis and Impact of the Appropriate Dogs'… DOI: http://dx.doi.org/10.5772/intechopen.95776*

estimated at over \$2 billion per year. Despite the substantial socio-economic impact, hydatidosis is still a neglected zoonosis [15].

In humans, hydatid cyst is the cause of significant morbidity and mortality worldwide and is responsible for a significant economic loss in the public health sector [16, 17]. Hydatid cyst has several consequences, including the direct costs of diagnosis, hospitalization, surgical treatment, post-surgical care, for the patient and family members, without forgetting the indirect losses of mortality, pain and social consequences of lost working days and the cessation of agricultural activities by those affected or at risk [16–18]. People with hydatid cysts never restore a perfect health condition even after they have recovered [4].

At the livestock animal level, it involves losses in production, and their importance varies according to the breed and type of production concerned [19]:


In sheep farming, it is estimated that 7–10% of milk losses, 5–20% of meat or whole carcass weight losses, and 10–40% of wool losses occurred (**Table 1**) [18]. In 1980, an assessment carried out in Italy [6] showed a 10% reduction in the commercial value of an infected sheep, a percentage which takes into account the cost of destroying viscera. It should be noted that the economic impact of infected viscera depends on the country's regulations and the number of animals slaughtered under veterinary control, as well as the cost of the equipment used [19]. According


#### **Table 1.**

*Reduction rate of animal products caused by hydatidosis [18].*

*Canine Genetics, Health and Medicine*

*Echinococcus granulosus*

**animals production**

been carried out in the world and in Morocco to evaluate chemoprevention in dogs in order to truncate the parasite cycle and reduce the incidence of the disease.

**2. Dogs vector of the major zoonotic diseases: an overview on** 

endemic situation upon human populations and livestock animals.

Hence, the purpose of this chapter is to compile recent data regarding the identification of the main source of infestation in dogs and the determination of the prevalence of infestation. As the canine population varies considerably from one region to another, like everywhere else in the world, in Morocco there are approximately 18,000 owned dogs and 3,000 stray dogs in endemic areas. A high prevalence of *E. granulosus* infestation in dogs has been recorded in these regions, estimated at 3.6% in Oulmes, 19.6% in Sidi Kacem and 23.7% in the Middle Atlas. This makes it possible to put the spotlight on the dog as the main reservoir and vector of this disease. Therefore, the risk of exposure is higher in stray dogs with access to rural slaughterhouses than in owned dogs, which is complicated to control. Hence, it is urgent the need for a very appropriate and regular chemoprevention program in dogs [7, 11].

The dog has a high importance in the social life of the human population. These multiple and diverse functions make it an indispensable domestic animal, particularly for households in rural areas where the relationship between dogs and humans is very close. Unfortunately, the risk of transmission of pathogenic agents from dogs to other animals, mainly mammals, is an issue of major concern. Dogs indeed can act as reservoirs of pathogens as they may transmit *Leishmania spp*. (leishmaniasis), *Leptospira interrogans* (leptospirosis), *Toxoplasma gondii* (toxoplasmosis), *Neospora caninum* (neosporosis), *Dirofilaria immitis* (dirofilaria/heartworm disease), *Brucella canis* (brucellosis), *Sarcoptes scabiei* (scabies), *Echinococcus spp.* (echinococcosis), *Rickettsia rickettsii* (Brazilian spotted fever). Various canine viruses (e.g. distemper virus, adenovirus, coronavirus, herpes virus, parvovirus), rabies virus, among other pathogens for both humans and wildlife [12, 13]. Especially, *Echinococcus granulosus,* is up to now one of the zoonosis with a considerable

Echinococcosis, the *Echinococcus granulosus* induced disease, is asymptomatic in dogs. Even with a high parasite load (from 1500 to 6000 worms per dog), this parasitosis may progress unperceived with no clinical signs. Moreover, due to the small size of the eliminated segments, no external signs can be seen. Nevertheless, anal pruritus can be induced following the penetration of gravid segments into the anal glands [14]. As the eggs are not visible by the human eye, there are no external signs of the infestation, explaining the danger of this parasite, which can easily spread and contaminate the environment, especially when dogs move from one place to another.

**3. Impact of hydatidosis disease upon human's population and livestock** 

Eggs of the *E. granulosus* parasite are disseminated in the environment by dogs. Thus, they are transmitted to a wide range of intermediate hosts, including sheep and humans, causing an infestation with the hydatid cyst (larval stage of the parasite) [7]. The abundance of stray dogs and slaughter practices that allow dogs' access to condemned offal, particularly in rural areas, contribute to the persistence of hydatidosis. Hydatidosis is 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. The economic burden of cystic echinococcosis on the global livestock industry has been

**80**

to a recent study by Saadi et al., the economic impact of hydatidosis on animal production in Morocco is very significant [17].

### **4. 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 dog's 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. Categories of dogs' population in Morocco**

In Morocco, the dog population is very diversified by the presence of different types of dogs: owned dogs and stray dogs or semi stray dogs. A study carried out in

**83**

**Figure 3.**

**Figure 1.**

**Figure 2.**

*Incrimination of Dog Vector of Cystic Echinococcosis and Impact of the Appropriate Dogs'…*

*Prevalence of* Echinococcus granulosus *in three categories of dogs in the middle atlas region.*

*Prevalence of* Echinococcus granulosus *in three categories of dogs in the Sidi Kacem region.*

*Prevalence of* Echinococcus granulosus *in three categories of dogs in the Oulmes region.*

*DOI: http://dx.doi.org/10.5772/intechopen.95776*

*Incrimination of Dog Vector of Cystic Echinococcosis and Impact of the Appropriate Dogs'… DOI: http://dx.doi.org/10.5772/intechopen.95776*

**Figure 1.** *Prevalence of* Echinococcus granulosus *in three categories of dogs in the middle atlas region.*

**Figure 2.** *Prevalence of* Echinococcus granulosus *in three categories of dogs in the Sidi Kacem region.*

*Canine Genetics, Health and Medicine*

**4.1 Dogs infestation**

production in Morocco is very significant [17].

to a recent study by Saadi et al., the economic impact of hydatidosis on animal

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

**4. Incrimination of dogs in transmissions of hydatidosis**

papillae and the oral cavity and then, by licking, in the dog's pelage.

42.9% in cattle, 11% in sheep and 1.5% in goats [24].

within the various categories of dog's populations in Morocco.

**5. Categories of dogs' population in Morocco**

and losses in livestock production.

**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

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

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

In Morocco, the dog population is very diversified by the presence of different types of dogs: owned dogs and stray dogs or semi stray dogs. A study carried out in

**82**

three regions of Morocco revealed that stray dogs were the most infested category by *E. granulosus*, representing a prevalence of 40% in the Middle Atlas Mountains, 33% in Sidi Kacem and 25% in Oulmès, followed by semi-stray dogs and owned dogs (unpublished study) (**Figures 1**–**3**).
