Cystic Echinococcosis in Algeria: the Role of Cattle as Reservoirs in the Dynamics of Transmission of Echinococcus granulosus to Humans via Dogs.

In North Africa, the parasite Echinococcus granulosus is transmitted in a synanthropic cycle evolving mainly between dogs (DH) and sheep (IH), but other animals like cattle are most often found to be more infested with hydatid cysts but their potential role in human contamination via dogs is unknown. The purpose of this study is to assess the prevalence and fertility rates of hydatid cysts in ruminants (cattle and sheep) in two slaughterhouses in central and eastern Algeria. Determining the frequency and fertility of cysts in cattle will assess the degree of involvement of this species, alongside sheep, in the epidemiological cycle of E. granulosus in Algeria. In the present study, prevalence rates were estimated at 4.9% and 10% in slaughtered ruminants, all species combined at the slaughterhouses of El Harrach and Souk Ahras, respectively. The distribution of the prevalence by species indicates higher infestation rates in cattle compared to sheep: 6% vs 3.9% and 37% vs 4.7% in the slaughterhouses of El Harrach and Souk Ahras, respectively. The survey results showed relatively low cyst fertility rates in cattle compared to sheep: 13.8% vs 43.7% and 33.3% vs 71.4% in the two slaughterhouses, El Harrach and Souk Ahras, respectively. The low fertility rate of cysts in cattle can be explained by a poor adaptation of the species, E. granulosus sensu stricto, previously identified by molecular analysis in all samples of hydatid cysts collected from cattle in Algeria. In conclusion, cattle infested with E. granulosus sensu stricto, with low fertility rates, play a minor role in the epidemiology of cystic echinococcosis in Algeria. It is rather an indicator of the persistence of cystic echinococcosis infection in endemic regions.

En Afrique du Nord, le parasite Echinococcus granulosus est transmis dans un cycle synanthropique évoluant principalement entre les chiens (HD) et les moutons (HI). Mais d'autres animaux comme les bovins se révèlent le plus souvent très infestés par les kystes hydatiques : leur rôle potentiel dans la contamination humaine via des chiens est inconnu. Le but de cette étude est d'évaluer la prévalence et les taux de fertilité des kystes hydatiques chez les ruminants (bovins et ovins) dans deux abattoirs du centre et de l'est de l'Algérie. La détermination de la fréquence et de la fertilité des kystes chez les bovins permettra d'évaluer le degré d'implication de cette espèce, aux côtés des ovins, dans le cycle épidémiologique d'E. granulosus en Algérie. Dans la présente étude, les taux de prévalence ont été estimés à 4,9 et 10 % chez les ruminants abattus, toutes espèces confondues dans les abattoirs d'El Harrach et de Souk Ahras respectivement. La répartition de la prévalence par espèce indique des taux d'infestation plus élevés chez les bovins que chez les ovins : 6 vs 3,9 % et 37 vs 4,7 % dans les abattoirs d'El Harrach et de Souk Ahras respectivement. Les résultats de l'enquête ont montré des taux de fertilité des kystes relativement bas chez les bovins par rapport aux ovins : 13,8 vs 43,7 % et 33,3 vs 71,4 % dans les deux abattoirs, El Harrach et Souk Ahras respectivement. Le faible taux de fertilité des kystes chez les bovins peut s'expliquer par une mauvaise adaptation de l'espèce E. granulosus sensu stricto, précédemment identifiée par analyse moléculaire dans tous les échantillons de kystes hydatiques prélevés sur des bovins en Algérie. En conclusion, les bovins infestés par E. granulosus sensu stricto, avec des kystes à faible taux de fertilité, jouent un rôle mineur dans l'épidémiologie de l'échinococcose kystique en Algérie. Il s'agit plutôt d'un indicateur de la persistance de l'infection à échinococcose kystique dans les régions endémiques.

Prevalence of Echinococcus granulosus taeniasis in stray dogs in the region of Constantine (North-East Algeria).

In North Africa, the domestic dog is regarded as the main reservoir for infection by Echinococcus granulosus of domestic livestock and man. In Algeria, there is very little data on the rate of infestation of dogs, while the prevalence of E. granulosus in the definitive host is a very reliable marker of the potential risk of transmission of cystic tapeworm to humans and livestock. To find out this information, a survey was conducted to assess the prevalence of infection with E. granulosus in stray dogs in the region of Constantine (North-East Algeria). We autopsied and examined 120 stray dogs, 22 (18.3%) of which were infected with E. granulosus, with an average intensity of infestation of 249 worms. The prevalence in the area of survey was evaluated: 15.5% (14/90) and 26.6% (8/30) dogs were parasitized by E. granulosus in urban and rural areas respectively. The influence of age on the rate of infection was very marked. In addition, the appreciation of the prevalence of parasitism by cestodes as a whole showed that 56 (46.6%) animals out of 120 were infected. Facing such a situation of endemic tapeworm parasitism, with a potential risk of transmission to humans, there is an urgent need to take measures to control and break the epidemiological cycles of the parasite.

[Targeting abattoirs to control cystic echinococcosis in Algeria]. / Le ciblage des abattoirs dans la lutte contre l'échinococcose kystique en Algérie.

Cystic echinococcosis (CE) is an important anthropozoonotic parasitic common in Algeria. The predominant life cycle of E. granulosus is a synanthropic cycle with domestic dogs as definitive hosts and livestock animals as intermediate hosts. Slaughter activity represents a potential source for dogs to access infected offal. The aim of the present study was to determine if the contact between dogs and potentially infected offal was possible in licensed abattoirs. Eighty-one private and public abattoirs located in eastern Algeria were assessed with respect to their level of protection against the intrusion of dogs.We have demonstrated that in 42 % of these abattoirs, dogs could easily come in contact with potentially parasitized offal. The most common incorrect practices were the dumping of offal freely into the environment, the feeding of dogs with offal, and the leaving of unattended offal in an unsealed chamber. Overall, some hazardous practices remained common customs of workers, and enough abattoirs remain non-compliant that the cattledog domestic cycle of CE is unlikely to be broken. Hence, some recommended measures to interrupt parasite transmission include the following: recognition of the importance of abattoirs in the maintenance of canine echinococcosis, the controlled and proper disposal of offal, the abolishment of the custom of feeding dogs with infected offal and improvements in the level of health education of abattoir staff.

Failure to observe cross-fertilization between the Echinococcus granulosus G1 and G6 strains after an experimental mixed infection of the definitive host.

The classification within Echinococcus granulosus is currently under debate. To assess the reproductive potential between the G1 and G6 strains, an experimental double infection was carried out in a dog. First, two fertile hydatid cysts were collected in Algeria from a cow and a dromedary. They were identified as being G1 and G6 with the markers coxI and nadI. Subsequently, a dog was inoculated with protoscoleces from these two cysts. Sixty days after infection, 85 adult worms were recovered from the intestine of the dog. Then, the two cysts and each of these individual parasites were characterized with the multilocus microsatellite EmsB and compared. For all worms, the scolex and the gravid proglottids, separately analyzed, provided an identical profile: the G1 profile was observed in 70 adults, and the G6 profile in the 15 others. No single worm exhibited a hybrid G1/G6 profile. This result suggests the absence of cross-fertilizing between the two taxa under the given experimental conditions, and so, the presence of a strong cross-reproductive barrier. This observation corroborates with the recent reclassification of G1 and G6 within two distinct species.