Modelling the transmission of Echinococcus granulosus in dogs in the northwest and in the southwest of Morocco.

Echinococcus granulosus (E. granulosus) infection was studied in 151 dogs in two regions of Morocco: 68 dogs in the northwest (Loukkos) and 83 dogs in the southwest (Tiznit). The mean prevalence rates of echinococcosis in dogs were 58.82% (46.23-70.63%) in Loukkos and 55.42% (44.10-66.34%) in Tiznit and the mean abundances of E. granulosus per dog were 75 (59-93) and 547 (504-595), respectively. The mean abundance of E. granulosus in dogs was fitted to a negative binomial distribution by the maximum likelihood techniques to define parameters. E. granulosus was aggregated in dogs in the two regions. The prevalence of infection and the abundance of E. granulosus in dogs were fitted to mathematical models in order to determine if the parasite population is partly regulated by definitive host immunity. The best fit was obtained with the models assuming the presence of immunity. The mean time of exposure to infection was similar in the two regions and ranged from 8 months to about 2 years. The infection pressures (number of E. granulosus) obtained per dog each year were 65 (8-294) in Loukkos and 476 (316-886) in Tiznit. The proportion of dogs susceptible to infection was still high along the life of the dogs in Loukkos, while it was not different from zero in old dogs of Tiznit.

Epidemiological study of the cystic echinococcosis in Morocco.

The objectives of this epidemiological study on cystic echinococcosis (CE) in Morocco (2001-2004) were to update the prevalence of CE in different animal species living in the most important areas of the country and to collect protoscoleces and germinal layers for genetic research purposes. The post mortem inspection concerned 2948 sheep, 2337 goats, 618 cattle, 482 camels and 455 equines (325 horses, 60 mules and 70 donkeys) in five different regions: the Rif (Mediterranean coast and high mountains of the Rif), the Loukkos (Atlantic northwest plain), the center (Rabat and Casablanca regions), the Middle Atlas mountains and the south (arid and semi desert areas). The global CE infection prevalence rates obtained were 22.98% in cattle, 10.58% in sheep, 12.03% in camels, 17.80% in equines and 1.88% in goats. The infection rates were especially high in the Middle Atlas in cattle (48.72%) and in the Loukkos in cattle and sheep (37.61 and 31.65%, respectively). The majority of infected cattle (49.6%) and sheep (52.1%) had hydatid cysts in both liver and lungs. Except for cattle, the liver was more infected than lungs in all the other animal species. Animals more than 5 years old were the most infected in all species. The mean CE infection rates of these animals were about 56% in cattle, 40% in sheep, 20% in camels, 17.80% in equines and 7% in goats. These rates were much higher in the Loukkos (85% of cattle and 59% of sheep) and in the Middle Atlas (68% of cattle and 45% of sheep) than in the other regions. Results showed that Echinococcus granulosus is in an endemic steady state with no evidence of protective immunity in the intermediate hosts. The mean numbers of infections per year are 0.099 for cattle, 0.063 for sheep, 0.03 for camels and 0.010 for goats.