The epidemiology of Taenia pisiformis infections in domestic dogs in Cairo.

The epidemiology of Taenia pisiformis infections in domestic dogs in Cairo, Egypt. Over 5000 street dogs humanely killed in a culling programme organized by the Egyptian Ministry of the Interior in the winter of 1986 and the spring of 1987 have been utilized to examine the final host epidemiology of the cestode Taenia pisiformis in Cairo. In the winter months the prevalence of infection was 63.4% and the mean intensity 2.82 per dog: by the spring of 1987 these values had risen to 70.8% and 3.78 respectively. These parasite burdens probably represent the highest infection levels with T. pisiformis yet described from urban dog populations anywhere in the world. The dispersion of T. pisiformis within the street dog population was assessed and found to be significantly aggregated and well described by a negative binomial model of overdispersion (variance/mean ratio: 5.16, coefficient k = 0.795). A separate analysis was carried out of infection in each of 18 circumscribed regional areas of Cairo which revealed considerable area-to-area differences with mean intensities varying between 1.62 and 6.54 and prevalences between 43.3% and 91.2%. The size structure of the winter and spring worm samples were very similar with about 45% of worms less than 35 cm in length, about 35% between 35 and 59 cm, about 20% between 60 and 100 cm and less than 5% greater than 100 cm in length. The epidemiological factors which lead to high T. pisiformis infection levels in Cairo dogs have been considered and the consumption of discarded rabbit offal containing Cysticercus pisiformis by street dogs is regarded as a crucial mode of transmission.