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New information was collected on cystic echinococcosis in livestock (camels, cattle and sheep) and humans in the central region of Sudan. The livestock data were collected in abattoir-based surveys in the towns of Omdurman, Tamboul and Wad Madani, between 1998 and 2001, and covered a total of 8205 animals. The highest prevalence of infection was found in the camels (44.6% of 242 infected), followed by the sheep (6.9% of 5595) and cattle (3.0% of 2368). Records were made of the sizes of the 1320 hydatid cysts detected in the livestock (907 in sheep, 71 in cattle, and 342 in camels), whether or not each cyst was fertile, and where it occurred in the body of the host. Cysts collected from cattle and camels where much more likely to be fertile (22% and 24%, respectively) than those from sheep (1%). Camels and cattle therefore appear to be the principal intermediate hosts for Echinococcus granulosus in central Sudan, whereas sheep apparently play a marginal role in transmission. In 2002, as a preliminary assessment of the public-health impact of the disease, 300 residents of a rural village 60 km west of Wad Madani were surveyed using a portable ultrasound scanner. Only one (0.33%) of the villagers investigated was found infected. The implications of these finding are discussed in terms of the various strains of E. granulosus and the role of each in human disease.

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The zoonotic cestode Echinococcus ortleppi (Lopez-Neyra and Soler Planas, 1943) is mainly transmitted between dogs and cattle. It occurs worldwide but is only found sporadically in most regions, with the notable exception of parts of southern Africa and South America. Its epidemiology is little understood and the extent of intraspecific variability is unknown. We have analysed in the present study the genetic diversity among 178 E. ortleppi isolates from sub-Saharan Africa, Europe and South America using the complete mitochondrial cox1 (1608 bp) and nad1 (894 bp) DNA sequences. Genetic polymorphism within the loci revealed 15 cox1 and six nad1 haplotypes, respectively, and 20 haplotypes of the concatenated genes. Presence of most haplotypes was correlated to geographical regions, and only one haplotype had a wider spread in both eastern and southern Africa. Intraspecific microvariance was low in comparison with Echinococcus granulosus sensu stricto, despite the wide geographic range of examined isolates. In addition, the various sub-populations showed only subtle deviation from neutrality and were mostly genetically differentiated. This is the first insight into the population genetics of the enigmatic cattle adapted Echinococcus ortleppi. It, therefore, provides baseline data for biogeographical comparison among E. ortleppi endemic regions and for tracing its translocation paths.