Sleeping sickness is caused by the Trypanosoma parasite, which is carried by the tsetse fly. The epidemic of Trypanosoma brucei rhodesiense sleeping sickness in eastern Uganda began in 1998 as a result of the movement of the livestock reservoir of the parasite and has continued to spread. Interventions to control the disease were put in place between January 2000 and December 2003 and consisted of mass treatment of livestock with long-acting drugs to kill the parasite. In this study Eric Fèvre (University of Edinburgh, Scotland) and colleagues looked at the prevalence of human infective T b rhodesiense in the cattle population of three villages in the Soroti district of Uganda, which had the intervention, and three where there had been no intervention. They found that there was no significant difference in the prevalence of the parasite in the villages with the intervention and those without it.
The investigators also report that since the first cases of sleeping sickness in 1998, 428 new cases were diagnosed in the Sorotic district over a 5-year period, and an additional 300 may have gone undiagnosed.
Dr Fèvre states: "To be effective, mass treatment interventions need to cover enough of the livestock population to prevent the transmission of parasites to tsetse. Similarly, effective tsetse control must reduce vector challenge sufficiently to effect transmission to human beings...As livestock movements results in the spread of T b rhodesiense, controlling such movements or treating livestock before movement is a matter of urgency...Outbreaks of T b rhodesiense in new areas are conceptually straightforward to prevent with effective veterinary interventions but, once established, very dif?cult to control."
See also accompanying comment.
Contact: Dr Eric M Fèvre, Centre for Tropical Veterinary Medicine, Royal School of Veterinary Studies, Easter Bush Veterinary Centre, Roslin, Midlothian, EH25 9RG, UK. Eric.Fevre@ed.ac.uk The University of Edinburgh press office T) 44-131-650-6382