Intestinal nematodes: disease burden, deworming and the potential importance of co-infection

Abstract

Intestinal nematodes affect the world's poorest communities through clinical morbidity associated with heavy infection and the economic consequences of reduced productivity. There has been a significant increase in funding and global support for mass treatment programmes. Local epidemiology is necessary if these programmes are to target the most affected communities, and new mapping tools and mathematical modeling methodologies are identifying the high degree of spatial heterogeneity and the relevance of polyparasitism in estimating attributable morbidity. Recent meta-analyses have highlighted the limited evidence base for many of the claims for treatment benefit. Programme evaluations are beginning to demonstrate good outcomes, but further work is required to assess public health benefit and sustainability of these campaigns. New drugs have been identified which may be necessary to counteract resistance; vaccine studies show early promise as a potentially sustainable approach in the longer term. Research on the impact of helminths and treatment on other diseases continues, with reassuring evidence that mass treatment does not increase prevalence of allergy, and potential treatment benefit for patients with HIV. The relationship with malaria is of particular concern, and further studies are needed to assess how best to integrate control of these diseases. There has been a major scale-up of mass treatment in recent years. In this climate, it is vital that such programmes are appropriately evaluated, and that well designed controlled trials assess the role of deworming in other groups.