Sarah Williams-Blangero, John L. VandeBerg and John Blangero
Parasitic diseases persist as major global health threats despite the dramatic advances in medical science that have occurred in the last 100 years. For some parasitic diseases, the prevalence today is similar to that observed 50 years ago even though new effective pharmacological treatments have been developed (Chan et al., 1994; Chan, 1997). The global health burden associated with these diseases is enormous. For example, using the disability adjusted life years (DALYs) measure of Murray (1994), it has been estimated that 39.0 million years of healthy life were lost worldwide due to soil-transmitted intestinal worm infections (hookworm, roundworm, and whipworm) and 35.7 million years to malaria in 1990 (Chan, 1997). By comparison, diabetes only accounted for 8.0 million years of healthy life lost in that same year, while motor vehicle accidents accounted for 31.7 million DALYs (Chan, 1997). Clearly there is a significant need for continued research aimed at identifying new mechanisms to more effectively prevent, treat, and cure parasitic diseases.
Genetic epidemiology is one of the scientific fields identified by Anthony Fauci, Director of the National Institute of Allergy and Infectious Diseases of the U.S. National Institutes of Health, as being critical for progress in infectious disease research in the 21st century, particularly in the area of host susceptibility (Fauci, 2001). Genetic epidemiological approaches are used to characterize the host genetic components influencing disease susceptibility and outcome. While these techniques have been commonly applied in studies of complex noninfectious diseases such as atherosclerosis, diabetes, and obesity, they have been applied to infectious diseases, and particularly parasitic diseases, relatively infrequently (but see Abel et al., 1991, 1992; Marquet et al., 1996; Williams-Blangero et al., 1997a, 1997b, 1999, 2002a, 2002b; Garcia et al., 1999).
The identification and characterization of individual genes influencing disease are the ultimate goals of genetic epidemiological studies of parasitic infections. These studies can facilitate drug discovery through identification of new mechanisms influencing susceptibility to, or progression of, disease that can be targeted in the drug development process (Dykes, 1996; Gelbert and Gregg 1997).