Low heritable component of risk for infection intensity and infection-associated disease in urinary schistosomiasis among Wadigo village populations in Coast Province, Kenya

• Published in: The American journal of tropical medicine and hygiene Vol. 70; no. 1; p. 57
• Main Authors: King, Charles H, Blanton, Ronald E, Muchiri, Eric M, Ouma, John H, Kariuki, H Curtis, Mungai, Peter, Magak, Philip, Kadzo, Hilda, Ireri, Edmund, Koech, Davy K
• Format: Journal Article
• Language: English
• Published: United States 01-01-2004
• Subjects: Adolescent; Adult; Aged; Aged, 80 and over; Animals; Child; Child, Preschool; Endemic Diseases; Female; Genetic Predisposition to Disease; Humans; Kenya; Male; Middle Aged; Parasite Egg Count; Prevalence; Schistosoma haematobium - growth & development; Schistosomiasis haematobia - genetics; Schistosomiasis haematobia - parasitology; Urinary Tract Infections - genetics; Urinary Tract Infections - parasitology; Urine - parasitology; Kenya
• ISSN: 0002-9637
• DOI: 10.4269/ajtmh.2004.70.57

To estimate their heritable component of risk for Schistosoma haematobium infection intensity and disease, we performed a community-based family study among an endemic population in coastal Kenya. Demography and family linkages were defined by house-to-house interviews, and infection prevalence and disease severity were assessed by standard parasitologic testing and by ultrasound. The total population was 4,408 among 912 households, with 241 identified pedigree-household groups. Although age- and sex-adjusted risk for greater infection intensity was clustered within households (odds ratio = 2.7), analysis of extended pedigree-household groups indicated a relatively low heritability score for this trait (h2 = 0.199), particularly after adjustment for common household exposure effects (adjusted h2 = 0.086). Statistical evidence was slightly stronger (h2 = 0.353) for familial clustering of bladder morbidity, with an adjusted h2 = 0.142 after accounting for household exposure factors. We conclude that among long-established populations of coastal Kenya, heritable variation in host susceptibility is low, and likely plays a minimal role in determining individual risk for infection or disease.