The relationship between Ascaris lumbricoides and malaria in children aged 1-4 years

Abstract

Soil-transmitted helminths (STH) are among the most prevalent of chronic human infections worldwide. More than 1.2 billion people are thought to be infected with one or more species of STH (de Silva et al., 2003). In nature, concomitant infections are the rule rather than the exception (Cox, 2001). The interaction between helminths and malaria has gained considerable attention from the scientific community (Basavaraju and Schantz, 2006; Mwangi et al., 2007). Animal and human studies have shown that there is an association between helminths and malaria (Spiegel et al., 2003; Helmby et al., 1998). The findings from studies investigating these co-infections are contradictory: some studies have shown that co-infection increases parasitaemia and clinical malaria (Briand et al., 2005), whereas others have shown co-infection to have the opposite effect (Brutus et al., 2006). Most of the human studies are observational in nature i.e. cross-sectional surveys (Tshikuka et al., 1996; Briand et al., 2005), case-control studies (Nacher et al., 2000; Nacher et al., 2001c) or longitudinal studies that monitor disease trends (Spiegel et al., 2003; Sokhna et al., 2004) and therefore fail to demonstrate causality. The thesis presented here represents an investigation of the relationship between soil-transmitted helminths and malaria in preschool children.