Deterring Truly Infected Individuals
Dishonest signals of infection may help to keep legitimately infected conspecifics at bay. Parasites often adaptively disrupt host defence mechanisms against other infections (Wakelin 1984). For example, helminths can suppress the immune response of their hosts in order to improve their own survival (Maizels et al. 2004) which can cause increased host susceptibility to other parasites (Helmby et al.1998; Su et al. 2005; Hartgers & Yazdanbakhsh 2006; Kamal & El Sayed Khalifa 2006) or make the costs of infection more severe (Marshallet al. 1999; Graham et al. 2005). Thus, genuinely sick individuals are predicted to exhibit heightened levels of disgust to promote avoidance of further infection (Oaten et al.2009). By mimicking being parasitized, a healthy individual could, therefore, deter truly infected conspecifics and reduce their chances of becoming legitimately infected (Loehle 1995).