Table 4. Interaction on an additive scale between the effects of parasites on the prevalence of ACE.

Exposure to multiple infections	Relative excess risk due to interaction (RERI)	P-value
Toxocara canis+Toxoplasma gondii	0.63(−0.03–1.29)	0.063
Toxocara canis+Onchocerca volvulus	−0.16(−1.28–0.97)	0.785
Toxocara canis+Plasmodium falciparum	−3.35(−18.27–11.58)	0.660
Toxoplasma gondii+Onchocerca volvulus	1.19(0.27–2.11)	0.011
Toxoplasma gondii+Plasmodium falciparum	−18.24(−68.93–32.46)	0.481
Onchocerca volvulus+Taenia solium	1.33(−2.48–5.79)	0.481
Onchocerca volvulus+Plasmodium falciparum	n.d*	n.d

^*Interaction could not be determined for O. volvulus and P. falciparum co-infection as there were no cases of ACE with exposure to O. volvulus infection without exposure to P. falciparum.

+RERI adjusted for age, sex, study site, education (none, primary, or secondary and above), employment, marital status and exposure to other assayed infections. A positive RERI indicates that the combined effect of the two parasites is greater than the sum of the individual effects.