ZINC-DEFICIENCY AND ZINC REPLETION - EFFECT ON THE RESPONSE OF RATS TO INFECTION WITH TRICHINELLA-SPIRALIS

The expulsion of a primary infection of Trichinella spiralis was studied in rats fed diets containing (per kg diet) either 3 mg Zn [zinc deficient (Zn-)] or 40 mg Zn [zinc adequate (Zn+)]. A dose of 2000 muscle larvae (ML) impaired weight gain (mg/g body wt) in all groups compared with uninfected controls [eg, 0-7 d postinfection (dpi): infected Zn-, -105 ± 10 (x̄ ± SEM); uninfected Zn-, 54 ± 19 (p < 0.001)]. In a study with 20.5 ML/g body wt, some Zn- rats were transferred at the time of infection to the zinc-adequate diet. [This was the zinc-repleted group (ZnR)]. Both groups retained a group of pair-fed controls (Zn-PF and ZnRPF). The percentage dose established at 7 dpi was similar in all groups (32.5-39.3%) but at 13 dpi recoveries were 19.4 ± 2.2% for Zn-, 0.1 ± 0.1% for Zn-PF, 1.6 ± 0.9% for ZnR, 0.6 ± 0.2% for ZnRPF, and 4.1 ± 2.2% for Zn+ (p < 0.001). Up to 13 dpi, all groups except ZnR lost weight. These results show that zinc deficiency impairs the expulsion of T spiralis in rats.