Generating super-shedders: co-infection increases bacterial load and egg production of a gastrointestinal helminth

Lass, Sandra; Hudson, Peter J.; Thakar, Juilee; Saric, Jasmina; Harvill, Eric; Albert, Réka; Perkins, Sarah E.

To assess potential differences in clearing of helminths between single and co-infected hosts, the numbers of adult helminths established in the gastrointestinal tract of sacrificed hosts were quantified. Adult H. polygyrus were found on days 12, 24 and 48 in both single and co-infected treatment groups. Prior to day 12, adult helminths had not established in either group. Significantly more adult helminths were found in coinfected mice (negative binomial GLM, d.f. ¼ 1, p ¼ 0.013; figure 6a ). The number of helminths in single infections decreased significantly between days 12 and 48, but not in co-infected mice (negative binomial GLM, time: d. f. ¼ 1, p , 0.001, figure 6a ). There was a marginally significant interaction between time and infection status with a stronger decrease of helminths in single compared to co-infected hosts (negative binomial GLM, time: treatment: d.f. ¼ 1, p ¼ 0.053). As we were interested in the consequences of co-infection on transmission potential, we calculated the number of eggs shed by each helminth, using eggs collected from host faeces prior to destructive sampling (figure 6b). Single and co-infected individuals, however, did not differ in the per capita ( per helminth) number of eggs (negative binomial GLM, treatment: d.f. ¼ 1, p ¼ 0.873).