  Anthelmintic resistance is a major threat to current measures for helminth
control in humans and animals. The introduction of anthelmintic vaccines, as a
complement to or replacement for drug treatments, has been advocated as a
preventive measure. Here, a computer-based simulation, tracking the dynamics of
hosts, parasites and parasite-genes, shows that, depending on the degree of
host-population mixing, the frequency of totally recessive autosomes associated
with anthelmintic resistance can follow either a fast dynamical regime with a
low equilibrium point or a slow dynamical regime with a high equilibrium point.
For fully dominant autosomes, only one regime is predicted. The effectiveness
of anthelminthic vaccines against resistance is shown to be strongly influenced
by the underlying dynamics of resistant autosomes. Vaccines targeting adult
parasites, by decreasing helminth fecundity or lifespan, are predicted to be
more effective than vaccines targeting parasite larvae, by decreasing host
susceptibility to infection, in reducing the spread of resistance. These
results may inform new strategies to prevent, monitor and control the spread of
anthelmintic resistance, including the development of viable anthelmintic
vaccines.
