An evolutionary suggests that health interventions can reduce not only the frequency of infectious disease but also the harmfulness of the causal organisms. Interventions that may accomplish this dual goal include hygienic investments such as vector proofing of housing, provisioning of safe water supplies, infrastructure that blocks transmission of durable propagules, the prevention of attendant-borne transmission in hospitals and reductions in the potential for sexual transmission. Vaccines can also reduce the frequency of infection and the harmfulness of the target organisms if they are designed to inhibit selectively the harmful variants in the target population. These approaches should help suppress the evolution of antimicrobial resistance because benign variants causing mild or asymptomatic infections will be less exposed to antimicrobial treatment, reducing the strength of selection for antimicrobial resistance. The interventions should improve health at low cost, which would be especially important for low-income populations.