4. Biodiversity Theme 4: Impacts on Human Health - What are some of the human diseases that are caused by organisms within this group? What are some of the beneficial effects of organisms within this group on human health? Although many of the human health issues relate to direct infection by organisms, many of the human health impacts can be indirect such as famines caused by crop destruction. Are there any examples of indirect effects on human health? What are some specific examples of organisms within this group that have impacts on human health?.