Protozoan infections are parasitic diseases caused by organisms formerly classified in the Kingdom Protozoa. Possible parasites include nematodes, copepods, protozoa, and helminths. Soil microorganisms can be classified as bacteria, actinomycetes, fungi, algae and protozoa. The fermenting organisms include bacteria, fungi, and protozoa. Some eukaryotic organisms, including a number of protozoa and helminths, are human parasites. Colonization by bacteria, protozoa or fungi can cause infection. Grasshoppers are affected by diseases caused by bacteria, viruses, fungi and protozoa. Plants, animals, fungi, slime moulds, protozoa, and algae are all eukaryotic. Public health pathogens can be present in swimming pools as viruses, bacteria, protozoa and fungi. Typically bacteria, protozoa, and microbial cysts are removed. They are active against bacteria and some viruses, fungi, and protozoa. Spores form part of the life cycles of many plants, algae, fungi and protozoa. Other causes may include certain chemicals, other bacteria, other protozoa, or parasitic worms. Silver has been shown to be effective against harmful bacteria, viruses, protozoa and fungi. This agent exhibits a broad range of microbicidal activity against bacteria, fungi, protozoa, and viruses.