(or ova) are a good indicator organism to assess the safety of sanitation and wastewater reuse systems for resource recovery because they are the most environmentally resistant pathogens of all pathogens (viruses, bacteria, protozoa and helminths) and can in extreme cases survive for several years in soil. Typically, helminth eggs are found in water, soil, and food sources that are contaminated with fecal matter which come from wastewater and sludge. Helminth eggs that are indicated in wastewater and sludge come from soil-transmitted helminths (STHs) which include Ascaris lumbricoides (Ascaris), Anclostoma duodenale and Necator americanus (hookworm), and Trichuris trichiura (whipworm). Ascaris and whipworm that are identified in reusable wastewater systems can cause certain diseases and complications if ingested by humans and pigs. Hookworms will plant and hatch their larvae into the soil where they grow until maturity. Once the hookworm eggs are fully developed, they infect organisms by crawling through the organism’s skin. According to the World Health Organization, to not cause significant infections from helminth eggs, there is only allowed to be ≤1 helminth egg per liter used for agriculture and irrigation. It is more likely to see higher concentrations of helminth eggs in the soil, wastewater, and sludge of underdeveloped countries that have an issue with sanitation practices. Examples include Tunisia, Peru, Ghana, Vietnam, and more. The technique used for testing depends on the type of sample. When the helminth ova are in sludge, processes such as alkaline-post stabilization, acid treatment, and anaerobic digestion are used to reduce the amount of helminth ova in areas where there is a large amount. These methods make it possible for helminth ova to be within the healthy requirements of ≤1 helminth ova per liter. Dehydration is used to inactivate helminth ova in fecal sludge. This type of inactivation occurs when feces is stored between 1-2 years, a high total solids content (>50-60%) is present, items such as leaves, lime, earth, etc. are added, and at a temperature of 30℃ or higher. See also Coliform bacteria Coliform index E. coli Indicator species References Bacteria Indicators