Changes to the environment can have a profound effect on parasite transmission, and many examples have been documented. Although such studies describe the changes that occur, they do not usually address the question of whether or not the environmental effects are reversible. Both manmade and natural perturbations can alter habitats, leading to either an increase or decrease in parasite transmission. Two different categories of manmade environmental changes, with examples and whether they can be reversed, are discussed. The first type is where habitats are intentionally altered to improve human well-being but produce unintended consequences to parasite transmission. The examples described include the Aswan High Dam, the Diama Dam, urbanization, and family ranching. The second type is where commercial interests intentionally alter habitats for profit or to avoid expensive treatment of waste products, which then changes parasite transmission. The examples discussed are commercial logging, salmon farming, and water pollution from pulp and paper mills. In some cases, government intervention has mitigated the effects on parasite transmission although the habitat remains altered (e.g., Aswan High Dam). In another example, once the habitat was returned to its normal state, parasite transmission diminished (family ranching). However, there are environmental perturbations that are not easily reversed, such as urbanization and those caused by commercial endeavors. In these cases, improvements to the economy, public advocacy, and special interest groups may reduce the problem of increased parasite transmission, although they will not likely be completely mitigated.