nitazoxanide being successfully used in human fasciolosis treatment in Mexico. There are also reports of bithionol being used successfully. Nitazoxanide has been found effective in trials, but is currently not recommended. Domestic animals Only clorsulon and albendazole are approved for use in the treatment of domestic animals in the United States, but the available flukicides used worldwide also include triclabendazole, netobimin, closantel, rafoxanide, nitroxynil, and oxyclozanide; however, this list of available drugs has some drawbacks. Closantel, nitroxynil, and oxyclozanide are not effective against young liver flukes and should only be used to treat subacute and chronic infections. Triclabendazole is effective at killing flukes of any age, but only those that cause acute infections; flukes that have remained in the body for long periods of time are becoming resistant to this drug. The timing of treatment is critical for success, and is determined by environmental factors and analysis of the expected distribution and prevalence of the disease. For example, in European countries that have large numbers of sheep, computerized systems predict when fascioliasis is most likely to make the biggest impact on sheep populations and how many sheep will most likely be affected. The predictions are dependent on guessing when environmental conditions that are most conducive to parasite multiplication will occur, such as amount of rainfall, evapotranspiration, and the ratio of wet to dry days in a particular month. If heavy infections are expected to occur, treatment for sheep should begin in September/October, then again in January/February, and finally in April/May; the amount of hatching fluke eggs is minimal during these times because they require a warm, wet environment, making treatment more effective. Epidemiology Human and animal fasciolosis occurs worldwide. While animal fasciolosis is distributed in countries with high cattle and sheep production, human fasciolosis occurs, excepting Western Europe, in developing countries. Fasciolosis occurs only in areas where suitable conditions for intermediate hosts exist. Studies carried out in recent years have shown human fasciolosis to be an important public health problem. Human fasciolosis has been reported from countries in Europe, America, Asia, Africa and Oceania. The incidence of human cases has been increasing in 51 countries of the five continents. A global analysis shows that the expected correlation between animal and human fasciolosis only appears at a basic level. High prevalences in humans are not necessarily found in areas where fasciolosis is a great veterinary problem. For instance, in South America,