It is well known that close contact with dogs, cats, or their waste can be asource of parasites, and that such parasites may cause illness, especially impaired digestion. However, the results of certain roundworm infections known as can be much more serious. Infection by the nematode parasite responsible for often occurs through waste-contaminated soil or physical contact with dogs and sometimes cats. The debilitating organism may trigger blindness if not properly treated. In addition to fevers and breathing difficulty, advanced cases of infection have been known to cause detachment of the retinas, leading to potentially permanent and serious ocular damage. While only a few cases are reported every year in Britain, thousands of cases of infection occur in the United States. Proper hand-washing can greatly mitigate the threat.