HOUSTON, Texas Individuals and families immigrating to the U.S. legally are required to pay for and undergo medical examinations by approved physicians; those who are deemed as having "inadmissible health-related conditions" are not allowed into the country. But the same standards are not applied to illegal immigrants, many of whom remain in the U.S. despite testing positive for diseases that would prevent law-abiding migrants from entering. ...tens of thousands of Central Americans entering the U.S. illegally. Some ...individuals have tested positive for illnesses including tuberculosis, chicken pox, and other viruses...most of them are not immediately deported. .. they stay and...