I don't know enough about the homeless to debate the issue, but Phil, you've just made a statistical claim ("overwhelming majority" or to paraphrase, significantly greater than 50%) without citing the source. A bit of nitpicking, of course, but then you asked others for their sources.
And that's entirely fair of you to ask.
The Treatment Advocacy Center (
www.psychlaws.org) estimates, in its fact sheet on the homeless, that one third of the 600,000 homeless persons (as estimated by the Department of Health and Human Services) are schizophrenics or manic depressives. Healing Hands, a publication of the HCH Clinicians' Network (
www.nhchc.org), estimates that 38% of homeless adults have mental health problems, while fully 46% of homeless men report alcohol problems (and 30% of them report drug problems).
The Treatment Advocacy Center's Fact Sheet cites a 1993 study of HIV among homeless men in a New York City shelter, in which 19 percent of those living in the shelter tested positive for the virus that causes AIDS. According to a later study (April, 2002) in the Journal of Clinical Astroenterology (Viral Hepatitis and Other Infectious Diseases in a Homeless Population), “Chronic hepatitis C and co-infections are common among the homeless population.”
Still another study,
Ectoparasitism and Vector-Borne Diseases in 930 Homeless People From Marseilles, published in the journal Medicine in January 2005, concludes grimly, “Homeless people are particularly exposed to ectoparasites...Over 4 years, 930 homeless people were enrolled. Lice were found in 22% and were associated with hypereosinophilia... Twenty-seven patients (3%) with scabies were treated... The uncontrolled louse infestation of this population should alert the community to the possibility of severe re-emerging louse-borne infections.”
What that boils down to when you add them together is that most homeless people have
either mental illness or substance abuse issues, while a very significant percentage of them present a very real threat of contagious disease or disease-bearing organisms.