Cystic Fibrosis a Possible Protection Against Other Diseases?

Author's Note: I had always wondered why, though my husband has frequent infections, he never seems to get the typical array of flus and viruses that go around. In fact I've never even seen him get food poisoning. Now it seems that there may be something to it.

When the study came out regarding CF and cholera,some scientists suggested that CF may in fact have developed in response to this and other diarheal diseases as those diseases killed far more children then CF. finding no proof of that however, it may simply be that the two illnesses simply don't coexist in the same person. Could this be why food poisoning seems never to take hold in my husband, even when we've eaten the same contaminated food? (See: Gabriel SE, Brigman KN, Koller BH, Boucher RC, Stutts MJ. Cystic fibrosis heterozygote resistance to cholera toxin in the cystic fibrosis mouse model. Science. 1994 Oct 7;266(5182):107-9)

Now it appears that CF may also offer some protection against Typhoid Fever.

"...the defective CFTR that allows Pseudomonas to accumulate in the lungs of CF carriers may protect them from typhoid fever. When [immunologist Gerald] Pier exposed mice with defective CFTR to S. typhi, less than a tenth as many bacteria entered the intestinal cells - presumably because they couldn't bind to the altered CFTR. If the same phenomenon holds true in people, Pier believes, it would have given people with one defective CF gene an evolutionary advantage: They would have been more resistant to typhoid fever than normal people, without having cystic fibrosis." From ScienceNow at: http://sciencenow.sciencemag.org/cgi/content/full/1998/506/2

Cystic Fibrosis and Tuberculosis

While two copies of the CF gene can be fatal, one gene may, as above, protect against Tuberculosis. Researchers from Yale suggest, "The gene that causes cystic fibrosis may persist in human populations because, although two copies of it kill, having just one copy protects against tuberculosis." The reserachers propose this in light of the cystic Fibrosis gene continuing to affect such a large population even though it would have seemed (before now especially - since treatments have gotten so much more effective) to be self limiting. Perhaps because the single gene provides such disease protection, it continues to be "valuable" genetically.

"So Europeans must have derived some advantage from one copy of the gene that made up for losing the people with two copies - possibly protection from disease, the researchers reasoned. Sickle cell anaemia is an example of such a disease that persists with high incidence in Africans, since having one copy of the gene protects against malaria." (See: http://www.newscientist.com/article/dn10013-cystic-fibrosis-gene-protect)

Could it be that simple? It's too early to tell, but I wonder what other advantages we gain from this disease surviving so long in our genetic history.