One of the favorite pastimes of liberalism is to try to inflict guilt on people of European descent for being part of a lineage that they believe, in the words of Bill Ayers at the Dartmouth Debate with Dinesh D'Souza, "murdered" the American Indians by way of contagious disease.

Calling it the "European Invasion," liberals believe that prior to Christopher Columbus' arrival American Indians were virtually disease-free. Never mind that syphilis, which originated in the New World, was brought back to Europe, where spirochete bacterium was not present until after Columbus and his fellow discoverers returned in 1493.

The Columbian theory concludes that invaders from across the sea brought to the Americas the scourge of bubonic and pneumonic plague, chicken pox, cholera, diphtheria, influenza, measles, scarlet fever, smallpox, typhus, tuberculosis, and whooping cough.

Even though Indian tribes were slaughtering each other, lefties argue that their lack of immunity was solely responsible for American Indians dying en masse after exposure to infectious diseases, and are persuaded that 80-90 percent of the Native American population perished after Europeans landed in the New World.

Whether that scenario is truth or fiction, there remains a problem with the argument. Liberals incessantly harp on the fate of unsuspecting American Indians being infected with European maladies, yet that outrage doesn't jibe with their insistence that amnesty be granted to illegal aliens, some of whom carry diseases eradicated long ago from North America.

At the turn of the century, immigrants coming to America through Ellis Island were screened for disease, just as law-abiding persons immigrating via legal channels today require a medical exam as part of the process. Meanwhile, irresponsible politicians on the left, who portray Christopher Columbus as a marauding murderer, choose to ignore the influx of modern-day intruders carrying with them highly-contagious Third World diseases into the US.

Liberal logic approves of government making vaccinations mandatory to protect the American public, but then proposes legalizing anywhere from 11 to 30 million completely unscreened illegal aliens.

The hypocrisy is stunning. Do amnesty advocates care that blood tainted with malaria, a disease eradicated from the USA back in the 1940s, was deemed responsible for outbreaks in California, New Jersey, NYC, and Texas?

How about Asian illegals introducing dengue fever, a viral disease previously unknown in the US, as well as hemorrhagic dengue fever, which is fatal if untreated?

Could it be that amnesty advocates feel that, as part of the retribution for white European ancestors contaminating America's indigenous people, hundreds of years later it's acceptable that innocent children require lifesaving platelet transfusions to cure dengue fever?

The Biblical scourge of leprosy, a "slow-growing bacillus...parasite with a tropism for peripheral nerves, skin, and mucous membranes...upper respiratory tract, anterior chamber of the eye, and the testes," is also within our borders. In 2002, there were only 900 total cases of leprosy in the US. In the next three years there were 9,000 , mostly in states with the largest immigrant populations.

Dr. William Levis, head of the New York Hansen's Disease Clinic, told Columbia News Service, "[Leprosy] is a real phenomenon. It's a public health threat. New York is endemic now, and nobody's noticed."

Do those hostile to 15th century European exploration feel that although it was once rare in America, an increase of reported leprosy cases adds to the multicultural diversity liberals embrace with such affection?

It would be interesting to hear whether or not Mr. Obama is of the opinion that "reconciling our values and principles as a nation of immigrants and a nation of laws" includes the high price of exposing Americans to leprosy.

Then there are contagions like Chagas Disease, a parasitic illness that was endemic to South and Central America but now infects between 100,000 and 500,000 illegal immigrants currently living in the US.

The CDC considers Chagas Disease one of the "neglected parasitic infections (NPI), a group of five parasitic diseases that have been targeted by CDC for public health action," another of which is guinea-worm. The guinea-worm parasite, an uninvited alien of a different kind, causes severe pain as the worm works its way though a human host's subcutaneous tissue.

Hepatitis A-E are viral infections that attack the liver. And then there's highly-contagious tuberculosis, which had been brought under control in the US, but thanks to a border that remains open, is growing harder to control.

Incurable Multi-Drug-Resistant (MDR) Tuberculosis, a strain resistant to all standard anti-TB drugs, is now on the rise in the US.

In an article in the Journal of the American Medical Association, Dr. Reuben Granich, a lead investigator for the CDC, concluded: "Reluctant to label the infected as 'illegal' or even 'undocumented' aliens...407 known cases of MDR-TB, 84% were 'foreign-born' patients, mainly from Mexico and the Philippines who'd been in the U.S. less than five years."

Recently, shoppers in Nyack, NY were exposed to measles in Palisades Center Mall. So, a word to the wise: the next time a French fry falls on the table in the food court or the handle of a shopping cart is grabbed, remember that along with open borders and liberal politicians come diseases and various deadly pathogens either formerly eradicated or never endemic to the US in the first place, are waiting for a new host, and you are nominated.

Meanwhile, despite the risk to the American people, food workers and produce handlers potentially carrying illnesses like blood-borne Hepatitis are doing "work Americans won't do." Then, instead of shielding the American public from catastrophe, politicians like Barack Obama, advocate for workers with potentially communicable diseases to stay.

So, once again the self-righteous left proves they are the champions of idiotic double standards. They condemn European-descended whites for murdering Native Americans centuries ago, while arguing on behalf of illegals currently spreading a plethora of deadly Third World afflictions with the potential to infect and kill millions of Americans.

Jeannie hosts a blog at www.jeannie-ology.com