The Why Files The Why Files --

Infection dissection

New bugs. New battles.
Clad in protective garments, two medical workers hold a crying child in a
hospital ward.Five years after the Ebola virus killed 286 people in Congo, the disease has reappeared in Uganda. Seventy-three people are dead to date.

Ebola, one of the most destructive and fatal new infectious diseases, causes massive bleeding, and most victims die within a week. The disease is highly contagious -- and untreatable.

A Medical Officer at Lacor hospital in Gulu, 224 miles north of the Ugandan capital, examines a child suspected of being infected with the Ebola virus Oct.17. Already, the fearsome virus has killed a reported 72 people in Uganda. AP Photo/Sayyid Azim

Ebola is one of many "emerging infectious diseases" that are causing alarm among public health types:

In 1997, a bird flu "jumped the species barrier" from chickens to people in Hong Kong. A similar "jump" caused an influenza epidemic that killed about 20 million people in 1918.

HIV, the cause of AIDS, is now known to mutate constantly, meaning it may continually escape drugs. Having already killed more than 19 million people, HIV is the deadliest of emerging infections -- unless you count malaria, an infection that often resists formerly effective drugs, and kills about three million every year.

Some strains of the old killer Staphylococcus aureus now resist vancomycin, the last-resort antibiotic. And many strains of a tuberculosis bacterium that's running rampant in Russian prisons and society resist drugs, threatening a return to medicine's dark age -- before antibiotics (see "Betrayal of Trust" in the bibliography).

West Nile virus, which reached New York City from the Middle East in 1999, is already entrenched on the U.S. East Coast. Whether West Nile, which killed seven in New York in 1999, will become a major menace is unknown, but it will pose "a heavy psychological burden," according to Andrew Spielman of Harvard Medical School. The virus, he notes, is carried by a midnight-feeding mosquito. "Whenever you wake up in the middle of the night, with a high C in your ears, you will always have to worry whether that buzz is loaded."

long wormlike elementThis filamentous virus causes the intense bleeding of Ebola disease. Courtesy Center for Disease Control, Special Pathogens Branch

Since the U.S. Institute of Medicine published "Emerging Infections" (see bibliography) in 1992, the subject has gotten considerable attention. According to one definition, "emerging infections" are:

new to humans (such as AIDS in the 1980s),

new to a geographic region (such as West Nile virus in the United States); or

no longer controlled by drugs that once worked (like malaria and some bacterial infections that have evolved resistance to drugs).

Map shows these three
countries in Central and Eastern Africa.In the past 25 years, Ebola has broken out in Sudan, Democratic Republic of Congo, and Uganda.

One reason for the renewed concern is the prospect of biological warfare by terrorists. But Spielman, an expert in emerging diseases, points to a second factor: the surge in global transportation. "People are carried hither and yon, agriculture moves animals and other living things around. Just in terms of spread, we are in an unprecedented period."

Transportation matters. Centuries ago, a quick-killing virus like Ebola was unlikely to spread far, certainly not across the globe. (There were, however, awful exceptions. For example, smallpox and other infections carried by European colonists decimated native Americans.)

But now that jet planes can lug pathogens across the globe in hours, we need to worry why pathogens are so crafty, and why diseases can suddenly "emerge" and infect thousands or millions.

Care to join The Why Files for a survey of emerging diseases?


Terry Devitt, editor; S.V. Medaris, designer/illustrator; Jenny Pearson, project assistant; David Tenenbaum, feature writer; Amy Toburen, content development executive

©2017, University of Wisconsin, Board of Regents.