Understanding the Real Threat
of the New Pandemic Plagues
[review] [excerpt] [endlinks] [purchase]

by Frank Ryan
HarperCollins Publishers, 1997

Reviewed by David Bradley

It always happens. At certain points in our history the prophets and soothsayers arrive in hordes announcing that the end of the world is nigh. The eve of the new millenium has special attractions for doomsday predictions. However, as this book details, there is at least one placard that should be taken seriously - that announcing the threat of emerging pandemic viruses.

Dr. Frank Ryan, a consulting physician in the UK, ably narrates this threat in Virus X. Taking us on a dramatic journey first to the heady altitudes of New Mexico in the early 1990s, he describes a phantom virus that attacked Navajo Indians. There were thirteen initial victims of this mystery disease, which turned Navajo society upside down. Almost every one of the afflicted died within hours of their first symptoms. Chest X rays of victims showed, instead of the healthy translucency of the normal aerated lung, a solid opaque white, the delicate air sacs flooded.

This manifestation pointed to a particular diagnosis: plague, a disease that rears its ugly head every so often in human society. It is in fact endemic in the New Mexico area, with several occurrences each year. There are two clinical forms of plague - bubonic, named for the buboes that erupt from the victim's skin, and septicemic, which spreads through the bloodstream like blood poisoning. Both are caused by the microbe Yersinia pestis. The septicemic form is the kind that seeds in the lungs, and coughing makes it extremely contagious.

This time, however, it turned out not to be plague at all but a new strain of hantavirus. Most worrisome is the fact that the disease is carried by one of the most widespread of American rodents, the charmingly named deer mouse. Why should it then restrict itself to the Navajo when the rest of America awaits its attention? Indeed, variants of the virus continue to turn up from Delaware and back to Albuquerque.

In Virus X, Ryan takes us through the drama of discovery - the people, the high-security research establishments, the uncoiling of viral RNA, and the eventual pinning down of a new species. This is the kind of biodiversity we can do without.

From New Mexico, Ryan travels to sub-Saharan Africa, describing the emergence there of a more publicly prominent and terrifying emergent: Ebola virus. This one is named for a gentle river several miles from the site of the first outbreaks. The terror of the villagers as they beg to see their dead loved ones is felt in Ryan's descriptions of the autopsies carried out with spartan equipment and none of the conveniences of a modern hospital.

Emerging infections are not new, of course. Numerous diseases have crept perniciously into the midst of humanity over the course of our history. Black Death reared its ugly head in only very recent memory, although the decimation of human life was on a far smaller scale than its earlier visits. The growing numbers of fevers, encephalitic viruses, arthritic viruses, hemorrhagic fevers, diarrhea-causing infections, HTLV, Legionella, Lyme disease, toxic shock syndrome, variants of HIVs, flesh eaters, and Ebola do seem to be getting more of an evolutionary grip. This, coupled with the growing threat of pathogen evolution in the form of drug resistance (e.g., seen with the recent reemergence of tuberculosis) suggests that Plague rides with the Four Horsemen of the Apocalypse.

In another narrative, we are led through the worst-ever recorded food-borne outbreak (from E. coli germ 0157:H7), manifested as bloody diarrhea, occurring in 1993. The epidemic had arisen from contaminated minced beef in hamburgers sold through a fast-food restaurant chain. More than 500 cases were identified, 56 of whom had developed kidney failure and four of whom (all children) had died.

Ryan suggests that although the questions before us are almost too appalling to contemplate, they must be faced. The most worrying is that the human species may be under threat from a pandemic virus, either emerging or changing. As we tear into the tropics, encroaching on the last remaining acres of precious wilderness, will a new virus - the equivalent of an airborne HIV - emerge, taking us into millennial oblivion?

We can hope that most of these new infections will behave as the various outbreaks of Ebola, Legionnaire's, Lyme disease, and even E. coli, have done so far, and restrict their life cycles to a closed-shop of a few very unlucky individuals. Ryan, though, is certain of one thing: the universe is not benign and we must do everything in our power to mitigate the danger.

At the time of writing, information released in the British Medical Journal prompts the question of whether HIV has become more aggressive. According to Italian researchers, the progression of the disease in almost three hundred patients recruited between 1985 and 1995 showed that patients with signs of infection after 1989 had a higher probability of immune system decline and a faster progression to full-blown AIDS than patients infected before then. The authors conclude that more virulent strains may have emerged in recent years.

Ryan covers well the emergence of the original HIV. What is most frightening is that like the hantavirus of the deer mouse, the forebears of the human virus do not seem to cause any harm to their original hosts. In 1982, two years after the discovery of the first human retrovirus, HTLV-1, Japanese researchers uncovered a related virus in the macaque, designated a simian T-lymphotropic virus, STLV. The discovery hinted that monkeys might be the source of human retroviruses, and as other researchers began to discover TLVs in more and more species around the globe, it was realized that primates had been infected possibly for hundreds of thousands of years. The viruses were genetically homologous with their human relatives the HTLVs, and the gap between species from nonhuman primate to people was not then such a huge leap of the imagination.

When, in 1984, Montagnier and his colleagues at the Pasteur Institute isolated the first of the AIDS viruses, they made this leap and asked whether their virus would cross-react serologically with the monkey virus SIV. It is now thought that simian AIDS viruses first infected African primates less than a million years ago. At that time even the monkeys may have suffered the emergence of the virus from another host. But the question remains of why many of these viruses are benign toward their natural host yet emerge as lethal in naive hosts. Is there a common characteristic between the likes of the hantaviruses, Ebola, and HIV-1 toward new hosts?

Forget the millennium bug of the computer world. The real bugs are out there, waiting to fulfill the prophecies.

David Bradley is a science writer based in Cambridge, UK. He specializes in chemistry and medicine and can also be found on ChemWeb.com as The Catalyst.

Excerpt