New World Disorder
Who Gave Pinta to the Santa Maria? Robert S. Desowitz. 288 pp. W.W. Norton, 1997. $25.
Rumor has it that it was Nina but no one knows. In this compact and entertaining book, Robert Desowitz revisits the age-old controversy surrounding the origin of venereal syphilis. Was syphilis gratuitously exported to Europe in exchange for the panoply of infectious diseases heaped on Amerindian populations, or was it an indigenous infection of the Old World?
Some have speculated that syphilis has ancient roots in Europe but was unrecognized as a clinical entity until it burst on the scene in 1495. In that year, Charles VIII, King of France, crossed the Alps into Italy with 50,000 mercenaries. Accompanying his polyglot army were some 800 camp followers, including many prostitutes. The invading host laid siege to Naples. Conditions were appalling for besiegers and besieged alike, and infectious diseases were rampant. Prominent amongst them was a malignant and hitherto unrecognized form of syphilis. Contemporary observers reported that the disease began with genital sores but progressed rapidly to abscess formation, ulceration and erosion of deeper tissues, including bone. Within a decade or two, however, syphilis declined in frequency and virulence, assuming a clinical expression similar to the disease we know today.
The foregoing scenario implies that venereal syphilis has been with us for a long time. Prior to 1495, it may have been lumped with other disfiguring diseases such as leprosy. However that may be, the geographic origin of syphilis is unresolved. It may have been indigenous to Europe or imported by Columbus's companions, some of whom joined the ill-fated Naples expedition.
Another possibility that has fascinated medical historians and anthropologists alike is that syphilis evolved more recently from another, closely related spirochete. There are three candidate organisms, namely those responsible for pinta—a disease of the New World—and the causal agents of yaws and bejel, both diseases of the Old World. The three organisms are serologically indistinguishable from one another and from Treponema pallidum, the causal agent of syphilis. Their individuality and hierarchical relationship are unlikely to be established short of DNA sequencing of the subject organisms, and this has not yet been done.
The problem of sorting out the relationship of syphilis to pinta, yaws and bejel is further complicated by the possibility that factors other than genetic mutation or the intrinsic pathogenic potential of the causal organisms influence disease transmission and its clinical expression. Climate and culture and genetic factors peculiar to the host may also be important. Two examples of disease resistance related to generic factors are cited by Desowitz. Both involve malaria. One is the association of the sickle-cell trait with resistance to P. falciparum, and the other is the resistance to P. vivax of individuals who lack Duffy factor, a surface marker of erythrocytes.
The exposure history of individuals to infectious agents is still another factor that can influence the prevalence or severity of disease. The protective power of antibodies formed in response to infection or vaccination is but one example of acquired resistance; another is to be found in the enhanced capacity of macrophages to kill or at least impede the intracellular growth of infectious agents. Cellular resistance to infection has been demonstrated repeatedly in laboratory experiments, but it also occurs in nature. The intertwined history of tuberculosis and leprosy can be interpreted in this way. Archaeological evidence points to an inverse relationship between the prevalence of tuberculosis and leprosy that spans at least two millennia and possibly much longer. When tuberculosis flourished, leprosy faded and vice versa. Mycobacterium tuberculosis is known for its capacity to induce a measure of resistance to M. lepra. Yet the periodicity of the two diseases could have a more complicated explanation. Aside from cross resistance, the ascendancy of one disease at the expense of the other may be related in part to climate, ecological considerations or the spread of disease as a consequence of commerce or military adventures.
The foregoing relationships are not explored in depth in Who Gave Pinta to the Santa Maria?; nevertheless, the reader is richly rewarded by accounts of the peregrinations of tropical diseases.
Some are described in greater detail than others, possibly because they combine tales of heroism and natural history with mystery revealed. Nowhere are those elements more impressively combined than in the conquest of yellow fever. Desowitz is an excellent storyteller. His historically accurate accounts are sprinkled with enlightening anecdotes reminiscent of Hans Zinssar's classic description of the history of typhus (Rats, Lice and History, Little, Brown Co., 1934). The author's admiration and affection for those involved is readily discerned. If one is prepared to ignore distracting typographical errors, both the professional and lay reader will find this book entertaining and informative.—Douglas D. McGregor, College of Veterinary Medicine, Cornell University