Pinta

Excerpt

When I lived in Honolulu, every mid-April I told my plover that he was an idiot. Why should he fly, nonstop, 4,000 to 5,000 miles simply for sex. "Stay here," I'd tell him. "There are great chicks in Honolulu. Maybe I can fix you up with that nice Hawaiian stilt I know." But my plover rejected all blandishments. In his elegant courting plumage of jet black bib and white shawl, he would, on a late-spring morning, leave his feeding territory -- that small patch of grass fronting my condominium's tennis court -- and wing his way north to Alaska or Siberia. In September, Deo volante, he'd be back bug picking on the Hawaiian turf.

In the very far North during the short, warm, humid summer, our plover rendezvoused not only with his ladylove but also with the mosquitoes, midges, ticks, and biting flies that awaited his return,

During my many years in sultry climates I have been bitten by tsetse flies, sand flies, black flies, horseflies, and mosquitoes of many varieties, as well as by ticks and mites; but nowhere in the Tropics have I been attacked by insects so viciously and massively as when flogging trout streams in the arctic watershed.The abundance of blood-sucking insects that proliferate during the short artic summer is simply amazing. They make life hen for humans and wildlife. And they also transmit the viruses that can affect human health. These arthropod-borne viruses are known collectively as arboviruses.

The "natural" hosts of many arborviruses are migratory birds such as the waterfowl that make epic seasonal flights to their arctic breeding grounds. Most arboviruses are not too fastidious and can spill over into mammalian populations -- wild, domestic, and human. Some arboviruses are transmitted by ticks (arthropods more closely related to spiders than to insects). Ticks and mites infest the nests of waterfowl, where they have easy access to a blood supply of chicks, which they infect with virus as they feed. Moreover, some viruses can be perpetuated from tick to tick via the tick's egg. If a female tick carries such a virus, it can enter her eggs and lie dormant over the winter. The egg develops; the larval tick hatches already loaded with virus and can pass it on to the bird or mammal on which it takes its first blood meals.

From the birds without frontiers and the mammals without frontiers and the swarms of vector mosquitoes and ticks at all frontiers, transarctic zoonotic arboviruses probably posed a health threat to the first Americans when they colonized Alaska. These people may also have carried viruses in their persons or in their accompanying domestic animals that became forever endemic in the Americas. Indeed some of those viruses may have proved highly lethal to the immunologically naive American wild mammals. Shortly after the arrival of humans in North America, many of the large mammals became extinct. Did a human virus or an introduced zoonotic virus from a domestic animal kill them off?.

The historical epidemiology of viral diseases is a vexing area of research because viruses are so small and often so mutable. "Here today, gone tomorrow" or "Gone today, here tomorrow" characterizes the changeability of viruses and how they come and go as threats to humans. Lassa fever and, most notably, AIDS came "from out of the blue" in our time. A great disease of the past, seemingly without parallel in our present time, was the plague of Athens. That mysterious disease killed one-third of the Athenian population during a twenty-year period beginning in 430 B.C. The only clinical description we have is from the philosopher-general Thucydides, who was himself stricken but recovered. It was a highly contagious disease giving rise to high fever; respiratory, intestinal, and neurological involvement; a rash; and gangrene of toes, fingers, and penis.

Nothing quite matches the Athenian plague in the present clinical logbook or in the subsequent historical medical logbooks. It disappeared with no evident recurrence elsewhere. It has, for many years, challenged diagnosticians who have proposed some thirty causative, mostly viral agents. I added a thirty-first and speculated that it was a form of Lassa fever (MD Magazine, May 1994). Lassa mostly fits Thucydides' account, except that Lassa doesn't make your penis fan off, but why quibble over small details?

COPYRIGHT 1997 Natural History Magazine, Inc.
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