Tiny Terrors

Peel back the soft green cover, and you might find menace skulking in a Virginia garden. A neighbor picked up a copperhead by its tail, which turned round to bite him (can you blame it?). Large wolf spiders enjoy nipping me while gardening (so far I have avoided black widows in our wood piles). As for brushes with poison ivy, I lather cortisone cream every week.

But it is not the bigger things that always hurt us most: sometimes we should fear the tiny ones even more (words are like that too.) Yersinia pestis slew more Europeans during the four peak years of bubonic plague than all the swords, pikes, bows and arrows of the Hundred Years War; the smallpox virus slaughtered more native Americans than the Winchester rifle; the Spanish flu killed more people than all the bombs, bullets, and gas grenades in the preceding First World War; and David Livingstone died from tropical diseases, not the mauling from a lion.

After breakthroughs with pencillin, sulfonamides, and new vaccines, there was a short period of medical hubris—it was believed that infectious diseases were in retreat and would soon be eliminated. The dream was quickly scuttled by the arrival of HIV-AIDS and drug-resistant bacilli, and now we have something else to worry about. TICKS.

They were always part-and-parcel of a tramp across a heather moor in northern Britain or through dense underbrush in the mid-Atlantic States. Back in the mid-1970s, I had heard that Rocky Mountain spotted fever was carried by ticks, but it sounded far away and nothing to worry about. Around the same time, there was news of a danger prowling backyards and woods where children play in Lyme, Connecticut. We learned that the new disease rides inside a tick as a spirochaete bacterium, Borrelia burgdorferi. (Taxonomists, please choose more memorable names, like, Lyme horribilis).

The first reports did not sound particularly alarming. The problem was rare and localized, and the symptoms mild. None of this is now true. Lyme took 20 years to reach Virginia and is spreading to all points of the compass and overseas (where it may have originated). We were told that if we removed a biting tick within 24 hours we would be fine even if was infected. If too late, then we were urged to rush to the doctor’s office for a course of tetracycline to stop the infection, whose signature is a bull’s eye rash, fever, and fatigue. Treated in time, we could forget about it—until the next bite. But if untreated, Lyme would likely progress to arthritis and painful joints.

That was the medical consensus, but untold numbers of people whose lives have been wracked with pain and wrecked by permanent tiredness never had a positive lab test result, even if they had good reason to suspect they had Lyme. Perhaps the disease agent had become disseminated to parts of the body that drugs and antibodies hardly reach?  This is where the controversy called “Chronic Lyme” started. When tests are negative (even admittedly poor tests), doctors presume an ailment probably has another cause and are understandably reluctant to start a long course of antibiotic treatment. Those doctors moved by their patients to go against standard medical protocols by providing aggressive i.v. antibiotics invoked the wrath of their own profession. There are many touching stories online of students who had to withdraw from school and adults who quitted work because of a suspected tick-borne illness, and so many more less well-known cases, like a young father we know of who died from complications of Lyme. It is natural to come down on the patients’ side of the argument, especially when they frustrated at being sidelined by mainline medicine and suspected of being malingerers or having a problem “all in their head.” To us, it seemed like a rerun of the doubts that used to surround chronic fatigue syndrome, of which our family has first-hand experience. For her remarkable book, Cure Unknown, the science writer, Pamela Weintraub, dug exhaustively into the science and sociology of Lyme, drawing too from the tragedy it brought to her own family.

Perhaps the storm is beginning to pass since the CDC announced last week that Lyme is an emerging public health crisis that is ten-times more prevalent than assumed because it has been under-reported and under-diagnosed. Every year in the United States alone there are 300,000 new cases, and numbers are probably going to rise.

The deer tick is mainly held responsible for transmitting Lyme, although it is not the only tick that feeds on deer, and deer are not the only animals that infect ticks. Even more complicated, ticks often carry more than one type of pathogenic bacterium, and the deer tick may not even be the worst of the bunch. Not much is plain and simple in parasitology.

One of my fellow master naturalists had hundreds of ticks on him after hiking in local woods in advance of a school party (the party was canceled). My record is a mere 16 ticks after mowing the lawn. I save them in alcohol until the end of the year when I identify the species to alert me to hazards. A more scientific way of surveying ticks is to drag a cotton sheet across a field or woodland floor, to which they cling hoping it leads to a meal.  Half of the ticks I found in our yard last year were lone star ticks, 10 % were “deer” ticks, 2% were dog ticks, and the rest were nymphs (too small to identify species).

Lone stars are not named for Texas (though they are found there as well) but because the females (the big-eaters) have a single white spot on their shield-like back. They probably don’t transmit Lyme or Rocky Mountain spotted fever, but are vectors of a small menagerie of bacteria, some of which are definitely pathogenic. Ehrlichia chaffeensis causes human monocytic ehrlichiosis in which the first symptoms resemble Lyme (generally without the bull’s eye) with pain, a blunted immune response, and even toxic shock syndrome. Half the cases can be serious enough to require hospital treatment, and according to the CDC the mortality rate peaked at 3.7% in 2003 (close to Spanish flu).

Now the good news is that not every tick is infected, but you never know which ones can be safely ignored. They can however be tested for genetic tell-tales of the bacteria they harbor. At the College of William & Mary, Matthias Leu is leading a study of the distribution of ticks in the Virginia Peninsula and is testing lone stars for E. chaffeensis using an extremely sensitive and specific DNA test (PCR). So far, he has found that almost 10% of the samples were positive for this bacterium, and most of them were found in public parks and recreation areas. Why there?

He found that in places where ticks are abundant so are the deer, but birds are scarce (they predate ticks). The Virginia Peninsula was originally a blanket of almost unbroken forest, but development is breaking it into small wooded fragments. As more woodland edges are formed, vegetation grows up that deer love. Throughout the East, the white-tailed deer population density has exploded; some biologists estimate there are 10- or even 100-times as many as in pre-colonial times. Not only have developers created ideal habitats for deer, but the major predators have been extirpated, hunting is limited, gardens are salad-bars for deer, and sometimes they are even fed deliberately.

When deer move into new areas they bring disease with them. Ticks become infected with the disease and the bacteria pass through their life cycle into other mammals, including mice, which become a disease reserve without suffering from it themselves. Setting up tree stands for hunters or bringing back wolves probably won’t make the problem go away. Chickens can help by gobbling up ticks and copperheads by swallowing rodents, but when we started tampering with nature we set in motion ecological changes that are hard or even impossible to reverse.

I wish I could end on a more optimistic note, but in the near future only constant vigilance will provide peace of mind. Those who venture out into woods and gardens during the warm months of the year should cover up with permethrin-treated clothes, but indiscriminate spraying is a bad idea because it kills our good friends, the pollinators. Each of us needs an intimate friend for daily inspections of our crooks and curves that we cannot see for ourselves. Choose someone with good sight because the tiny nymphs responsible for most cases are not much larger than the period at the end of this sentence. Antibiotics used promptly are safeguards, but people who pick up ticks most days can’t use them forever. We need a vaccine, but the only one available is for dogs. Smith Kline Beecham withdrew their human anti-Lyme vaccine years ago after lawsuits claiming it caused arthritis. We may want to knock government down in size, but we need it to step in for vaccine development where big pharma fears to tread.

Next Post: A Scythe for All Seasons