The Confounding Debate Over Lyme Disease in the South

The Confounding Debate Over Lyme Disease in the South

 

The debilitating tick-borne disease is well-documented north of the Mason-Dixon line, but does it exist beyond that?

 

By Wendy Orent

Kerry Clark never wanted to show that Lyme disease exists in the Southern United States by catching it himself. 

Clark is a medical entomologist at the University of North Florida in Jacksonville. A wiry man with graying brown hair, he is most at home in a kayak on the ponds behind the wooded Jacksonville campus. He jogs and lifts weights, when he is well enough to do so. 

Clark has spent years all over the South crawling through underbrush and kicking up leaf litter to collect ticks that transmit infections. Despite innumerable tick bites, Clark never had a medical problem until the day he dragged for ticks in the town of Fayetteville, a suburb south of Atlanta. 

Clark was giving a talk on Lyme disease at a gathering of the Dougherty County Medical Society in Albany, Ga., where he met Fayetteville resident Liz Schmitz, president of the Georgia Lyme Disease Association. When he heard how many people from Schmitz’s town had been sickened after tick bites, he agreed to come up and investigate. 

As Clark dragged for ticks with a white flannel cloth on a pole, hungry, aggressive lone star females with their distinctive white spots seemed to burst out. In less than an hour, he had collected hundreds of adults and younger nymphs. He remembers one practically leaping from the cloth onto his finger. And that, Clark guesses, is when a lone star tick nestled in his hair. When Clark found it several days later, it had already deposited its bacterial load into his body.

Since that day almost three years ago, Clark has been suffering from what he describes as intermittent pounding headaches, fatigue, odd twitches and “fuzziness.” He reports that weeks-long courses of antibiotics make him feel better, but when he goes off the drugs, the symptoms return. 

Clark is not alone. Other people from suburban communities around Georgia — and many other areas of the Southeast — report getting sick from what seems like tick-borne illness, too. 

A man in his 50s from Fayette County who prefers not to use his name developed severe neurological symptoms after a tick bite. Initially his right foot dragged, and he couldn’t use his right arm at all. He was diagnosed with the lethal neurodegenerative disease ALS (for amyotrophic lateral sclerosis, also known as Lou Gehrig’s disease.) ALS gradually kills off motor neurons, causing progressive paralysis. It initially leaves patients weakened, then in a wheelchair, and then, within a few years, unable to eat or breathe.

The last specialist sent him home to die. But after talking with Schmitz, the man sent Clark samples of his blood. Using polymerase chain reaction (PCR) testing to analyze fragments of foreign DNA in the man’s blood, Clark found evidence of Borrelia burgdorferi, the pathogen that causes Lyme disease. Now on antibiotics, the Fayette County man says he feels better than he has in years, and the rapid downward trajectory common to almost all ALS patients seems to have stalled. 

Clark also tested his own blood, where he found traces of B. burgdorferi along with another distinct genospecies (a bacterial species separated by divergence of genes), Borrelia andersonii, usually found in rabbits.

There is just one problem with this story: Many Lyme researchers, including some from the National Institutes of Health (NIH) and the Centers for Disease Control and Prevention (CDC), won’t believe a word of it. There is little or no true Lyme disease anywhere in the South, say these experts.

They cite plenty of evidence: In the Northeast, where Lyme is endemic, the disease is spread by nymphs (the tick’s juvenile form) of Ixodes scapularis, commonly known as blacklegged ticks. Blacklegged nymphs rarely bite humans down South, though researchers don’t agree as to why not. Adult blacklegged ticks do bite people, but because of their large size, they’re often noticed and picked off before they spread disease.

So if there is Lyme — or Lyme-like illness — in the South, what could be spreading it? The aggressive lone star tick, Amblyomma americanum, which frequently bites people as well as other animals, is a prime suspect. In the early 1990s, researchers realized its bite could cause a roundish, gradually spreading mottled red rash that was a virtual ringer for the erythema migrans (EM) rash, the classic signature of Lyme disease in the Northeast. 

But since few Lyme experts believe that the lone star can harbor and transmit Lyme Borrelia, the rash the tick leaves upon biting is never attributed to Lyme disease. Instead, in the South, the illness is called STARI, for Southern Tick-Associated Rash Illness. According to microbiologist Barbara Johnson, one of the top Lyme disease experts at the CDC’s Division of Vector-Borne Diseases in Fort Collins, Colo., STARI is relatively benign, presenting only with the rash and flulike symptoms of early Lyme. Its cause remains unknown. 

And this is where the CDC and researchers like Clark and his colleagues part ways: Clark recognizes that Lyme disease transmitted by blacklegged ticks is relatively infrequent in the South. But he believes that lone star ticks can transmit a similar spiral-shaped bacterium or spirochete to the one that causes Lyme disease. 

Other scientists disagree. While strains of Borrelia burgdorferi can be found in the South, says Jean Tsao, a Lyme researcher from Michigan State University, there is no bridge between the natural and the human world. Instead, the disease cycles are “cryptic,” meaning the spirochetes cycle quietly among ticks and animal hosts but have virtually no effect on human health. 

Getting to the truth here is critical — especially to the thousands of patients who believe they suffer from some form of Lyme disease acquired in the South. The confusion starts with the numbers. No one has any clear idea how many STARI cases exist because, unlike Lyme in the North, they are not reportable to state departments of health. 

Gary Wormser, an infectious diseases physician at New York Medical College and a recognized Lyme researcher, says STARI is “pretty widespread in the Southeast and south central part of the country.” Yet, Adriana Marques, chief of clinical infectious diseases at NIH, launched a study of STARI in 2002, and enrolled only three suspected patients over 10 years. 

But Marcia Herman-Giddens, scientific adviser for the Tick-Borne Infections Council of North Carolina, a research and advocacy organization, says she can’t believe anyone actively looking for STARI patients would come up with just three of them in a decade. Patients with Lyme or Lyme-like illness in the South likely number in the thousands, she says. 

The dispute leaves Southern patients who insist they have Lyme disease — or something much like it — angry and adrift. Because few doctors recognize their illness, they say, they are treated too late or not at all, and are allowed to slide into chronic illness as debilitating as untreated Lyme disease in the North.

Ixodes scapularisLarvaSize:Bite:phs are recognized as transmitters of anaplasmosis, babesiosis, Lyme disease and Powassan virus in the northern half of Ixodes scapularis' range. Larvae acquire pathogens after feasting on infected white-footed mice. Infected larvae release from the mice and grow into adolescent nymphs.

Ixodes scapularisNymphSize:Bite:t common vector for Lyme disease in the Northeast. In the South, they are generally buried too deep in leaf litter – to avoid the heat – to get at human hosts. The nymphs quest, or move to the tips of long grass and brush to wait for their next blood meal to wander by: a dog, a deer, or that accidental human host. Risk of human infection is greatest in late spring and summer, in the northeast, as nymphs become adults.

Ixodes scapularisAdult MaleSize:Bite: both female and male ticks have been known to bite people in the fall, winter and spring, when things cool off, but the CDC considers Ixodes scapularis an unlikely vector of disease in the South.

Ixodes scapularisAdult FemaleSize:Bite:larger mammals and occasionally bite humans, but are big enough that they are usually noticed before they get the chance to spread disease. Adult blacklegged ticks feed and mate on the ears and hide of deer, laying eggs that drop to the forest floor in late spring.

Amblyomma americanumLarvaSize:Bite:r can bite humans and pets during all three life stages – larva, nymph and adult. Lone star larvae emerge in mid-June and July. It may take up to three years for a lone star tick to complete its life cycle.

Amblyomma americanumNymphSize:arvae and nymphs feed on birds and deer, even lizards and have been known to transmit STARI, ehrlichiosis, tularemia, and other Lyme-like diseases, but the CDC does not recognize the lone star as a transmitter of true Lyme.

Amblyomma americanumAdult MaleSize:Bite:ales frequently bite people and animals, causing a bull's eye, or erythema migrans, rash, and both nymphal and adult ticks are associated with the transmission of pathogens to humans. Males die after mating

Amblyomma americanumAdult FemaleSize: < 3/16"Bite: Notoriously aggressive, lone star ticks – adults and nymphs -- can bite people all year round in the South. A. americanum is the prime suspect for tick-borne illness in that region. Females lay eggs in leaf litter on the ground in late spring and early summer, and then die.Legends of the North

That Lyme disease was first thought confined to the northeastern United States may be historical accident. Almost 50 years ago Polly Murray, an artist and mother from Lyme, Conn., noticed a strange increase of juvenile arthritis, a rare and sometimes disabling condition, among children living within a few blocks of her house. By 1975, she had launched a campaign to force doctors and scientists to figure out why so many in her town had swollen knees and elbows, persistent fatigue, difficulty concentrating, headaches and rashes, among a host of other symptoms.

Although Lyme disease, under other names, had already been described in Europe for a century, many public health experts initially thought the condition in Connecticut was unique. The CDC dispatched a rheumatologist to investigate the mysterious outbreak. That investigator, Allen Steere of Yale, initially described a largely rheumatologic syndrome notable for swollen knees and rash. While Steere later included meticulous descriptions of neurologic and cardiac manifestations of Lyme in his reports, the view of American Lyme disease — unlike European Lyme disease — as essentially rheumatologic persisted for years.

Another line of research dovetailed with Steere’s work, locking Lyme disease into place as a phenomenon of the Northeast. That work was conducted by Harvard entomologist Andrew Spielman, who had spent years studying the malaria-like parasite, Babesia, on Nantucket island off Cape Cod. By 1979, Spielman had identified Babesia’stick vector, Ixodes dammini, as a creature new to science.

I. dammini lived only in the North, and only I. dammini could be Babesia’s vector, Spielman said. When NIH entomologist Willy Burgdorfer discovered the Lyme spirochete inside what he identified as I. scapularis ticks from Fire Island, N.Y., in 1981, Spielman immediately claimed that those infected ticks weren’t scapularis, butdammini as well. The ticks’ limited range — the Northeast and the Midwest — restricted Lyme’s range too, and the casebook on Southern Lyme slammed shut. 

Spielman’s triumphant discovery was short-lived: Ixodes dammini was torpedoed at the hands of Spielman’s close friend, the Georgia entomologist and tick expert James H. Oliver. Ensconced at Georgia Southern University in Statesboro, Oliver was thinking hard about Spielman’s dammini tick, its identification and its distribution. Today a tall, courtly Southern gentleman with high cheekbones and a delicate frame, Oliver is known for building the National Tick Museum, perhaps the most extensive tick collection and library in the world. 

“When I started working in this area, I was told, point blank, Lyme disease was not in the South, and human Lyme disease could not occur — there were no ticks and no germs,” he recalls. But he was not convinced that the blacklegged ticks in the North and South differed much — or that Spielman’s discovery represented a separate species at all.

In a series of experiments from 1989-1990, Oliver demonstrated that so-called Northern deer ticks (dammini) and the blacklegged ticks (scapularis) found up and down the East Coast bit exactly the same animals in the lab. In 1992, he showed that even ticks from widely separated areas like Georgia and Massachusetts were genetically too similar to be different species. And breeding ticks from the North and South in the lab, Oliver demonstrated that a series of matings produced reliably fertile offspring — a crucial test of species boundaries.

Oliver’s definitive experiments blew up the idea that dammini was a new or separate species. The name dammini was dropped from the scientific literature. But Spielman’s framework — restricting Lyme to the Northern ticks — remained intact. 

The notion that the ticks in the North and the South were fundamentally different still lies at the heart of the controversy over Southern Lyme. Oliver attributed most of those differences to Southern heat: To avoid it,scapularis nymphs hide out under leaf litter, biting lizards and small mammals instead of questing for larger prey on tall grass or brush. 

Lyme researcher Gary Wormser saw the difference as more basic: “There’s no doubt that something somewhat like the deer tick exists in the South; it’s called the same name — Ixodes scapularis. But it has some differences in biological behavior and has a low infection rate with Borrelia burgdorferi.” What did it matter if the tick species were the same, if scapularis nymphs didn’t bite people in the South?

Exceptions to Spielman’s geographic rule ultimately emerged. By 1985, medical entomologist Robert Lane of the University of California in Berkeley demonstrated that B. burgdorferi was also carried by a West Coast tick named Ixodes pacificus. 

And in 1998, Mercer University entomologist Alan Smith learned for himself that while reclusive blacklegged nymphs might not often infect humans in the South, adults did. Bitten by an adult tick in the Piedmont National Wildlife Refuge, a forested area south of Atlanta, Smith developed an EM rash, which he regarded with aplomb despite a low-grade fever and flulike symptoms. His physician initially wanted to treat him with antibiotics. “Oh, no, that’s not necessary,” Smith told his doctor. “The CDC says there’s no Lyme in Georgia.”

Within months, he was nearly crippled. His wife dragged him back to the doctor, and he went on antibiotics. He improved immediately. “There’s definitely Lyme in Georgia,” he says now with a laugh. “It’s a lot of crap that blacklegged ticks don’t ever bite people in the South.”

Unlike heat-fleeing nymphs, scapularis adults do bite, but they’re easy to see and remove. If there really are thousands of cases of Lyme in the South, both Clark and Oliver say something else must be transmitting it: Amblyomma americanum, the lone star tick. And it is on the back of this fierce, ubiquitous, rapidly spreading tick that much of the mystery of Southern Lyme-like illness rests.

 

The entire link with images can be found at:  http://discovermagazine.com/2013/dec/14-southern-gothic