Thursday, July 26, 2007

MARYLAND NEWS: Increase in Lyme Disease

Kelly Strzelecki has a new reason to avoid ticks -- not that she needed one. "I hate them -- who doesn't?" she asked, prefacing her latest experience with the tiny bloodsuckers.

Her son, Graham, 7, developed a rash last month while the Catonsville family was attending a YMCA camp in tick-infested woods. A week later, the boy fell ill. "He had these unexplained fevers, and he was lethargic and kind of pale," recalled Strzelecki.

Medical tests showed Graham had contracted Lyme disease, a tick-borne infection that's notoriously difficult to spot and well-entrenched in the forests of Maryland and neighboring states.

Confirmed Lyme disease cases have grown steadily over the past decade in the United States. In Maryland, the number of reported cases more than doubled between 2001 and 2006 from 608 cases to 1,248, according to the Maryland Department of Health and Mental Hygiene.

As of July 14, the Centers for Disease Control and Prevention had received 675 unconfirmed reports in Maryland this year, a 26 percent increase over the same period last year.

Public health officials said the number of Lyme disease infections is probably on the rise, but cautioned that growing public awareness of the disease might also be responsible for more diagnoses.

Epidemiologists first recorded Lyme disease as a discrete illness in the United States in the mid-1970s, after a number of children in Lyme, Conn., developed joint pain and circular red rashes. Scientists identified Borrelia burgdorferi, the spiral-shaped bacteria that cause the disease, in 1983.

The bacteria are carried by tiny, black-legged ticks that are no larger than a sesame seed. Also known as deer ticks, they feed on deer, mice and other mammals, then pass the Lyme-causing bacteria to humans and domesticated animals. The ticks are particularly common in wooded areas with dense brush, tall grass and heavy leaf litter.

Most people contract the infection in May, June and July, but symptoms often appear in late summer and early fall.

Dr. Charles A. Haile, chief of infectious disease at Greater Baltimore Medical Center, said family doctors have become more comfortable diagnosing and treating Lyme disease in recent years.

In fact, he might not notice a rise in infections, he said, because general practitioners now refer fewer patients to specialists like him. "The expertise in diagnosing Lyme has grown a lot in Maryland over the past 10 years," he said.

The actual number of people contracting the disease may be on the rise as well. One possible reason, experts say, is the increasingly frequent collision between deer and mouse populations and suburban sprawl.

The five Maryland jurisdictions with the most reported Lyme cases are home to large suburban populations: Carroll, Anne Arundel, Frederick, Howard and Harford counties. Cecil County, which has one of the highest per capita rates of infection, is also one of the fastest-growing regions in Maryland.

"We continue to create the environment for the transmission of this disease," said John Krick, director of epidemiology and disease control programs at DHMH. "We build houses on newly cleared land, putting ourselves closer to the forest and wild animals."

While the deer population has fluctuated in recent years, the Maryland Department of Natural Resources estimates that there are about 240,000 white-tailed deer in Maryland, the same number as a decade ago. [Rooney: yes, but deer populations are increasing in the most populated areas and people are increasing in high deer density areas. The state level is the wrong level of analysis here].

Douglas Hotton, leader of DNR's deer management program, said deer numbers may have little to do with the spread of Lyme disease. In fact, he suggested that the very name "deer tick" is misleading. "It ought to really be called the 'mouse tick,'" he said, since the white-footed mouse is the main host for the Lyme-causing bacteria.

Hotton said only a few deer are required to sustain a large number of ticks, and that fluctuations in the population appear to have little effect on the incidence of Lyme disease. Water, which ticks require to thrive, may play a larger role in sustaining a tick population than the sheer number of deer and mice.

Efforts to reduce tick populations in neighborhoods with insecticides are effective, but difficult to implement statewide, Hotton said.

One device scientists have tried applies tick killer to a deer's neck when it sticks its head into a man-made feeder. Another method involves cardboard tubes stuffed with insecticide-soaked cotton balls. Mice use the cotton as nesting material and in the process coat their fur with the tick killer.

Removing brush and leaf litter around homes and edging yards and sports fields with buffer zones of gravel or wood chips can also reduce tick populations, according to the CDC.

Source (and full story):,0,1247.story

No comments: