Reuters Health
Because Lyme disease is difficult to diagnose in the absence of the characteristic "bull's eye rash," the illness can become entrenched and difficult to treat.
In such cases, symptoms such as memory loss, irritability and fatigue, may predominate, according to a study presented at the sixth annual Lyme Conference in Philadelphia.
"No one was studying chronic Lyme disease, yet a growing number of patients were suffering with chronic persistent symptoms even after antibiotic treatment," lead investigator Dr. Brian Fallon, from Columbia University in New York, told Reuters Health.
For their study, sponsored by the National Institute of Neurology and Stroke, Fallon's group recruited 37 patients who met strict conditions for having chronic Lyme disease. The team conducted brain-imaging studies and assessed the participants' response to re-treatment.
"Based on objective tests of physical impairment, we found that the patients had levels of functional disability comparable to what you would see with congestive heart failure, as well as pain comparable to what you might expect in patients coming out of surgery, and fatigue comparable to patients with multiple sclerosis," Fallon said.
Moreover, brain-imaging studies showed "that there are widespread deficits in blood flow and metabolism in patients compared to age- and education-matched controls."
"From a strictly objective stance these patients are quite impaired," Fallon maintained. "Chronic Lyme disease clearly exists and represents a major public health problem."
The researcher said that once chronic Lyme disease patients have been treated with a 3-week course of antibiotics, they are often told that any remaining symptoms are of a psychiatric nature.
"So patients are not only are experiencing a disease causing significant disability and pain, they are also experiencing invalidation of their illness by being told they are making it up, that 'it's all in their head'," he said.
One problem is that many of the initial tests for the disease are inadequate, so negative results should be followed by more sophisticated tests. On average, it takes 1.2 years for the correct diagnosis of chronic Lyme disease to be made.
"The reason is that certain patients do not present with classic signs of Lyme disease, such as rash or joint swelling. They might instead present with a chronic fatigue syndrome-like picture or gradual increasing verbal fluency problems or memory problems, or personality change with irritability."
Fallon noted that retreatment with antibiotics can help, but "unfortunately for many patients it's not the final answer, because some will get better and then relapse again months later."
"Perhaps 30 percent of patients will need to be given additional course of antibiotics," he added. However, "the optimal duration and extent of treatment has not yet been fully delineated."