Chronic Bacterial and Viral Infections in Neurodegenerative and Neurobehavioral Diseases

Garth L. Nicolson, PhD

Disclosures

Lab Med. 2008;39(5):291-299. 

In This Article

Lyme Disease

Lyme disease (LD) is the most common tick-borne disease in North America. It is caused by a tick bite and the entry of the spiral-shaped spriochete B. burgdorferi and other coinfections.[152] After incubation for a few days to a month, the Borrelia spriochete and coinfections migrate through the subcutaneous tissues into the lymph and blood where they can travel to near and distant host sites.[153] Transplacental transmission of B. burgdorferi and coinfections can occur in pregnant animals, including humans, and blood-borne transmission to humans by blood transfusion is likely but unproven. The tick-borne LD coinfections can and usually do appear clinically at the same time.[154]

Since the signs and symptoms of LD overlap with other chronic conditions, LD patients are often diagnosed with other illnesses, such as CFS or chronic arthritis.[150,151,153] About one-third of LD cases start with the appearance of a round, red, bulls-eye skin rash (erythema migrans) at the site of the tick bite, usually within 3 to 30 days.[154] Within days to weeks, mild flu-like symptoms can occur that include shaking chills, intermittent fevers, and local lymph-node swelling. After this localized phase, which can last weeks to months, the infection(s) can spread to other sites (disseminated disease), and patients then show malaise, fatigue, fever and chills, headaches, stiff neck, facial nerve palsies (Bell's palsy), and muscle and joint pain and other signs and symptoms.[154]

Lyme disease can eventually become persistent or chronic and involve the CNS and peripheral nervous system as well as ophthalmic, cardiac, musculoskeletal, and internal organ invasion. At this late chronic stage, arthritis, neurological impairment with memory and cognitive loss, cardiac problems (mycocarditis, endocarditis causing palpitations, pain, bradycardia, etc), and severe chronic fatigue are often apparent.[154,155] The signs and symptoms of the late chronic phase of the disease usually overlap with other chronic conditions, such as CFS, chronic arthritis, among others, as well as neurodegenerative diseases, such as AD, PD, ALS, etc, causing confusion in the diagnosis and treatment of the chronic phase in LD patients.[29,30,88,89,90,141,156,157,158] These late stage neuroborreliosis patients exhibit neuropathologic and neuropsychiatric disease similar to the neurodegenerative diseases discussed above.[31,89,128,156,157,158,159]

The involvement of coinfections in LD has not been carefully investigated; however, such infections on their own have been shown to often produce comparable signs and symptoms. Diagnostic laboratory testing for LD at various clinical stages is, unfortunately, not foolproof, and experts often use a checklist of signs and symptoms and potential exposures, along with multiple laboratory tests, to diagnose LD.[156]

Coinfections are common in LD, and we[148,155] and others[160] have found that the most common coinfection found with B. burgdorferi are various species of Mycoplasma, usually M. fermentans. In some cases, multiple mycoplasmal infections are present in LD patients.[148] Other common LD coinfections include: Ehrlichia species, Bartonella species, and Babesia species, and 10% to 40% of cases of LD show such coinfections.[148,149,150]Ehrlichia and Bartonella species are usually found along with Mycoplasma species in LD.[155,161,162,163,164,165,166,167,168,169,170,171,172,173,174,175,176,177,178,179,180,181,182,183]Bartonella species, such as B. henselae, which also causes cat-scratch disease,1[64] are often found in neurological cases of Lyme disease.[154,164] In addition, protozoan coinfections have been found with B. burgdorferi, such as intracellular Babesia species.[165] The combination of Borrelia, Mycoplasma, and Babesia infections can be lethal in some patients, and approximately 7% of patients can have disseminated intravascular coagulation, acute respiratory distress syndrome, and heart failure.[165]

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