Co-infections are downplayed by Steere et al.
Here is a response from Stricker et el. RE: co-infections:Coinfection in Patients with Lyme Disease: How Big a Risk?
Raphael B. Stricker,1 Andrea Gaito,3 Nick S. Harris,2 and Joseph J. Burrascano4
1Department of Medicine, California Pacific Medical Center, San Francisco, and 2IGeneX Laboratory, Palo Alto, California; 3Division of Rheumatology, Morristown Memorial Hospital, Morristown, New Jersey; and 4East End Medical Associates, East Hampton, New York
Reprints or correspondence: Dr. Raphael B. Stricker, California Pacific Medical Center, 450 Sutter St., Ste. 1504, San Francisco, CA 94108 ([email protected]).
SIR--In their study of coinfections in patients with Lyme disease, Steere et al. [1] found a 4% rate of coinfection with Babesia microti or Anaplasma phagocytophila in patients with an erythema migrans rash that was culture-positive for Borrelia burgdorferi. This coinfection rate was significantly lower than the average rate (21%) reported in other studies cited by Steere et al. [1], and the authors explain the discrepancy by alluding to "methodology" as a principal factor. Their explanation is probably correct, but not in a positive sense.
In studying only patients with an erythema migrans rash, the authors excluded perhaps ⩾40% of patients with Lyme disease who do not develop this rash [2, 3]. In fact, the same investigators previously reported a 26% rate of coinfection with B. microti or A. phagocytophila in patients with rashless Lyme disease [3]. Furthermore, Steere et al. [1] excluded 19% of patients with erythema migrans rashes that were culture-negative for B. burgdorferi. Because patients with Lyme disease do not always have positive skin culture results using current techniques [4-6], this patient group should have been included in the analysis.
A bigger problem with the study concerns the timing of serologic testing for coinfections. This testing was only performed at the time of erythema migrans appearance and then again after 3 weeks of antibiotic therapy. Serologic testing in this manner probably occurred too early or too late to detect an antibody response to the coinfecting agents [6]. Finally, it appears that PCR testing was only performed for patients who were seropositive for B. microti or A. phagocytophila. Because of the possibility of false-negative results of serologic testing , as described above, all patients should have been tested by PCR at repeated intervals to screen for coinfections. Thus, the low coinfection rate may have been due to methodological flaws in the study.
The results presented by Steere et al. [1] give a false impression that coinfections are rare in patients with Lyme disease, and this erroneous assumption may persuade health care providers to ignore persistent symptoms of polymicrobial infection in these patients. Coinfection with B. microti or A. phagocytophila in a mouse model of Lyme disease is associated with an altered immune response and exacerbation of symptoms of disease [7, 8]. Furthermore, newer coinfecting agents need to be considered in cases of Lyme disease, including the Babesia species WA-1 strain and Bartonella henselae [9, 10]. A recent study from California found a serologic prevalence of 23.5% for Babesia WA-1 in patients with Lyme disease in that state [9]. The true risk of polymicrobial infection in patients with Lyme disease requires better evaluation with more thorough serologic and molecular testing for known and emerging tickborne coinfections.
References
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2. Harvey WT, Salvato P. "Lyme disease": ancient engine of an unrecognized borreliosis pandemic? Med Hypotheses 2003; 60:742-59. First citation in article | PubMed
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9. Stricker RB, Harris NS, Yong DC, Winger EE. Clinical and seroepidemiologic characteristics of Babesia WA-1 coinfection in patients with Lyme disease in California [abstract 309]. J Invest Med 2003; 51(Suppl 1):S145. First citation in article
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