Friday, June 12, 2015

Changes in antibody reactivity to Bb three months after a tick

Mon Jun 8, 2015 4:38 pm (PDT) . Posted by: 

"Rick Laferriere" ri_lymeinfo 

*Changes in antibody reactivity to /Borrelia burgdorferi/ 
three months after a tick bite. A cohort of 1,886 persons. *
Dessau RB, Fryland L, Wilhelmsson P, Ekerfelt C, Nyman D, 
Forsberg P, Lindgren PE
Clinical and Vaccine Immunology, pii: CVI.00026-15. Online 
first, 2015 May 20. 


Lyme borreliosis is a tick-borne disease caused by the 
bacterium Borrelia burgdorferi. The most frequent clinical 
manifestation is a rash called erythema migrans. Changes in 
antibody reactivity to B. burgdorferi three months after a 
tick bite are measured using ELISA assays.

One assay is based on native purified flagella-antigen (IgG) 
and the other assay is based on a recombinant antigen called 
C6 (IgG or IgM). Paired samples were taken at the time of a 
tick bite and three months later from 1,886 persons in 
Sweden and the Åland Islands. The seroconversion or relative 
change is defined as the measurement units from the second 
sample divided by the first sample. Thresholds for the 
minimum level of significant change were defined as the 2.5% 
percentile to represent the random error level. The 
thresholds were 2.7 fold rises for the flagella IgG and 1.8 
fold rises for the C6 assays.

102/101 (5.4%) of 1,886 persons had a significant rise in 
antibody reactivity in the flagella or C6 assay. Among 40 
cases with a diagnosis of Lyme borreliosis the sensitivity 
of a rise in antibodies was 33% and 50% to the flagella 
antigen and the C6 antigen respectively. Graphical methods 
to display the antibody response and methods to choose 
thresholds for a rise in relative antibody reactivity are 
shown and discussed.

In conclusion, 5.4% of people with tick bites developed a 
rise in borrelia-specific antibodies above the 2.5% 
percentile in either ELISA assay, but only 40 (2.1%) 
developed clinical Lyme borreliosis.

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