Prospective study on the incidence of infection by Borrelia burgdorferi sensu lato after a tick bite in a highly endemic area of Switzerland.
Huegli D, Moret J, Rais O, Moosmann Y, Erard P, Malinverni R, Gern L.
Institut de Biologie, Laboratoire d'Eco-Epid�miologie, Universit� de Neuch�tel, 2000 Neuch�tel, Switzerland.
The periurban forest of Neuch�tel (Switzerland) is a high-risk area for Lyme Borreliosis, due to a high density of infected Ixodes ricinus ticks. In this study, we evaluated the risk of subclinical (seroconversion) and clinical infection after a tick bite in Neuch�tel inhabitants from 2003 to 2005.
Inhabitants have been invited, through media, to visit a physician after a tick bite.
A questionnaire was filled out and two blood samples were taken at 8-week interval. EIA screening tests for IgM and IgG (IMX system, Abbott) were applied for paired sera.
In case of a change in antibody titres between both samples, a homemade Western-blot using Borrelia afzelii, B. burgdorferi sensu stricto and B. garinii as antigens was performed.
Participants were included into two groups.
Group one included asymptomatic participants (n=255). Among them, nine (3.5%) seroconverted with seroconversion rates varying between 6.8% in 2003, 2.1% in 2004 and 2.3% in 2005.
Participants who developed clinical symptoms of LB were included into group two (n=14).
Erythema migrans (EM) was reported in 5.2% of participants (5.2%), varying between 7.5% in 2003, 5% in 2004 and 3.4% in 2005.
Ticks obtained from 186 participants were examined for B. burgdorferi infection by PCR/Reverse Line Blotting, and by Real Time PCR and tick attachment duration was estimated.
Among I. ricinus ticks collected from participants, 32.8% were infected by B. burgdorferi sensu lato. B. afzelii predominated among these ticks.
Globally, 65.9% of nymphs remained attached for more than 24h whereas only 38.3% of female ticks remained attached for more than 24h.
We observed that 6.6% and 2.4% of participants bitten by infected and uninfected ticks, respectively, developed EM.
Posted by hammond (Member # 32303) on :
Ha ha! 6.6% and 2.4% is waaay low! I 've always wondered about the rash "statistics" that are trotted around. I got Lyme just a fifteen minute drive from Lyme CT and never got a rash! I was WB positive from the get go. And of course I 'm not the only one.
I suppose Dr. Baker and the rest will simply say different "strain" of Bb, won't they? Thanks Tincup!
Posted by James1979 (Member # 31926) on :
Another messed up thing is that when they recommend that we take the IDSA prophylactic of a single dose of 200mg doxycycline, we have an 80% chance less of developing the rash, but it doesn't lower our chances of getting the disease! So basically their prophylaxis gives us more of a chance to go undiagnosed.
![[lol]](graemlins/lol.gif)