Lyme borreliosis incidence in two French departments: correlation with infection of Ixodes ricinus ticks by Borrelia burgdorferi sensu lato.
We conducted a prospective study to estimate the Lyme borreliosis incidence in two rural French departments, Meuse and Puy-de-Dôme. Concurrently, we investigated the prevalence of ticks infected with Borrelia burgdorferi sensu lato (sl) and Anaplasma phagocytophilum. The incidence of Lyme borreliosis decreased from 156 to 109/100,000 inhabitants in Meuse and from 117 to 76/100,000 inhabitants in Puy-de-Dôme in 2004 and 2005, respectively, corresponding to a decrease in the density of Ixodes ricinus nymphs infected with B. burgdorferi sl. During the same period, the density of adult ticks increased. Interestingly, B. valaisiana, a nonpathogenic species, infected adult ticks more often than nymphs. These results confirmed the correlation between the Lyme borreliosis incidence and the density of infected nymphs, a stage preferentially infected with B. afzelii. In contrast, we found a low rate of infection by A. phagocytophilum, ranging from 0% to 0.4% in Puy-de-Dôme and from 0.8% to 1.4% in Meuse, suggesting a low risk for humans.
Beytout
J
J
Department of Infectious Diseases, Clermont Ferrand, France.
George
J C
JC
Malaval
J
J
Garnier
M
M
Beytout
M
M
Baranton
G
G
Ferquel
E
E
Postic
D
D
D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D041081:Anaplasma phagocytophilum / Q000302:isolation & purification / Q000502:physiology; D000818:Animals; D025065:Borrelia burgdorferi / Q000302:isolation & purification / Q000502:physiology*; D005260:Female; D005602:France / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D018884:Ixodes / Q000382:microbiology*; D008193:Lyme Disease / Q000453:epidemiology* / Q000382:microbiology*; D008297:Male; D008875:Middle Aged; D009758:Nymph / Q000382:microbiology; D011156:Population Density; D011446:Prospective Studies; D017678:Sex Distribution